1. Make the cold drawn steel pipe structure and composition uniform, which is especially important for raw materials, because the rolling temperature and cooling rate of each section of hot rolled pipe are not the same, resulting in inconsistent structure. At high temperatures, atomic activity is intensified, the σ phase dissolves, the chemical composition tends to be uniform, and a uniform single-phase structure is obtained after rapid cooling.
2, eliminate work hardening, in order to facilitate the continued cold processing. Through the solution treatment, the lattice recovery of the twist, the elongated and broken crystal grains recrystallize, the internal stress is eliminated, the tensile strength of the steel wire is lowered, and the elongation is increased.
2. Restoring the inherent corrosion resistance of cold drawn steel tubes, due to the precipitation of carbides caused by cold working, lattice defects, so that the corrosion resistance of cold drawn steel pipes is reduced. After the solution treatment, the corrosion resistance of the cold drawn steel pipe is restored to a suitable state.