熱間工具鋼の軟窒化後窒素濃度分布に及ぼす合金元素の影響

概要

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Nitriding is widely applied to hot-work tool steel to improve the thermal fatigue, corrosion, and tribological properties. For improvement in life of hot-work tool steel, it is important to give the optimal thickness of compound layer and diffusion zone. Therefore, influenc of alloying elements on nitrogen concentration distribution in diffusion layer after nitrocarburiding was investigated in this study. Steels that added silicon, nickel, chromium, molybdenum, vanadium, tungsten and cobalt based on JIS-S40C were nitrocuarburized at 823 K for 18 ks. After this, the nitrogen concentration of these steels were mesured. The diffusion simulation that considered kinetics of nitride precipitation was examined, and the influence of the alloy element was arranged by reactive speed constant K that decided the generation speed of nitride. This simulation can forecast the nitrogen concentration distribution in the diffusion layer after nitrocarburiding at the nitriding temperature and the time in hot-work tool steel.