Sprocket heat treatment distortion mechanism:
Heat treatment distortion is one of the major defects in the heat treatment production process. Workpieces can cause changes in volume during heat treatment, such as volume expansion when heated and volume shrinkage when cooled. In addition, when the phase changes, the specific volume of each phase also causes a change in volume. For example, when a steel material is heated to a critical point above austenite, the austenite has a smaller specific volume, and the steel material changes during quenching. In martensite, expansion occurs due to the large specific volume of martensite. When the workpiece is heated and cooled, the temperature of the inner and outer layers is different, the phase change time is also inconsistent, and the non-uniformity of the structure, which will inevitably lead to heat treatment stress inside the workpiece, resulting in distortion of the workpiece.
Heating the sprocket to a higher temperature, followed by rapid cooling, results in heat treatment stress. At the same time, the workpiece shape, material composition, machining, the workpiece's own weight, and the placement method will also affect the heat treatment distortion of the workpiece. Workpiece quenching goes through three stages: heating process (release of internal stress), insulation (workpiece's own weight and high temperature creep), cooling (non-uniform cooling and phase change). The superimposition of stress in these three phases will cause the final quench distortion of the workpiece.
