The deformation and prevention knowledge of heat treatment of precision die is mentioned. Heat treatment deformation is the main defect of die treatment process. The precision complex mold is often discarded because of heat treatment deformation. It has been the key problem in the heat treatment production to control the deformation of the precision complex mold. In the process of quenching, the temperature difference caused by the inconsistency of heating and cooling rate of each part of the die section makes the volume expansion and shrinkage of the sections of the die section uneven and the uneven microstructure change, which causes the thermal stress caused by the "tissue stress" and the temperature difference inside and outside the mold. When the internal stress exceeds the yield limit of the mold, it will cause deformation or fragmentation of the die.

Even if the material of die material and steel are very good, but if the design of the die structure is not reasonable, such as thin edge, sharp angle, groove, abrupt step, great disparity of thickness and so on, it is easy to cause the die to be deformed after heat treatment.

1. The cause of deformation

   Because of the uneven thickness of the die and the sharp round angle, the heat stress and the tissue stress between the parts of the die are different, resulting in the different volume expansion of each part, which causes the die to be deformed after quenching.

2. Preventive measures

   When designing the mold, in the case of meeting the actual production needs, it is necessary to minimize the difference between the thickness of the mold and the structure, and the structure is asymmetrical. At the junction of the thickness and thickness of the mold, a smooth transition and other structural design should be used as far as possible. According to the deformation rule of the die, the machining allowance is reserved. After quenching, the die is rejected because of the deformation of the die.For special moulds with special shapes, uniform structure can be used to make cooling uniform during quenching.