The deformation of the mold after quenching, no matter what method is adopted, the deformation is unavoidable, but the following methods can be used to control the precision and complex molds that must strictly control the deformation amount.
1. Using quenching and tempering heat treatment
For precision and complex molds with low basic hardness requirements but high surface hardness requirements, quenching and tempering heat treatment can be performed after rough machining of the mold, and low temperature nitriding treatment (500″550ºC) after finishing. Due to the low mold nitriding temperature, There is no phase transformation of the matrix structure. In addition, the furnace is cooled to room temperature, and the cooling stress is less, and the mold deformation is small.
2. Using pre-heat treatment
For precision and complex molds, if the hardness requirements are not too high, pre-heated pre-hardened steel can be used, and the die steel (such as 3Cr2Mo, 3CrMnNiMo steel) can be pre-heated to reach the hardness in use (lower hardness is 25″35HRC , The higher hardness is 40″50HRC), and then the mold is processed and formed without heat treatment, so as to ensure the accuracy of the precision and complex mold.
3. Use age hardening die steel
Aging hardening steel can be used for precision and complex molds. For example, PMS (1Ni3Mn2CuA1.Mo) steel is a new type of aging mold steel. The hardness after solution quenching at 870ºC is about 30HRC, which is convenient for machining. After the mold is formed, it can be processed at about 500ºC. The high hardness of 40″45HRC can be obtained by the aging heat treatment, and the mold deformation is small, and only needs to be polished. It is an ideal steel for precision and complex molds.