Nondestructive Characterization of Microstructures and Determination of Elastic Properties in Plain Carbon Steel using Ultrasonic Measurements

Vera Lúcia de Araújo Freitas1, Victor Hugo C. de Albuquerque2, Edgard de Macedo Silva3, Antonio Almeida Silva1, João Manuel R. S. Tavares4 1

Universidade Federal de Campina Grande (UFCG), Departamento de Engenharia Mecânica (DEM), Av. Aprígio Veloso, 882, Bodocongó 58109-970, Campina Grande-PB, BRASIL Email: [email protected], [email protected]

2

Universidade de Fortaleza (UNIFOR), Centro de Ciências Tecnológicas (CCT), Núcleo de

Pesquisas Tecnológicas (NPT), Av. Washington Soares, 1321, Sala NPT/CCT, CEP 60.811905, Edson Queiroz, Fortaleza, Ceará, BRASIL Universidade Federal da Paraíba (UFPB), Departamento de Engenharia Mecânica (DEM), Cidade Universitária, S/N - 58059-900 - João Pessoa/PB, BRASIL Email: [email protected] 3

Centro federal de Educação Tecnológica da Paraíba (CEFET PB), Área da Indústria, Avenida 1º de Maio, 720 - 58015-430 - João Pessoa/PB, BRASIL Email: [email protected]

4

Faculdade de Engenharia da Universidade do Porto (FEUP), Departamento de Engenharia

Mecânica (DEMec) / Instituto de Engenharia Mecânica e Gestão Industrial (INEGI), Rua Dr. Roberto Frias, s/n - 4200-465 Porto, PORTUGAL Email: [email protected] Corresponding author: Prof. João Manuel R. S. Tavares Faculdade de Engenharia da Universidade do Porto Departamento de Engenharia Mecânica Rua Dr. Roberto Frias, s/n 4200-465 Porto, PORTUGAL email: [email protected], url: www.fe.up.pt/~tavares Phone: +351 22 5081487, Fax: +351 22 5081445

i

Nondestructive Characterization of Microstructures and Determination of Elastic Properties in Plain Carbon Steel using Ultrasonic Measurements

Abstract This paper presents a reliable and fast nondestructive characterization of microstructural and elastic properties of plain carbon steel, based on ultrasonic measurements for ultrasonic velocity and attenuation. Microstructures considered are: ferrite, pearlite, ferrite-pearlite and martensite. Ultrasonic velocities considered longitudinal and transverse waves and modulus of elasticity and modulus of shear were determined by correlations between them. In carbon steels, a lower value of ultrasonic velocity was observed for the martensite in relation to the other microstructures, while the opposite was observed in terms of ultrasonic attenuation. The results show that the use of ultrasonic measurements to obtain ultrasonic velocities and attenuations, in order to correlate them with the involved microstructures, as well as to determine the modulus of elasticity and modulus of shear, is very fast and reliable, permitting the characterization of nondestructive microstructural and elastic properties.

Keywords: Nondestructive testing; Microstructures; Plain carbon steel; Transverse and longitudinal wave velocities; Ultrasound; Materials characterization.

ii

1. Introduction One of the main purposes of nondestructive testing (NDT) is to ensure the functioning of components. The most common way of doing this is by checking for defects in components through one or a combination of different techniques of nondestructive testing. If defects are present, they are characterized by their location, dimension, orientation, shape and nature to define the acceptability of the component in the provided conditions established for the correspondent operation. Besides the characteristics of the defects, there are other parameters equally important in the evaluation of structural integrity of components, as well as their microstructural and mechanical properties. Usually, microstructural analysis is carried out through metallography, while mechanical properties are determined through mechanical tests. Often, destructive tests are performed on test pieces with standard dimensions and shapes, based on the assumption that they truly represent the material under analysis. Even though, technologies used in destructive tests increasingly reproduce the conditions of use of the component in question, the obtained results cannot truly presume how it will function in normal conditions, due to the unpredictability of some factors, such as environmental conditions, degradation of properties, micro-damages, residual tensions and other factors that may have a negative influence on its service life. Characterization of material properties through nondestructive testing takes on an increasingly important role, especially in the industry, as it can be used to monitor components during the manufacturing process, as well as while in operation. Some nondestructive techniques and applications include, for example, the use of X-ray images and CT-scan to analyze delamination defects in mixed materials [1, 2], the use

1

of thermographic images to analyze metals [3], the use of computer simulation and modeling to evaluate microstructures in different classes of cast iron from metallographic images [4, 5]. In addition to the nondestructive techniques previously mentioned, another technique widely used to analyze and characterize materials is ultrasonic testing. In characterizing internal structures of materials, interaction of the ultrasound signal with microstructures can be evaluated with regards to changes in the velocity of propagation, loss of amplitude (or attenuation) and analysis of backscattered signal [6, 7]. Therefore, several works have been developed based on ultrasonic measurements to obtain the sonic velocity and attenuation in order to evaluate the mechanical properties of different plain-carbon steel microstructures. For example, in duplex stainless steel subjected to different thermal aging conditions, the ultrasonic velocity undergoes significant modifications as it detects changes in stages due to the aging heat treatments applied, making it possible to follow and study the embrittlement kinetics [8, 9]. The evaluation of water immersed specimens of En3A, En9 and En25 steel behavior at 5 MHz ultrasound backscattered according to the Rayleigh angle has been correlated to the microstructure features induced by heat treatment [10]. The modulus of elasticity and internal friction of induction hardened and unhardened SAE 1050 steel at ambient temperatures were determined in [11] by resonant ultrasonic spectroscopy, in which all components of the internal-friction in martensite were higher than those of ferritepearlite, but lower than those of α-iron. Ultrasonic longitudinal wave velocity measured by the laser-ultrasonic technique is compared to dilatometry for the monitoring of austenite decomposition of low alloy steel [12], in which these techniques can be applied to monitor austenite transformation of real products in an industrial production

line that would be extremely difficult with dilatometry. The study of the influence of steel heat treatment on ultrasonic absorption measured by laser ultrasonics is proposed in [13], the analysis of ultrasonic attenuation and microstructural evolution in a lowcarbon steel (ASTM-A105), containing 0.21 wt.% C is performed in [14], and the measurement of ultrasound velocities and modulus of elasticity of steel at both sub-zero and elevated temperatures is done in [15]. The main aim of this work is to evaluate the capability of ultrasonic measurements to characterize different kinds of plain carbon steel microstructures, analyzing the ultrasonic velocities and attenuations, and then to obtain modulus of elasticity and modulus of shear in AISI 1006 (with ferrite microstructure), AISI 1020 (with ferrite-pearlite microstructure), AISI 1045 (with ferrite-pearlite microstructure and carbon content higher than that of AISI 1020, and consequently higher amounts of pearlite in normalized samples, annealed and quenched in oil; and with martensite microstructure when quickly quenched in water), and AISI 1080 (with pearlite microstructure). Thus, seven microstructure variations are analyzed through ultrasonic measurements: three of them with different carbon contents in the material - AISI 1006 with lower quantities of carbon, followed by AISI 1020, AISI 1045 and AISI 1080 respectively, and four other microstructures obtained through heat treatment on AISI 1045, provided that annealing, normalizing, oil quenching and water quenching are the heat treatments considered. These materials were selected because of their wide use in many industrial applications. For example, AISI 1006, which is soft and very ductile, has been used in applications that require severe bending and welding, such as panels for automobiles or appliances. In addition, AISI 1006 has also been used in magnetic core applications. On the other hand, AISI 1020 responds well to cold work and heat

treatments, combines good machinability, workability and weldability, and has been used in the manufacturing, for example, of shafts, gears, hard wearing surfaces, pins, chains and case hardened parts where core strength is not critical. AISI 1045 steel is valuable for induction- or flame-hardened components and suitable for most engineering and construction applications, like shafts, pins, axles, rods, studs, machine parts, bolts, gears, pinions, forgings and bulldozer edges. Finally, AISI 1080 has been used to construct, for example, general-purpose tools, springs and machinery parts that require high hardness and high resistance to wear. This paper is organized as follows: the following section presents the materials used, describes different heat treatments performed in order to obtain the intended microstructures, and indicates the ultrasonic measurements applied in their characterization. Section 3 presents the results, as well as a discussion on them. Finally, section 4 presents conclusions on advantages of nondestructive inspection based on ultrasonic measurements.

2. Materials and Methods The carbon steels considered in this study were AISI 1006, 1020, 1045 and 1080, because their microstructures can be identified through metallographic analysis by optical microscopy, which is important to evaluate the microstructures determined by ultrasonic measurements. The selected carbon steel samples, 5 of each type of steel analyzed, were adjusted to the following dimensions: AISI 1006 and 1080 with 50x20x12 mm3, AISI 1020 and 1045 with Ø25.4x12 mm2. After preparation, the samples underwent austenitization in an electric resistance furnace with a capacity of up to 1473 K (1200 °C) in order to homogenize their original

microstructures. Austenitizing temperatures were 1213 K (940 °C) for AISI 1006 samples and 1133 K (860 °C) for AISI 1020. These steel samples were later cooled in still air. Regarding AISI 1080, the austenitizing temperature was 1053 K (780 °C), and the samples were cooled inside the furnace to avoid the formation of undesired microstructures such as martensite and bainite. With respect to AISI 1045, four different kinds of heat treatment were analyzed and 5 steel samples were subjected to each treatment. Austenitizing temperature of 1113 K (840 °C) was employed. The first sample was quenched in water (WQ) with fast agitation in order for the whole extent, from the centre to the surface, to be formed exclusively of martensite microstructure; the second one was quenched in oil (OQ); the third and fourth samples were submitted to normalizing (N) and annealing (A) treatments, and cooled in still air. The samples of AISI 1045 were austenitized for 1 (one) minute per millimeter of thickness. After obtaining the microstructures, all the samples were examined through conventional metallographic testing, hereby undergoing sanding, polishing with diamond paste and chemical etching with a 3% nital, for subsequent analysis through optical microscopy, which aimed to identify and confirm the microstructures in each one of them. After confirming microstructures in each sample, they were first machined with a planer to adjust to desired dimensions; next, they were arranged to ensure parallelism between faces, eliminating roughness, visible irregularities, oxidations and other factors that influence ultrasonic measurements, which was performed after that. For ultrasonic characterization, the pulse echo technique and direct contact method were used to obtain ultrasonic velocity and attenuation parameters. As coupling material, SAE 15W40 lube oil was used for the longitudinal wave measurements while

honey was used for the transverse wave measurements. A Krautkramer ultrasound device (GE Inspection Technologies, USA, model USD15B) was used, connected to a 100 MHz digital oscilloscope (Tektronix, USA, model TDS3012B), which transmits the ultrasonic signals to a computer, so they can be processed. All signals were captured with 10,000 points with a sampling rate of 1 Gs/s. After acquisition, data were properly processed in order to determine ultrasonic velocities and attenuation involved. Ultrasonic velocity measurements for all samples were obtained by using commercial NDT ultrasonic transducers: three transducers for longitudinal wave measurements, one of 4 MHz (Krautkramer, Germany, model MB4S), another one of 5 MHz (Krautkramer, Germany, model MSW-QCG) and the third one of 10 MHz (Olympus, USA, model V112), and one transducer for the transverse wave measurements of 5 MHz (Valpey Fisher Corporation, USA, model SF052). The choice of these transducers was based on the authors’ previous experience in this kind of NDT and knowledge concerning the materials understudy [8, 9, 21]. For each sample, five signals with two adjacent echoes per signal were captured related to velocity measures. Next, the time between the first two echoes was measured through an echo overlapping algorithm [16]. With the wave propagation time and sample thickness values, obtained by using a micrometer at the same capture points of the ultrasound signals, it was possible to determine the average velocity of wave propagation through equation:

v=

2X , τ0

(1)

in which X is the thickness of the sample [m] and τ 0 is the time of the wave course [s] until the two adjacent echoes ( B1 and B2 ) overlap each other, and its value is determined considering: ∞

∫ B (t).B (t − τ)dt . 1

(2)

2

−∞

Although, the time measurement can be obtained directly from the oscilloscope, as previously mentioned, the echo overlapping method was used for it provides greater sensibility and maximum accuracy [16]. Ultrasonic attenuation was calculated from reduction of the amplitude of the ultrasound impulse, and quantified in terms of attenuation coefficient, α , [dB/mm] given as:

α=

A 20 log 0 , 2x A1

(3)

in which x is the sample thickness [mm], A0 is the amplitude of the first echo [dB], and A1 is the amplitude of the second echo [dB]. In order to calculate ultrasonic attenuation,

longitudinal waves with frequency of 4 and 5 MHz were considered, since the frequency of 10 MHz presented values very close to the ones from these frequencies. The modulus of elasticity (E) [GPa] and the modulus of shear (G) [GPa] were calculated based on the ASTM E 494-2005 (Measuring Ultrasonic Velocity in Materials) standard, through the equations:

E=

ρVT2 ( 3VL2 − 4VT2 )

(V

G = ρVT2 ,

2 L

− VT2 )

,

(4)

(5)

in which VL and VT are the longitudinal and transverse wave velocities [m/s], respectively, and ρ is the material density [g/cm3].

3. Results and Discussion Metallographic analysis and evaluation through optical microscopy qualitatively confirmed the microstructures of carbon steel AISI 1006, 1020 and 1080 presented in Figures 1a), 1b) and 1c), respectively. Figures 1d), 1e), 1f) and 1g) present the micrographs of AISI 1045 samples quenched in water, in oil, normalized and annealed, respectively. The micrographs presented in Figures 1a) and 1b) show typical microstructures of hypoeutectic steel AISI 1006 and 1020, respectively. These steels at room temperature are made up of proeutectoid ferrite and pearlite for the cooling temperature is close to equilibrium conditions; when the carbon content in the material gets closer to 0.77 wt.% C, the higher the quantity of ferrite the lower the carbon content and the higher the percentage of pearlite the closer it is to the eutectoid point. The AISI 1080 eutectoid steel presented an annealed pearlite microstructure when slowly cooled (inside the furnace), Figure 1c. Structural characteristics and properties of pearlite, which is formed by hardened ferrite, depend on the cooling velocity, which causes a difference in pearlite lamellar space. For this reason, pearlite is defined as thick and thin, which interferes in ultrasonic results. Thus, the smaller the lamellar space, the higher the value of ultrasonic velocity. Micrographs presented in Figures 1d) to 1g) for AISI 1045 hypoeutectoid steel samples, after heat treatment, present the expected microstructures for these steels based on the diagram of continuous cooling transformation (CCT): martensite, thin or thick

ferrite-pearlite. The martensite presented in Figure 1d) was generated from fast cooling in water with moderate agitation. As for its morphology, it is known that in alloys containing less than 0.6 wt%. C, the martensite grains are formed as parallel battens (long and thin plates) aligned in bigger structural entities called blocks. Microstructural details of martensite formed as batten are very thin and, therefore, difficult to be seen through optical microscopy. It is known that in a steel sample submitted to quenching heat treatment, the microstructures can differ significantly from the outer surface to its centre due to differences in cooling velocity, which decreases as it progresses towards the centre. When cooling velocity is enough to cause diffusion, other microcomponents can appear, like pearlite and bainite. In the case of the AISI 1045 sample submitted to heat treatment and quickly cooled in water, they were only made of martensite, as intended, Figure 1d. The microstructures expected for the samples of AISI 1045 quenched in oil, normalized and annealed are presented in Figures 1e) to 1g), respectively. The microstructural product identified was pearlite (thin or thick) plus proeutectoid ferrite. One can conclude that as the slower is the cooling, thicker is the pearlite. This means that the sample quenched in oil presents a microstructure composed of thin ferrite-pearlite, while in the annealed sample the microstructure is thick ferritepearlite, which changes the ultrasonic velocity and attenuation values of the materials. The obtained values of ultrasonic velocities related to longitudinal waves in 4, 5 and 10 MHz frequencies are presented in Figure 2a), and related to transverse waves in 5 MHz of frequency in Figure 2b), for the AISI 1045 microstructures resulting from heat treatments quenched in water (WQ) and in oil (OQ), as well as normalizing (N) and annealing (A) with cooling in the open air.

For the samples of AISI 1006, 1020, 1080 and 1045 annealed (A) and quenched in water (WQ), the values of the average longitudinal wave velocities are presented in Figure 3a), and the average transverse wave velocities in Figure 3b). The same microstructural characterization trend can be observed in these figures, in other words, the ultrasonic velocity for the sample of AISI 1045 annealed always presents the highest values, followed by the samples of normalized 1045 steels, 1045 quenched and cooled in oil, and finally, the sample of 1045 steel quenched and cooled in water forming a martensite structure with lower average ultrasonic velocity. The experimental ultrasonic velocities obtained for longitudinal and transverse waves were sensitive to microstructural variations due to heat treatments performed on samples of AISI 1045. However, they revealed to be minimally sensitive to variation of carbon content in samples of AISI 1006, 1020, 1080 and 1045 annealed and quenched in water, Figures 2 and 3. In the graphs presented in these figures, it is possible to observe the same behavior in all frequencies used, which allows us to conclude that the obtained results are reliable. Regarding the stages of AISI 1045, martensite presented the lowest ultrasonic velocity registered and thick ferrite-pearlite presented the highest. These results are in line with those obtained by Papadakis [17], Gür and Tuncer [18], and Gür and Cam [19]. For the other samples, the lowest velocity was seen in the AISI 1080 (pearlite) and the highest in AISI 1006 (ferrite) and 1020 (ferrite-pearlite), whose values are slightly higher than those found in AISI 1045 (ferrite-pearlite). Comparing ferrite (AISI 1006), pearlite (AISI 1080) and martensite (quenched in water AISI 1045) microstructures, a higher ultrasonic velocity for ferrite (5927.83 ± 4.12) can be observed, next for pearlite (5916.34 ± 1.60) and finally for martensite (5878.47 ± 2.91). These measurements were

obtained by considering longitudinal waves with 4, 5 and 10 MHz of frequency, by which a small increase in velocity for higher frequencies was verified. For transverse waves, 5 MHz frequency was considered. The lowest ultrasonic velocity verified for martensite can be explained by the great quantity of internal tension it presents, resulting from crystal lattice distortions caused by the increase in volume during the austenite-martensite transformation. The transformation of austenite into ferrite, pearlite or bainite can also cause an increase in volume, but this fact is not significant. Macro-tensions caused by thermal gradient are also minor when the geometry and the small thickness of the samples are considered. Previous studies showed that ultrasonic velocity decreases as the plastic deformation level of the material increases, due to an increase in discrepancy density [20]. According to Gür and Tuncer [18], the ultrasonic velocity in martensite is essentially affected by changes in the modulus of elastic of individual grains, in the crystal lattice distortion level and in the orientation of primary austenite grains. The ferrite structure does not have many variations in orientation of grains due to the thicker structure, and this facilitates propagation of ultrasound in this stage. The highest ultrasonic velocity is verified in thick ferrite-pearlite (AISI 1045 annealed (A)), due to a more ample space between pearlite lamella and higher quantity of ferrite. This means that in thicker stages, the velocity of ultrasound propagation will be higher. For the materials studied and the frequencies adopted, the ultrasonic measurements show that fine grain sizes led to lower ultrasonic velocity than coarse grain sizes, this was also observed by Albuquerque et al. [21]. However, the opposite behavior was reported by Palanichamy et al. [22]. Additionally, Hirsekorn in [23, 24] showed that ultrasonic velocity is not only dependent on grain size but also on

frequency. Besides the variation in terms of the grain size, ultrasonic measurements are also sensitive to the presence of new phases/precipitates resultant from thermal aging treatments [8, 9]. In addition, the type of microstructure also affects the ultrasonic measurements [11]: Martensite presents high resistance to ultrasound waves, because of its compact and fine granulation. On the other hand, pearlite presents less resistance to ultrasound waves in relation to martensite, since it is composed of ferrite and cementite. In the case of this microstructure, one can also consider fine pearlite, which exhibits small lamellar spacing, as well as the coarse pearlite that presents large lamellar spacing and consequently is lesser resistant to ultrasound waves than the fine pearlite. Finally, ferrite is the one that offers the least resistance to ultrasound waves as this microstructure presents equiaxial grain size and the largest grain size, when in comparison to martensite and pearlite. The influence of the ferrite microstructure on ultrasonic measurements was also verified during this work. Ultrasonic measurements are also directly related to the carbon content of the material understudy, and it has been commonly accepted that the higher the carbon content the lower the associate ultrasonic velocity is. Our experimental findings confirmed this behavior (Figure 3), which was also observed by Kim and Johnson in [11]. The average values of five ultrasonic attenuation measurements were considered for longitudinal waves in 4 and 5 MHz of frequency. Figure 4a shows ultrasonic attenuation results for microstructures of AISI 1045 samples after heat treatment, and Figure 4b shows the results for annealed (A) and quenched in water (WQ) AISI 1006, 1020, 1080 and 1045 samples.

Ultrasonic attenuations for different microstructures of AISI 1045 (martensite, thin and thick ferrite-pearlite) considering longitudinal waves in 4 and 5 MHz of frequency are presented in Figure 4. From this figure, it can be concluded that martensite was the most attenuating microstructure and thick ferrite-pearlite was the least. In our findings, no evident relation between ultrasonic attenuation and carbon content was observed, Figure 4b. The same difficulty to correlate ultrasonic attenuation with carbon content was observed by Bouda et al. in [25, 26]. The attenuation coefficient translates the spreading intensity of ultrasonic waves by grains in each stage, and it presented a pattern in the samples with 0.45% wt.% C, contrary to that of ultrasonic velocity in the same samples. However, these results cannot be compared because the materials were submitted to different heat treatments. Nevertheless, it should be noticed that the main purpose of this study was not to compare but to make correlations between microstructures and ultrasonic parameters. The steels were dynamically analyzed by ultrasound in order to obtain the associated modulus of elasticity and modulus of shear, according to the standard ASTM E-494-2005 based on 5 MHz of frequency, Table 1. The density values used, Table 1, are in agreement with the values found in the literature, see, for example, [27, 28, 29]. According to the aforementioned standard, the modulus of elasticity and modulus of shear obtained, through ultrasonic measurements, 1% of tolerance in their values. In order to measure attenuation intrinsic to the material, ultrasonic measurements must be performed with care, as many factors can contribute to its inaccuracy, such as beam divergence (diffraction) [7], coupling materials in the direct contact technique, unsteady pressure applied to the transducer and roughness [29]. Physical properties of the materials depend on the crystallographic direction in which the measurements were

taken. Since crystals in the metals are anisotropic, the modulus of elasticity can vary substantially depending on the direction considered. α-iron, for example, according to [6], has the following modulus of elasticity: 125.0 GPa, 210.5 GPa and 272.7 GPa for orientations [100], [110] and [111], and consequently the following average ultrasonic velocities 5440 m/s, 6190 m/s, and 6420 m/s, thus presenting a variation higher than 15%. According to Efunda [30], the modulus of elasticity for AISI 1006 to 1080 varies from 190 to 210 GPa, validating the results obtained in this study through ultrasonic measurements. The values of modulus of elasticity are also equivalent to those indicated by Kim and Johnson [31], obtained by ultrasonic resonance spectroscopy and those by Papadakis [17, 32], obtained through pulse echo ultrasound. Microstructural condition determines the elastic behavior of the material, as well as the ultrasonic velocity. A general approximation that can be used to evaluate modulus of elasticity in materials with variations in the microstructure of the tested area does not exist, due to the complexity of interactions among microstructural elements, such as the size and shape of grains, precipitations, distortions in the crystallographic lattice, pores and several types of irregularities, with ultrasonic wave propagation. The only existent procedure is based on the experimental dependence between ultrasonic velocities and respective microstructures, applied in representative samples as performed in this study.

4. Conclusions An evaluation of the potentialities of ultrasonic testing, mainly by considering ultrasonic

velocity

and

attenuation

measurements,

was

presented,

such

as

nondestructive approach for the identification of microstructures and elastic properties

in plain steels, caused by grain nucleating and growth. After detailed analysis of the results, it is possible to conclude: 1) The use of distinct carbon steel materials can provide a detailed analysis of the ultrasonic beam behavior in several material stages. The results point out that the ultrasonic parameters analyzed are sensitive to the obtained microstructures. 2) Ultrasonic velocities and attenuations indicate a good capacity to identify changes in the microstructure produced by heat treatments, but there was a minor difference in microstructures in terms of carbon content. For the analyzed steels, the ultrasonic velocity, either longitudinal or transverse waves, increased from the hardest stage (martensite) to the softest stage (ferrite) in all frequencies, while the opposite happened in ultrasonic attenuation. 3) The elastic constants (E and G) calculated from ultrasonic measurements, showed results coherent with those found in current literature obtained through dynamic and static methods. In general, the outcomes are very promising and can significantly contribute to the field of nondestructive characterization of materials and control of their mechanical properties through ultrasonic measurements.

Acknowledgments The second author thanks the financial support given by CNPq - National Counsel of Technological and Scientific Development, Brazil.

References

[1] V.H.C. de Albuquerque, J.M.R.S. Tavares, L.M.P. Durão, Journal of Composite Materials 2010. DOI: 10.1177/0021998309351244 (in press) [2] L.M.P. Durão, J.M.R.S. Tavares, V.H.C. de Albuquerque, A.T. Marques, A.G. Magalhães, A.A. Vieira, Materials and Manufacturing Processes 2010. (in Press) [3] F. Mabrouki, M. Genest, G. Shi, A. Fahr, NDT & E International. 42 (2009) 581588. [4] V.H.C. de Albuquerque, A.R. de Alexandria, P.C. Cortez, J.M.R.S. Tavares, NDT & E International. 42 (2009) 644-651. [5] V.H.C. de Albuquerque, P.C. Cortez, A.R. de Alexandria, J.M.R.S. Tavares, Nondestructive Testing and Evaluation. 23 (2008) 273-283. [6] E.P. Papadakis, Physical Acoustics. 12(1976) 277-374. [7] S.E. Krüger, J.M.A. Rebello, NDT & E International. 32 (1999) 275-281. [8] E.M. Silva, V.H.C. de Albuquerque, J.P. Leite, A.C.G. Varela, E.P. de Moura, J.M.R.S. Tavares, Materials Science and Engineering: A. 516 (2009) 126-130. [9] V.H.C. de Albuquerque, E.M. Silva, J.P. Leite, E.P. de Moura, V.L.A. Freitas, J.M.R.S. Tavares, Materials and Design. 31 (2010) 2147-2150. [10] D. Leviston, B. Bridge, NDT & E International. 21 (1988) 17-25. [11] S.A. Kim, W.L. Johnson, Materials Science and Engineering: A. 452-453 (2007) 633-639. [12] S.E. Krüger, E.B. Damm, Materials Science and Engineering: A. 425 (2006) 238243. [13] G. Lamouche, S. Bolognini, S.E. Krüger, Materials Science and Engineering: A. 370 (2004) 401-406.

[14] T. Ohtani, K. Nishiyama, S. Yoshikawa, H. Ogi, M. Hirao, Materials Science and Engineering: A. 442 (2006) 466-470. [15] E.H.F. Date, M. Atkins, G.V. Beaton, Ultrasonics. 9 (1971) 209-214. [16] ASNT 147 / 147WCD, Nondestructive Testing Handbook, Third Edition: Volume 7, Ultrasonic Testing, American Society for Nondestructive Testing, 2007. [17] E.P. Papadakis, Ultrasonic velocity and Attenuation: Measurement Methods withScientific and Industrial Applications. In: Physical Acoustics, Academic Press, New York. 12 (1977) 277-374. [18] C.H. Gür, B.O. Tuncer, Materials Characterization. 55 (2005) 160-166. [19] C.H. Gür, I. Cam, Materials Characterization. 58 (2007) 447-454. [20] R. Prasad, S. Kumar, Journal of Materials Processing and Technology. 42 (1994) 51-59. [21] V.H.C. de Albuquerque, T.A.A. Melo, D.F. de Oliveira, R.M. Gomes, J.M.R.S. Tavares, Materials & Design, DOI: 10.1016/j.matdes.2010.02.010 (in press) [22] P. Palanichamy, A. Joseph, T. Jayakumar, Baldev Raj, NDT & E International. 28 (1995) 179-185. [23] S. Hirsekorn, Journal of the Acoustical Society of America. 72(1982), 1021-1031. [24] S. Hirsekorn, Journal of the Acoustical Society of America. 73(1983), 1160-1163. [25] A.B. Bouda, S. Lebaili, A. Benchaala, NDT & E International. 36 (2003) 1-5. [26] A.B. Bouda, A. Benchaala, K. Alem, Ultrasonics. 38 (2000) 224-227. [27] AZOM

TM

. The A to Z of Materials and AZojomo.The AZo Journal of Materials

Online.

Available

at:

http://www.azom.com/Details.asp?ArticleID=2870#_Physical_Properties. Acessed in November, 2008.

[28] W.D. Callister Jr., Materials Science and Engineering: An Introduction, 7th ed., John Wiley & Sons Inc, New York, 2006. [29] N. Guo, M.K. Lim, T. Pialucha, Journal of Nondestructive Evaluation. 14 (1995) 919. [30] EFUNDA, Engineering Fundamentals. Available at: http://www.efunda.com. Accessed in September, 2008. [31] S.A. Kim, W.L. Johnson, Materials Science and Engineering: A. 452-453 (2007) 633-639. [32] E.P. Papadakis, Journal of Applied Physics. 35 (1964) 1474-1482.

FIGURE CAPTIONS Figure 1: Optical micrography of AISI samples: a) 1006, b) 1020, c) 1080, and 1045 heat treated and cooled in water d) and e) cooled in oil, normalized f) and annealed, both cooled in the open air g). (3% nital chemical etching.) Figure 2: Average ultrasonic velocity measurements for longitudinal waves with 4, 5 and 10 MHz of frequency a), and for transverse waves with 5 MHz of frequency for AISI 1045 under heat conditions b). Figure 3: Average ultrasonic velocity measurements for longitudinal waves with 4, 5 and 10 MHz of frequency a), and for transverse waves with 5 MHz of frequency for AISI 1006, 1020, 1080 and 1045 annealed (A) and quenched in water (WQ) b). Figure 4: Averages of ultrasonic attenuation for longitudinal waves with 4 and 5 MHz of frequency for AISI 1045 samples under different heat conditions and for AISI 1006, 1020, 1080 and 1045 annealed (A) a) and quenched in water (WQ) b).

TABLE CAPTION Table 1: Density value, average, minimum and maximum values of modulus of elasticity and modulus of shear of the plain carbon steels considered.

FIGURES

Figure 1

Figure 2

Figure 3

Figure 4

TABLE 1 Plain Carbon Steel

Density [g/cm3]

AISI 1006

7.86

Modulus of Elasticity [GPa]

Modulus of Shear [GPa]

212.92 212.44

82.73 82.41

211.89

81.88

212.01 AISI 1020

AISI 1045 (WQ)

AISI 1045 (OQ)

7.84

7.87

7.85

211.51

82.41 82.10

210.98

81.97

205.72

79.66

205.05

79.28 204.87

78.54

211.16

82.27

210.77

81.94 210.30

81.64

211.93 AISI 1045 (A)

7.83

211.35

82.33 82.08

210.77

81.56

211.26 AISI 1045 (N)

7.84

210.81

82.09 81.79

210.51

81.25

211.42 AISI 1080

7.85

211.12

82.48 81.95

210.84

81.52