摘要
通过显微组织观察、电子背散射衍射技术、拉伸试验、冲击试验等方法,研究了回火温度对Q420qENH钢板组织和力学性能的影响。结果表明:420~620℃回火的钢板组织为粒状贝氏体和铁素体,基体组织略微粗化,大尺寸M-A组元分解,但仍有部分细小较稳定的M-A组元得以保留,且呈弥散分布。与轧态钢板相比,620℃回火的钢板屈服强度从467 MPa升高至505 MPa,抗拉强度从655 MPa降低至589 MPa,屈强比从0.71升高至0.86,-40℃冲击吸收能量从175 J升高至278 J;脆硬相M-A组元含量降低不仅导致钢板屈强比升高,还降低了裂纹萌生倾向,且大角度晶界比例增加,阻碍裂纹扩展的能力增强,两者共同作用使得钢板的低温冲击韧性明显改善。在520~620℃回火的试验钢板具有高强韧性和较低屈强比的优异力学性能。
Effect of tempering temperature on the microstructure and mechanical properties of Q420qENH steel plate was studied by microstructure observation,electron back scatter diffraction technique,tensile test,impact test and other methods.The results showed that(a)the microstructure of the steel plate tempered at temperatures of 420 to 620℃was granular bainite and ferrite,the matrix structure was slightly coarsened,and the large-size M-A components were decomposed,but some small and stable M-A components were retained and dispersively distributed;(b)as compared with the rolled steel plate,the steel plate tempered at 620℃exhibited the increase in yield strength from 467 to 505 MPa,the decrease in tensile strength from 655 to 589 MPa,the increase in yield-tensile strength ratio from 0.71 to 0.86 and in impact absorbed energy at-40℃from 175 to 278 J;(c)the decrease in the content of brittle and hard M-A phase not only led to an increase in the yield-tensile strength ratio,but also an decrease in the tendency of crack initiation,and the proportion of large-angle grain boundaries increased,which enhanced the ability to prevent crack growth,the combined effect of the two made the low temperature impact toughness of the steel plate significantly improved;(d)the steel plates tempered at temperatures of 520 to 620℃obtained excellent comprehensive mechanical properties of high strength-toughness and low yield-tensile strength ratio.
作者
刘志平
赵丽洋
陈振业
魏浩
王青峰
LIU Zhiping;ZHAO Liyang;CHEN Zhenye;WEI Hao;WANG Qingfeng(State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,Qinhuangdao Hebei 066004,China;HBIS Group Co.,Ltd.,Shijiazhuang Hebei 052160,China)
出处
《上海金属》
CAS
2023年第4期56-61,70,共7页
Shanghai Metals
基金
国家重点研发计划(2017YFB0304800)
河钢股份有限公司与燕山大学联合重点研发项目(HG2019308)。
关键词
Q420qENH钢
回火
M-A组元
力学性能
Q420qENH steel
tempering
martensite-austenite(M-A)component
mechanical property
作者简介
刘志平,男,硕士,主要从事高性能耐候桥梁钢材料工艺设计研究,E-mail:lzpdmx@126.com。
