1、Designation:F232814Standard Test Method forDetermining Decarburization and Carburization in Hardenedand Tempered Threaded Steel Bolts,Screws,Studs,andNuts1This standard is issued under the fixed designation F2328;the number immediately following the designation indicates the year oforiginal adoption
2、 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 p
3、resence of decarburizationand carburization in the threaded section of hardened andtempered inch series 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 ar
4、e intentionally carburizedto achieve specific results.1.2 Two routine methods are described for measuring thelimits of and determining the presence of decarburization orcarburizationthe optical method and the microindentationmethod 1.Either method is appropriate for routine examina-tions.The microin
5、dentation method 2 shall be considered thereferee method.1.3 For the purpose of these tests,there are four classes ofhardened and tempered steel products for which specificmeasurements must be made with respect to their physicalproperties.1.4 The values stated in inch-pound units are to be regardeda
6、s standard.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 ap
7、plica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E3 Guide for Preparation of Metallographic SpecimensE384 Test Method for Knoop and Vickers Hardness ofMaterialsF1789 Terminology for F16 Mechanical Fasteners3.Terminology3.1 Definitions:3.1.1 carburizationp
8、rocess 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 com
9、pletedecarburization,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 insuf
10、ficient 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 w
11、hile heat treating threadedsteel products.Too much of either will adversely affect thesafety and performance of the threaded product.Therefore,limits have been established for three different product groups:the harder and greater the tensile strength of the product,themore susceptible to failure the
12、 product becomes if these limitsare exceeded.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 deficien
13、cies,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.1This test method is under the jurisdiction of ASTM Committee F16 onFasteners and is the direct responsibility of S
14、ubcommittee F16.01 on Test Methods.Current edition approved Aug.1,2014.Published September 2014.Originallyapproved in 2004.Last previous edition approved in 2011 as F2328 05(2011).DOI:10.1520/F2328-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service
15、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.Unite
16、d States1 4.3.1 Because an evaluation at a specific location may notbe representative of the whole part,the referee method em-ploys the microindentation method taken as an average ofevaluations conducted on four adjacent threads.This proceduresignificantly reduces the random test variables when comparedto testing on a single thread.4.4 Specifying this test method does not specify or implythat testing shall be for either decarburization or carburizationalone or for both conditions.When either tes
