海洋平台用钢E690奥氏体晶粒长大行为

Austenite grain growth behavior of offshore platform steel E690

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 austenite grain growth behavior of offshore platform steel E690 at different heating temperatures and holding time was investigated, and the effects of second phase particles on austenite grain size were also studied. The results show that the austenite grain size increases with heating temperature increasing. When the tested steel is heated under 850-950 ℃, the grain size of austenite grows normally. Under the temperature of 950-1000 ℃, abnormal grain growth appears, the average grain size of austenite almost doubled. Holding time has little effect on the austenite grain size, and with the holding time prolonged, the grain size does not change significantly. The size, volume fraction and distribution of second phase particles in steel play a key role in austenite grain growth. The critical grain size model which can describe the growth behavior of austenite grain is derived based on existing models and experimental data and can well explain the austenite grain growth behavior of the tested steel.