核电站用SA738Gr.B钢板热处理工艺研究

为满足SA738Gr.B核电站用钢较高的性能要求,在实验室试验的基础上,研究了工业化生产热处理工艺参数对钢显微组织和力学性能的影响。结果表明,钢板淬火时冷却速度5℃/s时,能够避免先共析铁素体的析出;淬火温度较高时,钢板具有更细小和均匀的板条贝氏体;随着淬火加热的保温时间延长,晶粒组织粗化且铁素体含量减少;随着回火温度的升高,晶粒粗化,同时贝氏体含量减少,铁素体含量增多;在工业化生产中,较大淬火水量下钢板的拉伸性能更优;随着回火时间的延长,钢板强度下降而冲击韧性提高。以920℃×2.0 min/mm加热、较高水量的Q2工艺淬火,并采用650℃×1.5min/mm的工艺回火,可使钢板的强韧性达到最佳匹配。

Study on Heat Treatment Process of SA738Gr.B Steel Plats for Nuclear Power Plant

In order to meet the high performance requirements of SA738Gr.B steel plate for nuclear power plant,on the basis of lab tests,heat treatment process parameters in industrial production are studied. The results showed that Pro-eutectoid ferrite precipitation can be avoided when quenching cooling rate greater than 5℃/s; The steel plates have smaller and more uniform lath bainite when quenching temperature is higher; With the extension of heating holding time in quenching,the grains are coarser and ferrite content reduces; With the increase of the tempering temperature,grains coarsen,and the content of bainite reduces,ferrite content increases; In industrial production,tensile properties is superior when water quantity of quenching is higher; With the increase of the tempering time,the steel strength decreases and the impact toughness increases. When the steel plate was heated in 920 ℃×2.0 min/mm,and subsequently quenched in Q2 program with higher water flow,then tempered in 650 ℃×1.5 min/mm,the best match of the strength and toughness can be achieved.