X線回折による各種材料の疲労破面の残留応力および半価幅測定

概要

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Residual stress and half-value breadth of the fatigue-fractured surfaces of various steels-such as WT-80c, SUS 403, SPY 50, SCMV 4 and S 35 C-were measured by X-ray diffraction. Fatigue tests were performed under the stress ratio R of 0 to 0.4. The half-value breadth b was found to increase with increasing the maximum stress intensity factor K_<max> but the residual stress σ_γ usually decreased with increasing K_<max>. The residual stress on the fatigue-fractured surface is said to be decomposed into four parts: that is (1) tensile residual stress due to monotonic deformation, (2) the release of stress due to fractured surface roughness, (3) compressive stress due to crack closure, and (4) compressive stress due to reversible plastic deformation. The present results were discussed in relation to the latter three causes. From tile measurement of the roughness of fractured surface, it was shown that the main reason whyσ_γ decreased with increasing K_<max> was the effect of roughness. Under the constant K_<max> condition, the larger the R value was, the larger the σ_γ was. This may be related to the reversible plastic deformation and/or to crack closure. Other factors which influence the relative position of σ_γ-K_<max> curve, such as yield stress, fracture mechanism, were also discussed.
社団法人日本材料学会の論文
1984-02-15