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4Cr13 Pellet die vacuum gas quenching furnace
(1) Cleaning and drying
As in the oil quenching process, the ring mold is cleaned with emulsifying degreaser, and the ring mold is cleaned in the cleaning machine for 3-4h to remove oil, rust and iron chips in the mold holes.After taking out, put into the ring mold drying machine, drying temperature 180C, time 3h.
When the bad mold is completely dry, put it into the furnace.Small deformation of vacuum heat treatment is one of its major advantages.However, the amount of deformation varies with the arrangement of the parts.At the same time, the workpiece placement also has an important impact on the hardness uniformity. Since vacuum heat treatment is heated by radiation, poor placement will inevitably result in serious shielding, and the heating effect will be affected.Therefore, the placement of the workpiece should be conducive to the airflow path (gas quenching) and oil circulation (oil quenching), there should be a certain gap between the workpiece and the workpiece, so that the hardness of all parts of the basket is uniform – caused, for slender type workpiece should be appropriate clip.
Test materials and methods
With, can be placed as far as possible suspension suspension, such a high temperature can reduce deformation.In order to ensure the uniform heating of the die end, die body, surface and inner hole in the process of ring mold heat treatment, without the phenomenon of underheating and overburning, and to ensure the uniformity of the overall quenching structure, the method as shown in FIG. 2.4 is adopted for furnace loading, and the actual effect is good.
Heat preservation by heating 650’C for 60min, 850’C for 75min, heating by quenching for heating. The upper limit is 1050C, using oil quenching, tempering by 200C for 180min after quenching.
(4) The holding time and the time for quenching pressure to maintain the average temperature can be calculated according to the amount of furnace charge and the wall thickness and hole size of the ring mold.
The nitrogen pressure used for quenching is selected according to the diameter and wall thickness of the ring mold. The diameter of the -general ring mold is 2.5~3. OPa is selected between 1.2mm~2.
(5) Tempering causes austenite transformation in the internal structure of the ring mold due to quenching. At the same time, there is thermal stress, which needs to be eliminated by tempering. Generally, for the purpose of obtaining the minimum residual thermal stress and the best wear-resisting hardness, low-temperature tempering at 180~200C is selected.
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