【摘要】 本文研究了2.25CrMo钢在Ac₁～Ac₃两相区加热淬火状态（未回火）及727℃回火后在538℃下的蠕变性能。试验表明,与这种钢的常规热处理（950℃正火,727℃回火）相比,对于淬火状态的复相组织,在高应力的蠕变加载条件下,具有较高的断裂寿命;但是在低应力的蠕变加载条件下,则断裂寿命较低,两曲线在应力—断裂时间坐标图上有一交点。对于淬火后经727℃高温回火的复相组织,则不论加载应力水平的高低,其蠕变断裂寿命比常规处理的要低得多。这是因为,在复相处理加热过程中,由于加热温度低,原奥氏体没有能得到足够的碳、及铬、钼等合金元素的溶入所致。这就说明,尽管这种复相组织状态在室温下具有高强度、高塑性,具有很高的疲劳裂纹扩展门槛值△K_th,但是不适用于要求长时高温蠕变性能的工作条件。更多还原

【Abstract】 The creep propeties of 2.25 CrMo steel at 538℃ was investigated in this paper. The duplexphase microstructure was obtained by means of quenching at the teperature between AC₁ to AC₃. Three types of microstructures were chosen: as-quenched, tempered and conventional heat treated. At high stress level the fracture time of the as-quenched duplex-phase microstructure was much longer than that of the conventional heat reatment. but at low stress level the conventional heat treatment lasted a long time. Two creep curves intersect each other. The 727℃ tempered duplex-phase microstructure behaved very poor creep property. The reason of this phenomenon was that the duplex-phase microstructure was impoverished in alloying Cr, Mo elements due to low quenching temperature. The present results indicated that in spite of the good combination of strength and ductility and high fatigue crack growth threshold at ambient temperature, the duplex-phase microstructure of 2.25 Cr Mo steel could not serve in the high temperature condition.更多还原