1、Designation:A384/A384M07(Reapproved 2013)Standard Practice forSafeguarding Against Warpage and Distortion During Hot-Dip Galvanizing of Steel Assemblies1This standard is issued under the fixed designation A384/A384M;the number immediately following the designation indicates the yearof original adopt
2、ion or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 Steel assemblies and subassemblies fabricated bywelding,such as composite struc
3、tural members,sash,weldments,etc.,that are to be hot-dip galvanized afterfabrication,are subject to warpage and distortion of thematerial due to the heating and cooling integral to the galva-nizing operation,particularly when it is necessary for theassembly to be dipped more than once to coat the en
4、tiresurface.1.2 This specification is applicable in either inch pounds orSI units.Inch pounds and SI units are not necessarily exactequivalents.Within the text of this specification and whereappropriate,SI units are shown in parentheses.2.Referenced Documents2.1 ASTM Standards:2A143/A143M Practice f
5、or Safeguarding Against Embrittle-ment of Hot-Dip Galvanized Structural Steel Products andProcedure for Detecting EmbrittlementA385 Practice for Providing High-Quality Zinc Coatings(Hot-Dip)A780 Practice for Repair of Damaged and Uncoated Areasof Hot-Dip Galvanized Coatings3.Factors in Warpage and D
6、istortion3.1 One of the most commonly distorted and warped mem-bers of assemblies is that of sheets or plates from No.20 gage0.812 mm to14in.6.35 mm in thickness which areassembled by welding or riveting to bar-size shapes,angles,channels,tees,etc.The sheets or plates have residual stressfrom the we
7、lding or riveting as well as stress from rollingoperations to bring the sheet or plate to its final thickness.Asthe sheet or plate is heated to galvanizing temperature,820 to850F(438 to 454C),the stress can be slightly relieved but theconstraint of the framing does not allow the stresses to becomple
8、tely relieved.The stress relief is minimal and,thus,theinternal stress level of the sheet or plate compounds because ofthe addition of the contraction forces.When the fabricationcools after galvanizing,the framing also restricts the contrac-tion of the sheet or plate further increasing internal stre
9、sses.Ifthe warpage or distortion is minimal,the fabrication may beacceptable but,if the distortion is significant,the fabricationmay need to be reworked with the sheet or plate attached to theframe after hot-dip galvanizing.3.2 Warpage is accentuated by the use of nonsymmetricalsections such as chan
10、nels.Regardless of size,channels that aregalvanized by themselves often require straightening aftergalvanizing.This is not true of an I-beam,pipe,H-column,orany other section that is symmetrical about both its major axes.Channels and other nonsymmetrical sections should be avoidedfor the framework o
11、f a sheet metal assembly that is to behot-dip galvanized whenever it is possible to use symmetricalshapes or sections as framing pieces.3.2.1 Checkered plate may also warp or distort duringgalvanizing due to the asymmetry of the plate design.Since allof the deformations are on one side of the plate,
12、the residualstress from fabricating the checkered plate may cause warpageor distortion.This may be accentuated by attaching checkeredplate to a frame before hot-dip galvanizing.3.3 The use of wide radii bends in corners is recommended.In the case of sheet metal,the product that has a right-anglebend
13、 in the sheet metal itself will remain flatter and be freerfrom distortion if the radius of the bend is as large as practical.For extremely tight bends that are integral to the fabrication,stress relieving in accordance with the section on Cold Work-ing and Thermal Treatment of Practice A143/A143M i
14、s rec-ommended to avoid warpage or distortion.3.4 Certainweldingpractices,weldsizesandconfigurations,and thickness differences between welded com-ponents can introduce imbalanced stresses into the weldments.If these stresses are combined with other stresses duringhot-dip galvanizing,the stress relie
15、ving effect of galvanizingmay permit distortion to occur.1This practice is under the jurisdiction of ASTM Committee A05 on Metallic-Coated Iron and Steel Products and is the direct responsibility of SubcommitteeA05.13 on Structural Shapes and Hardware Specifications.Current edition approved May 1,20
16、13.Published May 2013.Originallyapproved in 1955.Last previous edition approved in 2007 as A384/A384M-07.This practice is based upon the work of the Technical Services Committee of theAmerican Galvanizers Association.DOI:10.1520/A0384_A0384M-07R13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM Int
