(1) check the surface for defects such as decarburization and crack before heat treatment. These surface defects will seriously reduce the fatigue limit of the spring.
(2) quenching heating should pay special attention to prevent overheating and decarburization, do a good job in salt bath deoxidization, control the furnace gas atmosphere, strictly control the heating temperature and time
(3) in order to reduce deformation, the furnace loading mode of the spring during heating, the fixture form and the quenching cooling method during cooling.
(4) after quenching, it should be tempered as soon as possible and heated evenly. Fast cooling after tempering can prevent the brittleness of tempering and cause surface compressive stress, and improve the fatigue strength.
