Developments in Zinc Coatings
Benefiting Various End Use Applications MetalBulletin 20th Galvanizing & Coil Coating Conference, Istanbul September 2015 Esko Kauppinen, SSAB Europe
Contents ►About SSAB ►Alternative zinc coatings for innovative coated products ►Which coating properties give benefit to various end user needs ►Summary
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SSAB – global, highly-specialized steel company 3
SSAB in brief ►Nordic and US-based steel company with a global reach ►Leading producer of Advanced High Strength Steels (AHSS) and Quenched & Tempered steels (Q&T), standard strip, plate and tubular products as well as construction solutions ►About 17,000 employees in 50 countries ►Steel production facilities in Sweden, Finland and the US ►Annual steel production capacity of 8.8 million tonnes
►Structured across five divisions: • SSAB Special Steels, SSAB Europe, SSAB Americas, Tibnor, Ruukki Construction
►Listed on the Nasdaq OMX Stockholm and secondary listing on Nasdaq OMX Helsinki
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This is where we come from 1878 Domnarvets Järnverk, Borlänge
1914 Oxelösunds Järnverk AB
1940 Norrbottens Järnverk, Luleå 5
1956 IPSCO
1978 2007 Domnarvets SSAB acquires Järnverk, IPSCO Oxelösunds Järnverk AB and Norrbottens Järnverk become SSAB
1980 1960 1976 Tibnor becomes Rautaruukki Tibnor part of SSAB
2014 SSAB and Ruukki merge into one company
Steel production facilities in the Nordics & US 1
Luleå – employees 1,200
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Steel-making SSAB Europe
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Employees: 500 Heavy plate mill Scrap based EAF production R&D Centre
Raahe – employees 2,800 Steel-making, heavy plates and strip products, SSAB Europe
Hämeenlinna – employees 900 Coated strip products and tubes SSAB Europe
Montpelier, Iowa
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Mobile, Alabama Employees: 600 Heavy plate mill Scrap based EAF production Q&T lines
4 Borlänge – employees 2,100 Strip products SSAB Europe 1 2
5 Oxelösund – employees 2,300 Steel-making, heavy plates SSAB Special Steels
Strong globally and locally More than 50 countries of sales coverage
SSAB production sites Sales coverage
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Contents ►About SSAB ►Alternative zinc coatings for innovative coated products ►Which coating properties give benefit to various end user needs ►Summary
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WHY HDG? LIFE-CYCLE COST
Constant development since early 20th century Product name examples ”Magizinc, Magnelis, Corrender, Stroncoat, Superdyma” ”Galvalume” ”Galvannealed” ”Galfan” ”Alusi”
Source: Thomas Koll, 18th MetalBulletin Galvanizing & Coil coating conference
Alternative zinc coatings
Continuously and batch galvanized pure zinc (Z) Continuous
Lead containing zinc
Cross-section, batch
50…80 µm
Cross-section, contiuous 7…40 µm
Top view, lead-free zinc
Batch
►Continuously galvanized has the widest availability & applicability with uniform quality in cost effective package ►Batch galvanizing protects also the edges and gives the thickest coating layer
Alternative zinc coatings
Zinc alloy coatings Galfan (ZA) and ZnMg (ZM) with wide applicability Galfan
Top view, Galfan
ZnMg Top view, ZnMg
Cross-section Cross-section
► Galfan has excellent corrosion resistance – can double the time until red-rust vs. Zinc and beat corrosion resistance of ZnMg in real life corrosion environment ► Interest in ZnMg has risen in Europe aided by superior results in widely used accelerated corrosion tests
Alternative zinc coatings
Zinc alloy coatings Galvannealed (ZF) and (AZ) for selected applications Galvannealed
AZ Top view, AZ
Top & SEM view, ZF SEM cross-section
► Galvannealed is the standard material for car manufacturers in Japan – thanks to easy processability (galling, weldability) and paintability vs. regular zinc (Z) − Big market penetration never seen in European automotive market
► AZ is widely used in the US & Asia as CC substrate but seen as niche in Europe
CORROSION Resistance to corrosion is usually the 1st argument for or against a metallic coating – How do we measure it?
Corrosion categories for zinc CORROSION ENVIRONMENT
FIELD STATION FOR TESTING
CORROSION CATEGORY
Rural
Ryda (Sweden)
C2
Urban
Stockholm (Sweden)
C2
Marine
Bohus Malmön (Sweden) Brest (France)
C3
Industrial
Jianjing (China)
C4
Laboratory environment
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C5
C4 occasionally exists in Europe in marine or industrial environment, but it is uncommon
Cut edge protection Five years of outdoor exposure in Jiangjing, China, corrosion category C4, show no difference in cut edge protection between galvanized, Galfan and ZnAlMg coatings.
Galvanized Z275
Galfan ZA255
ZnAlMg ZM275
Thickness loss p.a. for Galfan and ZnMg is similar – approximately 1.3-2.5 times smaller than HDG
Accelerated salt spray tests (ISO 9227, ASTM B 117) It’s widely known among corrosion scientists that no correlation exists between performance in salt spray and outdoor conditions…why?
A CONSTANT HIGH HUMIDITY
A CONSTANT HIGH TEMPERATURE
VERY HIGH SALT CONCENTRATION
In reality, there is a great variation. Testing conditions alter the chemical reactions and the corrosion products.
Accelerated salt spray tests – Zinc vs. ZnMg
Source: European Comission, AUTOCOAT-Project Final Report, ref. EUR 26323
Seeing is believing… ZnMgAl coatings are up to 20 times better than galvanized coating in salt spray tests.
Appearance of a galvanized panel after testing in salt spray.
Appearance of a galvanized lamp pole after many years of outdoor use.
Vast difference in surface appearence when comparing samples exposed to salt spray test and outdoor exposure due to different chemical reactions.
Appearance of 50 years old galvanized roof in finnish countryside
Quotes
”The well-known ASTM B-117 salt spray test provides a comparison of cold rolled and galvanized steel within several hundred hours. Unfortunately, the salt spray test is unable to predict the well-known superior corrosion resistance of galvanized relative to uncoated rolled steel sheet.” Towsend, HE. ”Development of an Improved Laboratory Corrosion Test by the Automotive and Steel Industries”, Proceedings of the 4th Annual ESD Advanced Coating Conference, Dearborn, USA, 1994
Contents ►About SSAB ►Alternative zinc coatings for innovative coated products ►Which coating properties give benefit to various end user needs ►Summary
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Automotive
Alternative zinc coatings for Automotive ►Technical development and changing customer needs have revealed different demand drivers for alternative zinc coatings over decades ►Corrosion protection ►Cost efficiency
►Rise of Electro-galvanized
►Rise of HDG
►Availability ►Productivity
►Rise of Galvannealed in Asia Source: Nippon Steel News No.308. 10/2003
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ZnMg using now mainly same arguments as ► Galvannealed in Asia in the 80’s
Construction and infrastructure construction
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Sener – Solar thermal power solutions PRODUCT •
Structural parts for a 50MW solar heating plant with cylindrical parabolic collectors
CHALLENGE • • • •
Old structures were mainly assembled on site More pre-fabrication Reduced weight Good corrosion resistance
SOLUTION •
High Strength Steel + Galfan
BENEFITS • • • • •
Excellent corrosion resistance Improved precision in steel parts due to Lower weight More efficient production and logistics Technical education of personnel and support in product development from SSAB engineers
Araj– Silos with highly polished finish PRODUCT •
Silos for grain storage and drying facilities
CHALLENGE • • • •
Develop larger silos Find a reliable long-term supplier Silos need to be resistant to severe weather conditions Surface appearance need to be uniform in color and gloss
SOLUTION •
High Strength Steel + Galfan
BENEFITS • • • •
Excellent corrosion resistance Increased strength of the silo shells Nice shiny surface of the silos Increased capacity of the silo
Light engineering
Gazdevice – Galfan saves time PRODUCT •
Gas meter used to calculate the consumption of natural gas for private use
CHALLENGE • • •
Reduce costs by substituting electro galvanizing at remote production site with process with ready coated steel Heavy duty deep drawing and bending involved Good corrosion resistance needed
SOLUTION •
Substitute electro galvanizing of parts made of cold rolled steel with Galfan deep drawing grade
BENEFITS • • • • •
Excellent corrosion resistance Advanced deep drawing without micro cracks in the metal coating Shorter lead time since parts were not send away for galvanizing Improved control of qualite since everything is made in-house Reduce costs
Bobicompany – A more durable letterbox PRODUCT •
Letterboxes
CHALLENGE • • • •
Good corrosion resistance required Smooth, high quality appearance Welding a bottleneck in production Production • Maintenance of welding electrodes • Grinding time consuming and generated dust and noise
SOLUTION •
Change from galvanized to Galvannealed
BENEFITS • • • •
Improved surface appearance Improved corrosion resistance Earlier, welding tips were changed every third box, now series of 1.0001.500 boxes can be produced without need for change No need of grinding which result in less dust and noise in production
Batch Galvanizing Substitution
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Batch galvanizing process steps
PACKING
LOADING
TRANSPORT
UNPACKING
BATCH GALVANIZING
QUALITY CONTROL
PACKING
LOADING
TRANSPORT BACK
UNLOADING
UNPACKING
Substitution in infrastructure ►One main argument for batch galvanizing is the cut edge protection ►Important to notice that after longer exposure time the main failure mode of continuously galvanized is linear degradation ► The Finnish Transport Agency has approved following coatings to be used in poles for traffic signs − Batch galvanized 55 µm Zinc − Continuous galvanized 42 µm Zinc (Z600) − Aluzinc 25 µm (AZ185)
Z600
Batch galvanized
Contents ►About SSAB ►Alternative zinc coatings for innovative coated products ►Which coating properties give benefit to various end user needs ►Summary
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Improved competitive advantage with Galfan Longer life of products
Excellent corrosion resistance compared to zinc coated steel
Possibilities to make advanced forming
Excellent forming properties compared to zinc coated steel
v
More attractive appearance of painted products - Best painted surface
Excellent paintability
v
Longer life of painted products
Very good corrosion resistance as painted
v
Reduced welding costs
Longer electrode life and low galling on electrodes Reduced or no need for improving appearence of welds before painting
v
Reduced laser cutting costs
Good laser cutting properties
v
Improved competitive advantage with Galvannealed
More efficient forming and punching
No need for cleaning of tools due to galling on tool surface
Improved competitive advantage by substitution Improving competitive advantage by substituting batch galvanizing with Galfan or thick zinc layer, Z450 or Z600
Reduced production costs
Continuous galvanized steel shortens production lead-time due to reduced number of production steps
Reduced material costs
Continuous galvanizing is a more cost efficient production method compared batch galvanizing and total cost is lower
Long life of products
Thick zinc coating, Z450, Z600 or Galfan coatings give a very good corrosion resistance in normal environments
Rust Never Sleeps
• Salt spray testing cannot predict the corrosion rate in outdoor environments. • Only by testing in real conditions relevant and reliable corrosion data can be obtained.
SUMMARY ► Variety of zinc alloy coatings exist on market – often with overlapping technical properties and demand drivers ► So far zinc alloy coatings (ZM, ZA, ZF, AZ) exist only on niche markets − Geocraphic, application or technological ► Zinc magnesium is the first possible candidate in decades trying to break away from the niche ”stamp” 38
LIFE-CYCLE COST