Mold heat treatment process exactly how much of a role
Mold heat treatment is to potential mold material; improve the performance of the mold. The performance of the mold must be met: high strength (including high-temperature strength, resistance to thermal fatigue performance) high hardness (wear resistance) and high toughness, and also requires good mach inability, (including good polishing) weld ability and corrosion resistance and so on.
Mold heat treatment sub preliminary heat treatment, the final heat treatment, surface hardening of three parts.
Die forging Heat thermo mechanical treatment of new technology in recent years developed a new technology. Most mold the final forging temperature at about 850 ℃, after the last fire forging, not slow cooling, but the fast-cooling quenching, and then tempering or annealing of the ball. The move, is not only energy saving, more important is to improve the service life of the mold.
In hot mould has the problem of uneven size sensitivity. This mold cooling rate and section size. High temperature heating using conventional slow cooling and isothermal annealing process is difficult to eliminate, but there is still a long annealing cycle, oxidation burning large die life and low. Fast well spheroidizing annealing process, effectively solve the problem. Quick uniform fine annealing process is far higher than in the traditional annealing process heating temperature, heating the average temperature for a short time, rapid cooling, in order to obtain the residual carbide small, thin, high dislocation density and instability of the organization, and then to be Under the second furnace heating and cooling, that breakthrough ball isothermal quenching and tempering temperature and the temperature of the heating for a short time, average temperature, followed by annealing at higher than conventional cooling rate cooling to room temperature, thereby fast ball.
Mold heat treatment is important to ensure that the process tool performance has a direct impact on the mold manufacturing precision, strength plastic mold, mold working life, mold manufacturing costs.
Correct or tend to produce complex mold, processing of the mold deformation greater impact, compared to some of the mold heating process is evident, heating speed, often have a greater deformation.
(1) The cause of any metal deformation when heated to be expanded, the steel when heated, within the same mold, the temperature of each part of the unevenness (i.e., non-uniform heating) is bound to result in expansion of the various parts of the mold inconsistencies , thereby forming internal stress due to uneven heating. In the following phase transition temperature steel, uneven heating main thermal stress, uneven heating than the phase transition temperature, will produce unequal organization transformation, both produce organizational stress. Therefore faster heating, temperature of the mold surface and the central portion of the difference between the larger, the greater the stress, deformation of the mold heat treatment is greater.
(2) Preventive measures against complex molds in the following phase transition point should be heated slowly heated; in general, mold vacuum heat treatment deformation is much smaller than the salt bath furnace heating quenching. Preheating, low-alloy steel mold can be used for a warm-up; high-alloy steel molds for the second warm-up should be used.