T91/T92钢与不锈钢焊接接头硬度偏高的原因及热处理工艺优化

Analysis on Cause for Relatively High Hardness of Welded Joint of T91/T92 Steel and Stainless Steel and Optimization of Heat Treatment Process

从焊接电流、焊后热处理温度及热处理设备三方面,对超(超)临界电站锅炉T91/T92与不锈钢焊接接头T91/T92钢侧热影响区硬度偏高的原因进行了分析和试验验证,提出了相应对策。结果表明:焊接电流对焊接接头硬度的影响较小。焊后热处理温度低于730℃的异种钢接头T91钢侧热影响区硬度偏高。该异种钢焊口排列发生位移、履带式电热器焊后局部热处理的有效加热范围较小是造成接头T91钢侧热影响区硬度偏高的主要原因。因此,焊后热处理温度宜选择为730~770℃,并提出了一种新型马弗炉焊后局部热处理方法,其有效加热宽度为220 mm,能保证焊后热处理效果。

Cause for the relatively high hardness in the heat affected zone of T91/T92 steel side of the welded joint of T91/T92 steel and stainless steel in the ultra-supercritical power station boiler were analyzed and experimentally verified from three aspects such as welding current,temperature of post-welding heat treatment and heat treatment equipment,and corresponding countermeasures were proposed.The results showed that the influence of welding current on hardness of the welded joint was relatively small.The hardness in the heat-affected zone of T91 steel side of dissimilar steel joint after post-welding heat treatment at lower than 730℃was relatively high.The main cause for the relatively high hardness in the heat-affected zone of T91 steel side in the joint were the displacement of the arrangement of dissimilar steel craters and the small effective heating range of local post-welding heat treatment performed by a crawler-type electric heater.Therefore,the appropriate post-welding heat treatment temperature was 730 to 770℃,and a new type of muffle furnace for local post-welding heat treatment has been put forward,the effective heating width being 220 mm,being capable of ensuring the effectiveness of post-welding heat treatment.