v-ti微合金化貝氏體非調(diào)質(zhì)鋼再結(jié)晶奧氏體連續(xù)冷卻轉(zhuǎn)變

1、VTiVTi微合金化貝氏體非調(diào)質(zhì)鋼再結(jié)晶微合金化貝氏體非調(diào)質(zhì)鋼再結(jié)晶奧氏體連續(xù)冷卻轉(zhuǎn)變奧氏體連續(xù)冷卻轉(zhuǎn)變宋雪雁荊天輔劉文昌鄭煬曾鄧茂琦(東北重型機(jī)械學(xué)院)(長(zhǎng)春鋼鐵總廠)摘要用壓力膨脹儀測(cè)試了一種VTi微合金化貝氏體非調(diào)質(zhì)鋼熱變形后再結(jié)晶奧氏體的連續(xù)冷卻轉(zhuǎn)變動(dòng)力學(xué)曲線，并分析了轉(zhuǎn)變產(chǎn)物的顯微組織。實(shí)驗(yàn)表明，熱變形后該鋼不發(fā)生先共析鐵素體轉(zhuǎn)變的臨界冷卻速度為0.15℃s。在2～0.03℃s很寬的冷卻速度范圍內(nèi)，貝氏體相變溫度在480℃左右

2、。所得到的貝氏體形貌為無(wú)碳化物貝氏體鐵素體與殘余奧氏體平行排列的板條狀結(jié)構(gòu)；各種冷卻速度下所得的組織均可見少量TiN質(zhì)點(diǎn)，當(dāng)冷卻速度大于2℃s時(shí)，組織中無(wú)細(xì)微碳、氮化釩質(zhì)點(diǎn)析出。關(guān)鍵詞關(guān)鍵詞微合金化貝氏體連續(xù)冷卻轉(zhuǎn)變CONTINUOUSCOOLINGTRANSFMATIONOFRECRYSTALLIZEDAUSTENITEFAVTiMICROALLOYEDBAINITEFGINGSTEELSONGXueyanJINGTianfuLIUW

3、enchangZHENGYangzeng(NtheastHeavyMachineryInstitute)DENGMaoqi(ChangchunIronSteelComplex)ABSTRACTTheCCTdiagramoftherecrystallizedaustenitehasbeendeterminedfaVTimicroalloyedbainitefgingsteel.Themicrostructureofthespecimenc

4、ooledunderdifferentconditionswereanalyzed.Itisshownthatthecriticalcoolingratetoavoidproeutectoidferritefrmationis0.15℃s.Atthecoolingraterangingfrom2to0.03℃stheBstemperatureisabout480℃theCCTdiagramhasaflattop.Thelathlikec

5、arbidefreeferriteretainedaustenitehasbeenobservedbytransmissionelectronmicroscope.ThesizeofTiNprecipitesislessthat50nmfineVcarbonitrideshavenotbeenobservedwhenthecoolingrateisgreaterthan2℃s.KEYWDSmicroalloysteelbainiteco

6、ntinuouscoolingtransfmation與鐵素體—珠光體非調(diào)質(zhì)鋼相比，貝氏體非調(diào)質(zhì)鋼具有更優(yōu)良的強(qiáng)韌性配合。采用微合金化和適當(dāng)?shù)能堉乒に囬_發(fā)貝氏體非調(diào)質(zhì)鋼具有實(shí)際和理論意義，VTi復(fù)合微合金化鋼的再結(jié)晶控軋控冷新工藝是10多年來(lái)冶金工業(yè)重要的進(jìn)展之一。本文研究了一種VTi復(fù)合加入硅、錳的貝氏體鋼，分析了其熱變形后再結(jié)晶奧氏體的連續(xù)冷卻轉(zhuǎn)變動(dòng)力學(xué)及圖2CCT曲線Fig.2TheCCTdiagram表1CCT圖中不同冷速下的硬

7、度及組織Table1VariationofhardnessmicrostructurewithdifferentcoolingconditionsintheCCTdiagram編號(hào)1234567v℃s1155210.50.10.03HV463449393367347312296組織MMMB少量MBB少量FBFB2.22.2連續(xù)冷卻轉(zhuǎn)變所得的組織形貌對(duì)CCT圖中各冷速下的試樣進(jìn)行光學(xué)顯微組織觀察，其結(jié)果見圖3。圖3不同冷卻速度試樣的金相組