4

TH

International Conference

High Tech Die Casting 2008 9-10 April 2008 Montichiari (Brescia, Italy)

Organized by

Light Metals Study Group of Associazione Italiana di Metallurgia

in cooperation with

with the support of

Amafond

Assofond

Assomet



scientific committee Diran Apelian · WPI, USA Lars Arnberg · NTNU, University of Trondheim, Norway Franco Bonollo · DTG, Università di Padova, Italy Lorella Ceschini · Università di Bologna, Italy Mario Conserva · Edimet, Italy Enrico Evangelista · Università Politecnica delle Marche, Ancona, Italy Gian Luca Garagnani · Università di Ferrara, Italy Elisabetta Gariboldi · Politecnico di Milano, Italy Michael Gasik · Helsinki University of Technology, Finland Javier Goñi · INASMET, Spain John Jorstad · JLJ Technologies, USA Lothar Kallien · University of Aalen, Germany Plato Kapranos · The University of Sheffield, UK Wilfried Kurz · Swiss Federal Institute of Technology, Switzerland Asbjorn Mo · SINTEF, Norway Roberto Molina · Teksid Aluminum, Italy Bernardo Molinas · Venezia Tecnologie, Italy Claudio Mus · AIM, Italy Michel Rappaz · Swiss Federal Institute of Technology, Switzerland Farhad Rézaï-Aria · Ecole des Mines d’Albi Carmaux, France Roberto Roberti · Università degli Studi di Brescia, Italy Didier Rollez · Umicore Zinc Alloying, Belgium Mario Rosso · Politecnico di Torino, Italy Ingvar L. Svensson · School of Engineering, Joenkoeping University, Sweden Alberto Tiziani · DTG, Università di Padova, Italy Maurizio Vedani · Politecnico di Milano, Italy

organising committee Federica Bassani · Associazione Italiana di Metallurgia, Italy Franco Bonollo · DTG, Università di Padova, Italy Fabio Grosselle · DTG, Università di Padova, Italy Giulio Timelli · DTG, Università di Padova, Italy Stefano Zanolini · Edimet, Italy

scope







Started in 2002, the International Conference High Tech Die Casting (HTDC) has become, during the years, one of the primary events in the field of light alloys foundry. In 2008, the fourth edition of HTDC will be kept once again in Montichiari (Brescia, Italy) with the aim of covering all the topics related to die casting (gravity, low and high pressure) of Aluminium-, Magnesium-, Copper- and Zinc-based alloys. The Scientific Committee has succeeded in setting up an exhaustive Conference, with about 50 papers, offering an overview of all the scientific and technological innovations in the international scenario of Die Casting, which is continuously growing its industrial relevance. Papers and contributions, from a very qualified panel of experts, both academic and industrial, will cover the key-issues of the actual and future opportunities of  die casting processes, including - Alloys and related treatments, - Tooling and Equipments, - Exploitation by process evolution, - Metallurgical and mechanical challenges, - Design and applications of diecast components



H  TDC 2008 is organised by the Associazione Italiana di Metallurgia (AIM) and will be hosted by METEF, the main international exhibition on light alloys technologies.



We are looking forward to welcoming you in Italy!

Programme

Wednesday, 9th April 2008 – ITALIA ROOM

10.00/ 13.00 Registration 11.00 Foundry Roadmap forum: Foundry prospectives in emerging countries Event organised by METEF AIDA ROOM 14.00

Welcome addresses by: Prof. Walter Nicodemi, AIM President Prof. Franco Bonollo, AIM Light Metals Study Group President Dr. Mario Conserva, Edimet CEO Dr. Amedeo Alti, Assiral

SESSION alloys and related treatments Chairmen: F. Bonollo, L. Arnberg 14.10 Castability measures for diecasting alloys: fluidity, hot tearing, and die soldering B. Dewhirst, S. Li, P. Hogan, D. Apelian - Metal Processing Institute WPI, Worcester, USA

T autologically, castability is a critical requirement in any casting process. Traditionally, castability in sand and permanent mold applications is thought to depend heavily on fluidity and hot tearing. Given capital investments in dies, die soldering is a critical parameter to consider for diecasting. We discuss quantitative and robust methods to insure repeatable metals casting for diecasting applications by investigating these three areas. Weight reduction initiatives call for progressively thinner sections, which in turn are dependent on reliable fluidity. Quantitative investigation of hot tearing is revealing how stress develops and yields as alloys solidify, and this has implications on part distortion even when pressure-casting methodologies preclude hot tearing failures. Understanding the underlying mechanism of die soldering presents opportunities to develop methods to avoid costly downtime and extend die life. Through an understanding of castability parameters, greater control over the diecasting process can be achieved.

14.35 A new cost effective alternative for the rotary degassing of aluminium alloys M. Gittus, D. Whincup, A. Wynn - Morgan Molten Metal Systems, Worcester, UK

A new one piece degassing rotor, incorporating innovative SiC/Graphite material technology, and a purpose designed rotor head, has been specifically developed to provide foundries with

a more cost effective solution to the rotary degassing of aluminium alloys. This new rotor has been demonstrated to provide foundries with a real alternative to the industry standard impregnated machined graphite rotors which dominate this application. Material properties critical to the application are presented and compared with impregnated graphite. In service performance results for the new SiC/Graphite degassing rotor are presented, in comparison with a standard machined graphite rotor. At one aluminium foundry the machined graphite rotor lasted for 160 x 10 minute degassing cycles before the efficiency of the gas removal deteriorated due to erosion of the rotor head. Using the new SiC/Graphite degassing rotor, degassing cycles increased beyond 300. The new rotor head design also allowed a reduction in the rotor speed from 470 to 360 rpm with no loss in degassing efficiency and a reduction in nitrogen usage. The new rotor also displayed a more non-wetting surface, making it much easier to keep clean. The erosion of the shaft and rotor was considerably reduced compared to the machined graphite rotor. Further trials at a range of aluminium foundries have confirmed that erosion of the new SiC/Graphite material at the metal line is much slower than with machined graphite rotors and consequently lives of rotors have been typically doubled. This resistance to erosion also means that the rotor profile is maintained for the life of the rotor so there is no loss of degassing efficiency throughout its service life.

14.55 C ombining quality, ecology and economy in the metal treatment of aluminium alloys through the MTS 1500 process R. Simon - Foseco GmbH, Borken, Germany



T oday’s aluminium foundries operate under several needs. Environmental safe technologies are one of the future challenges for all foundries but especially for foundries using chlorine gas or chlorine releasing agents in their process. The MTS 1500 - automated Metal Treatment Station - is a recent development by FOSECO that addresses all the various needs of the foundry and is capable of making a significant contribution to the modern aluminium foundry.The novel design of the patented FDR rotor helps create the optimum vortex for the addition of the treatment products. Regarding the fluxes, a range of new fluxes branded COVERAL MTS has been specifically formulated for use with the MTS 1500. This range includes cleaning/drossing, sodium modifying, and grain refining. An agent for alcali and earth alcali elemet removal from aluminium melts is the latest development enabeling foundries to replace chlorine treatments. The MTS 1500 helps foundries to achieve better environmental performances by the use of fewer consumables (flux and inert gas), less dross produced, reduced emissions as well as shorter treatment times and melt superheat with associated energy savings. Case studies from various foundries illustrate contributions to obtain a healthier and safer environment in combination with economical improvements. A case study describes the replacement of inert gas plus chlorine gas injection by the new MTS 1500 process in a European piston foundry. The melt quality is compared providing spectral analyses results and Prefill curves. The environmental and economical impact is analyzed to show excellent improvements.

15.15 P redicting compositions/properties of aluminum die casting alloys using artificial neural network L. Wang, D. Apelian, M.M. Makhlouf, W. Hwang - Metal Processing Institute WPI, Worcester, USA

D  espite the large number of existing alloys and various alloy databases, identifying proper alloys for specific applications still remains a challenge. To facilitate the selection and prediction of aluminum die casting alloys, an electronic database “i-Select-Al” has been developed by MPI and NADCA. The key to the predictions is the determination of a relationship between alloy properties, alloy chemistry, and process variables. Theoretically, these relationships can be “accurately” determined using fundamental engineering, chemical, or physical principles. However, in practice, the underlying mechanisms of Al die casting alloys are not fully understood and difficult to be utilized. In this case, approximate empirical models must be considered. In version 1.0 of the software trend equations were generated. The nature of these trend equations limits the applicability and predictability of the software. To improve the prediction power of the software, relationships based on artificial neural network (ANN) were exploited in version 2.0 of the program. ANN has proven to be a highly flexible modeling tool, suitable to treat multiple-input conditions and nonlinear phenomena with complex relationships between input and output variables. This article presents ANN working mechanisms; specific considerations for ANN selection, development, and integration; operating principles of the module; comparisons of selected cases with experimental data; boundaries of applicability; and future developments. The results indicate that ANN is a valuable modeling tool for predicting properties-from-composition and composition-from-properties for aluminum die casting alloys.

15.35 P rogress in ductile aluminium high pressure die casting alloys for the automotive industry F. Casarotto, D. Dragulin, R. Klos, R. Franke - Aluminium Rheinfelden GmbH, Rheinfelden, Germany

T oday the die casting process is used to cast parts with high quality requirements such as engine cradles, cross members and nodes for space frame construction. This has presented the challenge to design alloys with superior mechanical properties. For crash relevant parts requiring high ductility (elongation > 12 %) one option to meet these properties is by heat treating a low iron Al-Si alloy to a T4 or T7 temper. However heat treatment can lead to part distortion and blistering resulting in higher costs for the producer. The second option is Al-Mg alloys type which fulfill these requirements in the as-cast state but the alloys are not easy to cast. Research was started using the easy to cast Al-Si alloy system targeting a high elongation (>12 %) and yield-strength (> 120 MPa) already in temper F and not showing any long term aging behavior. This paper will discuss the technical progress which began in the early 1990ies, gaining in importance with the first series space frame Aluminum car, continuing with structural parts applied in the as cast state and approaching a future with an increasing amount of light weight components replacing steel and heat treated Aluminum designs.

15.55 Coffee break

SESSION TOOLING AND EQUIPMENTS

Chairmen: M. Rosso, L. Kallien

16.10 Innovative technology. Release agents G. Natesh - Chem Trend, Howell, USA

T he presentation will describe the new concepts of water base release agents, specifically developed for the High Temperatures.The impact and the influence of high performance release agent in the modern Die casting process will be presented. It will be explained how it is possible to have faster cycle time, less down-time, less scraps, reduce the thermal shock using the new High temperature release agents.

16.30 D  evelopment of the New Hot-work Tool Steel Dominial HP 1 for die casting dies D. Deterding, I. Schruff - Kind & Co, Wiehl-Bielstein, Germany

T oday - more than in earlier years - the life time of die casting dies controls the profitability of the die casting process. Here the thermal fatigue resistance of the hot-work tool steel, which is directly influenced by the steel’s toughness and high-temperature strength, is a very important factor. A few years ago the special hot-work tool steel DOMINIAL TQ 1 had been introduced to the market combining high-temperature strength and high-temperature toughness in a way that had been unique at that time. Characterized by highest cleanliness and lowest concentrations of detrimental trace elements this steel has proved its suitability as a die steel for highest requirements in various die casting applications. As the excellent properties of DOMINIAL TQ 1 depend to a high degree on the alloy element molybdenum, which is exposed to extreme fluctuations of the market price on the stock exchange, it was the intention of Kind & Co to develop a new equivalent hot-work tool steel with a reduced content of the element molybdenum. The report will describe the alloy concept for the new hot work tool steel DOMINIAL HP 1 as well as the steel’s profile of properties and will also describe the results of industrial applications of this steel.

16.50 D  ie-casting; S.D.C. Steel, a continuous metallurgic innovation to meet with the problems F. Piana, A. Grellier - Aubert & Duval, Trezzano S/Naviglio, Italy

The abstract is not available

17.10



Thoughtness of mould, comparison of several testing methods C. Torriani - Siederia Consulting Srl, Torino, Italy E. Aspesi - La Pantastampi Srl, Cassano Maniago, Italy A. Silipigni - TAG Srl, Dolzago, Italy G. Zambardieri - SMT Srl, Pozzo d’Adda, Italy

A mould with min 500Kg critical mass will be provided of several Impact test rough specimen according to the common use and known specifications. the mould will be heat treated according NADCA spec. From the rough specimen and from the mould will be taken off sample for impact test. Trough the comparison we aim to have a key to interpret impact value deriving from specimens. we also aim to determinate if there is a method to carry out resilience of the mould with high significance and low costs of application.

17.30 I .M.S. (Integrated Monitoring System) full integrated programming and diagnostic system improve OEE in modern HPDC production cells R. Boni - Idra Srl, Travagliato, Italy

F oundry’s everyday challenge is related to cost reduction that means, in other words, to better equipment utilization and lower reject rate and get higher OEE (Overall Equipment Efficiency) levels. Fault tracing and repairing action are time consuming activity in a complex production cell with several equipments with indipendent operator interfaces. Idra has developed the Inject Computer II, his last generation of supervision system, that include beside machine setting and complete process control, integration of all peripherals equipments. Metal ladle and die spryer programs can be set in specific dedicated pages like other machine parameters. Other devices connected with profibus while must be programmed on their dedicated programming unit, have specific die setting launched with the HPDC program just recalling one program from Inject Computer II data base. More than 1.350 different alarms are available on I.C II display with a clear description, location of fault component and direction how to fix the problem. Hydraulic as well electronic schemes can be easily recalled on graphic colour display and each alarm message can be enriched with comments and pictures directly by machine’s user creating a multi media customized data base. Beside full comprehensive process control including machine’s parameters and other external values like metal and die temperature, die sprayer air pressure and release agent flow, the I.M.S gives a significant support aimed to down time reduction and boost the skill of foundry people.

17.50 Case studies of innovative diecasting machines A. Benini - Italpresse, Brescia, Italy

T his paper concerns the design and manufacturing of one innovative two-platen diecasting machine, together with the presentation of some case histories about the practical application. In the foundry world the high closing forces necessary to face the molten metal shot into the die cavity, are traditionally obtained through the “Toggle” mechanism with link rods: on the contrary, the two-platen machine closing force is provided by a completely hydrodynamic system. The main advantages coming from this engineering solution are represented by a far better linear relation between the involved physical quantities as well as an inner rigidity of the whole system. Nowadays, thanks to the outstanding technological progress, more and more innovative instruments and devices are available: the finite element (FE) simulations allow reliable complex structural calculations, while on the other side the evolution of electronics develops powerful and consistent instruments. All these elements represent a possible answer to the current request of machines able to meet elevated productive flexibility and repeatability, including a process simplification: a starting point to obtain structurally reliable products which also respond to elevated quality standards.

20.00 CONFERENCE DINNER at Villa Fenaroli Palace Hotel Via Mazzini 14 - Rezzato (Brescia)



Thursday, 10th April 2008 – ITALIA ROOM

SESSIONEXPLOITING DIECASTING BY PROCESS EVOLUTION

Chairmen: R. Roberti, D. Apelian

9.05 New developments in gas injection for high pressure die castings L. Kallien - Aalen University of Applied Sciences, Aalen

H  igh pressure die casting is a process which combines short cycle times and high productivity with the production of highly integrated metal parts of complex shape. Plastic injection molding is a comparable process for the production of plastic parts being similar in many aspects to die casting. Gas injection is a special variation of plastic injection molding allowing the production of hollow structures. The advantages of gas injection are free design of thick and thin walls in one part, local feeding pressure reduces sink marks and distortion and shorter cycle times. This paper discusses new results and achievements which have been gained at Aalen University of Applied Sciences.

9.30 M  etal casting using self-removing moulds produced by selective laser sintering N.K. Tolochko, Y.A. Shienok - Vitebsk State University, Vitebsk, Belarus T. Laoui - University of Wolverhampton, Telford, United Kingdom

I n the present paper, some phenomena related to the behaviour of metal casting processes based on the use of self-removing moulds were discussed. Selective Laser Sintering (SLS) as one of Rapid Prototyping and Manufacturing techniques was applied to fabricate moulds using powders containing quartz sand (average particle size 315 μm) mixed with epoxy-based polymer (25 vol. %) or paraffin (10 vol. %) binder. Moulds in the shape of a cylinder (20 mm in both diameter and height) possessing cavities in the shape of right-angle parallelepipeds (10×10×16 mm3) for casting the metal were made by SLS. Polymer and paraffin binders had melting points of 180°C and 54°C and thermo-induced chemical destruction points of 250°C and 200°C respectively. Various types of metals with different melting points (Tm) were used in the experiments: Rose alloy (Tm = 98°C), Sn-Pb alloy (Tm = 180°C), Zn (Tm = 427°C), and Al (Tm = 660°C). In the course of casting process, the moulds were subjected to breaking-down under the action of high temperature. In particular, the moulds with polymer binder were subjected to chemical destruction while those with paraffin binder were subjected to melting. Experiments showed that after filling the mould cavities with the molten metal, a skin of solidified metal was formed at the melt-mould boundary followed by the crystallization of the remaining liquid metal. As a result, in spite of mould breaking-down due to heat transfer, the metal ingot took the shape of the mould cavity.

9.50 P orosity reduction possibilities in commercial aluminium A380 and magnesium AM60 alloy components using the rheometal [TM] process O. Granath, M. Wessén, H. Cao - Jönköping University, Sweden

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T he Rapid Slurry Forming (RSF) technology, which is a vital part of the RheoMetalTM process, is capable of producing large amounts of metal slurries in short times. Unlike other rheocasting processes the RSF technology is based on an enthalpy exchange between two alloy systems to produce slurry with a certain solid fraction. A commercial component has been produced

from both aluminium A380 (EN AC 46000) and magnesium AM60 alloys by high pressure die casting (HPDC) and RSF rheocasting. The following procedure was used during the RSF rheocasting trials; melt dosing, slurry formation and manual pouring of slurry into the shot sleeve of the high pressure die casting machine. In the HPDC reference trials the automatic equipment of the machine was used for melt dosing. The aim of this paper is to investigate the possibility to reduce porosity, and the related effects on the tensile properties obtained in RSF rheocast components. Significantly reduced porosity content was obtained in the RSF rheocast A380 and AM60 alloy components, as compared to the HPDC components. This was confirmed by X-ray analysis, microstructure analysis, polished component sections and tensile testing. The turbulent filling behaviour in HPDC produces severe amounts of included gas type porosity. It was also found that gas pores were often connected to shrinkage type pores. Polished component sections revealed that a laminar die filling and a fine globular primary phase structured slurry material reduces porosity to large extents, even in poorly designed component regions.

10.10 I nfiltration of Freeze-Casting-Performs by high pressure die casting L. Kallien, T. Weidler - Aalen University of Applied Sciences, Aalen, Germany

T he goal of the research is to infiltrate freeze-casting ceramic preforms using the high pressure die casting process. The Al2O3-Freeze-casting-Preforms have been produced with a lamellar structure using freeze casting technology. A consortium of five Universities in Germany carries out this research project. These preforms have been processed by conventional high pressure die casting at different casting parameters. The resulting structure of the infiltrated composites was studied using 3D x-ray computed tomography with high resolution. No porosity and microcracks could be found within the castings.

10.30 T he effect of fabrication method on the microstructure of 5182 aluminum alloy feedstock for thixo-extrusion P. Kapranos - University of Sheffield, Sheffield, United Kingdom T. Haga - Osaka Institute of Technology, Osaka, Japan E. Bertoli, A. Pola, R. Roberti - Università degli Studi di Brescia, Brescia, Italy

E xtrusion is a well established technology for the production of complex sections of aluminum alloys. Thixo-extrusion in comparison to traditional hot-extrusion offers several advantages such as lower extrusion and friction forces, higher material fluidity, longer tool life etc… Aluminum alloy 5182 alloy is an important commercial alloy characterized by high strength and ductility, high corrosion resistance and good formability; it is commonly used for the production of wrought automotive components and it is also suitable for semi-solid applications thank to its wide solidification range. The aim of this paper is to attempt the shaping of 5182 Al-Mg alloy through the thixo-etrusion process using a ceramic tool and evaluating the effect of different routes of making the feedstock have on the semisolid microstructure. Particularly, three different methods were investigated: near-solidus casting, roll-casting using a cooling slope, and ultrasonic treatment of the alloy in the semi-solid range. All the samples produced were characterized by metallographic analysis in order to measure globule size and shape factor, as the main criteria used for assessing thixo-formability.

10.50 Coffee break

SESSION METALLURGICAL AND MECHANICAL CHALLENGES IN DIECASTING

Chairmen: G.L. Garagnani, I. Svensson

11.05 A comparative study of defects and mechanical properties in high pressure die cast and gravity die cast aluminium alloys S. Akhtar, L. Arnberg - NTNU, Trondheim, Norway M. Di Sabatino - Sintef Materials and Chemistry, Trondheim, Norway G. Timelli, F. Bonollo - Università di Padova, Vicenza, Italy

D  efects such as pores, hot tears, entrained oxides or macrosegregation can occur in aluminium die castings and will impair the mechanical properties. The nature, extent and distribution of such defects will, however, differ between die casting processes. To investigate these differences, a comparative study between gravity castings of an A356 alloy and high pressure die castings of an A380 alloy has been carried out. The defect distributions of the castings were investigated by metallography, radiography and fractography, and the tensile properties were measured. The gravity die castings were produced in a step mould with and without filter and at different controlled hydrogen concentrations in the melt. The U-shaped pressure die castings were produced with systematic variations of process parameters such as plunger speed, commutation point between first and second phase and pouring temperature. It has been found that both castings contain defects, primarily pores and oxides, and that the presence and distribution of these defects are highly sensitive to the process conditions. Significant variations of the defect distribution have, however, also been found in castings produced under the same conditions, particularly in the pressure die castings indicating the stochastic nature of defects in die castings. The dominating defect type in the gravity die casting is hydrogen porosity mainly at high hydrogen melt concentrations, whereas in the high pressure die castings, oxides and entrapped air porosity dominate. The tensile properties in both types of castings are affected by the amount and distribution of defects. This effect is particularly prominent for the pressure die castings where the defect area fraction has been found to determine the tensile strength. In the gravity castings, hydrogen porosity decreases the tensile strength, but this effect becomes significant only at quite high hydrogen melt concentrations. The tensile properties as well as the porosity also depended on the cross section of the castings.

11.30 T he influence of Fe content and cooling rate on the microstructure and mechanical properties of A380- die casting alloys S. Seifeddine, I. Svensson - Jönköping University, Jönköping, Sweden

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I n the present investigation, the microstructure and tensile properties of aluminium die-cast alloys, based on A380, are studied in details as a function of the iron and manganese content and solidification rate. One set of experiments was designed to examine the solely effect of Fe content, which varied from 0.1 up to 1.6 wt % and another set with manganese additions, Mn: Fe ∼ 1:2. Three solidification rates corresponding to ∼ 10, 25 and 60 µm in secondary dendrite arm spacing, SDAS, respectively were employed by using the unique gradient solidification technique. Microstructure analysis reveals that at relatively high cooling rates and iron levels, the iron-rich precipitates are suppressed to some extent and the strength is maintained at high

levels, but the ductility is gradually decreased. The amount of iron-rich intermetallics does not appear to influence the size and area fraction of porosity and consequently the result suggests that tensile properties have not been adversely affected by porosity level. These results offer additional insight into commonly discussed microstructure features and their role in the determination of the quality and soundness of Al-Si cast alloys.

11.50 A bout mechanical and fatigue strenght of HPDC aluminium based components M. Rosso, I. Peter - Politecnico di Torino, Torino, Italy G. Tonno - Fomt Spa, Grugliasco, Italy

T he work aims to focus the influence of the process parameters on the mechanical properties of high pressure die casting of aluminium alloys. Microstructural features and tensile properties have been observed and tested mainly on AlSi baed alloys, moreover axial fatigue tests have been done on suitable series of samples., using a servo-hydraulic machine. As specimens for both fatigue and mechanical tests have been drawn directly from production components, samples dimensions were the maximum allowed by component dimensions. On the transversal sections of samples the metallographic analysis has been performed, for the measurements of size and microstructural constituents, such as secondary dendrite arm spacing and porosity, have been carried out by means of optical microscopy, supported by an image analysis software.

12.10 Microstructure vs properties correlation in Al-Si cast alloys F. Grosselle, G. Timelli, F. Bonollo, A. Tiziani - Università di Padova, Vicenza, Italy E. Della Corte - Enginsoft, Padova, Italy

T he papers presents an investigation on mechanical behaviour of cast Al alloys, as a function of microstructure and processing history. EN-AB 46000 and 46100 alloys have been gravity cast using a step-bar permanent mould. Microstructural investigations have been carried out, leading to the evaluation of various quantitative parameters, such as SDAS or cell size of α-Al phase, average area, length, roundness and aspect ratio of eutectic Si particles, amount of primary α-Al phase and of eutectic, respectively. Results were obtained for steps of thickness 5, 10, 15 and 20 mm. Microstructural parameters have been correlated, on one side, with the results coming from the numerical simulation of the casting process (cooling rate, local solidification time) and, on the other, with the mechanical behaviour of the cast alloys (YS, UTS, elongation). In general, porosity level, SDAS and dimensions of eutectic silicon particles increased with section thickness and, consequently, mechanical properties decreased. In addition, a satisfactory agreement between simulation and experimental data has been found.

12.30 A bout properties of aluminium based components obtained through Liquid Forging process M. Rosso, I. Peter - Politecnico di Torino, Torino, Italy D. Innocente - Centro Ricerche Fiat, Orbassano, Italy P. Claus - Tecnopres, Chieri, Italy G. Tonno - Fomt Spa, Grugliasco, Italy R. Molina - Teksid Aluminum, Carmagnola, Italy

T he paper deals about a new patented process able to the production of high resistance and high toughness parts, taking into consideration also the tooling need. The molten alloy is introduced into the die cavity at low pressure, then the alloy is forged. The forging action takes place during the alloy solidification process, favouring the reduction of the duration of the process

and the production of parts characterised by very high mechanical and ductility properties. The very high mechanical characteristics of the produced parts are obtained thank to their very low porosity content, as well as to their unique microstructure features. Moreover, the process allow the optimisation of the yield of the alloy, in fact the feeding system and the risers are practically absent, this means minimum production of scraps to be recycled. After a short description of the main features of the equipment and of the process, the work take into consideration the aluminium based produced parts, in their as cast state and after T6 heat treatment, comparing their characteristics with those obtainable by the most traditional low pressure and gravity casting processes. In particular, samples for the evaluation of the tensile and impact mechanical properties have been machined from the produced parts to obtain their tensile strength and impact resistance, together with their ductility characteristics. The maximum attained hardness values have also been evaluated. Tensile strength higher than 440 MPa, with elongation up to 18% with hardness higher than 125 HB are easily attainable on Al alloys type A356. Light microscopy observations performed on the transverse section of polished samples and the analysis of the fracture surfaces after mechanical tests allowed to focus the attention on the microstructure details and to highlight the ductile aspects of the fracture to confirm the high quality and high performance of the produced parts.

12.50 Lunch 14.00 A probabilistic approach for modelling of fracture in magnesium die-castings C. Dørum, D. Dispinar, T. Berstad - Sintef Materials and Chemistry, Oslo, Norway O.S. Hopperstad - NTNU, Trondheim, Norway

Q  uasi-static material tests using specimens cut from a generic cast component have been performed to establish a database of the mechanical behaviour of the high-pressure die cast magnesium alloy AM60. In this work, the experimental data has been applied to establish a validated probabilistic methodology for finite element modelling of thin-walled die castings subjected to quasi-static loading. The material test specimens are modelled in the explicit finite element (FE) code LS-DYNA using shell elements. The cast magnesium alloy AM60 is modelled using an elastic-plastic constitutive model consisting of a high-exponent, isotropic yield criterion, the associated flow law and an isotropic hardening rule. A new probabilistic approach for modelling of fracture in thin-walled magnesium die-castings using finite element analysis is developed. The approach combines the ductile fracture criterion proposed by Cockcroft and Latham with the classical Weibull theory. Comparison between the experimental and predicted behaviour of the cast magnesium specimens gives very promising results.

14.20 Effect of artificial ageing on creep behaviour of Zemak5 die-casting alloy A. Pola, G. Cornacchia, R. Roberti - Università degli Studi di Brescia, Brescia, Italy D. Rollez, M. Gilles - Nyrstar R&D, Balen, Belgium

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H  igh pressure die casting is a well known and cost effective technology for producing cheap and accurate parts in zinc alloys. The advantage of this fine accuracy is, however, often lost due to the bad creep performance of the hexagonal structure of the zinc alloys. Zinc components obtained by high pressure die-casting also suffer from the variation of their mechanical performances with time because of natural ageing effect that induces a redistribution of metastable

phases. Concerning creep behaviour of Zamak 5 alloy, it was observed that the total strain during primary creep is influenced by ageing times; particularly it decreases continuously till an asymptotic value for the longest ageing times. The aim of this paper is to asses whether, during creep tests, may occur concurrent artificial ageing that interferes with the creep behaviour of the alloy. For this reason, different artificial ageing times and temperatures were investigated in order to reach steady state microstructure and mechanical properties and subsequently to compare them with the standard parameters used during zinc alloys creep test. The artificial ageing temperatures able to influence creep behaviour were found to be higher than those normally prescribed for mechanical trials.

14.40 Controlled diffusion solidification: application to metal casting K. Symeonidis, D. Apelian, M.M. Makhlouf - Metal Processing Institute WPI, Worcester, USA

I n the Controlled Diffusion Solidification Process two precursor alloys of controlled composition and temperature are mixed resulting in a predominantly globular microstructure without the use of any grain refiners. The undercooling experienced and the operating solidification mechanism during CDS has been studied. The formation of the globular microstructure is greatly related to the density of the primary crystals, which in turn is related to the degree of undercooling. The developed model points to the critical (as well as optimum) process parameters in order to attain highly refined globular microstructure; cooling rate and degree of mixing being the two important variables. The predictions of the model are directly compared to experimental data collected for the Al-Cu system. The results will be reviewed and discussed along with implications.

15.00 POSTER REVIEW AND BEST POSTER AWARD 15.20 Coffee break

SESSION DESIGN AND APPLICATIONS OF DIECAST COMPONENTS

Chairmen: G. Valentini, J. Jorstad

15.35 A luminum die casting rapid tooling: state of the art and innovative approaches C. Mus - MPI Research Associate, Aosta, Italy

D  ie cast and thin-walled HPDC structural components for automotive applications require sound knowledge during part/car design and production process set-up aimed at defining casting properties and performances. There is a need of representative prototypes in the early design phase. Those prototypes have to be as much as possible similar to the final process component both on dimensional features and mechanical properties in order to avoid misleading testing evaluation that may involve costly design/process changes in the optimization loop. On top of this, in nowadays product development, there is a need of reducing the time to market. Rapid prototyping techniques are prevalent in modern manufacturing methods. For foundry products, rapid tooling techniques are also becoming prevalent in reducing lead time and yielding metallic dies, able to provide high solidification rate of the cooling injected alloy and dimensional repeatability (both in wall thickness and overall casting sizes). The manufacturing of complex HPDC dies is an expensive and time consuming process. Rough machining of forged steel blocks, drilling of thermo-regulating circuits, EDM of cavities details and final assembly with surface finishing, completed with hand polishing operations typically requires several weeks to deliver large HPDC dies. Many efforts are in place to develop alternative techniques to produce shorter delivery HDPC dies able to successfully compromise die life, parts quality and time. A state of the art of available techniques and an overlook on innovative approaches on rapid tooling will be given and completed with case studies.

16.00 D  ie cast copper motor rotors: energy saving efficiency & economic feasibility J. Jorstad - J L J Technologies Inc, Richmond, USA M. Thieman - THT Presses Inc, Dayton, USA

R  eplacing aluminum with copper in the die cast squirrel cage conductor bars in electric induction motor rotors has enormous potential benefit in terms of improved efficiency, energy savings, reduced maintenance and reduced weight and cost. The major deterrent to that conversion has been the short tool life associated with casting molten copper; however, research sponsored by the Copper Development Association identified recommended tool materials and casting practices that significantly improve tool life. THT Presses, Inc. has developed a vertical die casting machine, design especially especially for casting motor rotors, and have demonstrated capability to cast a wide range of copper alloys and motor sizes on that equipment. THT’s Sub Liquidus rheocasting process provides future opportunity for even better tool life when die casting copper alloys.

16.20 New challenges and directions for high pressure die cast magnesium L. Zaffaina, F. Bonollo - Università di Padova, Vicenza, Italy R. Alain - Meridian Technologies Inc.

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M  agnesium, being the lightest structural material, is attractive whenever weight is a problem. Transport industry is looking for solutions to deal with increasing energy cost and pollution: the main way is to make light vehicles. Application of magnesium alloys is extending to many new

components and engineers have to deal with material’s weakness such as creep resistance, corrosion protection and flammability. This work is an attempt to plot the directions of the ongoing developments on applications’ frontier.

16.40 C ombining innovation and risks while assuring high performances and cost reductions: the designer’s choices S. Magrini - CNH Spa, Modena, Italy E. Costa, E. Ferri, G. Donzelli - Cermet - Sez. ISML, Cadriano di Granarolo, Italy



T he designer role is crucial in the life of a business, but not always it is understood in all its implications. In fact the designer is requested to accomplish tasks and take responsibilities regarding: - Compliance with the component/group/system functionality specifications (performances and durability) - Compliance with the binding regulations (conformity with laws, directives and rules) - Compliance with the business policies social responsibility, sustainability, etc.) - Compliance with the cost specifications (cost reduction) Governing all these categories might be extremely complex and this, until the recent past, lead to the adoption of a basically conservative approach, turned to “polishing” the implementation details of consolidated products and obtaining some marginal profit, without leaving much scope for more original solutions considered too risky a priori. The growing competition on the international market with non-European competitors has drastically changed the reference scenario, leading to an increasingly greater pressure towards the research of technological solutions able to generate forms of competitive advantage on the products coming from the growing economies. This innovation has considerably modified the approach that the designers have to take when they are involved in a competition recovery program (cost reduction): the conservative reasoning based on the development of small marginal updating is no longer winning; therefore, the designers skills to take their unconventional choices shall be enhanced as they are right to hit the planned targets. This scenario confirms how the innovation in the materials and related technologies is of primary importance as a strategic factor to remain competitive in the short and medium term future. As a case to be studied for this new scenario, we have included in the paper an application referred to the agricultural machinery sector where, through a careful redesigning work, we succeeded in developing a safety component (clutch pedal), traditionally built up with the assembly by arc welding of carbon steel blank parts, using die-cast aluminum alloys. This has allowed, keeping an equal resistance to the expected working stresses, to integrate several functional parts in only one element, thus improving the fit-for-purpose degree of the component and bringing significant advantages from the point of view of cost reduction, such as to put the new component into production. Taking as starting point the surrounding elements that have characterized this experience, the paper also includes some methodological considerations on the new challenges that the designers shall face and about the importance of an adequate knowledge of the “innovative” material properties and of the relevant technological transformation processes.

17.00 Squeeze cast automotive applications and design considerations Z. Brown, C. Barnes, J. Bigelow - Contech U.S., Kalamazoo, USA P. Dodd - Contech UK, Welshpool, United Kingdom

W  ith increasing emphasis on vehicle weight reduction, the demand for lighter weight automotive components continues to increase. Squeeze casting is an established shape-casting pro-

cess that is capable of producing light-weight, high integrity, automotive components that can be used for structural applications. In recent years the squeeze casting process has been used with various aluminum alloys to produce near-net shape components requiring high strength, ductility, pressure tightness or high wear resistance [1]. Squeeze casting has proven to be an economical casting process for high volume applications and offers design and materials engineers an alternative to conventional casting processes such as gravity permanent mold (GPM), low pressure die casting (LPDC), sand cast aluminum/ iron, and conventional high pressure die casting (HPDC). This paper describes Contech’s squeeze casting technology (P2000TM) and provides examples of high volume automotive components manufactured at Contech. This paper also includes product design considerations, an overview of process simulation techniques, a comparison of mechanical properties, and case studies for select automotive components.

17.20 Die casting for chassis components V. Ilotte - Fonderie 2A, Santena, Italy

I n 2006 Volvo 3P North America launched a request for quotation for some component of its new chassis. These parts are the brackets which are holding the radiators in the truck. Their main function is to sustain the radiator under the normal solicitations of the road and under the accidental ones. “fonderie 2a”, foundry specialized in the production of small, medium and large die-casted components, was one of the partner which Volvo 3P inquired. Its proposal consisted in developing a piece obtained by aluminium high pressure die-casting. This solution showed a signifi! cant economic gain in the final cost of the component. It has then been decided to launch a first study in order to enter more in the detail of the solution proposed. “fonderie 2a” had to engineer the parts, taking into consideration the specifications of Volvo 3P in the fields of mechanical strength, reliability and mountability. In order to answer to these requests, “fonderie 2a” first designed the pieces in order to find a compromise between high pressure die casting requirements and Volvo 3P specifications. Once found the best design, “fonderie 2a” proposed the best alloy for such application together with a specific heat treatment in order to improve the mechanical properties of the parts and validated it by FEM simulation. At the end, “fonderie 2a” realised the first prototypes which have been tested on different platforms: the final results showed that the new pieces can fulfil Volvo 3P’s requirements. Following these very positive results, Volvo 3P decided to homol ogate this new application and introduced them on its trucks.

17.40 P rediction of the deformation of an automotive door panel casting using simulation M. Aloe - Calcom ESI SA, Lausanne, Switzerland

The abstract is not available

18.00 Closure of the Conference

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POSTER







X -Ray diffraction applied to the analysis of surface residual stresses in aluminium die casting moulds and its relation to heat checking A. Argüelles, J.M. Artimez, R. Coto - Centro Tecnológico del Acero y Materiales Metálicos, Avilés, Spain A. Martinez, E. Carreira, J. Romero - Fundació ASCAMM, Cerdanyola del Vallès, Spain F.J. Belzunce - Universidad de Oviedo, Oviedo, Spain

T he surface of die casting moulds is subjected to thermal cycles spanning a wide range of temperatures in short periods of time. As a consequence, thermal fatigue cracking usually occurs. Cracks, or heat checks, initiate as the result of successive expansions and contractions, sometimes accompanied by microstructural changes. These actions induce tensile residual stresses which, in turn, promote the initiation of cracks at the mould surface. Even though such cracks do not affect the mould integrity, they become an important problem as they decrease the surface quality of injected products. Their dimensions range from several micrometers to 2 mm in length, and from less than 1 mm to more that 50 mm in depth. Residual stresses in die casting moulds are not only produced during service but even during their fabrication processes. The knowledge of residual stresses accumulated at the die casting mould surface could lead to the prediction of heat checking. Thus, the mould could be changed before the products quality was affected. In this sense, a non-destructive, fast and precise enough technique is needed for the in-situ measurements of residual stresses. Taking into account such criteria, Xray diffraction has been selected. The present work was devoted to the analysis of surface residual stress by Xray diffraction in a used mould subjected to a great number of thermal cycles. By means of this technique and with the aid of metallographic analysis, the relation between surface residual stresses and fatigue cracks was analysed, looking for a maximum threshold value of stress that allowed us to anticipate the failure of the mould. From this study, suitability of X-ray diffraction as an analytical technique for predicting surface quality of moulds before failure was evaluated.

T he microstructure, porosity and mechanical properties of AE44 magnesium die castings T. Rzychon, A. Kielbus - Silesian University of Technology, Katowice, Poland

T he need for weight reduction in aerospace and automobile industries has stimulated engineers and scientists to develop the new materials for these applications. AZ91, AM50 and AM60 magnesium alloys are frequently employed to manufacture components for automotive sectors. However, their applications are restricted when the temperature surpasses 130 °C. Rare earth elements are added to the magnesium alloys, in order to improve their elevated temperature property. Recently, Hydro Magnesium has developed a new HPDC alloy, AE44 (4% Al and 4% RE), which has attractive high temperature mechanical properties, diecastability and corrosion resistance. The AE44 magnesium alloy has been poured in a hot chamber high pressure die casting machine with a metallic mold. The process parameters (plunger velocity in 2nd phase, melt temperature, die temperature) have been varied to understand the process-microstructure and process-mechanical properties relationships. Optical microscopy (Olympus GX-70), scanning electron microscopy (Hitachi S3400) and X-ray diffraction (Philips X’Pert) were used to examine the microstructure of this alloy. The porosi-

ty was calculated by comparing of the theoretical and measured density and by quantitative metallography. Tensile testing was carried out on a screw driven Instron machine at room and elevated temperature. The microstructure of AE44 alloy consists of equiaxed grains of α-Mg solid solution with lamellar of Al11RE3 and globular Al2RE intermetallic phases. The increase of plunger velocity in 2nd phase results in the increase of gas porosity and in the decrease of grain size, volume fraction of intermetallic phases, tensile strength and yield strength. The change of melt and die temperature has not influence on the microstructure and mechanical properties of AE44 alloy.



P roduction of aluminum-silicium alloy wheels by low pressure die casting in Argentina M.R. Ricci - Melt. R&D Metallurgical Center, Campana, Argentine





A new reference die for mechanical properties evaluation in diecasting Part 1 - Design and process optimisation G. Timelli, F. Grosselle - Università di Padova, Vicenza, Italy F. Voltazza - Toolcast, Brugine, Italy E. Della Corte - Enginsoft, Padova, Italy





A new reference die for mechanical properties evaluation in diecasting Part 2 - Microstructural investigations and tensile testing G. Timelli, F. Grosselle, F. Bonollo - Università di Padova, Vicenza, Italy F. Voltazza - Toolcast, Brugine, Italy L. Capra - RMC, Brescia, Italy







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T he leader producer of Al-Si wheels in Argentina for OEM by low pressure die casting, request a consultant in order to increase performance of the production cycle and quality of die casts. It was done successfully. They were not able to achieve the ASTM E155 standards of production specifications that established the form and distribution of defects observed by means of X rays 100% control on the line. They reached down to 30% of scrap wheels, and ASTM E155 tolerates up to 10%. It was applied the cause/effect method of Isikawa fishbone diagram, according with producer politic of continue quality improve aim. The analysis method included also metallographic analysis, simulation of low pressure die casting with LOW PRESSURE INTERFACETM. The prognosis took care of transfer knowledge of metallurgical technology to the personnel. The procedure was novel for the argentine foundry sector and caused a remarkable increase in technological quality and management. Basically, the solution resulted in the modification of production parameters of low pressure machines, times and methods of production cycle. It was achieved a maximum scrap of 6%, higher at times of the European OEM producers, say by OEM inspectors.

E valuation of mechanical properties in high-pressure die-casting is a relevant issue, which is not fully covered by existing International Standards. This paper presents the design and the set up of a reference-die, to be used for the production of castings suitable for various kinds of technological tests. The selection of processing parameters, carried out with the help of numerical simulation and of NDT techniques (radiographic inspections, I.R. camera), is described.

C ast to shape specimens have been produced using a multicavity reference-die. EN-AB 46000 and 46100 alloys have been high-pressure die-cast. The molten metal has been

submitted to different degassing treatments. About 400 pieces have been produced with systematic variations of process parameters such as plunger speed and commutation point between first and second phase. Microstructural investigations have been carried out on representative specimens where the thickness ranged from 6 to 1 mm. The amount of primary α-Al phase has been evaluated and it is observed to increase with increasing specimen thickness. In general surface regions show a lower amount of α-Al phase than the central location of specimens. Furthermore, a complete mechanical characterisation has been performed on flat tensile specimens and it is shown how mechanical properties depend upon process parameters.





E nhancements of HPDC dies resistance trough thermal barriers and/or PVD nanocoatings D. Ugues, E. Torres, M. Rosso - Politecnico di Torino, Torino, Italy

W  ear and failure of HPDC tooling involve a complex interaction between various mechanisms. In particular wear and heat checking cause failure due to different phenomena, for example to the so-called washout damages on working die surfaces, being attributed to erosion, corrosion and soldering; however thermal fatigue could be the most important failure mode in die casting applications. Different tooling materials and suitable heat treatments are available for the manufacturing of high performance dies and tools, both play an important role to contrast the thermal fatigue damages. The paper discuss the most important features related to the optimal choice among the available hot working alloys and the optimisation of their heat treatments for the HPDC applications. Moreover, further improvements of tooling performances can be attained thank to suitable coatings. In particular, the use of wear resistant thermal barriers applied by advanced thermal spray technologies can give a strong contribution to the increase of die life and performances. Different type of thermal sprayed coatings for the protection of HPDC dies are here presented; the samples have been obtained by plasma and HVOF processes and the results of wear and heat checking tests are here discussed. Moreover, the sector of surface thin PVD coatings is constantly enhancing in order to meet the increasing demand for improved performances of tooling. Advanced PVD coatings are designed to withstand severe mechanical and thermal stress conditions. A CrAlSiN nanostructured coating system was deposited on the base material, modulating the chemical composition so as to increase either the chromium or the aluminium-silicon content. Experimental samples have been obtained to test hardness properties, wear and heat checking resistances. The obtained results and the main microstructural features are here presented and discussed.

A n investigation on the diffusion bonding ability of WC-Ni ceramic-metal composites A. Erol, A. Yonetken, M. Cakmakkaya - Afyonkarahisar Kocatepe University, Afyonkarahisar

I n this study, the production of particle reinforced ceramic-metal composites and their diffusion bonding have been carried out. WC reinforcement particles were Ni plated by electroless technique. Two sets of specimens were prepared; first group of specimen was produced from WC and Ni powders which were seperately used for sintering and second group of specimen were produced from WC powders which were Ni plated by electroless technqiue and then sintered. Specimens composed of 70wt% WC and 30 wt% Ni were sintered at temperature range 900°C - 1300°C under Ar atmosphere. An attempt to diffusion bond of specimens sintered at 1200°C were succesfull at 1170°C under Ar atmosphere. Average hardness values were found to be

259HV and 346HV for first and second group of specimens, respectively, that were determined by taking measurement from 15 different points. Hardness measurments showed that the hardness value increases as the distance to bond line dec! reases. In addition, it was shown that the hardness values for the specimens produced from electroless Ni plated WC powders have higher hardness values compared to other set of specimens. The bondline of diffusion bonded specimens were examined using optical and Scanning Electron Microscope.



R  ole, functions and heat transfer of die coating in the aluminum die casting process G. Muneratti - Foseco Srl, Vermezzo, Italy



ALSPEK MQ: a device to indicate the cleanliness of an Aluminium melt R. Kendrick - Foseco FS Ltd, Tamworth, United Kingdom





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N  umerical modelling of heat transfer in the casting process can reveal the likely occurrence of defects such as solidification shrinkage. However, for accurate models of solidification it is necessary to have accurate data with which to solve the problem. This means not only accurate values for the thermal conductivity, specific heat capacity, density and latent heat for the particular alloy under consideration, but also accurate values for the heat transfer coefficient, h, that describes the boundary condition of the mathematical problem, i.e., how the heat is transferred from the casting to the mould. Although various aspects of the permanent mould casting process have been studied and developed, such as alloy selection, machine automation, runners and feeders design, etc., little attention has been given to the products (and their properties) and methods for preparing the surface of the die. After a brief description of the role and functions of die coatings, this paper resumes a recent work developed for Foseco Int. by Griffiths and Kawai of Birmingham University, which investigated heat transfer during the die casting of Al alloys where the dies are coated with different commercial die coatings. Examination of the casting-coated die steel interface in experiments intended to duplicate gravity die casting conditions has led to an improved understanding of the heat transfer mechanism during casting solidification. Evaluation of these mechanisms has led to equations to predict the heat transfer coefficient in Al die casting that can lead to improved solidification modelling. This estimation of the heat transfer coefficient has shown the important role played by the occurrence of a layer of air trapped between the casting and coating surfaces that is responsible for the majority of the insulation at the casting-die interface during casting solidification. The thermo physical properties of the major Foseco Dycote has been included in the Foseco Pro Module, a package that can be used associated with Magma in order to obtain accurate simulation.

T he expectation of the performance of many types of castings continues to grow and so the quality requirements of the castings themselves must improve. Foundries response time and stock are also being reduced and so right first time becomes a given. To ensure castings are consistent and predictable there is a growing realization that critical parameters such as metal cleanliness must be measured prior to casting. There are existing, accepted methods for measuring the cleanliness of an Aluminium melt but these can be both slow and costly. ALSPEK MQ has been developed to offer the foundry a practical, simple, rapid and meaningful method of measuring and bench marking the cleanliness of an Aluminium melt. ALSPEK MQ generates a Metal Quality Index (MQI) in less than a minute at an affordable cost. A 1.5 kg sample is tested directly in the bath with no loss of metal. ALSPEK MQ can be used to compare Aluminium melts in different stages of preparation generating a MQI, which foundries can use as part of their process control and quality control procedure.



The first part before die casting in magnesium R. Poss, H-P. Reichel - LMPV, Karlsruhe, Germany



T he influence of die casting parameters on microstructure and mechanical properties of AJ62 magnesium alloy A. Kielbus - Silesian University of Technology, Katowice, Poland











D  ie casting of Magnesium alloys is not something really new, but how can you be sure that the component fits in your system and will do it its work? If you are working with aluminium you take a piece of aluminium and machine it. Than you can check the properties. But where do I get magnesium plates for maching? We produce magnesium plates and wrought products and we can machine them to parts for a complet system. We also can weld Magnesim parts, even casted parts. Our presentation will give you an idea what you can do before you start your magnesium die casting production. When the production is running we are searching for a new task. And we also can repair old parts which are not anymore produced. LMPV, L=Light, M=Metal, P=Production and V=Machining, German word for “Verarbeitung”.

T he AJ62 magnesium alloy exhibit good elevated-temperature tensile properties, excellent creep resistance and good castability. This alloy contains approximately 6% aluminum and about 2,5% strontium. Typically, it is used in automotive industry for the engine crankcase and power-train components. The study was conducted on Mg-6Al-2Sr-0.5Mn alloy (AJ62). Die casting was carried out on 280 tone locking force hot-chamber die casting machine. For the microstructure observation, a Olympus GX+70 metallographic microscope and a HITACHI S-3400N scanning electron microscope with a Thermo Noran EDS spectrometer equipped with SYSTEM SIX were used. The phase identification of these alloys was identified by X-ray diffraction (JDX-75). The examination of the mechanical properties was conducted on an Instron machine at two temperatures: ambient and 175¢XC. After hot-chamber die-casting, only the (Al,Mg)4Sr eutectic + solid solution ƒÑ and the globular precipitate of the Mn5Al8 phase were observed. In castings with thicker walls, a massive Al3Mg13Sr phase was also present. The presence of the massive Al3Mg13Sr phase depends on the solidification rate. Variations of plunger velocity in 2nd phase have the significant effect on porosity formation and mechanical properties. The increase of plunger velocity led to decrease of mechanical properties due to inrease of casting porosity.

U  ltrasounds: a new technology for alloys degassing, grain refinement and obtainment of a thixotropic structure A. Pola, A. Arrighini, R. Roberti - Università degli Studi di Brescia, Brescia, Italy

T he obtainment of a microstructure free of porosity and characterized by fine grains ensures high mechanical performances of casting components. Based on this assumption, many resources have been frequently spent for the improvement of grain refinement and degassing treatments usually performed on alloys during foundry processes. High pressure die-casting pieces, moreover, suffer from porosity induced by the fluid flow turbulences originated in the injection phase. Different technologies, as semisolid process, have been studied in order to avoid, or at least reduce, air entrapment during die filling, enhancing castings quality. Ultrasound waves applied to fluids create cavitation phenomena: in liquid metals they cause an increase of the number of the solidification nuclei, with the subsequent obtainment of a fine grain microstructure that involves higher mechanical properties. The aim of this study is to demonstrate how the application of ultrasonic waves, characterized by proper frequency, on

liquid aluminium and zinc alloys can strongly modify their microstructure, in terms both of grain refinement, without addition of expensive inoculants (as TiB2), and of gas porosity reduction. Cavitation phenomena, in fact, can enact a degassing, because of the coalescence of gas bubbles inside the liquid that, increasing in their size, can easily escape from the melt. An ultrasonic equipment was properly manufactured in order to allow the treatment of liquid metals; different tests were carried out on the molten alloys, changing working temperatures, ultrasound application times, moulds etc. All the produced samples were completely characterized by metallographic investigations in order to evaluate the effect of process parameters on castings quality. Ultrasonic treatment was also applied to solidifying alloys to verify its applicability in producing feedstock materials for thixocasting as an alternative and environmental safe system to the commercial ones. Comparisons between samples produced via mechanical and ultrasonic stirring were performed in order to evaluate the potentiality of the new technology used. Metallographic analysis made on semisolid samples showed, finally, a better microstructure, in terms of globule shape and size, for the ultrasound treated castings than those produced by traditional method.







T ensile and fatigue behaviour of an AlSi10Cu alloy cast under controlled solidification conditions L. Ceschini, I. Boromei, A. Morri - Università di Bologna, Bologna S. Seifeddine, I.L. Svensson - Jönköping University - School of Engineering, Jönköping, Sweden





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Classification criteria for defects in diecast components E. Gariboldi - Politecnico di Milano, Milano, Italy M. Rosso - Politecnico di Torino, Torino, Italy F. Bonollo - Università di Padova, Vicenza, Italy

T he paper describes the work carried out by the WG “Quality of die-casting parts” of the Diecasting technical committee of Italian Association of Metallurgy. The main kinds of defects originated in diecasting processes are reviewed and described in terms of origin, morphology, possible corrective actions. Some classification criteria are proposed, with the aims of making available an useful tool for diecasting foundries and of improving the quality of products.

A number of technical articles have been published in the literature about the correlation between microstructure and mechanical properties of cast A356 aluminium alloy, while few data are available on other hypoeutectic Al-Si alloys with high silicon content, such as the A354. In this work three AlSi10Cu casting alloys, with different content of Fe (from 0.1 to 0.5 wt%) and Mn (from 0 to 0.25 wt%) were cast. A special apparatus was used to produce cast samples under controlled solidification conditions, in order to obtain microstructures with two values of the secondary dendrite arm spacing (SDAS), equal to about 8 μm and 50 μm. The cast were heat treated at the T6 condition before machining the tensile and fatigue specimens. Microstructural characterization of the alloys was carried out by optical (OM) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Image analyses were performed on the optical micrographs to evaluate SDAS, grain size, as well as size and distribution of the casting defects (gas pores and shrinkage cavities). In order to relate these microstructural features with the mechanical behaviour of the tested alloys, tensile and rotating bending fatigue tests were performed. SEM analyses of the broken specimens were carried out, in order to study the fracture mechanisms. The static mechanical properties, as yield strength, ultimate tensile strength and elongation to fracture have been evaluated for

the selected alloys and cooling conditions. The material has also been evaluated in respect of elastic and plastic deformation. The fatigue tests and fractographic analyses showed that casting defects, whose size and distribution is strictly related to the solidification conditions mainly control the fatigue behaviour. High density of large gas pores and shrinkage cavities, were observed in the specimens with the larger SDAS value, of 50 μm, leading to a low fatigue resistance, about 60 MPa, and a wide scatter of data. On the contrary, a significantly high fatigue resistance, about 180 MPa, was measured in the specimens characterized by a low density of small casting defects, related to the lower SDAS value of 8 μm. No significant differences between the alloys with different Fe and Mn content was instead observed, being dominant the effect of the solidification defects and SDAS.



Process optimisation: a case history about an engine bracket S. Antonioni, S. Di Rosa - Centro Ricerche Fiat - Trento Branch, Trento, Italy



How the tream technology can be implemented into HTDC R. Pederzoli - Meccanica Pi.Erre, Bedizzole, Italy





The abstract is not available

The abstract is not available

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general information Conference Secretariat AIM - Associazione Italiana di Metallurgia Piazzale Rodolfo Morandi, 2 · I - 20121 Milano Italy. tel. +39 0276397770 · +39 0276021132 · fax +39 0276020551 e-mail: [email protected] conference website: www.aimnet.it/htdc2008.htm CONFERENCE VENUE The Conference will be held at Centro Fiera del Garda (Italia Room) · Via Brescia 129 in Montichiari (Brescia, Italy). HTDC 2008 will be hosted by METEF, the main international exhibition on light alloys technologies. Language English will be the Conference language. A simultaneous translation service (English-Italian) will be provided. proceedings The proceedings will be published on cd-rom and issued to delegates on arrival at the Conference. REGISTRATION INFORMATION AIM MEMBERS RATES Delegates € 350,00 (Revenue Stamp included) Speakers / Chairmen of session € 290,00 (Revenue Stamp included) AIM Junior Members Free STANDARD RATES Delegates € 430,00 (Revenue Stamp included) Speakers / Chairmen of session € 370,00 (Revenue Stamp included) Student * € 180,00 (Revenue Stamp included) Accompanying persons € 72,00 (VAT included) (includes Conference Dinner) *Students will have to provide valid proof of student status. Standard Student rate includes entrance to technical sessions and poster session, conference bag with a copy of the conference proceedings, coffee breaks and lunch. AfterMarch 9th, 2008 the above rates will be subject to an extra charge of € 100,00.

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Suggested Hotels The list of suggested hotels available on Metef web site: www.metef.it Due to heavy request because of the METEF, we advise to book hotels as soon as possible.

registration form Please complete and return this form by March 9th, 2008 to: ASSOCIAZIONE ITALIANA DI METALLURGIA - AIM Piazzale Rodolfo Morandi 2 · I · 20121 Milano, Italy tel. +39 0276021132 / 0276397770 · fax +39 0276020551 e-mail: [email protected] · VAT entry no. 00825780158 conference website: www.aimnet.it/htdc2008.htm

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TH

9-10 April 2008

High Tech Die Casting 2008

International Conference

Montichiari · Italy

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m b y non-transferable bank draft or cheque, negotiable in Italy, to the order of Associazione Italiana di Metallurgia - AIM m bybank transfer, to the order of Associazione Italiana di Metallurgia - AIM at “Banca Popolare Commercio e Industria”, Branch no. 2 - Milano, account no. 000000022325 - cod. ABI 05048 - CAB 01602 - cin L, IBAN: IT92L050480 1602000000022325, swift code POCIITM1002. The transfer order must specify the name of the delegate and the reference “HTDC 2008”. A copy of the transfer order must be sent to AIM, together with the Registration Form. m bycredit card Visa, American Express, Diners cards, Carta Sì, and cash at the registration desk in Montichiari ONLY FOR DELEGATES. We inform you that data collected will be treated following the normal institutional activity of AIM. In accordance to article 130 of the D.lgs 196/03 in every moment the interested party has the right to oppose the treatment of one’s personal data. Your data will be dealt with in accordance of the D.lgs. in 30th June 2003 n.196, guaranteeing the rights of the interested parties foreseen in the 7 art. of the Decree.We also inform you that AIM will communicate to foreign partners the personal data only for above reasons. We also inform you that your personal data will be on the list of the conference participants. We also inform you that the holder of the personal data is AIM in Milan in P.le Morandi 2, while owner of the personal data is prof. Walter Nicodemi, available near the AIM offices. m In the case that you do not want to appear on this list you may block the mail box

Date

Signature

30

time table WEDNESDAY, 9 APRIL 2008

AIDA ROOM 11.00 Foundry Roadmap forum: Foundry prospectives in emerging countries ITALIA ROOM 14.00 Welcome addresses 14.10 Alloys and related treatments



15.55 Coffee break



16.10 Tooling and equipments



20.00 Conference dinner

THURSDAY, 10 APRIL 2008

ITALIA ROOM 9.05 Exploiting diecasting by process evolution 10.50 Coffee break 11.05 Metallurgical and mechanical challenges in diecasting



12.50 Lunch



14.00 Metallurgical and mechanical challenges in diecasting



15.00 Poster overview and best poster award



15.20 Coffee break



15.35 Design and applications of diecast components



18.00 Closure of the Conference

Sponsored by

Conference Secretariat

Associazione Italiana di Metallurgia

Piazzale Rodolfo Morandi, 2 I - 20121 Milano Italy tel. +39 0276397770 +39 0276021132 fax +39 0276020551 e-mail: [email protected] AIM website: www.aimnet.it conference website: www.aimnet.it/htdc2008.htm