First, galvanized square tube and fixture should be removed before the heat treatment of oil, residual salt, paint and other foreign objects;

Second, the first used in the vacuum furnace fixture, should be no less than the required degree of vacuum in the work under the degassing purification;

Third, deformation of the workpiece in the heat treatment process, should be heated on a dedicated fixture. Preheating methods are: a preheat to 800 ℃, the second preheating to 500-550 ℃ and 850 ℃, a warm-up speed should be limited;

Fourth, for complex shapes or sharp changes in section and the effective thickness of the workpiece should be preheated;

Fifth, there are not through-hole groove of the workpiece, casting and welding parts and processing of stainless steel forming parts, generally should not be heated in a salt bath furnace;

Six, galvanized square tube heating should have enough holding time, according to the effective thickness and thickness of the workpiece (the actual thickness multiplied by the workpiece shape factor);

Seven, martensitic stainless steel and heat-resistant steel galvanized square tube before quenching to room temperature after cleaning, cryogenic treatment or tempering, welding and subsequent heat treatment between the time interval should not exceed 4 hours;

Eight, according to the requirements of galvanized square tube and surface conditions using alkaline washing, water-soluble cleaning agent, chlorine solvent sandblasting, shot peening and other methods for cleaning;

Nine, after correction should be carried out in the lower than the original tempering temperature stress relief annealing, the shape of the complex or size requirements of the workpiece, after correction in the tempering with the fixture with tempering correction;

Ten, when the mechanical properties of galvanized square tube unqualified, repeated heat treatment, but the number of repeated quenching or solid solution generally not more than twice. Replenishment of galvanized square tube tempering is not counted as repeated treatment. Quenched or tempered martensite stainless steel and heat-resistant steel after tempering the workpiece should be pre-heated, annealed or tempered before tempering.