THE RELATIONSHIP BETWEEN X-RAY RESIDUAL STRESS NEAR THE CRACK AND CRACK OPENING/CLOSING BEHAVIOR CONTROLLING FATIGUE CRACK PROPAGATION IN Ti-6Al-4V ALLOY

概要

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Using the X-ray method of stress measurement for Ti-6Al-4V alloys, the residual stress near the crack was measured for annealed(AN)and solution treated and aged(STA)titanium alloys, under the condition that the measured X-ray stress was in satisfactory agreement with the applied stress under tension. The residual stress measured in the wake of the propagating fatigue crack, σ_r, was compressive, resulting in a smaller crack opening displacement, COD, than theorized. The measured σ_r and COD-values let us understand the fatigue crack propagation rate da/dN in terms of the effective stress intensity factor K_eff. As a result, the da/dN under the same K_eff-value was smaller in the AN specimen with zigzag crack growth than in the STA specimen with straight crack growth, although the da/dN-K_eff relationship under various stress amplitudes was represented by a straight line in a log-log scale separately for the AN and STA specimens.
社団法人日本材料学会の論文
1998-09-15