ZG0Cr13Ni5Mo马氏体不锈钢模拟焊接HAZ组织与性能

Microstructure and mechanical properties in simulated HAZ of 0Cr13Ni5Mo martensitic stainless steel

建立ZG0Cr13Ni5Mo马氏体不锈钢焊接热影响区 (HAZ)CCT图 ,模拟不同焊接热循环条件下热影响区组织并对其硬度、冲击韧度及金相组织进行研究。结果表明 ,热影响区只发生A→M相变 ,相变开始点Ms 基本不受冷却速度的影响 ;随冷却速度的降低 ,硬度略有下降。与母材相比 ,模拟热影响区的硬度有较大幅度提高 ,冲击韧度有较大幅度下降 ;冷却速度对硬度和冲击韧度影响不大。在模拟多层多道焊接热循环的条件下 ,层道间的热处理作用不明显 ,5 90℃焊后热处理是使热影响区冲击韧度得以恢复的必要途径。

By simulating the welding thermal cycle, the continuous cooling transformation diagram of heat-affected zone (HAZ) of ZG0Cr13Ni5Mo martensitic stainless steel was established. The diagram indicates that there are no other transformation but austenite→martensite in HAZ, and the cooling rate has no obvious effect on the temperature Ms of martensite initial transformation. The hardness of simulated HAZ decreases slightly as the cooling rate decreases. By using Gleeble thermal simulation technique the microstructures of HAZ at various welding thermal cycles were simulated, and the hardness, impact toughness and microstructures were investigated. The results show that the hardness of simulated HAZ is much higher than base metal's hardness, and the impact toughness of simulated HAZ is much lower than the base metal's. In the single thermal cycle simulating the root pass welding, the cooling rate has no effect on hardness and impact toughness of simulated HAZ. In multi-thermal cycles simulating the multi-pass welding, the heat treatment between passes and layers is not significant. Postweld heat treatment at 590 ℃ is an essential way to improve the impact toughness of HAZ greatly.