配分温度对Q-P-T钢组织与性能的影响

Effect of partitioning temperature on microstructure and mechanical properties of Q-P-T steel

采用SEM、TEM、EBSD、XRD等手段,研究了Q-P-T工艺配分温度(320、380和450℃)对28Mn2SiCrNiMo钢组织及性能的影响规律。结果表明:试验钢在320℃配分后,获得针状下贝氏体+马氏体+残留奥氏体组织;380℃配分后,获得板条状上贝氏体+马氏体+残留奥氏体组织;450℃配分后,组织为马氏体+残留奥氏体,无贝氏体生成。当配分温度为320℃时,强度、塑性和韧性的配合达到最佳,强度为1524MPa,总伸长率为18.7%,V型缺口冲击功为58J。配分过程中贝氏体的形成,分割原奥氏体晶粒,细化组织,阻碍了裂纹的扩展,使得试验钢的冲击韧性大幅提升。

A novel quenching-partitioning-tempering process was employed on a 0.28C-2.2Mn-1.6Si-0.4Cr-0.6Ni-0.28Mo（ mass%）steel,and the effect of partitioning temperature on microstructure and mechanical properties of the experimental steel was studied by means of SEM,TEM,EBSD technique and XRD.The results show that the microstructure of the experimental steel consists of martensite（ M）,acicular lower bainite and retained austenite（ RA） when the partitioning temperature is 320 ℃; martensite,lath-shaped upper bainite and retained austenite microstructure is obtained when partitioning temperature is 380 ℃; when partitioning temperature is 450 ℃,the microstructure is composed of only martensite and retained austenite（ without bainite）.The excellent combination of mechanical properties of the steel is obtained when partitioning temperature is 320 ℃,with tensile strength of 1524 MPa,total elongation of 18.7%,and Charpy-V absorbed energy of 58 J.The formation of bainite in the partitioning process divides the prior austenite grains,refines the finial multiphase microstructure,hinders the propagation of the crack,and results in the significant increase of the impact toughness of the test steel.