中文摘要：

利用研制的气室式局部干法水下焊接试验系统，在300mm水深环境的试验水槽中，进行了水下平板堆焊和坡口对接焊验证性工艺试验，并对水下坡口对接焊焊缝进行了显微组织和硬度的测试分析，结果表明：在气室排水密封良好的前提下，送丝速度、焊接速度、摆动速度和摆动周期等参数对焊缝成形和焊接质量的影响较大，通过不同焊接参数的优化组合，可以获得优良的气室式局部干法水下焊接焊缝成形；水下焊接环境对焊缝的显微组织和硬度产生一定影响，由于焊缝周围及背面水的快速冷却作用，焊缝中心区域出现了部分魏氏体组织，同时焊缝中心区域的硬度较热影响区高，出现了一定淬火硬化现象．

英文摘要：

Due to the relatively large gas space and better flexibi ity, chamber local dry underwater welding has a better application prospect in repairing offshore gas and oil pipeline and nuclear spent fuel pool. With the development of chamber local dry underwater welding system, the verification test of build-up welding and butt welding were conducted in a 300 mm depth water environment, and the microstructure and hard- ness of butt weld were analyzed. The results show that with the premise that the chamber was well sealed, the wire feed speed, welding speed, weaving speed and weaving period have a great influence on the weld formation and welding quality. By optimizing different welding parameters, a good appearance of chamber local dry underwater welding weld can be obtained; Underwater welding environment has influence on hardness and microstructure of weld; Due to the rapid cooling effect of water back and around the weld, some widmanstatten structure appear in the center region of the weld, the hardness in the central region is higher than that in the heat affected zone and, hardening phenomenon appeared.