Let’s continue with the last article of the High alloy H13 steel manufacturing technique，EDM&H13 Heat treatment process.
Let’s continue with the last article of the High alloy H13 steel processing technique，EDM&H13 Heat treatment process.
(4) EDM
EDM is an indispensable finishing method in the modern mold manufacturing process. During spark discharge, the local instantaneous temperature is over 1000 ° C, which melts and vaporizes the metal at the discharge. On the surface of the EDM process, there is a thin layer of molten and re-solidified metal with many microcracks. Under the microscope, this thin layer of metal has a bright white color, that is, a bright white layer. Studies have shown that, for high alloy H13 steel, the microstructure of the surface bright layer formed by EDM is primary martensite, residual austenite, and eutectic carbide, and there is a large amount of untempered primary martensite. Micro cracks. When the
high alloy H13 steel mold is subjected to a load during work, these microcracks can easily develop into macrocracks, which results in the mold being prone to early fracture and early wear.high alloy H13 steel molds should be tempered again after EDM to eliminate internal stress, but the tempering temperature should not exceed the highest tempering temperature before EDM.
(5) Heat treatment process
Reasonable heat treatment process can make the mold obtain the required mechanical properties and improve the service life of the mold. However, if heat treatment defects occur due to improper design or operation of the heat treatment process, the bearing capacity of the mold will be seriously endangered, causing early failure and shortening the working life. Heat treatment defects include overheating, overburning, decarburization, cracking, uneven hardened layer and insufficient hardness. After the highly alloy H13 steel mold has been in service for a certain period of time, when the accumulated internal stress reaches a dangerous limit, the mold should be destressed and tempered, otherwise the mold will crack due to internal stress when it continues to serve.
Ms Sharon Wan
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