ASTM_G_101_-_04_2015.pdf

Designation:G10104(Reapproved 2015)Standard Guide forEstimating the Atmospheric Corrosion Resistance of Low-Alloy Steels1This standard is issued under the fixed designation G101;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This guide presents two methods for estimating theatmospheric corrosion resistance of low-alloy weatheringsteels,such as those described in Specifications A242/A242M,A588/A588M,A606 Type 4,A709/A709M grades 50W,HPS70W,and 100W,A852/A852M,and A871/A871M.Onemethod gives an estimate of the long-term thickness loss of asteel at a specific site based on results of short-term tests.Theother gives an estimate of relative corrosion resistance basedon chemical composition.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.2.Referenced Documents2.1 ASTM Standards:2A242/A242M Specification for High-Strength Low-AlloyStructural SteelA588/A588M Specification for High-Strength Low-AlloyStructural Steel,up to 50 ksi 345 MPa Minimum YieldPoint,with Atmospheric Corrosion ResistanceA606 Specification for Steel,Sheet and Strip,High-Strength,Low-Alloy,Hot-Rolled and Cold-Rolled,withImproved Atmospheric Corrosion ResistanceA709/A709M Specification for Structural Steel for BridgesA852/A852M Specification for Quenched and TemperedLow-Alloy Structural Steel Plate with 70 ksi 485 MPaMinimum Yield Strength to 4 in.100 mm Thick(With-drawn 2010)3A871/A871M Specification for High-Strength Low-AlloyStructural Steel Plate With Atmospheric Corrosion Resis-tanceG1 Practice for Preparing,Cleaning,and Evaluating Corro-sion Test SpecimensG16 Guide for Applying Statistics to Analysis of CorrosionDataG50 Practice for Conducting Atmospheric Corrosion Testson Metals3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 low-alloy steelsiron-carbon alloys containinggreater than 1.0%but less than 5.0%,by mass,total alloyingelements.3.1.1.1 DiscussionMost“low-alloy weathering steels”contain additions of both chromium and copper,and may alsocontain additions of silicon,nickel,phosphorus,or otheralloying elements which enhance atmospheric corrosion resis-tance.4.Summary of Guide4.1 In this guide,two general methods are presented forestimating the atmospheric corrosion resistance of low-alloyweathering steels.These are not alternative methods;eachmethod is intended for a specific purpose,as outlined in 5.2 and5.3.4.1.1 The first method utilizes linear regression analysis ofshort-term atmospheric corrosion data to enable prediction oflong-term performance by an extrapolation method.4.1.2 The second method utilizes predictive equations basedon the steel composition to calculate indices of atmosphericcorrosion resistance.5.Significance and Use5.1 In the past,ASTM specifications for low-alloy weath-ering steels,such as Specifications A242/A242M,A588/A588M,A606 Type 4,A709/A709M Grade 50W,HPS 70W,and 100W,A852/A852M,and A871/A871M stated that theatmospheric corrosion resistance of these steels is“approxi-mately two times that of carbon structural steel with copper.”Afootnote in the specifications stated that“two times carbonstructural steel with copper is equivalent to four times carbon1This guide is under the jurisdiction of ASTM Committee G01 on Corrosion ofMetals and is the direct responsibility of Subcommittee G01.04 on AtmosphericCorrosion.Current edition approved Nov.1,2015.Published December 2015.Originallyapproved in 1989.Last previous edition approved in 2010 as G10104(2010).DOI:10.1520/G0101-04R15.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 structural steel without copper(Cu 0.02 maximum).”Becausesuch statements relating the corrosion resistance of weatheringsteels to that of other steels are imprecise and,moreimportantly,lack significance to the user(1 and 2)4,the presentguide was prepared to describe more meaningful methods ofestimating the atmospheric corrosion resistance of weatheringsteels.5.2 The first method of this guide is intended for use inestimating the expected long-term atmospheric corrosionlosses of specific grades of low-alloy steels in variousenvironments,utilizing existing short-term atmospheric corro-sion data for these grades of steel.5.3 The second method of this guide is intended for use inestimating the relative atmospheric corrosion resistance of aspecific heat of low-alloy steel,based on i