铁素体-贝氏体复相组织低碳钢的力学特性_图文

1、215Vol.21No.5 200710CHINESE JOURNAL OF MATERIALS RESEARCH October200711,21331.1100042.1100043.201900,./(I(II.,I.I400MPa,0.35.=Kn/ .,TG1421005-3093(200705-0517-06 Mechanical behaviors of a low carbon steel with a duplexmicrostructure of bainite and ferriteLI Long1DING Hua1,2WEN Jinglin2SONG Hongmei3Z

2、HANG Pijun31.School of Materials and Metallurgy,Northeastern University,Shenyang1100042.The State Key Lab.of Rolling and Automation of Northeastern University,Shenyang1100043.Baosteel Technology Center,Baoshan Iron&Steel Group Co.,Shanghai201900*Supported by National Natural Science Foundation of Ch

3、ina No.50271015.Manuscript received September10,2006;in revised form April23,2007.*To whom correspondence should be addressed,Tel:(02483687746,Email:hding ABSTRACT Controlled rolling followed by accelerated cooling process was carried out to investigate the microstructure and mechanical properties o

4、f a low carbon steel with a duplex microstructure of bainite and ferrite.The duplex microstructure may be classied as the grain boundary allotriomorphic ferrite/bainite(I typeand equiaxed ferrite and bainite(II type.The stressstrain curves were obtained by tensile testand mechanical behaviors of the

5、 tested steels were analyzed.Optical microscopy and transmission electron microscopy were used to characterized the duplex microstructures consisting of ferrite and bainite.The results show that the bainitic ferrite possesses lathshaped and there are a lot of carbides in I type matrix.The yield stre

6、ngth exceeds400MPa and work-hardening exponent is greater than0.35for the tested steel with I type structure.KEY WORDS metallic materials,low carbon steel,ferrite,bainite,work-hardening,ow stress curve,14;,5.,*No.50271015.2006910;2007423.:,6.,1,7,.P B Pickering Mo-B8,.9,10./,9,11.Mo Cr Mn,.51821/,.1

7、(,%:C0.10,Si 0.23,Mn 1.06,S 0.006,P 0.009,N 0.0016.50kg ,50mm 100mm 120mm.,612mm.Gleeble1500A r3680(5/s,ThermocalcA e3842.8.450mmTMCP (ThermoMechanical Controlled Process.1200,2h.1.(Finish rolling temperature,FRT850(A e3800(A e3A r3.,50.,3540/s.(Coiling temperature,CT500,.,INSTRON4206,5mm/min,.3.LEI

8、CA Q550IW .LEICA Q550IW.0.2mm,EM400T.22.11,/9(I,1a,(II,1b.A r3Thermocalc A e3,800A r3A e3,850A e3.(1,1Table 1Inter-pass reduction distribution in hot rolling processRolling passParameter 12345Outlet thickness/mm 35221410 6.5Rolling temperature/11001000950900,880850,800Reduction/%30.037.136.428.632.0

9、Strain0.360.460.450.340.43 1Fig.1Optical microstructures of tested steel with dierent nish rolling temperature (a850(sample1,(b800(sample 25:51921(TEMFig.2TEM micrographs of sample 1(aferrite laths,(bcarbides.(1a,850.,;,.,(GBA,(BF(2a.,Fe 3C(2b.800,24,13,.2.22,I s 420MPa,s /bII.I,(20%,.,1.II,80%,1.II

10、,.,.dd=0(1(1,.,1dd1.1dd./4.,3HSLA/(DP12.HSLADP3.3,2Table 2Mechanical properties of controlled rolling and accelerated cooling plate steelWork-hardening MicrostructureSample FRT/CT/s /MPa b /MPa s /b 5/%exponent n ln K type 1850490510428.1532.20.8023.00.3720.0017.1110.003I 2(Longitudinal337.7456.50.7

11、438.00.3840.001 6.9240.002II 2(Transverse800500520347.8470.70.7434.50.3540.0016.9250.002II520 21DP12of controlled rolling and accelerated cooling plate steelAl Ps/MPab/MPa5/%0.030.009416661280.050.008566642 23.231ddFig.3Relationship between1ddandof dierentsteel412Fig.4Stress versus strain curves of

12、the tested steel with I and II type microstructure/,1ddHSLA DP.,1dd.4,I II1dd,.(=Kn(2 ,K;n.n u=u.n u,n u.,n n=d ln/d lnp:n.n0.1650.225,n0.110.12,DP n0.180.20,0.2612,/n0.38( 2,n3;/0.3714(HSLAn(0.36 .II,(;,.,12.,.2.34,I(1 ,II(2.12.I,(2,;II,I,.5(2.5,I II ,.,5:5215Fig.5Comparison with measured and calcu

13、lated re-sults ofow stress of the tested steels(aItype(sample1,(bII type(sample2,longi-tudinal,(cII type(sample2,transverse.,.,(2.3,.A e3,/;A e3A r3,./,0.35.1 B.Q.Han,S.Yue,Processing of ultrane ferrite steels,Journal of Materials Processing Technology,136, 100(20032P.J.Hurley,P.D.Hodgson,Formation

14、of ultra-ne fer-rite in hot rolled strip:potential mechanisms for grain renement,Materials Science and Engineering,302A, 206(20013Z.Q.Sun,W.Y.Yang,J.J.Qi, A.M.Hu,Deformation en-hanced transformation and dynamic recrystallization of ferrite in a low carbon steel during multipass hot deforma-tion,Mate

15、rials Science and Engineering,334A,201(2002 4CUI Wenfang,LIU Chunming,WU Jianghua,Formation of ultrane ferrite in low-carbon steels,Chinese Journal of Materials Research,20(3,240(2006(,20(3,240(20065W ANG Guodong,LIU Xianghua,LI Weijuan,DU Linxiu, ZHANG Hongmei,Industrial rolling trials of super-SS4

16、00 steel,Iron and Steel,36(5,39(2001(,Super-SS400,36(5,39(20016YANG Ping,CHANG Shouhai,CUI Fenge,SUN Zuqing, Orientational characteristics of ferrite during strain en-hanced transformation in a Q235plain carbon steel,Chi-nese Journal of Materials Research,16(3,251(2002(,Q235,16(3,251(20027H.Ding,L.L

17、i,C.Z.Yang,D.Sun,L.X.Du,Microstructures of an ultrane grained SS400steel in an industrial scale, J.Mater.Sci.Technol.,22(2,145(20068F ANG Hongsheng,ZHENG Yankang,HUANG Jinfeng, BO Xiangzheng,Prospect of bainitic steels,Metal Heat Treatment,(7,11(1998(,(7,11(19989P.G.Xu, B.Z.Bai,H.S.Fang,Z.J.Wang,J.P

18、.Wang, Y.K.Pan,Development of grain boundary allotriomorphic ferrite/granular bainite duplex steel,Journal of University of Science and Technology Beijing,10(2,39(200310K.Hussain,R.R.De Los Rios,Microstructural eect on tensile and fatigue behaviour of C-Mn steel,Journal of Materials Science,32,3565(199711XU Pingguang,F ANG Hongsheng,BAI Bingzhe,YANG Zhigang,Toughness of Grain Boundary Allotriomorphic Ferrite/Granular Bainite Duple