1. The workpiece and fixture should be cleaned of foreign matter such as oil, residual salt and paint before heat treatment.
2. The fixture used for the first time in the vacuum furnace shall be continuously degassed and disposed of at a vacuum not lower than the vacuum demanded by the workpiece.
1. Deformable workpieces during heat treatment should be continuously heated on a common fixture
2. The workpiece should be placed in the invalid heating zone
1. For workpieces with a messy shape or a sharp change in cross section and a large ineffective thickness, continuous preheating should be performed.
2. The preheating method is: one preheating is 800?C, the second preheating is 500~550?C and 850?C, and the temperature of one preheating temperature should be bound.
1. Workpieces, castings and weldments with not-through holes and machined stainless steel workpieces are generally not suitable for heating in salt bath furnaces
2. The workpiece heating should have a satisfactory holding time, which can be continuously calculated according to the invalid thickness and condition thickness of the workpiece (the theoretical thickness multiplied by the shape factor of the workpiece) with reference to Table 5-16 and Table 5-17.
1. When the martensitic stainless steel heat-resistant steel is air-cooled, it should be scattered in a monotonous place.
2. Martensitic stainless steel and heat-resistant steel can be continuously cleaned, cryogenically disposed or tempered after quenching to room temperature
3. After the workpiece is quenched, it should be tempered in time. The distance should not exceed 4h. The carbon content of the steel used in the workpiece (the mass fraction of carbon) is low. The shape of the workpiece is messy and should not exceed 16h.
4. For welded assemblies consisting of martensitic stainless steel and heat-resistant steel, the time between welding and this subsequent heat treatment should not exceed 4h.