P92钢中Laves析出相演化规律研究

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.