The main purpose of solution treatment of stainless steel castings is to dissolve carbides or other precipitated phases in the solid solution and obtain a supersaturated single-phase structure. Austenitic stainless steel, austenitic manganese steel, duplex stainless steel castings and precipitation hardening stainless steel castings generally should be 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 as-cast structure of steel castings depends on the chemical composition and solidification process. Generally, dendrite segregation is relatively serious, the structure is extremely uneven, and the grains are coarse. Therefore, steel castings generally require heat treatment to eliminate or reduce the effects of the above problems, thereby improving the mechanical properties of steel castings. In addition, due to differences in the structure and wall thickness of steel castings, the structural shapes of various parts of the same casting are different, resulting in considerable residual internal stress. Therefore, steel castings (especially alloy steel castings) should generally be delivered in a heat-treated state.

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

The heat treatment of steel castings is based on the Fe-Fe3C phase diagram to control the microstructure of steel castings to achieve the required performance. Heat treatment is one of the important processes in the production of steel castings. The quality and effect of heat treatment are directly related to the final performance of steel castings.