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1、第35卷第9期北京科技大學(xué)學(xué)報(bào)Vb1.35NO.92013年9月JournalofUniversityofScienceandTechnologyBeijingSep.2013回火溫度對(duì)淬火后30MnB5熱成形鋼組織與性能影響程俊業(yè),趙愛民函,陳銀莉,汪志剛,曹佳麗北京科技大學(xué)冶金工程研究院,北京100083囟通信作者,E—mail:aimin.zhao@ustb.edu.ca摘要將30MnB5熱成形鋼進(jìn)行淬火和回火處理,利用掃描電鏡、透射電鏡、能譜儀和拉伸性能檢測(cè)等方法研究了不同回火溫度后的顯微組織和力學(xué)性能變化.經(jīng)200℃保溫2min回火后熱
2、成形鋼的綜合力學(xué)性能最佳,抗拉強(qiáng)度為1774MPa,總伸長(zhǎng)率為8%,強(qiáng)塑積達(dá)14GPa-%以上,該性能滿足熱成形后作為汽車結(jié)構(gòu)件的使用要求;并且隨著回火溫度的升高,力學(xué)性能呈非單調(diào)性變化.200℃低溫回火后,主要為板條馬氏體和£碳化物,位錯(cuò)密度略有降低,析出的E碳化物粒子呈針狀分布在馬氏體板條內(nèi),長(zhǎng)度方向大小為i00nm左右,并與位錯(cuò)發(fā)生釘扎作用.隨著回火溫度的升高,板條馬氏體發(fā)生回復(fù)和再結(jié)晶,板條邊界逐漸模糊,并向等軸狀鐵素體轉(zhuǎn)變,位錯(cuò)密度顯著降低,£碳化物逐漸向低能態(tài)的近球形滲碳體轉(zhuǎn)變并粗化至200nm左右,對(duì)位錯(cuò)的釘扎作用也隨之減弱.關(guān)鍵詞
3、熱成形鋼;回火;碳化物;微觀組織;力學(xué)性能分類號(hào)TG156.5;TG142.1Efectoftemperingtemperatureonthemicrostructureandmechan—icalpropertiesof30MnB5hotstampingsteelafterquenchingCHENGYun—ye,ZHAOAi—min函,CHEN佗.1i,WANGZhi—gang,Cao0一liMetallurgicalEngineeringResearchInstitute,UniversityofScienceandTechnologyBe
4、ijing,Beijing100083,China函Correspondingauthor,E—mail:aimin.zhao@ustb.edu.cnABSTRACT30MnB5hotstampingsteelwasquenchedandtemperedatdiferenttemperatures.Theefectsoftem—peringtemperatureonthemicrostructureandmechanicalpropertieswereinvestigatedbyscanningelectronmicroscopy,transmi
5、ssionelectronmicroscopy,energydispersivespectroscopy,andtensiletesting.Thebestmechanicalpropertieswereobtainedafterthesteelbeingtemperedat200℃for2min,whicharethetensilestrengthof1774MPa,thetotalelongationof8%,andtheproductoftensilestrengthandelongationmorethan14GPa·%.Itcanmee
6、ttherequire—mentforautomotivestructuralpartsafterhotstamping.Themechanicalpropertiesnon—monotonicallychangewithtemperingtemperature.Themicrostructureofthesteeltemperedat200℃islathmartensiteandE-carbides.a(chǎn)ndthedislocationdensitydecreasesslightly.TheE-carbideparticleswiththesiz
7、eofabout100nminlengthareneedle—likedistributedinmartensitelathsandpinnedwithdislocations.Whenthetemperingtemperatureincreases,therecoveryandrecrystallizationoflathmartensiteoccur,thelathboundarybecomesmoreandmoreobscure,andthedislocationdensitydecreasessharply.Furthermore,som
8、eofthelathmartensitetransformsintoequiaxedferrite,andthe£·carbidesgr