The processing method of steel pipe

Steel pipe processing furnace:
1. In the process of heat treatment, the workpiece that is easy to deform should be stopped on the special fixture
2. The workpiece should be placed in the effective heating zone

Warm-up:
1. For workpieces with complex shapes or sharp changes in cross-section and large effective thickness, stop preheating
2. The methods of preheating are as follows: the first preheating is 800oC, the second preheating is 500~550oC and 850oC, and the temperature rising speed of the first preheating should be limited

Heating:
1. Workpieces with grooves and no holes, castings and weldments, and processed stainless steel workpieces are generally not suitable for heating in a salt bath furnace
2. There should be enough heat preservation time for workpiece heating, and the calculation can be carried out according to the effective thickness and conditional thickness of the workpiece (the actual thickness multiplied by the shape factor of the workpiece) referring to Table 5-16 and Table 5-17

Cool down:
1. When the heat-resistant martensitic stainless steel is air-cooled, it should be scattered in a dry place
2. Steel pipe. Martensitic stainless steel and heat-resistant steel can be cleaned, cryogenically treated, or tempered before quenching and cooling to room temperature
3. The workpiece should be tempered in time after quenching. Generally, the time interval should not exceed 4h. The carbon content (mass fraction of carbon) of the steel used for the workpiece is low, and the shape of the workpiece is simple, so it should not exceed 16h.
4. For welding assemblies composed of martensitic stainless steel and heat-resistant steel, the time interval between welding and subsequent heat treatment should not exceed 4h

Liquidation:
1. According to the workpiece requirements and surface conditions, use alkali washing, water-soluble cleaning agent, chlorine solvent sandblasting, shot blasting, and other methods to clean up
2. Generally, pickling is not used for cleaning