Prevention of heat treatment deformation

The deformation causes of precision and complex molds are often complex, but as long as we master the deformation law, analyze the causes of its occurrence, using different methods to prevent mold deformation can be reduced, but also can be controlled. Generally speaking, the heat treatment deformation of precision and complex die can be prevented by the following methods.

(1) Reasonable selection of materials. For the precision and complex die, the fine material of the micro-deformation die steel (such as air quenching steel) should be selected, the die steel with severe carbide segregation should be forged reasonably and quenched and tempered, and for the larger and unforged die steel, the solid solution double refinement heat treatment can be carried out.

(2) The mold structure design should be reasonable, the thickness should not be too different, the shape should be symmetrical, the deformation rule should be mastered for large deformation molds, the machining allowance should be reserved, for large, precise and complex molds can be adopted combined structure.

(3) Precision complex molds shall be pre-treated to eliminate the residual stress in the machining process.

(4) Reasonable selection of heating temperature, control of heating speed, for precision complex mold can take slow heating, preheating and other balanced heating methods to reduce mold heat treatment deformation.

(5) On the premise of ensuring the hardness of the mold, try to adopt pre-cooling, step-cooling quenching or temperature-quenching processes.

(6) For precision and complex moulds, vacuum heating quenching and deep cooling treatment after quenching should be adopted as far as conditions permit.

(7) Pre-heat treatment, aging heat treatment and temperature-nitriding heat treatment can be used to control the precision of some precise and complex molds.

(8) When repairing mold holes, air holes, wear and other defects, use cold welding machine and other repair equipment with little heat influence to avoid deformation in the repair process.

In addition, proper heat treatment process (such as hole plugging, hole binding, mechanical fixation, appropriate heating method, correct choice of mold cooling direction and movement direction in the cooling medium, etc.) and reasonable tempering heat treatment process are also effective measures to reduce the deformation of precision and complex mold.