Study On Welding Process And Property Of Underwater Dry Flux-cored Wire Double-pulse Welding Of S32101 Duplex Stainless Steel

Underwater welding is a special welding method, which is significant for the development of subsea resources, marine military projects and nuclear power equipment. Since underwater dry welding gets the best seam among the variety of underwater welding methods, it has been widely used in marine engineering construction and maintenance. S32101 duplex stainless steel has excellent weldability, mechanical properties and corrosion resistance, and it has been widely used in nuclear power equipment.In this paper, average current, intense pulse proportion, ratio of intense pulse than weak pulse and water depth were used as independent variables to design the duplex stainless steel underwater dry welding test based on response surface method. We also measured the weld shaping, then tested the pitting resistance, the tensile property and the impact properties on the seam center and heat affected zone. The front weld width and the evaluation indexes of back weld shaping coefficient, the pitting potential, the tensile strength and the impact energy of the seam center and the heat affected zone were used as responses to established the surface response models. The law of the effects which welding process factors have on the responses were analyzed. The results are as follows.With the increase of the average current, the front weld width becomes larger. With the increase of the intense pulse proportion, the front weld width first becomes smaller then larger. With the increase of the ratio of intense pulse than weak pulse and the water depth, the front weld width first becomes larger then smaller. With the increase of average current, the back weld shaping becomes worse. With the increase of the intense pulse proportion, the ratio of intense pulse than weak pulse and the water depth, the back weld shaping first becomes better then worse, and gets the best status when the intense pulse proportion is 45%, the ratio of intense pulse than weak pulse is 0.55 and the water depth is 20 m.With the increase of average current and the water depth, the tensile property first becomes better then worse. With the increase of the intense pulse proportion, the tensile property become better. With then increase of the ratio of intense pulse than weak pulse, the tensile property become worse. The influence of the average current on tensile is greatest, followed by the intense pulse proportion, and the influence of the ratio of intense pulse than weak pulse and the water depth are little. With the increase of average current and the intense pulse proportion, the impact property on seam center first becomes better then worse. With the increase of the ratio of intense pulse than weak pulse, the impact property on seam center becomes better. With the increase of the water depth, the impact property on seam center becomes worse. The influence of average current and water depth on the impact property on seam center are great. With the increase of average current and the intense pulse proportion, the impact property on heat affected zoon first becomes better then worse. With the increase of the ratio of intense pulse than weak pulse, the impact property on heat affected zoon becomes better. With the increase of the water depth, the impact property on heat affected zoon first become worse then better.With the increase of average current and the water depth, the pitting resistance becomes worse. With the increase of the intense pulse proportion and the ratio of intense pulse than weak pulse, the pitting resistance first becomes better then worse, and gets the best status when the intense pulse proportion is 45%, the ratio of intense pulse than weak pulse is 0.55.