recrystallization annealing? After the spring roll forming, the recrystallization annealing treatment must be carried out to stabilize the spring geometry and reduce the deformation during quenching. Recrystallization annealing temperature is 550 ~ 650 ℃, the heat preservation of air cooling after 1 ~ 1.5 h. A small amount can be carried out in the salt bath furnace, and the atmosphere is controlled by continuous resistance furnace. 2) quenching? In the quenching heat of the salt bath furnace, the spring should be evenly fastened with wire, or the spring sleeve will be heated on the core rod. When heating, ensure that the spring surface is oxidized and decarbonized. Salt baths should be carefully deoxidized. Can also be used in controlled atmosphere box-type furnace heating, the heating temperature is 850 ℃ + 10 ℃, insulation 10 ~ 15 min, from quenching oil cooling. 3) temper? After quenching, tempering can be done twice. To rectify tempering, correct the tempering temperature should be lower than the final tempering temperature 20 ℃ or so commonly, insulation 10 ~ 15 min, from air cooling. Then the final tempering is carried out. After the spring size is corrected, the spring is installed on the tempering fixture to make the final tempering. Tempering fixture shall ensure that the pitch and free length of the spring meet the requirements. The tempering temperature is 420, plus or minus 10, and the temperature is 30~35min. 4) shot blasting? In order to improve the fatigue strength of the spring, the shot blasting is needed. The diameter of the projectile is 0.3~0.5mm. When compressed air is used, the compressed air pressure is 0.4~ 0.5mpa; With a centrifuge shot, the linear velocity of the projectile is 70m/s. The service life of the spring treated with shot blasting can more than double.