水下局部干法焊接预热技术及专用排水罩的研制

研制开发了一种带有预热功能的水下局部干法焊接专用排水罩. 该排水罩具有水下预热功能，适用于水下局部干法药芯焊丝半自动焊工艺，预热温度可达60～80℃. 排水罩内设计有一块覆盖于坡口周围的预热钢板，正式焊接前首先在该板上进行预热焊接，通过热传导来实现对焊接坡口的预热作用. 使用该排水罩在水池中进行了模拟焊接试验. 结果表明，焊接接头质量达到AWS D3.6M:2010规定的A级焊缝的各项性能要求. 与其它水下焊接方法的试验结果对比发现，采用所研制的带预热功能的固定式排水罩进行水下局部干法焊接时接头的最大硬度显著降低，韧性也有明显提高.

Local-dry underwater welding preheating technology and development of special drain cover

A kind of special fixed drain cover used for local-dry underwater welding has been developed. The drain cover can be used for semi-automatic local-dry underwater welding process with flux-cored wire and had the function of underwater preheating before welding, by which preheating temperature can range from 60 to 80 ℃. Preheating welding was performed before groove welding by heat conduction from preheating plate covered on the groove in the drainage cover. The welding experiment results carried out in a pool using the drain cover indicated that the welding joint quality reached class A according to AWS D3.6M standard. The maximum hardness of welding joint decreased significantly, while toughness improved dramatically by using fixed drainage cover with preheating function compared with other underwater welding methods.