1、Designation:F194007a(Reapproved 2014)Standard Test Method forProcess Control Verification to Prevent HydrogenEmbrittlement in Plated or Coated Fasteners1This standard is issued under the fixed designation F1940;the number immediately following the designation indicates the year oforiginal adoption o
2、r,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 test method covers a procedure to prevent,to theextent possible,internal hydroge
3、n embrittlement(IHE)offasteners by monitoring the plating or coating process,such asthose described in Specifications F1137 and F1941.Theprocess is quantitatively monitored on a periodic basis with aminimum number of specimens as compared to qualifying eachlot of fasteners being plated or coated.Tre
4、nd analysis is used toensure quality as compared to statistical sampling analysis ofeach lot of fasteners.This test method consists of a mechanicaltest for the evaluation and control of the potential for IHE thatmay arise from various sources of hydrogen in a plating orcoating process.1.2 This test
5、method consists of a mechanical test,con-ducted on a standard specimen used as a witness,for theevaluation and control of the potential for IHE that may arisefrom various sources of hydrogen in a plating or coatingprocess.1.3 This test method is limited to evaluating hydrogeninduced embrittlement du
6、e only to processing(IHE)and notdue to environmental exposure(EHE,see Test Method F1624).1.4 This test method is not intended to measure the relativesusceptibility of steels to either IHE or EHE.1.5 This test method is limited to evaluating processes usedfor plating or coating ferrous fasteners.1.6
7、This test method uses a notched square bar specimenthat conforms to Test Method F519,Type 1e,except that theradius is increased to accommodate the deposition of a largerrange of platings and coatings.For the background on TestMethod F519 testing,see publications ASTM STP 5432andASTM STP 962.3The str
8、ess concentration factor is at a Kt=3.1 6 0.2.The sensitivity is demonstrated with a constantimposed cathodic potential to control the amount of hydrogen.Both the sensitivity and the baseline for residual hydrogen willbe established with tests on bare metal specimens in air.1.7 The sensitivity of ea
9、ch lot of specimens to IHE shall bedemonstrated.A specimen made of AISI E4340 steel heattreated to a hardness range of 50 to 52 HRC is used to producea“worst case”condition and maximize sensitivity to IHE.1.8The test is an accelerated(24 h)test method tomeasure the threshold for hydrogen stress crac
10、king,and is usedto quantify the amount of residual hydrogen in the specimen.The specimen undergoes sustained load and slow strain ratetesting by using incremental loads and hold times underdisplacement control to measure a threshold stress in anaccelerated manner in accordance with Test Method F1624
11、.1.9 In this test method,bending is used instead of tensionbecause it produces the maximum local limit load tensile stressin a notched bar of up to 2.3 times the yield strength asmeasured in accordance with Test Method E8/E8M.A fastenerthat is unintentionally exposed to bending on installation mayat
12、tain this maximum local tensile stress.1.10 The values stated in inch-pound units are to be re-garded as standard.The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered standard.1.11 This standard does not purport to addre
13、ss all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:4D1193 Specification
14、 for Reagent WaterE4 Practices for Force Verification of Testing MachinesE8/E8M Test Methods for Tension Testing of Metallic Ma-terials1This test method is under the jurisdiction of ASTM Committee F16 onFasteners and is the direct responsibility of Subcommittee F16.93 on QualityAssurance Provisions
15、for Fasteners.Current edition approved Aug.1,2014.Published November 2014.Originallypublished as approved in 1998.Last previous edition approved in 2007 asF1940 07a.DOI:10.1520/F1940-07AR14.2Hydrogen Embrittlement Testing,ASTM STP 543,American Society forTesting and Materials,1974.3Hydrogen Embrittl
16、ement;Prevention and Control,ASTM STP 962,AmericanSociety for Testing and Materials,1985.4For 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 International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 E18 Test Methods for Rockwell Hardness of Metallic Ma-terialsE29 Pr
