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对试验钢进行了不同的两相区直接淬火+回火处理。对试样显微组织进行了观察,并对力学性能进行了检测,研究了淬火温度和回火温度对试验钢组织和性能的影响。结果表明,钢板回火显微组织以多边形铁素体+岛状回火马氏体为主。随着直接淬火温度的升高,回火马氏体含量增加,铁素体含量减少,组织中少量珠光体逐渐转变为贝氏体;屈服强度和抗拉强度均升高,屈强比先保持恒定后有所升高,伸长率逐渐下降,冲击功则是先大幅降低后几乎不变。当回火温度低于400℃时,马氏体形态没有明显改变;当回火温度超过500℃时,马氏体岛开始分解,碳化物析出量增加。随着回火温度升高,抗拉强度几乎呈线性降低,屈服强度则先升高后降低,屈强比升高,伸长率和冲击功先下降后提高。
The test steel was subjected to different direct quenching + tempering two-phase zone. The microstructure of the sample was observed, and the mechanical properties were tested. The effects of quenching temperature and tempering temperature on the microstructure and properties of the test steel were studied. The results show that the tempered microstructure of the steel plate is dominated by polygonal ferrite + island tempered martensite. With the increase of direct quenching temperature, the content of tempered martensite increases, the content of ferrite decreases, and a small amount of pearlite gradually turns into bainite in the microstructure. The yield strength and tensile strength both increase, and the yield ratio keeps first After the constant increase, the elongation decreased gradually, the impact power is reduced substantially after the first almost unchanged. When the tempering temperature is below 400 ℃, martensite morphology does not change significantly; when the tempering temperature exceeds 500 ℃, the martensite island begins to decompose and the amount of carbide precipitation increases. With the increase of tempering temperature, the tensile strength almost linearly decreases, the yield strength increases first and then decreases, the yield ratio increases, and the elongation and impact work first decrease and then increase.