GALVALUME Sheet Carbon Steel Specs

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GALVALUME Sheet Carbon Steel Specs

Transcript of GALVALUME Sheet Carbon Steel Specs

  • USS Galvalume sheet is a cold rolledsteel sheet with a coating of analuminum -zinc-silicon alloy, applied bythe continuous hot-dip process. Thecoating gives Galvalume steel sheet thebest properties of aluminum -coatedand galvanized steel sheets.

    The presence of aluminum in thealuminum -zinc alloy coating providesimproved barrier corrosion resistanceand heat reflectivity to the cold rolledsteel substrate . The addition of zincprovides a high level of galvanic pro-tection against corrosion at cut edges,cracks and scratches.

    Galvalume 's surface has a small,uniform spangle and a smooth , brightappearance that makes it attractivewhen used for exposed unpaintedapplications.

    Long -term economyBecause of the two-way protectionafforded by the aluminim-zinc coating,Galvalume sheet offers at least twice theservice life of galvanized steel with thesame coating thickness. In some areas,the service life is extended three to fourtimes. This has been verified by actualatmospheric exposure corrosion testsconducted over a period of more than 17years in environmental conditions rangingfrom rural to severe marine atmospheres.These test results are much more signifi-cant than laboratory accelerated testsbecause they show the performance in thesame environments as those encounteredin actual service. Observations on testpanels exposed for as long as 21 yearssubstantiate the fact that Galvalume offerslong term durability.

    USS Galvalume costs about the same,on a per-square-foot basis, as USS G-90galvanized sheet. Therefore, because itlasts longer, Galvalume is a low cost-per-year alternative to other coated sheet.

    a. Galvalume Coating Cross-Section

    b. Modernized exit end of the Galvalume coating lineat the USS Irvin plant near Pittsburgh. The line's new

    features give USS Galvalume a competitive edge inoverall product quality.

    Galvalume is a trademark ofBethlehem Steel Corp.

    Convenient availability-Irvin PlantUSS makes Galvalume sheet on one ofthe three coating lines at its Irvin Plantsheet-processing facility. The IrvinGalvalume line is equipped with moderncoating equipment and its workers haveyears of production experience with zincand aluminum coating. Located in thePittsburgh area, Irvin provides a conven-ient shipping point for Galvalume sheet.

    USS Galvalume sheet is available insteel thicknesses from 0.015 inch to0.052 inch, in widths to 48 inches, withyield strength levels to 80 ksi. (minimum)Two surface finishes are available:regular spangle (small, uniform brightspangle) and extra-smooth (matte finishfor applications where critical surfacefinish is desired).

    Triple Spot TestCoating Minimum oz./ft2 (g/m2)Designation (total both sides)

    Al-rich area

    Zn-rich area

    Alloy bond layerSteel

    Coating thickness

    USS offers two coating weights for mostapplications, 0.50 ounce per square foot(150 g/m2) and 0.55 ounce per squarefoot (165 g/m2) as shown in the chartbelow. Designations for these coatingsare AZ50 and AZ55, respectively. TheAZ55 coating is specified for unpaintedmetal buildings. The AZ50 coating, whichhas a thickness approximately equivalentto a G90 galvanized coating, is recom-mended for prepainted metal buildingapplications, and most other applications.Lighter coating weights are available forspecial applications that require enhancedformability or weldability.

    Single Spot TestMinimum oz ./ft2 (g/m2) Thickness, mil(total both sides) (per side)

  • USS Galvalume sheetqualities (ASTM A792)Commercial QualityGalvalume steel of this quality is intendedprimarily for bending and moderate form-ing applications. Typical applicationsinclude overhead doors, toaster partsand walk-in cooler panels.

    Lock Forming QualityGalvalume sheet of this quality is intendedprimarily for use in fabrication where thematerial will be subjected to lock formingor other bending operations that involvesmall bend radii. High speed forming andthe tight bends involved in lock formingimpose severe requirements-in excessof the formability requirements ofCommercial Quality-on both the basemetal and the coating. Typical applicationsinclude ductwork, downspouts, trim partsand brackets.

    Structural(Physical) QualityASTM A792

    * None specified

    M

    Structural (Physical ) QualityUSS Galvalume steel sheet of this qualityis intended for use where load-bearingcapability is a consideration in design.It is provided to meet specified mechanicaltest properties including yield strength,tensile strength and elongation. The mini-mum mechanical property requirementsof the various grades when specified toASTM A792 are shown in the table below.Typical applications include metal buildingroofing and siding.

    ASTM A792 Specification - Mechanical Properties

    Yield StrengthMinimum

    Tensile StrengthMinimum

    Grade (ksi) MPa (ksi) MPa33 33 230 45 31037 37 255 52 36040 40 275 55 38050A 50 345 65 45050 B 50 34580 80 550 82 570

    Elongationin 50 mm (2")Minimum %

    2018161212

    c. In-line tension leveler provides unsurpasseduniform flatness for.better appearance in yourfinished products.

    d. Operators' console includes a microprocessor-based controller to regulate the new tension leveler.

    e. Galvalume coil, ready for shipping.

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    71

  • Corrosion resistanceUSS Galvalume's unique coating compo-sition of aluminum and zinc offers superiorcorrosion resistance.

    Long -term durabilityThe aluminum causes the Galvalumecoating to behave somewhat like analuminum coated steel in that it helps toform an insoluble oxide film on the surfaceof the coating. This film shields both thecoating and the steel from water and air.In this way it provides not only long-termprotection of the steel but also protectionagainst excessive corrosion of the coatingitself.

    Surface protectionUnless otherwise specified, USSGalvalume sheet is chemically treated(passivated) and oiled with a vanishingoil to prevent the formation of storagestains. When properly passivated,USS Galvalume sheet is significantlymore resistant to storage staining thangalvanized sheet.

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    Cut edge protection

    The zinc causes the Galvalume coatingto behave somewhat like a zinc (galvan-ized) coating. On exposure to water ormoisture, the zinc in the Galvalumecoating enters into an electrochemicalreaction with exposed steel at a cut edge,crack or other break in the coating. Thisreaction is the critical feature that inhibitscorrosion of exposed steel.

    Best all-aroundcorrosion protectionThe result is long-term performance. USSoffers its customers a limited 20-year,6-month warranty against rupture, perfora-tion or structural failure due to corrosionwhen Galvalume sheet is used in roofingor siding applications, exposed to normalatmospheric conditions.

    USS Galvalume sheet's combinedprotection of aluminum and zinc has beenshown to provide a minimum of twice thecorrosion resistance-in most atmosphericenvironments-and as much as four timesin some environments than galvanizedsteel having the same coating thickness.

    This superior performance has beendemonstrated by exposure tests con-ducted in a wide range of environments,as shown in the chart below.

    Atmospheric corrosion losses of Galvalume steeland galvanized steel after 13 years ' exposure 30to horizontal (average top and bottom surface).Coating Loss (m)

    25.0

    22.5

    2.5

    0 (Severe Marine) (Marine)

    Edge appearance of coated sheets after 13-yGalvanized (G90)

    Galvanized(G90)

    (Industrial)

    Galvalume(AZ50)

    (Rural)

    ear industrial exposure.Galvalume (AZ55)

  • Prepainted GALVALUME SHEET

    USS Prepainted Galvalume combines asuperior paint system with the excep-tional corrosion resistance of thealuminum -zinc alloy coating. Thecombination provides a prepaintedsheet product that has long -term dura-bility not previously attainable. Thisnew standard of durability is the basisfor the USS 20 -year , 6-month limitedwarranty against substrate perforationfor Prepainted Galvalume.

    USS Prepainted Galvalume sheet hasthe same range of attractive colors andfinishes as other coated steel products.For Prepainted Galvalume, the two-coatpaint system includes primers formulatedspecifically for Galvalume to minimizeedge creep and improve adhesion of thetop coat paint film. In addition, USSPrepainted Galvalume receives a chromatepretreatment on the coil-coating line to

    further improve corrosion resistance.These steps along with rigorously con-trolled processing practices and qualitycontrol on the coil paint lines result in ahigh-performance prepainted steel sheet.

    Today's Prepainted Galvalume andprepainted galvanized sheet exhibit com-parable rates of edge creep on the basisof accelerated corrosion tests and severalyears atmospheric exposure.

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    Experience shows that PrepaintedGalvalume offers distinct advantagesover prepainted galvanized steel: Better overall paint adhesion during roll

    forming. Less crazing of the paint at bends, thus

    reducing the amount of direct contactof the aluminum-zinc coating and steelwith corrosive media.

    Less chance of storage staining at jobsites.

    Improved corrosion protection at paint-damaged areas.These advantages-combined with the

    improved paint systems and processingdevelopments-make new PrepaintedGalvalume an outstanding product formetal buildings.

  • GALVALUME SHEET...

    Compatibility withother materialsMost of the fabrication and buildingmaterials used with galvanized steelcan be used with Galvalume steel.

    Avoid lead and copper. These twometals will react with Galvalume as theydo with galvanized sheet and can resultin accelerated corrosion of the coatingwherever contact is made. Avoid use oflead-such as lead nails, lead washersand lead flashing. Contact with copperand water runoff from copper flashi