The influence of precision mould heating heat treatment process

Heating speed, the influence of precision mould as after the heat treatment deformation is generally considered to be caused by cooling, this is not correct. Especially complex, precision mould processing technology of the right of the mould deformation tend to produce bigger effect, the comparison of some mould heating process can obviously see that heat faster, tend to produce bigger deformation. ( 1) Any deformation causes metal heating expansion, due to steel during heating, uneven within the same mold, the temperature of each part, The uneven heating) Will inevitably cause the mould parts of the expansion of the inconsistencies, thus forming internal stress due to the uneven heating. In steel below phase transition temperature, uneven heating main produce thermal stress, more than phase change temperature heating uneven, also can produce organization transformation range of sex, both organizational stress. So the faster the heating, the temperature of the mold surface and center difference, the greater the stress is, the greater the mold heat treatment after deformation. ( 2) Preventive measures for complex precision mould heating should be slow when heating below the phase transition point. In general, mold vacuum heat treatment deformation is much smaller than salt bath furnace heating quenching. Adopting preheating, for low alloy steel mold to adopt a preheating ( 550 - 620oC） ； Double preheating (should be adopted for high alloy steel mould 550 - Oc and 800-620 850oC） 。