1. Why is it difficult to weld stainless steel? Answer: The main process difficulty is: <1> The stainless steel material has strong thermal sensitivity, and the residence time is slightly longer in the temperature range of 450--850 °C, and the corrosion resistance of the weld and the heat-affected zone is seriously reduced. <2> Thermal cracks are prone to occur. <3> Poor protection and serious high temperature oxidation. <4> The linear expansion coefficient is large, resulting in large welding deformation. 2. Why should effective technological measures be taken for welding austenitic stainless steel? Answer: The general process measures are: <1> Welding materials should be strictly selected according to the chemical composition of the base metal. <2> Small current., fast welding; small line energy, reduce heat input. <3> Thin-diameter welding wire, electrode, no swing, multi-layer multi-pass welding. <4> Forced cooling of the weld and heat affected zone to reduce the residence time at 450-850°C. <5> Argon gas protection on the back of TIG weld. <6> The welds in contact with the corrosive medium are welded last. <7> Passivation treatment of welds and heat-affected zone.
