高 C 高 Mo 系および高 C 高 Cr 系粉末冶金工具鋼の組織と機械的性質

概要

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Steel powders containing (2.28, 2.65)%C-(13.23, 17.32)%Mo-3.9%Cr-7%W-3.5%V-9.4%Co and (3.12, 3.61)%C-(12.69, 12.31)%Cr-1.0%Mo have been produced by water-atomization. Fully densified steel bars have also been made by sintering in a vacuum, hot-extrusion and hot-forging. Microstructures and mechanical properties of the dense steels have been investigated as a function of heat treatment. In the high-carbon and high-molybdenum steels, fine nodules of M_6C (Mo, W-rich) type carbide and fine rods of M_2C (Mo-rich) type carbids are uniformly distributed. It is also observed that fine nodules of M_7 C_3 (Cr-rich) type carbides are uniformly distributed in the high-carbon and high-chromium steels. High hardness is easily obtainable by heat treatment. Grinding is also easy because of the uniform distribution of the fine carbides. However, transverse rupture strength and notch toughness are relatively low. Wear resistance of the steels is improved by increasing the diameters of the unsoluble carbides. Strength and toughness may be improved by sufficient reducing of the oxygen contents of the dense steels.
社団法人日本鉄鋼協会の論文
1977-05-01