| 摘要 |
PURPOSE:To improve a heat resistant cracking property by forming >=2 layers of a plating layer on the surface. CONSTITUTION:A plating layer is formed >=2 layers by subjecting to >=2 layers plating on the surface of a metal die. The penetration from the surface up to the base metal of the inner part on the majority part of minute cracks existing inside the plating layer is controlled accordingly. The local oxidation of the base metal is therefore prevented and the generation of extra fine cracks which become the nuclear for thermal crack is controlled. Namely the generation of thermal cracks is reduced finally. Because of therefore the thermal cracks caused by minute cracks exsisting in the chrome plated layer of a metal die being reduced widely, the wear resistance and thermal resistant cracking property are improved.
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