TP347H TP439 TP410 seamless stainless steel pipe

Do you know the welding method of TP347H TP439 TP410 seamless stainless steel pipe?

1.1. Welding method: According to the welding characteristics of stainless steel, the heat input should be reduced as much as possible. Generally, two methods of manual arc welding and tungsten argon arc welding are used. For Φ>100 mm, argon arc welding is used for bottoming and arc welding filling. cover. Pipes with Φ≦100 mm and wall thickness less than 5mm shall be fully welded by argon arc welding, pipes with wall thickness greater than or equal to 5mm shall be bottomed by argon arc, and the cover surface shall be filled by arc welding. 

1.2. Electric welding machine: Because stainless steel welding is prone to produce arc tungsten and shrinkage pores, it needs to be equipped with a special argon arc welding machine with high frequency arc ignition and current attenuation characteristics. 

1.3. Welding consumables: Welding wire adopts Φ2.5/PP-TIG316L, and welding rod adopts: Φ2.5-3.2/A022. Before use, remove oxide layer and oil stain on the surface of welding wire and wipe clean with acetone or alcohol; welding rod should be dried at 200-250 ℃ 1h, store it in a thermal insulation cylinder and use it as needed. 

1.4. Welding current: The thermal conductivity of stainless steel is low, about 1/3 of that of carbon steel, the resistivity is about 5 times that of carbon steel, the coefficient of linear expansion is about 50% larger than that of carbon steel, and the density is greater than that of carbon steel, so the welding current should be less than Carbon steel welding current. The welding machine adopts DC reverse connection during manual arc welding, and DC forward connection during argon arc welding. In the welding bottom layer, small-diameter welding consumables and low current should be used as much as possible to reduce the welding line energy and improve the fluidity of the deposited metal. Due to the poor thermal conductivity of stainless steel, a small current should be used to avoid the redness of the welding core during the welding process of the electrode, and the overheating and volatilization of the gas protective component in the coating, resulting in a decrease in the protection effect of the slag of the electrode. The welding seam with a large pair of gaps is continuously oscillated by a single-side continuous wire feeding torch, and the fluidity of the liquid metal is melted and combined with the base metal on the other side to prevent undercut on one side.