连退参数对980MPa级复相钢显微组织和力学性能的影响

THE INFLUENCE OF CONTINUOUS ANNEALING PARAMETERS ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF 980 MPA MULTIPHASE STEEL

利用Gleeble-3500热模拟试验机、光学显微镜和冷场扫描电镜,研究了连续退火工艺参数对980 MPa级复相钢显微组织和力学性能的影响。结果显示:随着均热温度的提高,铁素体含量逐渐减少,贝氏体、马氏体等强化相的含量逐渐增加,钢的屈服强度也逐渐提高,呈现一定的相关性。但是,细晶强化效果、固溶强化效果和相变强化效果的平衡是抗拉强度保持相对稳定的主要原因。随着过时效温度的提高,由于钢中马氏体、贝氏体产生分解和回火软化效应,导致抗拉强度、屈服强度和屈强比逐渐降低。

The influence of continuous annealing parameters on microstructure and mechanical properties of 980 MPa grade multi-phase steel were researched by Gleeble-3500 thermal simulator,optical microscope and cold field scanning election microscope.The results showed that the ferrite content declined gradually along with the increase of soaking temperature,while the content of bainite,martensite and other strengthening phase increased gradually,and the yield strength of steel also increased gradually,showing a certain correlation.However,the main reason why the tensile strength remains relatively stable was the balance of fine-grain strengthening effect,solution strengthening effect and phase transformation strengthening effect.With the increase of over-aging temperature,the tensile strength,yield strength and yield strength ratio declined gradually,which were attributed to the decomposition of martensite and bainite in steel and tempering softening effects.