连续退火对1500MPa级22MnB5钢组织与力学性能的影响

Effects of Continuous Annealing on Microstructure and Mechanical Properties of 1500MPa Grade 22MnB5 Steel

采用连退模拟器模拟1500 MPa级热成形钢22MnB5不同的连退退火工艺,通过拉伸试验机进行力学性能试验,并用金相显微镜观察退火后组织。研究了不同退火工艺对钢性能的影响,分析了最优性能试样的金相组织。结果表明:在100 m/min带速下,加热温度780℃、缓冷温度610℃、快冷温度460℃、时效温度430℃工艺下,获得最低强度:屈服强度为486 MPa,抗拉强度为623 MPa。与最低强度对应的金相组织为珠光体和铁素体,珠光体比例为40%~50%,组织均匀。取该样板模拟热冲压参数,进行平板淬火,性能满足1500 MPa级热成形钢要求,组织全部为马氏体,无脱碳层。

A continuous annealing simulator was used to simulate different annealing processes for 1500 MPa grade hot forming steel 22MnB5.The mechanical properties were tested by tensile testing machine and a microstructure after annealing was observed by metallographic microscope.The effect of different annealing processes on the properties of 22MnB5 was studied and the metallographic microstructure of spcimen corresponding to the optimal properties was analyzed.The results show that,under the conditions of 100 m/min band velocity,heating temperature of 780℃,slow cooling temperature of 610℃,fast cooling temperature of 460℃and aging temperature 430℃,the optimum performance is obtained,the yield strength is 486 MPa,the tensile strength is 623 MPa.The metallographic microstructure corresponding to the optimal performance is pearlite and ferrite,and the pearlite ratio is 40%-50%.The plate is used to simulate hot stamping parameters by flat plate quenching.After quenching,the properties meet the requirements of 1500 MPa grade hot forming steel,and the microstructure is all martensite without decarbonization layer.