Why should stainless steel pipes undergo solution annealing treatment?
The solution treatment has three points.
1. Make the structure and composition of the steel pipe uniform, which is especially important for the raw materials, because the rolling temperature and cooling rate of each section of the hot-rolled wire are different, resulting in an inconsistent organizational structure.
2. Eliminate work hardening in order to facilitate continued cold work.
Through the solution treatment, the twisted lattice is restored, the elongated and broken grains are recrystallized, the internal stress is eliminated, the tensile strength of the steel pipe decreases, and the elongation increases.
3. Restore the inherent corrosion resistance of stainless steel.
The precipitation of carbides and lattice defects due to cold working reduce the corrosion resistance of stainless steel. After solution treatment, the corrosion resistance of the steel pipe is restored to its original state.
For stainless steel pipes, the three elements of solution treatment are temperature, holding time and cooling rate. The solution temperature is mainly determined by the chemical composition.