Welding process and treatment of stainless steel cross

Stainless steel cross usually need to be welded when they are installed. Because of the particularity of material, stainless steel cross are different from ordinary pipes when they are welded. And the treatment of welds after welding is also different. The welds of stainless steel cross are not only beautiful but also rusty. What is the welding and treatment process of stainless steel cross?

　　Because of the different sizes of Stainless Steel Equal Butt Welding Cross, according to the unique welding place of stainless steel cross, as far as possible to reduce the heat input, manual arc welding and argon arc welding are used. For d > 159 mm, argon arc welding is used to bottom and manual arc welding cover. D < 159 mm full-purpose argon arc welding, stainless steel cross welding technical requirements are as follows:

　　DC reverse connection is used in manual arc welding and DC forward connection is used in argon arc welding.

　　Before welding, the welding wire should be brushed off with stainless steel cross brush and washed with acetone. The welding wire should be dried at 200-250 C for 1 hour and used as needed.

　　Before welding, the oil contamination in the range of 25 mm on both sides of the groove is cleaned up, and the range of 25 mm on both sides of the groove is washed with acetone.

　　In argon arc welding, the diameter of nozzle is 2 mm, tungsten pole is hollow tungsten pole, specification 2.5 mm.

　　When welding stainless steel cross by argon arc welding, the back must be protected by argon gas to ensure the back forming. The flow rate is 5-14L/min and the front argon flow rate is 12-13L/min.

　　The thickness of weld seam should be as thin as possible during bottom welding. It should fuse well with the root and form a gentle slope when arc closing. If there are shrinkage holes in arc closing, they should be polished by a polishing machine. Arc extinguishing must be initiated in the groove. When arc extinguishing, arc pits should be filled to prevent arc pit cracks.

　　Because the stainless steel cross is austenitic stainless steel cross, in order to prevent carbide precipitation sensitization and intergranular decay, the interlayer temperature and cooling rate after welding should be strictly controlled. The interlayer temperature during welding should be controlled below 60 C. After welding, it must be immediately water-cooled, and sectional welding should be adopted. This symmetrically dispersed welding sequence can increase the cooling rate of the joint and reduce the welding stress.