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采用箱式电阻炉对试验钢进行了三种不同淬火温度的淬火+高温回火热处理,并对试样的显微组织进行了观察,对拉伸和冲击力学性能进行了检测。结果表明,在两相区淬火的试样的显微组织以多边形铁素体+岛状马氏体为主,随淬火温度升高,铁素体含量逐渐降低,马氏体含量逐渐增加,晶粒逐渐细化;回火组织以回火马氏体+铁素体为主,与淬火组织相比,铁素体明显粗化,马氏体含量下降,马氏体板条特征逐渐消失,铁素体晶界有较多碳化物析出;随淬火温度升高,回火后钢板屈服强度、伸长率和低温冲击韧性均逐渐升高,抗拉强度先提高后略有下降;试验钢经800℃淬火+500℃回火能获得优良的综合力学性能。
Three kinds of quenching and tempering heat treatment were carried out on the test steel with a box type resistance furnace. The microstructure of the sample was observed and the tensile and impact mechanical properties were tested. The results show that the microstructure of the sample quenched in the two-phase region is dominated by polygonal ferrite + island martensite. With the increase of quenching temperature, the ferrite content gradually decreases and the martensite content gradually increases. The crystal The microstructure of the tempered martensite and ferrite is mainly tempered. Compared with the quenched structure, the ferrite obviously coarsens, the content of martensite decreases, the characteristics of the martensite lath gradually disappear. With the increase of quenching temperature, the yield strength, elongation and low temperature impact toughness of the steel plate gradually increase after the tempering, and the tensile strength first increases slightly and then decreases slightly. ℃ quenching +500 ℃ tempered to obtain excellent mechanical properties.