980 MPa级冷轧复相钢力学性能的多元调控

采用Gleeble-3500热模拟试验机、拉伸试验机和光学显微镜研究了连续退火工艺中均热温度、缓冷温度和过时效温度对980 MPa级复相钢力学性能及组织的影响规律。结果表明,经连续退火处理后980 MPa级复相钢组织为典型的铁素体、贝氏体、马氏体组织,随均热温度的提高,贝氏体和马氏体含量逐渐增加,从而提高抗拉强度和规定塑性延伸强度;缓冷温度则能改变新生铁素体晶粒大小及马氏体含量,从而调控复相钢力学性能;随着过时效温度的升高,部分颗粒状碳化物开始析出,能够降低马氏体的强度即改善复相钢塑性。从多元调控的角度逐步优化980 MPa级复相钢的综合力学性能,最终确定均热温度800 ℃、缓冷温度700 ℃和过时效温度340 ℃为最优工艺参数。

Multiple regulation on mechanical properties of 980 MPa cold-rolled multi-phase steel

By performing the Gleeble-3500 annealing simulator, tensile testing machine and optical microscope, the effects of soaking temperature, slow cooling temperature and overaging temperature on mechanical properties and microstructure of 980 MPa multi-phase steel were investigated during the continuous annealing process. The results indicate that 980 MPa multi-phase steels are composited of typical ferrite, bainite and martensite. The contents of bainite and martensite increase with the rise of soaking temperature, enhancing the yield strength and tensile strength accordingly. The slow cooling temperature is related to the size of new ferrite and the content of martensite, which possesses the adjustability of mechanical properties. With the increase of overaging temperature, granular carbides appear gradually and can reduce the strength of martensite, which further improves the plasticity of multi-phase steels. From the view of multiple regulation on comprehensive mechanical properties of 980 MPa multi-phase steels, the optimal parameters are selected as soaking temperature of 800 ℃, slow cooling temperature of 700 ℃ and overaging temperature of 340 ℃.