What Are The Benefits Of Vacuum Heat Treatment Technology And Why Do The Workpiece Deform？

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Benefits of vacuum heat treatment technology:

First, because the vacuum heating mainly relies on heat radiation at high temperature, the effect of low temperature convection is weak, so heating is slow, the temperature difference between the surface and the core of the workpiece is small, the expansion and contraction are more uniform, and the thermal stress caused is small, thereby reducing the final deformation of the workpiece Small and uniform hardness.

Second, the use of vacuum heat treatment technology can achieve bright quenching. The workpiece is heated under atmospheric pressure without contact with air, and the surface will not be oxidized. When the vacuum degree in the furnace is pumped to 1-10-1Pa, the surface of the workpiece achieves the purpose of non-decarburization and non-carburization. The purpose of bright quenching.

Third, vacuum heat treatment technology can realize heating without oxidation and decarburization. Since the molds are heated under vacuum, the oxygen partial pressure of the residual gas is extremely low, the surface is not oxidized, decarburized, and does not form any toxic products.

Fourth, the use of vacuum heat treatment technology can reduce the machining allowance after heat treatment. Because there is no oxidation and decarburization, vacuum heat treatment has little distortion and is clean and bright, it is widely used for vacuum quenching and vacuum carburizing of oil pump nozzles, which can avoid the use of salt bath furnaces to cause the inner holes of the couplings to be sometimes cleaned by residual salt. Dirty or use of protective atmosphere causes black tissue (decarburization) on the surface.

Fifth, the use of vacuum heat treatment technology can improve the plasticity and strength of the workpiece. The solid metal is heat-treated under vacuum, and the surface has a degassing effect, thereby improving its plasticity and strength.

Why Do The Workpiece Deform:

First, when the heat treatment technology is used to process the mold, especially in the quenching process, the temperature difference caused by the inconsistency of the heating and cooling speed of each part of the mold section, coupled with the unequal time of the structure transformation, makes the mold section The volume expansion and contraction of each part is not uniform, and the organization transformation is not uniform, which causes “organization stress” and thermal stress caused by the temperature difference between the inside and outside of the mold. When the internal stress exceeds the yield limit of the mold, it will cause the deformation of the mold.

Second, it is affected by the heating speed. During quenching and heating, the faster the heating speed, the greater the thermal stress generated in the mold, which is likely to cause deformation and cracking of the mold. Especially for alloy steel and high alloy steel, due to their poor thermal conductivity, special attention should be paid to preheating. High-alloy molds with complex shapes need to be preheated several times.

Editor: Frank Lee

Copyright: SIMUWU Vacuum Furnace