First, the processing and loading of steel pipes:
1. During the heat treatment process, workpieces that are easy to deform should be heated on a special fixture
2. The workpiece should be placed in the effective heating zone
Second, preheating:
1. For workpieces with complex shapes or sharp changes in cross-section and large effective thickness, preheating should be stopped
2. The preheating methods are: one preheating is 800oC, the second preheating is 500~550oC and 850oC, and the temperature rise rate of the first preheating should be limited
Third, heating:
1. Workpieces with grooves and no through holes, castings and welded parts, and processed stainless steel workpieces are generally not suitable for heating in a salt bath furnace
2. The workpiece should be heated for a sufficient insulation time, which can be based on the effective thickness and conditional thickness of the workpiece (the actual thickness multiplied by the workpiece shape coefficient ) Refer to Table 5-16 and Table 5-17 for calculation
Fourth, cooling:
1. When martensitic stainless steel and heat-resistant steel are air-cooled, they should be scattered in a dry place
2. Before the martensitic stainless steel and heat-resistant steel are quenched and cooled to room temperature, they can be cleaned, cryogenically treated, or tempered
3. The workpiece should be tempered in time after quenching. 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 workpiece shape is simple, and it should not exceed 16h
4. For welded assemblies composed of martensitic stainless steel and heat-resistant steel, the time interval between welding and subsequent heat treatment should not exceed 4h
Fifth, cleaning:
1. According to the requirements and surface conditions of the workpiece, use alkali cleaning, water-soluble cleaning agent, chlorine solvent sandblasting, shot blasting, and other methods for cleaning
2. Generally, pickling is not used for cleaning
Post time: Jan-13-2025