| 摘要 |
PROBLEM TO BE SOLVED: To provide excellent nanocrystal alloy steel powder having high strength/toughness, its bulk material and a production method thereof. SOLUTION: The alloy steel bulk material comprises the aggregate of nanocrystal alloy steel particles which contain solid solution type nitrogen and solid solution type carbon at 0.01 to 2.5% (mass) in combination and are 0.3 to 1.0 in the ratio C<SB>SS</SB>/N<SB>SS</SB>of the mass C<SB>SS</SB>of the solid solution type carbon and the mass N<SB>SS</SB>of the solid solution type nitrogen. The carbon is made to exist therein in addition to the nitrogen as the toughness improvement promoting substances of the bulk material. The nanocrystal alloy steel powder of a high nitrogen concentration is produced by mixing the respective fine powders of alloy steel forming components of iron and chromium, nickel, manganese or carbon, etc., together with substances for nitrogen sources and subjecting the mixture to mechanical ironing (MA). The nanocrystal alloy steel bulk material is thereafter produced by caking the alloy steel powder by electric discharge plasma sintering, forging, rolling, etc. COPYRIGHT: (C)2007,JPO&INPIT
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