卷取温度对热轧高扩孔钢FB590组织及性能的影响
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摘要
通过光学显微镜、扫描电镜、透射电镜和拉伸试验机等设备,研究了卷取温度对首钢热轧高扩孔钢FB590组织、拉伸性能、扩孔率的影响。结果表明,卷取温度可显著改变高扩孔钢FB590基体组织类型、铁素体晶粒尺寸及强化相Nb C形态。随着卷取温度的降低,屈服强度及扩孔率升高。通过组织观察发现,较高的卷取温度促进了珠光体生成。低温卷取时基体组织为铁素体和粒状贝氏体双相组织,铁素体晶粒尺寸较小,且强化相Nb C细小弥散分布,铁素体基体屈服强度显著提高,缩小了铁素体相与贝氏体相间的硬度差进而提高了扩孔率。
Effects of coiling temperature on microstructure,tensile properties and hole expansion rate of Shougang hot rolled hole expansion steel FB590 were studied by optical microscope,scanning electron microscope,transmission electron microscope and tensile testing.The results show that the microstructure,the grain size of ferrite and the strengthening phase Nb C morphology of FB590 change significantly under different coiling temperatures. With the decrease of coiling temperature,the yield strength and the hole expansion rate increase.It is found that higher coiling temperature promotes the formation of pearlite. Under low coiling temperature the matrix structures are ferrite and granular bainite,the ferrite has small grain size,the enhanced phase Nb C is small and distributes dispersively,the yield strength of the ferritic matrix increases significantly,and the hardness difference between ferrite phase and bainite phase is reduced and the hole expansion rate is improved.
Effects of coiling temperature on microstructure,tensile properties and hole expansion rate of Shougang hot rolled hole expansion steel FB590 were studied by optical microscope,scanning electron microscope,transmission electron microscope and tensile testing.The results show that the microstructure,the grain size of ferrite and the strengthening phase Nb C morphology of FB590 change significantly under different coiling temperatures. With the decrease of coiling temperature,the yield strength and the hole expansion rate increase.It is found that higher coiling temperature promotes the formation of pearlite. Under low coiling temperature the matrix structures are ferrite and granular bainite,the ferrite has small grain size,the enhanced phase Nb C is small and distributes dispersively,the yield strength of the ferritic matrix increases significantly,and the hardness difference between ferrite phase and bainite phase is reduced and the hole expansion rate is improved.
引文
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[2]郭子峰,冯军,白永立,等.首钢汽车结构用热轧酸洗带钢SAPH440的开发[J].锻压技术,2015,40(2):60-64.GUO Zifeng,FENG Jun,BAI Yongli,et al. Development of hotrolled and pickled strip steel SAPH440 for automobile structure of Shougang[J]. Forging&Stamping Technology, 2015, 40(2):60-64.
[3]庞厚君,段宏伟. 60 kg汽车用热轧高扩孔钢生产与应用[J].宝钢技术,2012,(2):41-45.PANG Houjun,DUAN Hongwei. Production and application of hot-rolled high hole-expansion steel(60 kg grade)for automobile[J]. Bao-Steel Technology,2012,(2):41-45.
[4]李久茂,陈新平,牛超,第二代先进高强钢TWIP钢在车身典型零件上的应用[J].锻压技术,2017,42(9):46-50.LI Jiumao,CHEN Xinping,NIU Chao. Application of the second generation AHSS of TWIP steel for typical automobile parts[J].Forging&Stamping Technology. 2017,42(9):46-50.
[5]刘大海,许钢碧,常春. DP780高强钢板温热成形极限图及其计算模型[J].塑性工程学报,2017,24(2):192-197.LIU Dahai,XU Gangbi,CHANG Chun. Forming limit diagram and its calculation model for DP780 high strength steel sheet at elevated temperatures[J]. Journal of Plasticity Engineering,2017,24(2):192-197.
[6]杜飞,夏琴香,肖华,等. DP600高强钢板杯形件单道次拉深旋压成形质量分析[J].锻压技术,2017,42(1):54-59.DU Fei,XIA Qinxiang,XIAO Hua,et al. Analysis on forming quality of high strength steel DP600 cup-shaped part during singlepass deep drawing spinning[J]. Forging&Stamping Technology,2017,42(1):54-59.
[7] ISO 16630-2003 Metallic materials-Method of hole expanding test[S].
[8] JEWOONG L,SEOK-JAE L,BRUNO C,et al. Effect of microalloying elements on the stretch flangeability of dual phase steel[J]. Materials Science and Engineering A,2012,536(20):231-238.
[9]管丽,刘雅政,周乐育.热变形后冷却速度对铁素体-贝氏体微合金钢组织演变的影响[J].特殊钢,2007,28(3):35-37.GUAN Li,LIU Yazheng,ZHOU Yueyu,et al. Effect of cooling rate on structure evolution of hot deformed ferrite-bainite micro alloying steel[J]. Special Steel,2007,28(3):35-37.
[10]王孟,刘斌,刘永前.冷却工艺对热轧高扩孔钢组织与性能的影响[J].钢铁研究,2016,44(4):30-33.WANG Meng,LIU Bin,LIU Yongqian,et al. Effect of cooling process on microstructure and properties of hot-rolled steels with high hole-expanding ratio[J]. Research on Iron and Steel,2016,44(4):30-33.
[11] FANG X,FAN Z,RALPH B,et al. The relationships between tensile properties and hole expansion property of C-Mn steels[J]. Journal of Materials Science,2003,38(18):3877-3882.