コバルト基鍛造合金のクリープ破断特性におよぼす粒界のジグザグ化の影響

概要

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Effect of serrated grain boundaries on the creep-rupture properties of a wrought cobalt-base HS-21 alloy are investigated in the temperature range from 1089K (816℃) to 1311K (1038℃). The strengthening mechanism of serrated grain boundaries is then discussed based on the authors' grain-boundary fracture model, in which the recovery effect by diffusion of atoms is taken into account. Specimens with serrated grain boundaries showed higher creep-rupture strength and larger rupture ductility than those with normal straight grain boundaries. Especially, large difference in the rupture ductility occurred at the lower temperatures. A ductile grain-boundary fracture was observed on the specimens with serrated grain boundaries, but typical grain boundary facets were found in specimens with straight grain boundaries, except high-temperature low-stress conditions. The results of the theoretical discussions based on the model suggested that the strengthening effect of serrated grain boundaries is correlated to the change in the creep-fracture mechanism of specimens with the creep-rupture test conditions.
社団法人日本鉄鋼協会の論文
1990-01-01