The heat conduction efficiency of stainless steel is about 1/3 of carbon steel, the resistivity is about 5 times and the linear expansion coefficient is about 50% larger than that of carbon steel, so the welding bottom using small diameter welding materials and small current to avoid the electrode core red and coating gas protection volatilization. The 316L welding rod/wire and electrode compositionĭC reverse connection for manual arc welding, dc forward connection for argon arc welding. The electrode shall be dried at 200-250 ℃ for 1h and then stored in the heat preservation tube for immediate use. Remove oxide layer and oil (by acetone or alcohol) from wire surface. Φ ≦ 100 mm and wall thickness less than 5 mm 316L use argon arc welding pipe, pipe wall thickness is greater than or equal to 5 mm to argon arc, arc welding filler cover surface.īecause stainless steel welding easy to produce arc ignition tungsten and shrinkage hole, high frequency arc ignition and current attenuation characteristics of the special argon arc welding machine is the ideal choice. Φ > 100 mm 316 l steel pipe adopts argon arc welding, arc welding filler cover surface. Welding method, welding characteristics of stainless steel make the heat input should be minimized, manual electric arc welding and tungsten argon arc welding is the most commonly used methods. Therefore, the chemical composition of 316L pipes and fittings and welding materials must be strictly controlled to ensure the balance of Austenitic elements (Ni, Mn, C, N, etc.) and Ferritic elements (Cr, Mo, Si, etc.) formed in weld metal after welding, so as to obtain good welding joint performance. The effects of all these elements on steel are not simply superimposed, nor do they cancel each other out. Molybdenum can diffuse and form special carbides under high tempering temperature, which can improve the resistance to hydrogen erosion and secondary hardening under high temperature and pressure, but the toughness of stainless steel will be affected by the high content of molybdenum. Chromium can significantly increase the brittle transition temperature of steel, and the impact value decreases with the increase of chromium content. Therefore, the content of sulfur and phosphorus should be strictly controlled. The grain boundary characteristics of 316L are sensitive to trace impurities such as sulfur and phosphorus, which easily lead to welding thermal crack. However, too high manganese content will reduce the corrosion resistance. Meanwhile, it can also improve the distribution shape of sulfide and make thin-film FeS into sphere distribution, thus improving the crack resistance of the weld. Manganese can replace FeS as MnS, which has the function of desulfurization. Silicon, soluble in Ferrite, has the effect of strengthening and oxidation resistance, but the high content will seriously affect the weldability of 316L steel. 316L offers good welding performance, but the high carbon content will make it easy to produce grain boundary carbon and chromium compounds in the welding process, reducing its corrosion resistance.
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