Preventing method of mold steel cold treatment defect

Mold steel and more for the high-carbon alloy steel, quenched austenite and some still did not change into martensite, retained in the state of use as a residual austenite, affect the use of performance. If placed below zero to continue cooling, can promote residual martensitic transformation of austenite,

Specific prevention methods can be divided into two points

(1) After quenching and cooling before the mold frame is placed in boiling water for 30-60min, to eliminate 15% -25% quenching internal stress and stabilize the retained austenite, then -60 ℃ conventional cold treatment, or -120 ℃ cryogenic treatment, the lower the temperature, the more the retained austenite into martensite volume, but not all the end of the transformation, the experiment shows that about 2% -5% retained austenite retained as needed a small amount of residual Austenite can relax stress, play a buffer role, due to the residual austenite soft and tough, can partially absorb martensitic rapid expansion energy, ease the phase transition stress;

(2) After the cold treatment is finished, the mold frame is taken out and heated in hot water to eliminate the stress of 40% -60% cold treatment. After the temperature is raised to room temperature, the tempering should be promptly carried out, the stress of the cold treatment is further eliminated, the cold treatment crack is prevented from being formed, Formwork products stored and used without distortion.