Regarding the post-weld heat treatment of stainless steel plates, based on the relevant regulations of various countries, the following is a more appropriate treatment attention point, mainly based on temperature and altitude as the basis for classification.

For high-strength chromium stainless steel, preheating is required to remove hydrogen, and the temperature range is 150-400°C. The post-weld heat treatment temperature range of martensitic stainless steel is 730-800°C. The post-weld heat treatment temperature range of ferritic stainless steel is 730-800°C, and then rapid cooling is required to avoid embrittlement. However, there is no fixed standard for austenitic stainless steel that requires heat treatment after welding. It only needs to be used as a stainless steel plate. When the thickness is very large, the temperature range of 900-1100°C can be selected for heat treatment, and then water cooling or air cooling is carried out according to the thickness of the plate. As for austenitic ferritic duplex stainless steel and nickel-based alloys, there are currently no relevant regulations.

According to temperature classification, the following three temperature ranges of heat treatment can be used for post-weld heat treatment of stainless steel plates.

The first is low-temperature post-weld heat treatment, that is, the temperature is lower than ≤500°C. Heat treatment of chromium-nickel austenitic stainless steel at 200-400°C can reduce the peak stress, about 40%, but the total stress is not reduced. many. Austenitic stainless steel is rarely heat treated at 400-500°C. Low temperature treatment is not suitable for high strength chromium stainless steel.

The second type is medium-temperature post-weld heat treatment, that is, the temperature range is 550-820°C. The purpose of medium-temperature heat treatment is mainly to remove stress. This heat treatment can be used as composite stainless steel, which can relieve stress on both the base layer and the stainless steel cladding.

For ferritic and martensitic stainless steels, post-weld heat treatment is usually performed in the range of 600-730°C to optimize notch toughness. Austenitic ferrosite duplex stainless steel is not suitable for medium temperature treatment because it will cause the precipitation of ɑ phase and carbides. When austenitic stainless steel is used in composite steel, it can be treated at 540-700°C to relieve stress. Austenitic stainless steel is usually not suitable for heat treatment at 550-800°C, because this temperature range will promote the formation of intergranular corrosion.

The third type is high-temperature post-weld heat treatment, that is, the temperature is higher than 900°C. The purpose of this is to dissolve harmful precipitates in the weld and heat-affected zone generated during welding. After high temperature treatment, cooling treatment is also required along with the weld. When austenitic stainless steel is treated at 900°C, harmful carbides and metallographic phases in the weld can be dissolved, making the performance closer to that of the base material. After tempering martensitic stainless steel, treatment at 900°C can enhance the mechanical properties of the stainless steel plate.