Ti-6Al-4V合金の回転曲げ疲労におけるき裂発生および初期き裂伝ぱ過程(<小特集>強度設計・安全性評価小特集)

概要

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Characteristics of crack initiation and propagation in rotating bending fatigue tests were investigated on Ti-6AI-4V alloy. Successive observations were made by the plastic replica method to deter-mine the physical meaning of fatigue limit o_w, and crack propagation behavior was studied using a small crack growth law. The main results obtained are summarized as follows. (1) When σ is over σ_w, microcracks appear at α phase. (2) The fatigue life is determined by the crack propagation period except for the stress near the fatigue limit. (3) When σ is equal toσ_w, no microcracks are observed on the specimen after 10^7 cycling of stress under a metallurgical microscope. Therefore, the fatigue limit is determined by the limiting condition for the initiation of microcrack. (4) The relation dl/dN ∝σ^nl holds whenσ/σ_<0.2>>0.6, and the relation dl/dN ∝ ΔK^m holds when σ/σ_<0.2>>0.5.
社団法人日本材料学会の論文
1992-10-15