Abstract: The tempering embrittlement and its overaging phenomenon (counter^segregation) of alloy steel 2.25Cr-1Mo at tempering temperature have been studied. The non-equilibrium segregation law of phosphorus in alloy steel 2.25Cr-1Mo (0.15C, 2.32Cr, 0.95Mo, 0.009P) tempering at 650 °C for 140 h was obtained with using the kinetics theory of non-equilibrium segregation r The test results showed that critical time t_c of phosphorus non-equilibrium segregation in alloy steel 2.25Cr-1Mo at 650 ℃ was 20 h, at this time the atomic concentration of phosphorus at grain boundary increased to maximum value 2.79% from 0.016% at original status. According to kinetic calculation of test data, the obtained calculated curve conformed with the test results which verified the diflusion mechanism of non-equilibrium grain segregation for vacancy-complex model.

Key words: Alloy Steel 2.25Cr-1Mo, Temper Embrittlement, Non-Equilibrium Segregation, Overaging

摘要： 研究了2.25Cr-1Mo合金钢在回火温度下时效处理时,发生回火脆化和回火脆化的过时效反偏聚现象。应用非平衡偏聚的动力学理论,确定了成分(%)为0.15C、2.32Cr、0.95Mo、0.009P的2.25Cr-1Mo合金钢在650℃140 h回火时钢中磷的非平衡晶界偏聚规律。试验得出,2.25Cr-1Mo合金钢650℃磷非平衡偏聚的临界时间t_c为20 h,晶界磷的原子浓度,由初始状态的0.016%提高至最大值2.79%。根据试验数据进行的动力学计算,得出的计算曲线与试验结果吻合,验证了非平衡晶界偏聚空位-复合体模型的扩散机制。

关键词: 2.25Cr-1Mo合金钢, 回火脆化, 非平衡偏聚, 过时效