ASTM_B_849_-_02_2013.pdf

Designation:B84902(Reapproved 2013)Standard Specification forPre-Treatments of Iron or Steel for Reducing Risk ofHydrogen Embrittlement1This standard is issued under the fixed designation B849;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.INTRODUCTIONWhen atomic hydrogen enters steels and certain other metals,for example,aluminum and titaniumalloys,it can cause a loss of ductility,load carrying ability,or cracking(usually as submicroscopiccracks)as well as catastrophic brittle failures at applied stresses well below the yield strength or eventhe normal design strength for the alloys.This phenomenon often occurs in alloys that show nosignificant loss in ductility,when measured by conventional tensile tests,and is referred to frequentlyas hydrogen-induced delayed brittle failure,hydrogen stress cracking,or hydrogen embrittlement.Thehydrogen can be introduced during cleaning,pickling,phosphating,electroplating,autocatalyticprocesses,porcelain enameling,and in the service environment as a result of cathodic protectionreactions or corrosion reactions.Hydrogen can also be introduced during fabrication,for example,during roll forming,machining,and drilling,due to the breakdown of unsuitable lubricants as well asduring welding or brazing operations.Parts that have been machined,ground,cold-formed,orcold-straightened subsequent to hardening heat treatment are especially susceptible to hydrogenembrittlement damage.The results of research work indicate that the susceptibility of any material to hydrogenembrittlement in a given test is related directly to its trap population.The time-temperaturerelationship of the heat treatment is therefore dependent on the composition and structure of steels aswell as plating metals and plating procedures.Additionally,for most high-strength steels,theeffectiveness of the heat treatment falls off rapidly with a reduction of time and temperature.1.Scope1.1 This specification covers procedures for reducing thesusceptibility or degree of susceptibility to hydrogen embrittle-ment or degradation that may arise in electroplating,autocata-lytic plating,porcelain enameling,chemical conversioncoating,and phosphating and the associated pretreatmentprocesses.This specification is applicable to those steels whoseproperties are not affected adversely by baking at 190 to 230Cor higher(see 6.1.1).1.2 The heat treatment procedures established herein havebeen shown to be effective for reducing the susceptibility ofsteel parts of tensile strength 1000 MPa or greater that havebeen machined,ground,cold-formed,or cold-straightenedsubsequent to heat treatment.This heat-treatment procedure isused prior to any operation capable of hydrogen charging theparts,such as the cleaning procedures prior to electroplating,autocatalytic plating,porcelain enameling,and other chemicalcoating operations.NOTE11 MPa=145.1 psi.1.3 This specification has been coordinated with ISO/DIS9587 and is technically equivalent.1.4 The values stated in SI units are to be regarded as thestandard.2.Referenced Documents2.1 ASTM Standards:2A919 Terminology Relating to Heat Treatment of Metals(Withdrawn 1999)3B242 Guide for Preparation of High-Carbon Steel for Elec-troplating1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.02 on Pre Treatment.Current edition approved May 1,2013.Published May 2013.Originallyapproved in 1994.Last previous edition approved in 2007 as B849 02(2007).DOI:10.1520/B0849-02R13.2For 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 B322 Guide for Cleaning Metals Prior to ElectroplatingB374 Terminology Relating to ElectroplatingB851 Specification for Automated Controlled Shot Peeningof Metallic Articles Prior to Nickel,Autocatalytic Nickel,or Chromium Plating,or as Final Finish2.2 ISO Standards:ISO2080 ElectroplatingandRelatedProcessesVocabulary4ISO/DIS 9587 Pre-Treatments of Iron or Steel for Reducingthe Risk of Hydrogen Embrittlement42.3 Federal Standard:QQ-C-320 Chromium Plating(Electrodeposited)53.Terminology3.1 DefinitionsMany of the terms used in this specifica-tion can be found in Terminology B374,A919,or ISO 2080.4.Requirements4.1 Heat treatment shall be performed on basis metals toreduce the risk of hydrogen embrittlement in accordance withTable 1.The duration of heat treatment shall commence in all