The main purpose of solid solution treatment of stainless steel castings is to dissolve carbides or other precipitated phases in solid solution to obtain a supersaturated single-phase structure. Castings of austenitic stainless steel, austenitic manganese steel, duplex stainless steel castings and precipitation hardening stainless steel should generally be solid solution treated. The choice of solution temperature depends on the chemical composition and phase diagram of the cast steel. The temperature of austenitic manganese steel castings is generally 1000 ℃ - 1100 ℃; the temperature of austenitic chromium-nickel stainless steel castings is generally 1000℃-1250℃.

The higher the carbon content in cast steel and the more insoluble alloying elements, the higher its solid solution temperature should be. For precipitation hardening steel castings containing copper, the hardness of the steel castings increases due to the precipitation of hard copper-rich phases in the as-cast state during cooling. In order to soften the structure and improve the processing performance, the steel castings need to be solid solution treated. Its solid solution temperature is 900℃-950℃.

The as-cast structure of steel castings depends on the chemical composition and solidification process. Generally, there are relatively serious dendrite segregation, very uneven structure and coarse grains. Therefore, steel castings generally need to be heat treated to eliminate or reduce the impact of the above problems, so as to improve the mechanical properties of steel castings. In addition, due to the difference in the structure and wall thickness of the steel castings, various parts of the same casting have different organizational forms and generate considerable residual internal stress. Therefore, steel castings (especially alloy steel castings) should generally be delivered in a heat-treated state.