Effect of heat treatment on precision stamping process

Effect of heat treatment on precision stamping process
Influence of heating speed of precision stamping die: the deformation of die after heat treatment is generally considered to be caused by cooling, which is incorrect. Mold, especially the complex precision mold, whether the processing technology is correct or not often has a greater impact on the deformation of the mold. The comparison of some mold heating processes shows that the heating speed is fast, and often produces large deformation.
(1) Causes of deformation
Any metal must expand when heated. Because the temperature of each part in the same die is not uniform (that is, the uneven heating) will inevitably lead to the inconsistency of the expansion of each part in the mold, thus forming the internal stress of uneven heating. Under the temperature below the transformation point of steel, the uneven heating mainly produces thermal stress. When the temperature exceeds the transformation temperature, the uneven heating will also produce the non-uniform structure transformation, which will produce the structural stress. Therefore, the faster the heating speed is, the greater the temperature difference between the die surface and the center, the greater the stress, and the greater the deformation of the die after heat treatment.
(2) Preventive measures
The complex precision mould should be heated slowly when heated below the phase transition point. Generally speaking, the deformation of mould in vacuum heat treatment is much smaller than that in salt bath furnace. Preheating can be used for low alloy steel mould (550-620oc) and secondary preheating (550-620oc and 800-850oc) for high alloy steel mould.