X80海底管线钢焊接接头晶粒长大规律研究

Study on Grain Growth Behavior in Thermal Process of Welding X80 Pipeline Steel

本文研究了一种适用于海底管道X80级管线钢在不同峰值温度下的奥氏体晶粒长大规律。结果表明，当奥氏体化温度低于950℃时，试验钢有较小的晶粒尺寸。奥氏体化温度超过1100℃，晶粒平均截距开始明显增大，一旦奥氏体化温度上升到1300℃时，奥氏体晶粒已显著粗化。分析表明，试验钢奥氏体晶粒平均截距D和奥氏体化温度T的定量关系为：D=1．63×10^5exp（-1．13×10^4／T）。当奥氏体化温度为950℃和1100℃时，奥氏体晶粒平均截距D和保温时间t的定量关系分别为：Dmc=8．62t^0.21和D—t=24．52t^0.21。研究结果对于X80级管线钢海上焊接工艺参数的制定有着非常重要的意义。

The grain growth behavior in thermal process of welding a X80 grade pipeline steel is investigated. It is found that when heating temperature lower than 950℃, the experimental steel has a smaller grain dimension. Once heating temperature is above 1100℃, the austenite grains grow rapidly. When heating terperatnre within the 900℃- 1300℃ range, the relationship between the average austenite grain size and heating temperature of the experimental steel can be well described by an equation D = 1.63×10^5exp（-1.13×10^4/T）. And the relationship between the average austenite grain size and heating time is D950℃ = 8.62t^0.21 and D 1100℃=24.52t^0.21, while the experimental steel is heated at 950℃ and 1100℃. These results are important s i gn i fi canee for high temperature processing process of welding X80 grade pipeline steel.