P92钢中Laves析出相演化规律研究

Evolution of Laves Phase Precipitates in P92 Steel

设计了P92钢的等温时效试验和恒定载荷蠕变间断试验方案,对试验后的试样进行了微观组织观察,确定了析出相的形貌和成分。对Laves析出相微观组织图像进行了二值化处理,提取了特征参数,绘制了材料Laves析出相特征参数随试验时间的变化曲线,基于曲线特征分析了Laves析出相的演化规律。研究结果表明,P92钢试验初期为Laves相的析出阶段,表现为析出相颗粒数量、尺寸及面积占比的快速增加;试验中期为析出的Laves相渐趋饱和,并且开始不断聚积和粗化的阶段,表现为析出相颗粒数量下降,但尺寸持续增加;试验末期为Laves相颗粒的持续粗化阶段,表现为钢中Laves相数量的继续减少,总量基本不变。研究结果还表明,应力对Laves相的析出具有促进作用。

The isothermal aging tests and constant load creep intermittent tests of P92 steel were designed.After tests,the microstructure of P92 steel was observed and the morphology and composition of precipitated phase were determined.The microstructure images of Laves precipitates were binary processed,and the characteristic parameters were extracted.The curves of characteristic parameters with service time were drawn.The evolution law of Laves precipitates was analyzed based on the curve characteristics.Test results show that the precipitation of Laves phase occurs at the initial stage of test,which is characterized by the rapid increase of the number,size and area proportion of precipitated particles.In the middle stage,Laves phase precipitation becomes saturated gradually,and begin to accumulate and coarsen continuously,which shows that the number of Laves phase particles decreases but the size increases.At the end stage,the amount of Laves phase in steel continues to decrease,and the total amount remains basically unchanged.Test results also show that the stress can promote the precipitation of Laves phase.