采用激光电弧复合焊技术焊接了T91耐热钢, 在750 ℃下对焊接接头进行了不同时间的高温时效处理, 研究了焊缝、热影响区及母材的组织演化, 并对析出物进行了分析。结果表明, 随着高温时效处理时间的增加, 焊缝中的晶粒逐渐增大, 马氏体板条宽度增加并逐渐碎化为亚晶结构, 析出物逐渐粗化并向晶界或亚晶界聚集, 显微硬度逐渐减小。不同时效处理时间下的焊接接头均断裂于母材。

The T91 heat resistant steels are welded by the laser-arc hybrid welding technique. The high temperature aging treatments of welded joints for different time at 750 ℃ are conducted and the microstructure evolutions of weld, heat affected zone and base metal are investigated. The corresponding precipitation is also analyzed. The results show that, with the increase of high temperature aging time, the grain size in the weld gradually increases, the width of the martensite lath increases and the martensite laths are gradually broken into subgrain structures. Simultaneously, the precipitation gradually coarsens and gathers to the grain or subgrain boundary and the micro-hardness gradually decreases. After the treatments for different aging time, the fractured positions of all welded joints are within the base metals.