等温压缩对高强度汽车钢WHT1300HF的马氏体相变及微观组织的影响

Effect of Isothermal Compression on Martensite Transformation and Microstructure of High Strength Automobile Steel WHT1300HF

通过等温形变研究了形变参数(形变温度、形变速率、形变量)对高强度汽车钢WHT1300HF的微观组织转变和形貌的影响规律。研究结果表明:增加奥氏体等温形变量,有利于铁素体的缺陷形核,促进了形变奥氏体向铁素体转变;奥氏体的形变强化导致马氏体相变阻力增大,马氏体相变开始温度(Ms)下降,细小晶粒数量和小角度晶界数量增多;增加奥氏体等温形变(40%)速率能同时促进马氏体和铁素体相变,但马氏体体积分数和小角度晶界数量减少,细小晶粒数量略有提高;降低等温形变温度加剧奥氏体的形变强化,导致Ms温度下降,马氏体体积分数、小角度晶界比例减少,细小晶粒数量增多,铁素体含量明显增加。

By utilizing the isothermal deformation, the effect of the deformation parameters （deformation temperature, strain rate, deformation amount） on the phase transformation and microstructure of the high strength automobile steel WH1300HF was investigated. The results show that increasing the isothermal deformation amount of the austenite is conducive to the defect nucleation of the ferrite, promotes the ferrite transformation of the de- formed austenite, and the deformation strengthening of the austenite lead to the increasing of the resistance of martensite transformation, which causes the decreasing of M,, the increasing of the number of small-angle grain boundaries and the number of the small grains. Increasing the isothermal deformation （40%） rate of the austenite promotes the martensite transformation and the ferrite transformation, but, the volume fraction of martensite and the number of small-angle grain boundaries are reduced, and the number of the small grains is increased. Reducing the isothermal deformation temperature intensifies the deformation strengthening of the austenite and results in the decreases of M., volume fraction of martensite and the proportion of the small-angle grain boundaries and significant increases of the number of the small grains and the amount of the ferrite.