The solution temperature is determined mainly by chemical composition.Generally speaking, the solution temperature of alloy elements with many kinds and high content should be increased accordingly.Especially for the steel with high content of manganese, molybdenum, nickel and silicon, the softening effect can be achieved only by increasing the solution temperature and making it fully dissolved.However, stabilized steel, such as 321 stainless steel tube, when the solution temperature is high, the carbides of stabilized elements are fully dissolved in austenite, which will precipitate in the form of Cr23C6 at the grain boundary during subsequent cooling, resulting in intergranular corrosion.In order to prevent carbides (TiC and NbC) of stabilized elements from decomposition and solid solution, lower solid solution temperature is generally adopted.
For stainless steel seamless pipe, the three elements of solution treatment are temperature, holding time and cooling speed.What is the role of seamless stainless steel pipe solution treatment?

1.the stainless steel seamless tube structure and composition uniform, which is particularly important for raw materials, because the hot rolled pipe sections of rolling temperature and cooling speed is not the same, resulting in inconsistent organizational structure.At high temperature, atomic activity intensifies,σ phase dissolves, chemical composition tends to be uniform, and homogeneous single-phase structure is obtained after rapid cooling.

2.eliminate work hardening, in order to continue cold processing.After solution treatment, the distorted lattice is restored, the elongation and broken grains are recrystallized, the internal stress is eliminated, the tensile strength of the wire decreases, and the elongation increases.

3.restore the inherent corrosion resistance of stainless steel pipe.Due to carbide precipitation and lattice defects caused by cold processing, the corrosion resistance of stainless steel tube decreases.After solution treatment, the corrosion resistance of seamless stainless steel tube is restored to the best state.