梯度结构中间坯制备超细晶低碳钢的组织特性与强化机理  

Microstructure Characteristics and Strengthening Mechanism of Ultrafine-Grain Low-Carbon Steel Prepared by Gradient-Structure Intermediate Billet

作　　者：李慧杰 韦浩 徐晓宁 叶其斌[1,2] LI Hui-jie;WEI Hao;XU Xiao-ning;YE Qi-bin(State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China;Institute of Research of Iron&Steel,Shagang,Jiangsu province,Zhangjiagang 215625,China.)

机构地区：[1]东北大学轧制技术及连轧自动化国家重点实验室,辽宁沈阳110819 [2]江苏省(沙钢)钢铁研究院,江苏张家港215625

出　　处：《东北大学学报（自然科学版）》2023年第11期1578-1583,1590,共7页Journal of Northeastern University(Natural Science)

基　　金：辽宁省科技重大专项(2020JH1/1010001)。

摘　　要：通过中间坯超快冷工艺,在0.2%C-2%Mn普碳钢中获得表层铁素体和心部马氏体的梯度层状组织,实现了钢板压下量约50%的大变形温轧.大变形马氏体经450℃和530℃退火后,制备出平均晶粒尺寸为0.52μm和0.66μm的超细晶组织.利用扫描电镜(SEM)、电子背散射衍射(EBSD)和准静态拉伸试验等手段,研究了超细晶钢板的微观组织与力学性能.结果表明,相较于610℃退火粗晶钢板,450℃和530℃退火超细晶钢的屈服强度可提升2~3倍,平均屈服强度分别达到了1475 MPa和1196 MPa,延伸率也显著下降.晶界强化和位错强化是超细晶钢强度提升的主要强化机制,而加工硬化率降低导致了超细晶钢的塑性下降.A gradient structure with ferrite-martensite-ferrite layers was obtained in a 0.2%C-2%Mn plain steel by applying ultra-fast cooling during intermediate passes of hot rolling.The large deformation and warm rolling of steel plate with reduction of about 50%is realized,which provides heavily deformed martensite to form ultrafine-grained ferrite with average grain sizes of 0.52μm and 0.66μm by annealing at 450℃and 530℃,respectively.The microstructure and mechanical properties of the ultrafine-grain steel sheets were studied by scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and quasi-static tensile tests.The results show that the yield strength of the ultrafine-grained steel is 2~3times higher than that of coarse-grain steel annealed at 610℃,arriving at 1475 MPa and 1196 MPa respectively by annealing at 450℃and 530℃,but the elongation is significantly reduced.Grain boundaries strengthening and dislocations strengthening are the major strengthening mechanisms for improving the strength of ultrofine-grained steel,while the decrease of work hardening rate leads to the decrease of plasticity of ultrafine grained steel.

关 键 词：梯度结构 超细晶钢 微观组织 强度 塑性 

分 类 号：TG335.11[金属学及工艺—金属压力加工]