負の応力比下での SM50A 鋼溶接材の疲労き裂伝ぱ挙動

概要

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The crack propagation behavior of welded material SM50A under a negative stress ratio condition was evaluated with the maximum stress intensity factor K_<max> and the effective stress intensity factor range ΔK_<ett>. The crack opening stress σ_<op> was measured by means of the strain interference method. The crack opening stess σ_<op> in the welded metal was lower than that in the base metal due to the tensile residual stress. Also, the negative value of the crack opening stress σ_<op> was measured in the case of the welded metal. Therefore, the relation between K_<max> and the crack propagation rate da/dN was found to be different between the welded metal and the base metal. However, the relationship between ΔK_<eff> and da/dN could be evaluated with the same equation in all the present experimental cases. Thus, it is confirmed that ΔK_<eff> is one of the reasonable parameters for the evaluation of fatigue crack propagation and the strain interference method is useful for the measurement of crack opening point.
1992-11-15