Stainless steel welding technical requirements and quality assurance measures

For the ferritic stainless steel, grain growth in the heat affected zone, welding joint ductility and toughness sharp decline, brittle, easy to form cold cracks in the welding residual stress. Welded austenitic stainless steel welding process is improper or inappropriate choice of welding materials, prone to intergranular corrosion, welding hot cracking and embrittlement of welded joints and a series of defects, a direct impact on the performance of welded joints and weld quality.

For the more common austenitic stainless steel, in the welding process in claim small line energy fast short arc welding, minimize weld overheating, in order to prevent overheating by weld generated coarse columnar grain structure, reducing the welding residual stress , thereby preventing the welded joint stress corrosion cracking and the hot crack generation. Because weld overheated decreases, correspondingly reduces the residence time of the weld metal in sensitizing temperature, intergranular corrosion of welded joints tend to decrease.

Manual tungsten arc welding then stainless steel, using ordinary DC TIG welding machine, welding machine in the best conditions allowed.

Due to the low thermal conductivity of austenitic stainless steel, in the same welding current than structural steel can be obtained a large depth of penetration. Weld in order to obtain a certain size in order to prevent overheating, the welding current should be smaller than when welding ordinary low-alloy steel from 10% -20%, and the fine diameter wire. This can achieve a desired depth of penetration, and also allows a relatively reduced cross section of the weld bead, and to help improve the crack resistance of the weld of the welding current is relatively reduced.