904L super austenitic stainless steel is a kind of high alloyed austenitic stainless steel with very low carbon content. It has good mechanical properties, process properties and strong corrosion resistance. There are practical applications in industrial fields such as processing, oil refining, coking, etc., and can also be used in pressure vessels and other fields. The application in these fields cannot be separated from the support of welding technology. Therefore, the research on its welding performance provides support for its further extensive application. . In this paper, molten inert gas shielded welding (MIG) is used, and the welding wire is ER385 to weld 2mm and 7mm thick 904L super austenitic stainless steel plates respectively. The welding process parameters are changed, and the microstructure of the welded joints is observed and analyzed. At the same time, the hardness test and impact performance mechanical performance test were carried out on the welded joints. Determine the most suitable process parameters, so that the performance of the obtained welded joint can be adapted to the manufacturing and working conditions. The results show that: 904L super austenitic stainless steel is not sensitive to heat input and has no obvious heat affected zone. During the welding process, since the composition of the fusion zone is the remelting combination of the base metal and the welding wire, the solidification composition is different from the base metal and the weld, which is dominated by A mode, and the grain size is small, resulting in poor impact performance of the welded joint. The mechanical properties near the weld fusion zone are relatively good.
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