OS0739 SUS304鋼の高温多軸疲労き裂進展の定量的評価(構造用材料の疲労挙動と寿命評価,オーガナイズドセッション)

概要

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Fatigue crack growth tests under multiaxial loading condition were conducted at elevated temperature. Cyclic tension and torsion was applied to the thin-walled cylindrical specimens of SUS 304 stainless steeL By using DC electrical potential drop (PD) method, fatigue crack growth under multiaxial loading condition was evaluated. Under multiaxial loading condition, two types of fatigue crack growth were observed; "tensile type" crack, which propagates along the direction perpendicular to the maximum principal stress, σ1 and "shear type" crack, which propagates along the diiection of maximum shear stress, τ_<max> The type of the crack observed for a test depends on the value of △τ/△σ and shape of the initial notch Broadly speaking, the tensile type crack growth was observed under the conditions of △τ/△σ≦0.22 and △τ/△σ≧2.l6, whereas the shear type crack growth or mixture of the both growth type were observed under the intermediate condition of △τ/△σr. Using the crack length projected to the direction of τ_<max>, shear type fatigue crack growth was quantified. From these results, the characteristics of shear type fatigue crack growth were discussed.
2009-07-24