超強力マルエージ鋼の強度と靱性におよぼす前オーステナイト結晶粒径の影響

概要

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The prior austenite (γ) grain sizes have been controlled in the range of 7∿80μm using cold working-recrystallization treatment, and these effects on tensile properties and fracture toughness have been investigated for a 2750MPa grade 17Ni-20Co-6Mo-1.5Ti maraging steel. Tensile properties were strongly dependent on the prior γ grain size. Tensile strength and reduction of area mainly exhibited a linear function of the reciprocal of the square root of the prior γ grain size, but the unstable fracture in a low stress level occurred without showing reduction of area when the prior γ grain sizes were coarser than a critical size. Fracture toughness was almost independent of the prior γ grain size and the fracture mode was quasi-cleavage type. Thus, it was concluded that the prior γ grain size had the pronounced influence on crack initiation but no or only a small effect on crack propergation.
1981-07-01