【英文标准名称】:StandardTestMethodforTensileStrain-HardeningExponents(n-Values)ofMetallicSheetMaterials
【原文标准名称】:金属薄板材拉伸应变硬化指数(n值)的标准试验方法
【标准号】:ASTME646-2007
【标准状态】:现行
【国别】:
【发布日期】:2007
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E28.02
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:指数;机械测试;金属;薄板材;拉伸应变;测试
【英文主题词】:
【摘要】:Thistestmethodisusefulforestimatingthestrainattheonsetofneckinginauniaxialtensiontest(1).Practically,itprovidesanempiricalparameterforappraisingtherelativestretchformabilityofsimilarmetallicsystems.Thestrain-hardeningexponentisalsoameasureoftheincreaseinstrengthofamaterialduetoplasticdeformation.Thestrain-hardeningexponentmaybedeterminedovertheentireplasticstress-straincurveoranyportion(s)ofthestress-straincurvespecifiedinaproductspecification.Note38212;Thestraininterval10x2013;20%iscommonlyutilizedfordeterminingthen-valueofformablelowcarbonsteelproducts.Thistestmethodisnotintendedtoapplytoanyportionofthetrue-stressversustrue-straincurvethatexhibitsdiscontinuousbehavior;however,themethodmaybeappliedbycurve-smoothingtechniquesasagreedupon.Note48212;Forexample,thoseportionsofthestress-straincurvesformildsteeloraluminumalloyswhichexhibityield-pointelongationorLuuml;dersbandsmaybecharacterizedasbehavingdiscontinuously.Note58212;Cautionshouldbeobservedintheuseofcurve-smoothingtechniquesastheymayaffectthen-value.Thistestmethodissuitablefordeterminingthetensilestress-strainresponseofmetallicsheetmaterialsintheplasticregionpriortotheonsetofnecking.Then-valuemayvarywiththedisplacementrateorstrainrateused,dependingonthemetalandtesttemperature.1.1Thistestmethodcoversthedeterminationofastrain-hardeningexponentbytensiontestingofmetallicsheetmaterialsforwhichplastic-flowbehaviorobeysthepowercurvegivenintheIntroduction.Note18212;Asinglepowercurvemaynotfittheentirestress-straincurvebetweenyieldandnecking.Ifsuchisthecase,morethanonevalueofthestrain-hardeningexponentcanbeobtained(2).1.2Thistestmethodisformetallicsheetmaterialswiththicknessesofatleast0.005in.(0.13mm)butnotgreaterthan0.25in.(6.4mm).1.3Thevaluesstatedininch-poundunitsaretoberegardedasthestandard.TheSIequivalentsshownmaybeapproximate.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.
【中国标准分类号】:H22
【国际标准分类号】:77_140_50
【页数】:9P.;A4
【正文语种】: