Spring quenching and tempering treatment
Helical springs and leaf springs with larger dimensions are usually heat treated after thermo forming to achieve the required performance of the spring. Sometimes springs that need to be cold formed with annealed materials are also subjected to final heat treatment. According to the working characteristics of the spring, the spring is required to be quenched into martensite after being heated to an austenite state, and then tempered at a medium temperature to obtain a tempered toustenite structure with high strength and high elastic limit.
The tempering treatment after the spring is formed
Springs need to be tempered after forming, usually in the following situations:
1. Hot-rolled coil springs usually large coil springs with large spring steel diameters need to be hot-rolled, then the spring must be quenched after forming Tempering treatment to obtain the required performance of the spring. There are generally two methods for the tempering and tempering of the coil springs of hot coil forming:
(1) Reheating for fire and tempering treatment. That is, after the hot coil is formed, it is cooled to a lower temperature (below Ar1) or room temperature, and it needs to be reheated to After the austenite state, it flashes and tempers.
(2) Using the residual heat after hot coil forming to directly conduct fire and tempering can save energy, improve efficiency, and shorten the production cycle, but the premise is that the spring still has a high enough temperature when the hot coil is completed, that is, the material is still in Austenitic state. Therefore, the time required for hot coiling (including shaping) is short, and the requirements for equipment conditions and operation techniques are high.
2. Leaf springs are generally bent in the hot state. Normally, bending and quenching are one process, that is, the leaf spring is heated and pressed on the leaf spring bladder, and the oil is cooled under the tightening state to complete the fire process.
3. Springs formed with soft materials (annealed materials) in this case must be treated with tempering and tempering after forming, such as suspension springs with larger sizes (wire diameters in the range of 10-20 mm), flat steel Scroll springs, etc. made of larger sizes.