ASTM_F_2328M_-_14.pdf

Designation:F2328M14Standard Test Method forDetermining Decarburization and Carburization in Hardenedand Tempered Threaded Steel Bolts,Screws,Studs,andNuts(Metric)1This standard is issued under the fixed designation F2328M;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.Scope*1.1 This test method covers procedures for measuring,classifying,and determining the presence of decarburizationand carburization in the threaded section of hardened andtempered metric steel bolts,screws,studs,nuts and similarparts which have been heated to facilitate fabrication or tomodify their mechanical properties.This test method is notintended to address products which are intentionally carburizedto achieve specific results.1.2 Two routine methods are described for measuring thelimits of and determining the presence of decarburization orcarburization;the Optical Method and the MicroindentationMethod 1.Either method is appropriate for routine examina-tions.The Microindentation Method 2 shall be considered thereferee method.1.3 For the purpose of these tests,there are five classes ofhardened and tempered steel products for which specificmeasurements must be made with respect to their physicalproperties.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address 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:2A574M Specification for Alloy Steel Socket-Head CapScrews(Metric)E3 Guide for Preparation of Metallographic SpecimensE384 Test Method for Knoop and Vickers Hardness ofMaterialsF835M Specification for Alloy Steel Socket Button and FlatCountersunk Head Cap Screws(Metric)F912M Specification for Alloy Steel Socket Set Screws(Metric)F1789 Terminology for F16 Mechanical Fasteners3.Terminology3.1 Definitions:3.1.1 carburizationprocess or result of increasing thecarbon content of the surface layers of the steel fastenerproduct.3.1.2 decarburizationin accordance with TerminologyF1789,is a loss of carbon from the surface layer of the fastener,normally associated with heat treatment.3.1.3 gross decarburizationalso known as completedecarburization,is characterized by a sufficient carbon loss toshow only clearly defined ferrite grains.3.1.4 partial decarburizationcharacterized as a loss ofcarbon sufficient to cause a lighter shade of tempered marten-site than that of the immediately adjacent base metal,but asbeing of insufficient carbon loss to show clearly defined ferritegrains.4.Significance and Use4.1 Decarburization and carburization are two surface con-ditions created,either intentionally or unintentionally,as witha pre-existing condition created during the rod rolling process,the rod/wire annealing process,or while heat treating threadedsteel products.Too much of either will adversely affect thesafety and performance of the threaded product.Therefore,limits have been established for four different product groups:the harder and greater the tensile strength of the product,themore susceptible to failure the product becomes if these limitsare exceeded.1This test method is under the jurisdiction of ASTM Committee F16 onFasteners and is the direct responsibility of Subcommittee F16.01 on Test Methods.Current edition approved Aug.1,2014.Published September 2014.Originallyapproved in 2004.Last previous edition approved in 2014 as F2328M 07(2014).DOI:10.1520/F2328M-14.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.2 When testing to a particular product specification thatlists the dimensions and microindentation data to be used,thatdata shall take precedence over the tables in this test method.4.3 There are only two viable methods available to detectthese deficiencies:either by the visual method or the microin-dentation method.Both methods are used for routine inspec-tions when evaluations are conducted at a single location on theproduct sample.Because an evaluation at a specific locationmay not be representative of the whole part,the referee methodemploys the microindentation method taken as an average ofevaluations conducted on four adjacent threads.This proceduresignificantly reduces random test variables whe