Stainless steel tube heat treatment main purpose is to change the inner pipe metal matrix structure, improve the hardness of stainless steel pipe, but because it is not fundamentally change the pipe morphology, and therefore can not effectively improve the strength and toughness of the stainless steel tube. Stainless steel tube quenching temperature should be selected in the actual critical temperature 30-70 ℃, due to the poor thermal conductivity of steel, the holding time is generally about twice increase than steel.

Meanwhile, in order to reduce the quenching stress, before quenching should be in the air pre-cooling, oil quenching medium generally use force to avoid quench cracking can also take early oil (cooled to 200-300 ℃) air cooling approach. After stainless steel tube quenching, martensite matrix structure can become or troostite after tempering tempered into sorbite, which is quenching, tempering process and tempered stainless steel pipe other pipe is no essential difference after quenching should be tempered stainless steel. Stainless steel can also be isothermal quenching isothermal quenching medium may be hot oil or nitrate, for example, at 830-870 ℃, and then heated quenched 280-350 ℃ isothermal nitrate. Steel pipe quenching or isothermal quenching, improve the mechanical properties than ordinary gray cast iron is remarkable.

In order to improve the surface hardness and wear resistance of stainless steel pipe, can be flame surface hardening, high-frequency surface hardening and chemical heat treatment, wherein a high frequency or an intermediate frequency surface hardening most applications. High, medium frequency surface hardening with the heating time is short, less oxidation and decarbonization, deformation is small, and easy operation, the heating temperature is usually 850-950 ℃, stainless steel pipe because of poor thermal conductivity, and low melting point, the heating rate is not too fast, otherwise prone to cracking or melting. High, medium frequency processing stainless steel tube not only can improve the surface hardness and wear resistance, but also significantly improve the fatigue strength, increase service life, the other, Machine Tool electrical contact surface of the heating is a typical example of a stainless steel tube surface hardening. In order to get a good matrix organization to ensure the stainless steel tube inside surface hardening and mechanical properties can be obtained after high hardness, surface heat treatment before the best before normalizing or quenching and tempering treatment.