10CrNi_(2)Mo_(3)Cu_(2)V耐热钢的高温析出与脆化机制

High temperature precipitation and brittleness mechanism of 10CrNi2Mo3Cu2V heat-resistant steel

利用光学显微镜、扫描电镜、力学性能测试等方法,分析了10CrNi_(2)Mo_(3)Cu_(2)V耐热钢锻件的脆化原因,并研究了钢在1050~850℃区间的高温析出行为,及其对冲击韧性的影响。结果表明,锻件脆化由粗大的链状M6C相引起,950~850℃温度区间,钢中发生M_(6)C相的高温析出行为,导致冲击韧性恶化。析出温度区间内,降低温度、延长时间均能促进析出相的形核与长大,使M_(6)C相含量增加,尺寸长大,分布更加聚集,逐渐形成链状形貌。Mo元素偏析能够提高M_(6)C相的开始析出温度、增加相含量。锻造温度是影响高温析出行为的关键因素,应控制终锻温度不小于950℃,避免锻后脆化。

The reason for brittleness of 10CrNi_(2)Mo_(3)Cu_(2)V heat-resistant steel forging was analyzed by optical microscope, SEM and test of mechanical properties. High temperature precipitation behavior of the steel in temperature interval of 1 050-850 ℃ which influences impact toughness was also investigated. The results show that M_(6)C phase distributes continuously after forging and causes the forging becoming brittleness. The steel occurs high precipitation behavior of M_(6)C phase that causes impact toughness deteriorating in temperature interval of 950-850 ℃. Decreasing temperature or prolonging soaking time could accelerate nucleation and growth of M_(6)C phase, which make amount increasing, size growing up. And then the precipitated phase forms continuously distributed morphology at last. Segregation of Mo element could decrease initiated precipitation temperature and content of M6C phase. Forging temperature is the critical influence factor of high temperature precipitation. As result, final forging temperature should not below 950 ℃ to avoid brittleness after forging.