The heat treatment process of stainless steel pipes differs according to the type of stainless steel pipe. The following are several common stainless steel pipe heat treatment processes:

1. Austenitic stainless steel:
①Solution treatment: Heating to the solid solution temperature (usually 950~1150℃), so that all carbides and martensite formed by cold working are dissolved and transformed into austenite, and then air-cooling and cooling are selected according to different chromium and carbon contents. Cooling methods such as water cooling or air cooling.
②Stabilization treatment: For austenitic stainless steel containing Nd or Ti, heat to 870~950℃, keep warm for 2~4 hours and then cool slowly (such as air cooling or furnace cooling).
③Stress relaxation treatment: eliminate internal stress, usually kept at 275~450℃ for 0.5~2 hours to improve mechanical properties.
④Stabilization treatment: Heating to 900°C to dissolve chromium carbide and prevent chromium carbide from precipitating between crystals.

2. Martensitic stainless steel:
①Annealing treatment: adjust the internal structure of the material.
②Quenching treatment: The steel is austenitized and then cooled at an appropriate cooling rate so that the workpiece undergoes structural transformation such as martensite in the cross-section to improve strength and hardness.
③Tempering treatment: Heat the quenched workpiece to an appropriate temperature maintain it for some time, and then cool it as required to obtain the required structure and performance.

3. Ferritic stainless steel: The purpose of heat treatment is mainly to eliminate or weaken the adverse effects of the second phase. Common process steps include annealing.

4. Precipitation hardening stainless steel: The heat treatment process includes solid solution treatment, conditioning treatment, and aging treatment, aiming to improve the performance of the material through solid solution strengthening and aging strengthening.

The specific parameters of these heat treatment processes (such as temperature, time, cooling method, etc.) will be adjusted according to the specific composition, required performance, and application scenarios of the stainless steel pipe. The heat treatment process can improve the mechanical properties, corrosion resistance, organizational structure, etc. of stainless steel pipes, and is an indispensable and important process step in the manufacturing and application of stainless steel pipes.

It should be noted that heat treatment of stainless steel pipes needs to be carried out under strictly controlled environmental conditions to ensure the desired results. Improper heat treatment can cause material performance degradation or other problems. Therefore, in practical applications, the appropriate heat treatment process should be selected according to the specific situation, and the relevant operating specifications and safety requirements should be followed.