焼結鉄の靱性に及ぼすMoとNiの影響

概要

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The purpose of present work was to evaluate the effects of molybdenum and nickel additions on impact properties of iron compacts, in relation to the activation of sintering process, to the solution hardening of ferritic matrix, and also to the decrease of ductile-brittle transition temperature. Samples were prepared by compacting and sintering the reduced-ore iron powders (NC100⋅24) which contained either 1-8% of reduced molybdenum powders of 3μ in mean diameter, or 2-10% of carbonyl nickel powders of the same mean diameter. The pressing was performed under the pressure of 2-9 t/cm2 and the sintering for 1 hr at 1100-1350°C in hydrogen. Results were summarized as follows: The addition of molybdenum increased the impact strength above the transition temperature, as the result of a remarkable densification due to the activated sintering in a phase. The addition of nickel decreased the impact strength above the transition temperature due to the superior effect of solution hardening. The addition of both elements apparently reduced the ductile-brittle transition temperature. This reduction caused the increase of impact strength at room temperature, when 2% of nickel was added. The abnormal brittleness, which was often observed in the impact test of high density sintered iron at room temperature, also appeared when 1-10% of nickel was added, but disappeared with the addition of 4-8% of molybdenum.
社団法人粉体粉末冶金協会の論文