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粉末冶金热成形零件正在变为特别适用的汽车零件。日本现在使用的汽车结构材料是锻轧的碳钢、铬钢及铬-钼钢。在这些材料中,表面硬化铬钢与铬-钼钢用于变速器齿轮和差速器齿轮。钢中的铬与钼可确保其良好的淬透性。可是,烧结时铬易被氧化,故难以使用粉末冶金热成形铬-钼钢。因此,粉末冶金热成形材料一般采用镍-钼钢粉(4600预合金粉)。为实际用于汽车的高强度零件,研究了粉末冶金热成形镍-钼钢的表面硬化淬透性,并与铬-钼锻钢(4118)进行了比较。
Powder metallurgy thermoformed parts are becoming particularly suitable for automotive parts. Automotive structural materials currently used in Japan are wrought carbon steel, chrome steel and chrome-molybdenum steel. Among these materials, case hardened chrome steel and chrome-molybdenum steels are used for transmission gears and differential gears. Chromium and molybdenum in steel ensure their good hardenability. However, chrome is susceptible to oxidation during sintering, making it difficult to use powder metallurgy thermoformed chromium-molybdenum steels. Therefore, powder metallurgy thermoforming materials generally use nickel - molybdenum steel (4600 pre-alloyed powder). The hardened steel hardened by powder metallurgy for nickel-molybdenum steels has been studied for high-strength parts that are actually used in automobiles, and compared with the chromium-molybdenum forgings (4118).