Tempering process code

The purpose is to eliminate the internal stress when quenching tempering, stable organization to increase toughness, need mechanical properties. Quenching parts must pass a tempering treatment. ( A) The preparing work before tempering 1) Artifacts should be cleaned after quenching, surface should be clean, must not have saline, filthy thing in the world. 2) Classifies various parts according to the tempering temperature, tempering temperature same parts together. 3) The same parts will tempering, neatly packed in a mesh of wire inside, and then into pit type furnace heating, long and thin parts is pay attention to prevent bending deformation. 4) Check the thermometer table is correct. Production of each when blow-in please make relevant personnel to correct the thermometer table. ( 2) Tempering operation: 1. According to the parts needed to meet performance requirements, tempering can be divided into low temperature tempering, medium temperature tempering and high temperature tempering and artificial aging four a) Low temperature tempering: - in 150 250 ℃, the purpose is to reduce the hardness to eliminate the residual stress after quenching, on the basis of improving martensite tetragonality, reduce the brittleness. b) Medium temperature tempering: - in 250 Between 500 ℃, the purpose is to make the parts need enough hardness and elastic limit and ultimate strength. c) High temperature tempering: - in 500 Within the range of 650 ℃, the purpose is to obtain a higher toughness and strength and elasticity. 2. Furnace charging temperature: well type 40 ℃ tempering furnace can improve furnace charging, the purpose is to avoid temperature drop too much. Nitrate bath furnace electrode can improve the 20 ℃ furnace. 3. Tempering temperature tempering temperature is mainly decided by the hardness of parts required, the relationship between different materials require different hardness and tempering temperature (see schedule For reference) 4. Holding time, See table 2) Effective thickness 2021 - or less 4041 - 6061 - 8081 - 100101 - 40-120 holding time air furnace 6060 - 9090 - 120120 - 150150 - 180180 - 15-210 salt furnace 2525 - 3635 - 5050 - 6565 - 8080 - 955. Cooling in air cooling after tempering in principle, but should pay attention to: a) Parts have temper brittleness, high on the alloying elements should be done in oil cooling after tempering. b) For convenient cleaning, also can be in hot water cooling. ( 3) Tempering matters should be paid attention to when operating a) Nitrate furnace heating temperature shall not exceed 550 ℃, the explosion danger in order to avoid overheating. b) Important and batch larger parts, should first try a back, check the hardness after qualified, can batch furnace. The operator should pay attention to when the quenching quality, in order to prevent the quenching occurs when problem to temper the work, not easy to analysis problem.