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分析了不同加热温度和保温时间下海洋平台用钢E690奥氏体晶粒的长大行为,同时研究了第二相粒子对奥氏体晶粒大小的影响。结果表明,奥氏体晶粒尺寸随着加热温度的升高而增加,在850~950℃之间奥氏体的晶粒尺寸增加属于正常的长大行为,而在950~1000℃之间出现了晶粒的异常长大,奥氏体平均晶粒尺寸几乎增加一倍。保温时间对奥氏体晶粒尺寸影响较小,且随着保温时间延长,晶粒增长不明显。钢中第二相粒子的尺寸、体积分数和分布状态对奥氏体晶粒长大起关键作用。在已有模型和试验数据的基础上,推导出能够描述奥氏体晶粒长大临界尺寸的模型,该模型很好地解释了试验钢奥氏体晶粒的长大行为。
The growth behavior of the austenite grains of the offshore platform steel E690 under different heating temperature and holding time was analyzed. The influence of the second phase particles on the austenite grain size was also studied. The results show that the grain size of austenite increases with the increase of heating temperature. The increase of austenite grain size at 850-950 ℃ belongs to normal growth behavior, but appears at 950-1000 ℃ The abnormal grain growth, the average grain size of austenite almost doubled. The holding time has little effect on the austenite grain size, and with the holding time prolonging, the grain growth is insignificant. The size, volume fraction and distribution of second-phase particles in steel play a key role in austenite grain growth. Based on the existing models and experimental data, a model capable of describing the critical grain size of austenite grains is deduced. This model can well explain the growth behavior of austenite grains in the test steel.