Austenitic stainless steel is softened through solution treatment. Generally, the stainless steel pipe is heated to approximately 950–1150℃ and held at that temperature for a period of time. This allows carbides and various alloying elements to fully and uniformly dissolve in the austenite. Then, it is rapidly quenched in water for cooling. Carbon and other alloying elements do not have time to precipitate, resulting in a pure austenitic structure. This process is called solution treatment.

The effects of solution treatment on stainless steel pipes are threefold.
First, it ensures a uniform microstructure and composition. This is particularly important for the raw materials, as the rolling temperature and cooling rate of different sections of hot-rolled wire rod vary, resulting in inconsistent microstructures. At high temperatures, atomic activity intensifies, the σ phase dissolves, and the chemical composition tends to be more uniform. Rapid cooling then yields a uniform single-phase microstructure.
Second, it eliminates work hardening in the stainless steel pipe, facilitating further cold working. Through solution treatment, distorted crystal lattices are restored, elongated and broken grains recrystallize, internal stress is eliminated, and the tensile strength of the stainless steel pipe decreases while its elongation increases.
Third, solution treatment restores the inherent corrosion resistance of stainless steel pipes. Cold working causes carbide precipitation and lattice defects, reducing the corrosion resistance of stainless steel. Solution treatment restores the corrosion resistance of stainless steel pipes to their original state.

For stainless steel pipes, the three key factors in solution treatment are temperature, holding time, and cooling rate. The solution temperature of stainless steel pipes is mainly determined by their chemical composition. Generally speaking, the more alloying elements and the higher their content, the higher the solution temperature of the stainless steel pipe should be. Especially for steels with high manganese, molybdenum, nickel, and silicon content, only by increasing the solution temperature to ensure complete dissolution can a softening effect be achieved. However, for stabilized steels, such as 1Cr18Ni9Ti, when the solution temperature is high, the carbides of the stabilizing elements fully dissolve in the austenite, and during subsequent cooling, they precipitate at the grain boundaries in the form of Cr23C6, causing intergranular corrosion. To prevent the carbides of the stabilizing elements (TiC and NbC) from decomposing and dissolving, the lower limit of the solution temperature is generally used.