一方向凝固および単結晶超合金切欠材の773Kにおける高サイクル疲労強度評価

概要

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For studying the effect of crystallographic orientation and stress concentration on fatigue properties at 773 K, high cycle fatigue tests were conducted on conventional casting superalloys MM 247, directionally solidified superalloy CM 247 LC and single crystal superalloy CMSX-2. Following conclusions were obtained. 1) Fatigue cracks were initiated at material defects in smooth specimen, and the ratios of fatigue limit to tensile strength were lower than 0.3. 2) Loading conditions made the difference in fatigue limits of smooth specimen, that is, the predicted values from notched fatigue > rotating bending fatigue > axial loading fatigue, which is considered to be caused by the difference of the extent that material defects could take part in fatigue crack origins. 3) Notched fatigue strength of CMSX-2 can be unifiedly expressed by resolved shear stress in fatigue limit diagram, which is independent of crystallographic orientation.
一般社団法人日本機械学会の論文
2003-06-25