Zinc-MagnesiumCoated Steel Sheets

Less is More

2

Contents

New Protection for Steel SheetsThinner, more resistant, environmentally friendlier ........................................ Page 3

Metallic CoatingsA success story ........................................................................................ Page 4

Properties for the FutureMore corrosion-resistant and more conserving resources ............................. Page 6

Super-Thin CoatingBig Advantages ........................................................................................ Page 9

High-Precision ProductionFinishing continuously ................................................................................ Page 10

Processing OptionsMulti-purpose and Highly Efficient .............................................................. Page 12

Application examplesConvincing in Practice ............................................................................... Page 14

Exemplary Environmental ProtectionDurable and 100-per-cent Recyclable ......................................................... Page 18

Zinc-Magnesium Coated Steel SheetLess is More ............................................................................................ Page 19

PUBLICATION INFORMATIONPublisher: Stahl-Informations-Zentrum, Postfach 10 48 42, 40039 Düsseldorf, Germany Tel.: +49 (0)211 6707-967, Fax: +49 (0)211 6707-344, E-mail: siz@stahl-info.de, Internet: www.stahl-info.deEditorial office and staff: Stahl-Informations-Zentrum together with the „Arbeitskreis organisch beschichtetesBlech und Band im Fachausschuss für Feinblech“ (Working group for organic coated sheet and strip of thetechnical committee for sheet steel), of the Materials Committee, Steel Institute VDEh

This document represents the translation of the German “Dokumentation 566: Zink-Magnesium-veredelteFeinbleche – Weniger ist mehr”, edition 2012. Reproduction of, or excerpts from this publication are onlypermitted with written consent of the Publisher and citation of the source. The information contained hasbeen carefully researched and edited. However, the Publisher assumes no liability for its contents.

Photo credits/sources: (illustrations with kind permission of) cover page, large photo: IMS Ingenieurgesell-schaft mbH, Hamburg, photographer: Rakesh Rao; cover page, column right, second photo from top aswell as page 14: Welser Profile Deutschland GmbH, Bönen; page 15 above: IMS Ingenieurgesellschaft mbH,Hamburg, photographer: Joseph Silveira; page 17 below: Kaltenbrunner GmbH, Munich; page 18 left: 123rf.de.All other photographs have been made available by members of the editorial group.

Edition 2013

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Steel Sheets made of the strongestgrades contribute to light-weight construc-tion while at the same time making designengineering safer – as evidenced in auto-mobile manufacturing, for example. Theadvantages: on the one hand, less rawmaterial is required for production, whileon the other, fuel consumption and CO2

emissions drop considerably. Significantadvances, however, are not only takingplace in terms of steel grades – the steelindustry is also developing innovative so-lutions for corrosion protection as well.

With the development of zinc-magnesium(ZM) coatings for commercial use, newlevels of performance have been achievedin technical properties, as well as in climate protection, sustainability, and efficient resource utilisation.

Zinc-magnesium coated steel sheets offernotably improved corrosion resistancecompared to conventional zinc-coatedsteel for many applications. In addition, increased protection at cut edges and atscratches is provided by its “self-healing”property. Thanks to these beneficial prop-erties, products manufactured using stripsteel coated with zinc-magnesium offerenhanced corrosion protection. Moreover,its excellent characteristics of subsurfacemigration of paint is noteworthy.

Steel strip exiting the hot-dip bath

Steel sheets with a zinc-magnesium coat-ing contribute to improving the ecologicalbottom line of steel products. This is attrib-utable to lower consumption of valuableresources and energy, simplified process-ing, and extended product life, while thematerial can be recycled with no loss inquality at the end of each life cycle.

New Protection for Steel SheetsThinner, more resistant, environmentally friendlier

4

Metallic CoatingsA success story

Although zinc-magnesium coatings werefirst introduced in 2007, the market isgrowing rapidly – with sales doubling almost annually. In fact, zinc-magnesiumcoated steel sheets represent the fastest-growing groups of steel products. This isthe preliminary peak of a success storythat began with zinc coatings about 60years ago.

Economic NecessityCorrosion – colloquially ‘rust’ – is an eco-nomic problem of huge dimensions. Reli-able estimates put damage due to rust atabout 100 billion Euros annually in Ger-many alone. The industrialised countriesare forced to spend up to four per centof their gross domestic product combat-ing corrosion damage. Whether massivesteel-beamed projects like bridges, orthin-walled components like façades outof steel sheets – without corrosion pro-tection, they would require expensive

maintenance and have short life spans.The numbers mentioned make it clearthat investments in preventative corro-sion protection are meaningful and eco-nomically worthwhile.

Continuous GalvanizingVarious grades of steel are used in mak-ing steel sheets, depending on the applica-tion involved. Different protection systemshave been developed to protect the steelfrom corrosion. In order to protect indus-trial-scale big quantities of steel sheetsfrom corrosion, one of the most impor-tant processes is continuous hot-dipping,also referred to as continuous strip galva-nizing. Instead of zinc-plating individualparts, strips are integrally provided withmetallic coatings by steel producers.

2007 2008 2009 2010 2011

100300500700900

1,1001,3001,5001,7001,9002,100Index of market growth for

zinc-magnesium coated steel

sheet (2007 = 100)

5

Tailored PropertiesZinc (Z) as a coating consists of about 99 per cent zinc and was first employedfor corrosion protection of sheet steel in 1959. Aluminium-silicon coatings (AS),using an aluminium alloy containing aboutten per cent silicon were introduced in1972 for high-performance thermal appli-cations. Zinc-aluminium coatings (ZA) fol-lowed in 1984. In addition to zinc, thesecontain about five per cent aluminium and possess excellent forming properties.Zinc-iron coatings (ZF), which are producedby diffusion annealing and usually containeight to twelve per cent iron, providinggood weldability, arrived on the marketshortly thereafter and have been employedin the automobile industry in particular.Aluminium-zinc coatings (AZ) appeared onthe market in 1988. In addition to zinc,these contain about 55 per cent alumini-um, as well as small amounts of silicon.Thanks to their even greater corrosion

Introduction of metallic

coatings in the European

markets

Coil-stock

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

Zinc-magnesium coating (ZM)

Aluminium-zinc coating (AZ)

Zinc-iron coating (ZF)

Zinc-aluminium coating (ZA)

Aluminium-silicium coating (AS)

Zinc coating (Z) 1959

1972

1984

1986

1988

2007

resistance, AZ coatings excel particularlyin non-painted condition, as required inroofing and façade applications for ex-ample. Zinc-magnesium (ZM) representsthe newest advance in metallic coatings(2007) and combines a range of espe-cially advantageous properties.

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Properties for the FutureMore corrosion-resistant and more conserving resources

In the past, there was a simple maxim: the thicker the zinc coating on steel sheet,the better the protection against corrosion.However, the increasing scarcity of rawmaterials, climbing energy prices, and the rising global requirements for environ-mental protection led to rethinking. Opti-mizing of metallic coatings for corrosionprotection was needed. The goal was challenging: improve corrosion protectionand achieve a broad range of processingproperties, while using reduced coatingthickness so that the material could beadapted and employed for as wide a rangeof end products as possible.Cross-section from samples

of zinc and zinc-magnesium

coatings

Eutectic phase of MgZn2 with Zn and Al

Paradigm ChangeWith the development of zinc-magnesiumcoatings, the steel producers have metthese challenges. Despite the reducedamount of material employed and lowerenergy expenditures in manufacture, im-proved corrosion protection with a simul-taneous reduction in the coating thicknesswas achieved for many application areas.In addition, excellent downstream process-ing properties were obtained.

Alloy CompositionThe zinc-magnesium alloy used in the coat-ing contains in addition to zinc up to eightper cent magnesium and aluminium in total. A cross-section of samples viewedunder the microscope reveals the differ-ences between zinc and zinc-magnesiumcoatings. The magnesium-aluminium ad-mixture can be recognised as darkerphases beside lighter zinc grains. Whatare the results?

Examination at the Atomic LevelThe combined action of oxygen and wateris the primary cause of corrosion. Thesurface of every metal exposed to air iscovered by a metal oxide layer. However,the thickness, chemical reactivity, andelectrical conductivity of this oxide layerare different for every metal. On alumini-

Zinc

Steel

Steel

Zinc

10 µm

10 µm

7

um, for example, this layer is inert andelectrically non-conducting. As a result,the aluminium beneath the oxide layerstays protected from corrosion. With ironand certain grades of steel, this layer iselectrically conductive. If it comes intocontact with oxygen and water in the form of condensation or rain, e.g., oxidationcontinues unimpeded into the metal be-neath the oxide layer. Put simply, rust con-tinues to eat into the material.

Half a Coating ThicknessZinc-magnesium is an optimal anti-corro-sion coating for steel. This outstandingprotection is based on the effects of twosignificant mechanisms: cathodic protec-tion and barrier effect.

The general cathodic protection affordedby a zinc-magnesium coating is compara-ble with that of a conventional zinc coat-ing. However – and this is what makes the difference – the zinc-magnesium-alu-minium alloy additionally builds up a verydense and highly ordered oxide barrierlayer against corrosion of the coated sur-face. It displays a significantly improvedbarrier effect against proceeding corro-sion. The result: only half as much coat-ing thickness is required for zinc-magne-sium compared to zinc, depending on thekind of corrosive load. In other words, itis a distinctly thinner coating – one that

Zinc and zinc-magnesium

coatings in salt spray test

Various metallic coatings

in salt spray test

nevertheless displays comparable corro-sion resistance especially in salt air envi-ronments.

Considerably Higher Corrosion ResistanceIn order to test the corrosion resistanceof materials, they are exposed to extremeconditions in the laboratory. These con-ditions, however, cannot exactly simulateall environmental conditions. In the saltspray test, galvanized steel sheet sam-ples are sprayed with a solution of tablesalt. Differences are readily apparent to the naked eye. While the zinc-coatedsamples are almost completely coveredin white rust after 48 hours, those with thezinc-magnesium coating remain almostunchanged in appearance. The first redrust appeared in the zinc coating after

Zinc Zinc-magnesium24 hours

Zinc Zinc-magnesium48 hours

Coating thickness [ µm]0

Test

dur

atio

n to

firs

t red

rust

[hou

rs]

1,000

800

600

400

200

0

5 10 15 20 25

Aluminium-zinc

Zinc-magnesium

Zinc-aluminium

Zinc

8

72 hours. In contrast, the samples withzinc-magnesium coating lasted 500 hours.That means the zinc-magnesium coatedsteel sheet samples exhibited about seventimes higher corrosion resistance in thesalt spray test for the same coating thick-ness.

Excellent Barrier EffectZinc-magnesium coatings offer an addi-tional important advantage in the unpaint-ed as well as in the painted condition. Thezinc-magnesium complex reacts at cutedges or in scratches by forming a solid

Schematic representation of

the corrosion reaction

Bright corrosion of zinc and

zinc-magnesium coatings

barrier layer. The result is that the reac-tion of oxygen and iron is slowed. Dam-ages to the surface get in effect “healed”.For painted surfaces, the subsurface migration, e.g. around scratches, is con-siderably reduced.

The improved corrosion protection ofzinc-magnesium can already meet the in-creasingly strict EU guidelines. Approvalsfor Class III corrosion protection of mate-rials in accordance with DIN 55928-8 andCorrosivity Category C3 in accordancewith DIN 55634 have been issued.

Zinc (coating thickness: 10 µm) Zinc-magnesium (coating thickness: 7 µm)336 hours

Paint

Zinc

Steel

Fe

Red rust

Fe2+

Zn

Zn2+

e –

OH – O2

Paint

Zinc-magnesium

Steel

Fe

Stable barrier layer

Zn, Mg

Zn2+, Mg2+

e –

OH – O2

Galvanized steel sheet with organic coating

Zinc-magnesium coated steel sheet with organic coating

9

Users gain a wealth of advantages withzinc-magnesium coatings – for almost consistent converting process. Depend-ing on the purpose and employment ofthe end product, different variants andnew combinations of them are availableto processors.

The Same Barrier Performancewith Thinner CoatingFor products with sufficient barrier pro-tection already, zinc-magnesium coatingsallow lower coating thickness.

At the same time, a zinc-magnesium coat-ing of the same thickness as a convention-al zinc coating enjoys significantly highercorrosion resistance. This permits proces-sors to offer products with extended life-time.

Products with Greater StiffnessWith the reduced coating thicknessmatched by the same good corrosionprotection properties, processors canchoose strip with a thicker steel substratefor the same coil weight. This means theproduct stiffness is enhanced for the sameproduct thickness.

More Square Meter of Steel Sheetsfor the Same TonnageFor products that do not have to meetregulatory approvals, a second variant isto maintain the same gauge of steel sub-strate. The total thickness of sheet is lessdue to the reduced coating thickness –and this means more square meter ofsteel sheets for the same tonnage. In thecase of common sheet gauges, this areaadvantage can run up to four per cent.

Visually Attractive as wellZinc-magnesium coated steel sheets pos-sess a homogenous, metallic, semi-matteto gloss surface.

Super-Thin CoatingBig Advantages

• Excellent corrosion performance, especially in salt air environments

• Greater flexibility in product designing and product properties with respect tocorrosion resistance

• Savings in material for the same corrosion performance

• “Self-healing” ability at cut edges andaround scratches

• Stronger surface with reduced abrasion, thereby much better formability

• For roll forming on a case-by-case basis, abstaining from lubricants, reducing clean-up effort of tools and minimisingwaste disposal

• Longer lifetime and useful lifetime of products

• Conservation of valuable resources• Environmentally-friendly and energy-

efficient production

Examples of the same

level of protection

Standard steel sheet

Variant 1: higher stiffness for thesame total sheet thickness

Variant 2: more square meter per ton of steel for the samestiffness

Overview of Advantages

Zinc

Steel

Zinc

0.02 mm

0.96 mm

0.02 mm

Zinc-magnesium

Steel

Zinc-magnesium

0.01 mm

0.98 mm

0.01 mm

Zinc-magnesium

Steel

Zinc-magnesium

0.01 mm

0.96 mm

0.01 mm

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High-Precision ProductionFinishing continuously

Zinc-magnesium coated steel sheets aremanufactured in continuous hot-dip coat-ing lines using the same process as con-ventional metallic coatings.

Continuous StripThe steel strip is delivered in coils. It isjoined by a welding machine into one continuous strip that runs through the entire coating line and is cut again intothe individual coils afterwards.

AnnealingInitially, the strip must be warmed in anannealing oven in order to set the desiredmechanical properties of the substrateduring re-crystallisation. The cold rolledhardened strip – the strip has been coldrolled before hand – acquires a softerstructure. Simultaneously, the surfacecomposition is altered and allows betterwetting in the subsequent galvanizingprocess.

GalvanizingHere, the strip proceeds through the zincpot containing the molten coating alloy.The strip is led through the zinc-magne-sium bath via guide rolls and leaves it ver-tically. The coating thickness can be setby high-precision gas knives. Integratedcontrol systems assure uniform coating.

Cooling and Temper RollingThe strip is cooled down in multistage airand water cooling zones. Subsequently, itcan be cold rolled in a skin-pass mill standfor setting the desired material propertiesand surface structure. E.g., the coatedstrip can be provided with a pre-definedsurface roughness, giving improved form-ing and painting properties lateron.

Surface TreatmentThe strip can be oiled, sealed, chemicallypassivated or gets a subsequent organiccoating. Finally, it is cut at the previousweld joins and wound again into individualcoils.

Hot-dip coating plant for manufacturing steel sheet

with zinc-magnesium coating

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Available DimensionsZinc-magnesium coated steel sheet isusually offered in thicknesses of 0.4 to3.0 mm. The available coatings run from

Strip after leaving the coating

pot and passing the gas-knives

70 to 350 g/m2, corresponding to thick-nesses of approximately 5 to 25 µm perside. The range of steel grades extendsfrom low carbon steels that can be welldeep drawn to steels with high proofstrength. The provisions contained in theGerman Steel Iron Materials (SEW) Data-sheet 022 in conjunction with DIN EN10346 apply to hot-dip steel sheet withzinc-magnesium coating.

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Processing OptionsMulti-purpose and Highly Efficient

The processing properties of zinc-magne-sium coated steel sheet are superior tothose of the standard galvanized versionin many ways. In particular, this includesminimised abrasion during forming, as the zinc-magnesium coating possesses a higher surface hardness than conven-tional zinc coatings. That reduces the expense of cleaning the facility and ex-tends the useful lifetime of the machines.

FormingThe coefficient of friction influences theforming behaviour of a material. Investi-gations have shown that the coefficient offriction for zinc-magnesium is similar to or

Roll forming: galvanized steel

sheet with lubricant (left) and

zinc-magnesium coated sheet

steel without (right)

better than that of zinc. The commonlyused forming processes require corre-spondingly just small adaptions on thetooling for zinc-magnesium.

The reduced coating thickness offersprocessors an important advantage: thinner coatings allow easier forming. Afurther benefit: in multi-stage formingprocesses, there is no cold shut betweenthe material and the forming tool thanksto the greater surface hardness of zinc-magnesium coated material.

The formation of zinc filaments is signifi-cantly reduced when roll forming zinc-mag-nesium finished sheet steel compared tozinc, also thanks to the harder surface.The material can therefore be processedfor many applications without rolling emul-sion and thus without the subsequentclean-up of the production line. That ismore economical, reduces operating andmaintenance costs, and protects the en-vironment.

WeldingResistance spot welding and laser beamwelding are the main joining techniques forthe initial stages of automotive bodyshellwork. The weldability of zinc-magnesiumis comparable to zinc for both techniques.

Test set-up: laser beam

welding an automobile inner

door panel of zinc-magnesium

coated steel sheet

13

Phosphating and paintingA well-formed phosphate layer facilitatesgood adhesion of the subsequent paintlayer. Zinc-magnesium coatings can beeasily pre-treated with typical standard

phosphating used in the automobile in-dustry. The paintability is identical to thatof a standard galvanized surface.

Zinc Zinc-magnesium

General properties• Superior surface ■ ■

• Suitable for varnishing ■ ■

• Resistance to acids ■ ■a)

• Resistance to bases ■ ■a)

• Temperature resistance ■ ■

Corrosion behaviour• Without varnish

– Surface without deformation ■ ■

– Bending shoulder ■ ■

– Cutting edge ■ ■

• Varnished, coil coated– Surface without deformation ■ ■

– Bending shoulder ■ ■

– Cutting edge ■ ■

Forming properties• (Micro) cracking ■ ■

• Abrasion ■ ■

• Best formability requested ■ ■

Joining• Spot welding ■ ■

• Soldering ■ ■

• Bonding ■ ■b)

• Mechanical joining ■ ■

Note:

The information given in this table charac -

terizes the present level of experiences and

apply for comparable product thicknesses

and coating masses. It should be considered

that the use of ZM coating offers the appli -

cation of reduced coating masses.

The given classification is not valid for all

kinds of application. In cases of doubts, the

manufacturer should be consulted for advice.

a) For use in sour or basic media, a specific

test is required for lower coating masses

considering, that depending on the require-

ment or test conditions the classification

into a better or worse class may be pos-

sible.

b) Due to excentric load path at high load

level, mild grades and/or thin steel sheets

tends to lower portions of cohesive failure

mode.

Legend:

■= especially recommended

■= recommended

■= standard

■= less appropriate

■= still to be clarified

Comparison of the properties of steel sheet with zinc and with zinc-magnesium coating

14

Application examplesConvincing in Practice

Zinc-magnesium coated steel sheet canbe employed in practically all applicationareas. The product advantages of zinc-magnesium are essential especially in acorrosive environment or for increasedprotection requirements.

Construction Components Without Organic CoatingsDue to their excellent factory-providedcorrosion resistance, zinc-magnesiumproducts are suitable for use in construc-tion areas not requiring painted substruc-tures. They can therefore be employedfor façades, solar installations, roofdrainage, scaffolding planks, pipe ductingand insulation, as arms and rollers inawnings and blinds as well as for fencing.Profiles for drywall framing made of zinc-magnesium coated steel sheet can evenbe inserted directly into moistly concrete.A good example of its capability is a roll-formed steel beam for the construction in-dustry that is manufactured from 1.5 mmthick steel sheet with the grade S250GD

Tubular steel beams of

zinc-magnesium coated

steel sheet

and with a zinc-magnesium coating of120 g/m2. It offers a convincing combina-tion of corrosion protection, cathodic pro-tection, and scratch resistance. The steelbeam thus has properties that otherwisecan only be obtained by additional coatingprocesses.

Construction Components With Organic CoatingsZinc-magnesium alloy coatings can be coilcoated with all the common organic coat-ing systems. Thanks to the high specificcorrosion resistance the coating thicknessof zinc-magnesium steel sheet, being or-ganically coil coated, can be sharply re-duced in comparison to traditional zinccoatings. ZM-coated substrates that are to be used for organic coated structuralcomponents employ coating weights of70 to 140 g/m2 as a rule. The reduceduse of zinc in this case conserves its re-sources, as normally a layer of 275 g/m2

is used. The insulation panels at India’sBharati Research Station in the Antarcticare an example of the extreme capabilityof resistance. At temperatures down to mi-nus 45 °C, extreme performance require-ments are presented to S320G+ZM140with an organic coating.

15

Vehicle Manufacturing In automotive construction, zinc-magne-sium coated steel sheet can be employedfor diverse components of the body-in-white that are subject to highly corrosive,salt-bearing loads. Practical examples aredemonstrating the advantages: in a jointresearch project, a steel producer and automobile manufacturer are developinga mud guard with a zinc-magnesium coat-ing. The investigations confirm that theweldability and behaviour of the paint areas excellent as with zinc coatings used up to now. Instead of electrolytically gal-vanized steel, zinc-magnesium coatedsteel can be used for the mud guards infuture, offering improved properties forthe product.

The driver compartment, mud guards,and roof hoops are typical applications inutility vehicles. In addition, steel sheet witha zinc-magnesium coating is suited for usein trailers and motor homes.

India’s Bharati Research Station just prior to completion: insulation panels of zinc-magnesium coated steel sheet

with organic coating fulfil the most demanding requirements, even at temperatures down to minus 45 °C.

Mud guard with zinc-magnesium coating:

weldability and paint behaviour are as

excellent as they are with conventional

zinc coatings.

16

Industrial and Housekeeping-Related ApplicationsSteel sheet with zinc-magnesium coatingis ideal for industrial hi-rise racks and other shelving systems. In these applica-tions, the material is exposed to heavymechanical loading every day and meetsthese high demands for robustness thanksto its enhanced abrasion resistance. If minor surface damages occur, such asscratching, however, “self-healing“ by thezinc-magnesium coating reduces the riskof progressive corrosion damage andthereby increases the lifetime of the rack.

In the home, zinc-magnesium profiles canbe employed in humid areas as well as fordomestic appliances that are constantlyexposed to high moisture levels, such aswashing machines or dryers.

Hi-rise rack storage:

supports and shelves of steel

sheet with zinc-magnesium

coating

Wheelbarrow basket of deep-drawn

sheet steel: a simpler grade of steel

can be used thanks to the zinc-

magnesium coating

Advantages of zinc-magnesium for garden-ing tools not only include longer storagelife of the end products, but also advan-tages during their manufacture. E.g.,wheelbarrow baskets can be producedfrom a simpler grade of steel such asDX54D+ZM140 (zinc-magnesium) insteadof from DX56D with an aluminium-zinccoating. Additionally, material coated withzinc-magnesium shows less friction in theforming tool and requires considerablyless drawing oil. The previous materialtype had to be heavily oiled to avoid crack-ing of the sheet during deep drawing.

17

Trapezoidal profile for

industrial buildings

Ventilation pipes

Parking systems

Guard rails

• Architecture and construction– Trapezoidal and panelled profiles

as well as insulation panels – Window frames– Industrial and garage doors– Scaffolding planks

• Vehicle manufacturing– Automobiles– Utility vehicles– Trailers, motor homes

• Motorway equipment – Guard rails

• Domestic appliances• Engineered homes

– Cable and ventilation ducts– HVAC– Solar installations

• Storage engineering• Device engineering

– Wheelbarrows• Agriculture

– Silo construction

Possible application for steel sheet with zinc-magnesiumcoatings

18

Exemplary Environmental ProtectionDurable and 100-per-cent Recyclable

Steel provides a significant contribution in meeting the challenges and achievingthe ambitious goals of environmental andclimate protection. Through economicsense and ecological responsibility, theconsumption of resources in steel pro-duction has been significantly reducedover the past years. In addition, steel canbe recycled as often as desired with noloss of quality and it thereby fulfils the requirements for a closed material cycle.

Greenhouse: profiles of zinc-

magnesium coated steel sheet

form the supporting construction

Innovative metallic coatings such as zinc-magnesium help to expand this positiveecological balance. The lifespan of prod-ucts manufactured from steel sheet is increased and the consumption of the respective alloying elements reduced. Of course, zinc-magnesium coated steelsheet is absolutly recyclable.

Zinc-magnesium coatings contain no hazardous materials and thus conform to European REACh chemical regulations(Registration, Evaluation, and Authorisationof Chemicals).

High-strength steel grades facilitate forexample light-weight automobile con-struction techniques that reduce vehicleweights. At the same time, new steels allow higher engine efficiencies. Both ofthese contribute to reducing fuel con-sumption and CO2 emissions of vehicles.

19

As the newest generation of metallic coat-ings, zinc-magnesium coated steel sheets(ZM) possess considerably improved cor-rosion protection. This permits coatingthicknesses to either be significantly re-duced, respectively structural componentscan be realised which exhibit extendedcorrosion protection, thereby conservingresources and protecting the environment.Improved processing properties help re-duce manufacturing costs.

Specific information about availability andusage is offered by technical representa-tives in the customer service departmentsof steel producers.

The following standards and directives apply:• DIN 55634: Paints, varnishes and coatings – Corrosion protection of supporting

thin-walled building components made of steel• DIN 55928-8 (replaced by DIN 55634): Corrosion protection of steel structures by

paints and coatings – Part 8: Corrosion protection of supporting thin-walled building components (withdrawn)

• DIN EN 10143: Continuously hot-dip coated steel sheet and strip –Tolerances on dimensions and shape

• DIN EN 10346: Continuously hot-dip coated steel flat products –Technical delivery conditions

• SEW 022: Continuously hot-dip coated steel flat products –Zinc-magnesium coatings – Technical delivery conditions

The following publications of the Stahl-Informations-Zentrum contain further information:• Characteristic Properties 093 – E: Continuously Organic Coated Steel Flat Products• Characteristic Properties 095 – E: Continuous Hot-Dip Coated Steel Strip and Sheet

Zinc-Magnesium Coated Steel SheetLess is More

Frames made from organic

coated zinc-magnesium

steel sheet for mounting

photovoltaic elements

Standards/Directives

Stahl-Informations-Zentrumim Stahl-ZentrumP.O. Box 10 48 42 · 40039 Düsseldorf, GermanySohnstrasse 65 · 40237 Düsseldorf, GermanyE-mail: siz@stahl-info.de · www.stahl-info.de