On 2018-08-08 14:48:54
Mould heat treatment deformation prevention
Mold heat treatment deformation, mold heat treatment prevention
As is known to all, in the heat treatment of die, especially in the quenching process, due to the mold section parts caused by the inconsistency of the heating and cooling speed of temperature difference, combined with the organization transformation range of sex, make mold section swell-shrink uneven size, each part of organization transformation of uneven, leading to "stress" and the thermal stress caused by temperature difference between inside and outside. When its internal stress exceeds the yield limit of the die, it will cause the deformation of the die.
First of all, the forging mold steel to carry out tempering heat treatment, so that the uniform distribution of carbide, fine and diffuse sostenitic structure, so as to reduce the deformation of complex precision mold heat treatment, to choose as far as possible less carbide segregation mold steel, not cheap, choose small steel mills produced poor material steel. The die steel with severe carbide segregation should be forged reasonably to break the carbide crystal block, reduce the uneven distribution of carbides and eliminate the anisotropy of properties. For the mold with larger size or unforged, the solution can be used to refine the carbide, uniform distribution, rounded edges and corners, to reduce the mold heat treatment deformation.
Reasons this is because the steel mould ellipse in a certain direction of the distribution of the existence of uneven carbide, carbide expansion coefficient is smaller than the steel matrix was about 30%, heating it prevent mold inner hole expansion, cooling and prevent mold inner hole shrinkage, uneven deformation in the mold inner hole, make the mould of the round hole appear oval. Generally speaking, Cr12MoV steel is microdeformation steel, should not appear large deformation.