卷取温度对热轧高扩孔540HE钢组织和性能的影响
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摘要
采用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)和拉伸试验机研究了卷取温度对工业生产的高扩孔540HE钢微观组织、力学性能及扩孔率的影响。结果表明:卷取温度变化可显著改变试验钢的铁素体晶粒尺寸、(Ti,Nb) C析出相形态和贝氏体含量,从而影响其力学性能及扩孔率。随着热轧卷取温度的降低,试验钢的屈服强度及抗拉强度升高,断后伸长率降低,扩孔率略有增加。低温卷取时铁素体晶粒尺寸较小,贝氏体含量增加,贝氏体细小且分布均匀;(Ti,Nb) C析出相细小弥散分布,可显著强化铁素体基体从而减小其与贝氏体硬度差异,有利于扩孔率的提升。
Effect of coiling temperature on the microstructure,mechanical properties and hole expansion rate of commercial high hole expansion 540 HE steel was studied by using optical microscope(OM),scanning electron microscope(SEM),transmission electron microscope(TEM)and tensile test machine.The results showed that the change of the coiling temperature could significantly change the grain size of ferrite,morphology of(Ti,Nb) C precipitates and the bainite content in test steel,thus affecting the mechanical properties and the hole expansion rate of the steel.With the decrease of coiling temperature,the yield strength and tensile strength of the test steel increased,the elongation decreased and the hole expansion rate increased slightly.When coiling at lower temperature,the grain size of ferrite was small,the content of bainite increased and bainite was fine and evenly distributive.The(Ti,Nb) C precipitates were fine and disperse distribution,which could significantly strengthen the ferrite matrix,thereby reduce the hardness difference between ferrite and bainite,which was beneficial to an improvement in the hole expansion rate.
Effect of coiling temperature on the microstructure,mechanical properties and hole expansion rate of commercial high hole expansion 540 HE steel was studied by using optical microscope(OM),scanning electron microscope(SEM),transmission electron microscope(TEM)and tensile test machine.The results showed that the change of the coiling temperature could significantly change the grain size of ferrite,morphology of(Ti,Nb) C precipitates and the bainite content in test steel,thus affecting the mechanical properties and the hole expansion rate of the steel.With the decrease of coiling temperature,the yield strength and tensile strength of the test steel increased,the elongation decreased and the hole expansion rate increased slightly.When coiling at lower temperature,the grain size of ferrite was small,the content of bainite increased and bainite was fine and evenly distributive.The(Ti,Nb) C precipitates were fine and disperse distribution,which could significantly strengthen the ferrite matrix,thereby reduce the hardness difference between ferrite and bainite,which was beneficial to an improvement in the hole expansion rate.
引文
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[2]利成宁,袁国,周晓光,等.汽车结构用热轧双相钢的生产现状及发展趋势[J].轧钢,2012,29(5):38-42.
[3]HYUN D I,OAK S M,KANG S S,et al.Estimation of hole flangeability for high strength steel plates[J].Journal of Materials Processing Tech,2002,130(2):9-13.
[4]康永林,邝霜,尹显东,等.汽车用双相钢板的开发与研究进展[J].汽车工艺与材料,2006(5):1-5.
[5]方鸿生,徐平光,白秉哲,等.一种新的复相组织---仿晶界型铁素体/粒状贝氏体[J].金属热处理,2000,25(11):1-5.
[6]LEE J,LEE S J,DECOOMAN B C,et al.Effect of microalloying elements on the stretch-flangeability of dual phase steel[J].Materials Science and Engineering A,2012,536(1):231-238.
[7]商艳,丁桦,王卫卫,等.含Nb低碳FB钢组织与扩孔性能的研究[J].钢铁,2008,43(10):74-77.
[8]商艳,韩庆生,郭营利,等.TMCP工艺对车轮钢组织及扩孔性能的影响[J].中国冶金,2008,18(10):15-19.
[9]蔡明晖,丁桦,李晓滨,等.高扩孔钢变形奥氏体的连续冷却转变[J].东北大学学报(自然科学版),2008,29(11):1576-1580.
[10]雍岐龙.钢铁材料中的第二相[M].北京:冶金工业出版社,2006.
[11]雍岐龙,孙新军,郑磊,等.钢铁材料中第二相的作用[J].科技创新导报,2009(8):2-3.
[12]代晓莉,郭佳,李飞,等.580 MPa级热轧高扩孔钢的组织与性能[J].上海金属,2015,37(1):23-27.