工業用高純度チタニウム材の繰返し平面曲げ疲労き裂進展機構

概要

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Large grain specimens (0.3 mm thick) with average grain size of 10 mm in diameter were fatigued under alternate plane bending to clarify the micromechanism of fatigue crack growth in high purity titanium (KS40S).For a crystallographic study of fatigue fracture surface,the stereomicrophotogrammetry technique was incorpotated with the X-ray microbeam Laue technique,which was used to determine the orienration of specimen surface.The fatigue fracture surfaces comprised of (0001),{1010},{1011},{1012},{1121} and {1120} planes.The (0001) cleavage facet appeared in grains with specimen axes in the angular domain of φ<65°,φbeing the angle between a specimen axis and a basal plane normal.Twinning played an important role on fatigue crack growth behavior.The formation of a microcrack on {1010} and {1120} planes was discussed in association with a sessile dislocation a/3 <1100> resulting from the following reaction of a/3 <1120> dislocations on the {1010} primary slip planes:a/3[2110]+a/3[1120]→a/3[1100]+2/9 a[1120]+a/9[2110] Crystallographic aspects of fatigue deformation were heterogeneous in the process zone wake of a crack in one grain.
社団法人日本材料学会の論文
1993-10-15