Quenching and tempering are important steps that affect […]
Quenching and tempering are important steps that affect the heat treatment deformation or cracking of stamping die parts. For parts of the mould parts that are important for quenching (such as punches and dies) that are prone to deformation or cracking, effective protective measures should be taken to make the shape and section of the part symmetrical and the internal stress balanced. Commonly used protection methods are as follows:
a. bale method;
b. filling method;
c. Blockage method.
Determination of heating temperature
When the quenching heating temperature is too high, the austenite grains are coarse, and oxidation and decarburization are caused, and the tendency of deformation and cracking of the parts is increased. In the specified heating temperature range, the quenching heating temperature is low, which causes the inner hole of the part to shrink and the pore size to become smaller. Therefore, the upper limit of the heating temperature specification should be selected; for alloy steel, if the heating temperature is too high, the inner hole will be expanded and the pore size will become larger. Therefore, the lower limit of the heating temperature should be selected.
Improvement of heating method
For some small stamping embossing dies or elongated cylindrical parts (such as small punches), it can be preheated to 520--580 °C before being heated in a medium temperature salt bath furnace to quenching temperature, than directly using an electric furnace or The deformation of the reheating and quenching parts of the reverberatory furnace is significantly reduced, and the tendency of cracking can be controlled. Especially for high-alloy steel mould parts, the correct heating method is: preheating (temperature 530--560 °C), and then rising to quenching temperature. During the heating process, the high temperature period should be shortened as much as possible to reduce the quenching deformation and avoid the production of small cracks.