直流電位差法による高張力鋼HT60の疲労き裂伝ぱ速度の信頼性工学的研究

概要

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Fatigue crack growth tests under tension-tension loading were performed on center-notched specimens of a high strength steel HT60, and the statistical property of fatigue crack growth rate da/dN was studied by testing 36 specimens under the same automatically using the DC electrical potential method and a microcomputer. The experimental data were analyzed from the viewpoint of the composite variability model of the fatigue crack growth rate which had been proposed by the present authors. The model parameters were estimated by a new method proposed in this paper as well as by the one proposed previously. The result of data analysis was compared with the previous result of 2024-T3 Al alloy. When expressing C in the Paris equation da/dN=C(ΔK)^m as C=C*gl where g and l correspond to inter-specimen variability and intra-specimen variability of c respectively, the coefficients of variation of g and l for HT60 were approximately of the same magnitude as those for 2024-T3 Al alloy. On the other hand, the correlation distance for intra-specimen variability was smaller for HT60<han for 2024-T3 Al alloy. When a straight line log(da/dN)=1ogC_s+m_slog(ΔK) was fitted to the data of each specimen, m_s and logC_s of each specimen followed normal distributions approximately and strong negative correlation was found between m_s and logC_s. This property was quite similar to that for 2024-T3 Al alloy.
社団法人日本材料学会の論文
1992-05-15