摘要
某核电项目核岛主蒸汽隔离阀制造过程中发现该阀门闸板钴基堆焊密封面存在贯穿性裂纹。通过对钴基合金堆焊裂纹成因机理、焊接接头的应力影响以及其他相关因素进行分析,得出其主要原因是工艺评定的验证性不足,未充分考虑闸板焊接结构不对称、堆焊厚度等因素的影响。针对堆焊的焊前处理、焊接结构、焊接工艺参数、热处理工艺、过程控制等方面进行了优化改进,具体措施为:在原搭接区域留10 mm的环带不加工,降低两种工艺搭接处的应力集中;优化堆焊层数至两层;在保证堆焊质量的前提下,尽量选用小的焊接电流和焊接速度;提高预热温度,进行后热处理等。改进后闸板堆焊焊缝一次合格率达到100%,为后续国内各核电厂同类核岛主蒸汽隔离阀密封面堆焊裂纹的处理提供了参考。
A main steam isolation valve has a penetrating crack on the cobalt-based surfacing sealing surface of the valve gate plate during the manufacturing. Through analyzing the mechanism of cobalt base alloy surfacing crack formation, the influence of stress on welded joints and other related factors, it is concluded that the main reason is that the validation of process qualification is insufficient, and the influence factors such as the asymmetry of valve gate plate welding structure and the thickness of surfacing are not fully considered. The treatment before surfacing, welding structure, welding parameters,heat treatment process, process control and other aspects are optimized and improved. The measure is as follows: leave 10mm ring strip in the original lap area, reduce the stress concentration at the lap of two kinds of processes, and optimize the number of surfacing layers to two layers;On the premise of ensuring the surfacing quality, select small welding current and welding speed as far as possible;Increase the preheating temperature and carry out the postweld heat treatment. The primary pass rate of gate surfacing weld reaches 100%. This measure provides some references for the subsequent treatments of the sealing surface cracks on the same kind of main steam isolation valve in nuclear island in domestic nuclear power plants.
作者
朱奇敏
张志强
肖瑞旺
张顺达
孙福成
吴义党
王伟波
ZHU Qimin;ZHANG Zhiqiang;XIAO Ruiwang;ZHANG Shunda;SUN Fucheng;WU Yidang;WANG Weibo(China Nuclear Power Engineering Co,Ltd.,Sbenzhen 518124,China)
出处
《电焊机》
2022年第11期95-100,共6页
Electric Welding Machine
关键词
主蒸汽隔离阀
钴基合金
堆焊
贯穿性裂纹
main steam isolation valve
cobalt base alloy
surfacing
penetrating crack