含磷高强IF汽车钢的应变硬化及微观结构特征
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摘要
为了研究含磷高强IF汽车用钢应变硬化特性与微观结构特征,借助万能拉伸试验机测试试验钢的应力-应变曲线,利用光学显微镜、扫描电子显微镜附件电子背散射衍射仪、透射电子显微镜等分析试验钢的组织、织构、滑移带及位错结构等。结果表明,添加质量分数0.056%磷的高强IF钢冷轧板在810℃退火120 s以后,得到多边形铁素体晶粒,屈服强度为212 MPa,抗拉强度为367.5 MPa,塑性应变比r值为2.45,应变硬化指数n为0.28。{111}面织构体积分数达到65%。钢中有极少纳米析出相Ti C及尺寸较大的Mn S与Ti_4C_2S_2析出相。应变量从0.5%增加到11%,位错密度增大,位错结构形态有位错线、蜂窝状位错与梯形位错等。
In order to research the strain hardening characteristic of high strength IF bearing phosphorus,the stress-strain curve is measured by tensile testing machine and the microstructure,textile,slip band,dislocation are analyzed by optical microscope,scanning electron microscope,transmission electron microscope respectively. The results showed that the polygonal ferrite grain were obtained of the high strength IF steel bearing 0.056% phosphorus annealed at 810 ℃ for 120 s. The yield strength of the high strength IF steel bearing was 212 MPa and tensile strength was 367.5 MPa. The plastic strain ratio r was 2.45 and the strain hardening index n was 0.28. The volume fraction of {111} plane texture was 65%. There are a small quantity of nano-size precipitates of Ti C and bigger Mn S and Ti_4C_2S_2. The dislocation density increased when the strain increasing from 0.5% to 11% and the dislocation structure was dislocation lines,cellular dislocation and trapezoidal dislocation.
In order to research the strain hardening characteristic of high strength IF bearing phosphorus,the stress-strain curve is measured by tensile testing machine and the microstructure,textile,slip band,dislocation are analyzed by optical microscope,scanning electron microscope,transmission electron microscope respectively. The results showed that the polygonal ferrite grain were obtained of the high strength IF steel bearing 0.056% phosphorus annealed at 810 ℃ for 120 s. The yield strength of the high strength IF steel bearing was 212 MPa and tensile strength was 367.5 MPa. The plastic strain ratio r was 2.45 and the strain hardening index n was 0.28. The volume fraction of {111} plane texture was 65%. There are a small quantity of nano-size precipitates of Ti C and bigger Mn S and Ti_4C_2S_2. The dislocation density increased when the strain increasing from 0.5% to 11% and the dislocation structure was dislocation lines,cellular dislocation and trapezoidal dislocation.
引文
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[2]王畅,于洋,刘珂,等.含磷高强IF钢热轧轧裂的形成原因及控制[J].中国冶金,2016,26(1):17.(WANG Chang,YUYang,LIU Ke,et al.Forming reason and control of strip fracture in high strength IF steel containing phosphorus during hotrolling process[J].China Metallurgy,2016,26(1):17.)
[3]SONG X L,YUAN Z X,JUAN J,et al,Phosphorus segregation behavior at the grain boundary in a Ti-IF steel after annealing[J].Scripta Materialia,2010,63:446.
[4]SONG Xin-li,PENG Kun,YUAN Ze-xi,et al.Texture,grain boundary characterization and segregation of phosphorus in an annealinginterstitial free steel[J].Journal of Iron and Steel Research,International,2014,21(9):844.
[5]Yasuhara E,Sakata K,Kato T.Effect of boron on the resistance to secondary working embrittlement in extra-low-C cold-rolled steel sheet[J].ISIJ International,1994,34(1):99.
[6]SONG Xin-li,YUAN Ze-xi,JUAN Jia,et al.Boron and phosphorus segregation behavior at grain boundary in a Ti-IF steel after annealing[J].Advanced Material Research,2011,152/153:320.
[7]李峰,吕家舜,敖列哥,等,连续退火工艺对Nb-Ti-IF钢性能及再结晶织构的影响[J].钢铁,2008,43(1):64.(LI Feng,LU?Jia-shun,AO Lie-ge,et al.Influence of continuous annealing on properties and recrystallization texture of Nb-Ti-IF steel[J].Iron and Steel,2008,43(1):64.)
[8]Quadir M Z.A microstructure study of the origins ofγrecrystallization texture in 75%warm rolled IF steel[J].Acta Materialia,2006,54(16):4337.
[9]Saha R,Ray R K.Texture and grain growth characteristics in a boron added interstitial free steel after cold rolling and annealing[J].Materials Science and Engineering:A,2010,527(7/8):1882.
[10]Speich G R,Miller R L.In Structure and Properties of Dual Phase Steels[M].New York:AIME,1979.
[11]刘国勋.金属学原理[M].北京:冶金工业出版社,1980.(LIUGuo-xun.Principle of Metals[M].Beijing:Metallurgical Industry Press,1980.)
[12]李春光,蒋光锐,章军,等.深冲IF钢应变硬化指数n值研究[C]//全国轧钢生产技术会议.无锡:中国金属学会,2014:544.(LI Chun-guang,JIANG Guang-rui,ZHANG Jun,et al.Study on the n value of the steel strain hardening index of deep impact IF steel[C]//National Rolling Steel Production Technology Conference.Wuxi:The Chinese Society for Metals,2014:544.)
[13]李龙,丁桦,杜林秀,等,低碳铁素体贝氏体复相钢的拉伸应力-应变曲线分析[J].材料热处理学报,2007,28(5):46.(LILong,DING Hua,DU Lin-xiu,et al.Analysis of stress-strain curves by tensile test in low carbon steel with a duplex microstructure of bainite and ferrite[J].Transactions of Materials and Heat Treatment,2007,28(5):46.)
[14]余海燕,周辰晓,沈嘉怡.应变硬化指数模型及其在汽车前纵梁成形和回弹防真中的应用[J].汽车工程,2016,38(6):772.(YU Hai-yan,ZHOU Chen-xiao,SHEN Jia-yi.Strain hardening index model and its application to the forming and springback simulation of a front side rail[J].Automotive Engineering,2016,38(6):772.)
[15]亢占英,郑建平.热镀锌双相钢应变硬化特性研究[J].宝钢技术,2015(2):32.(KANG Zhan-ying,ZHENG Jian-ping.Study of strain hardening characteristic of hot dip galvanized dualphase steel[J].Bao Steel Technology,2015(2):32.)
[16]余永宁.金属学原理[M].北京:冶金工业出版社,2003.(YUYong-ning.Principles of Metallography[M].Beijing:Metallurgical Industry Press,2003.)