Three Elements And Functions Of Stainless Steel Seamless Pipe Solution Treatment

　　The solution temperature is mainly determined by the chemical composition. Generally speaking, with many types of alloying elements and high content, the solution temperature should be increased accordingly. Especially for stainless steel with high content of manganese, molybdenum, nickel and silicon, the softening effect can be achieved only by increasing the solution temperature and fully dissolving it. However, in stabilized steels, such as 321 stainless steel tubes, the carbides of stabilized elements are fully dissolved in austenite when the solution temperature is high, and precipitated at the grain boundaries in the form of Cr23C6 during subsequent cooling, resulting in intergranular corrosion. In order to make the carbides of stabilized elements (TiC and NbC) do not decompose and do not solute, the lower limit solution temperature is generally used.

　　For stainless steel seamless pipes, the three elements of solution treatment are temperature, holding time and cooling speed. What is the role of stainless steel seamless pipe solution treatment?

　　1. make the stainless steel seamless pipe organization and composition uniform, which is especially important for raw materials, because the rolling temperature and cooling speed of each section of the hot rolled pipe are not the same, resulting in inconsistent organizational structure. At high temperature, the atomic activity intensifies, 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 continue cold processing. Through solution treatment, the twisted lattice is restored, the elongated and broken grains are recrystallized, the internal stress is eliminated, the tensile strength of stainless steel is reduced, and the elongation is increased.

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