Ti-15V-3Cr-3Sn-3Al合金のき裂発生および初期き裂伝ぱ特性

概要

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Characteristics of crack initiation and propagation in rotating bending fatigue tests were investigated in a Ti-15V-3Cr-3Sn-3Al alloy. Successive observations were made through the plastic replica method to clarify the physical meaning of fatigue limit, and the crack propagation behavior was studied using a small crack growth law. The main results are summarized as follows. ( 1 )When σ > σ_ω, microcracks appear at β single phase. ( 2 ) Crack initiation lives are smaller than 10% of the lives for the final fracture. Therefore, the total fatigue life is mainly determined by the crack propagation life. ( 3 ) When σ=σ_ω, no microcracks are observed on the specimen after 10^7 cycles under a metallurgical microscope. Therefore, the fatigue limit in this material is determined by the limiting condition for the initiation of a microcrack. ( 4 ) The crack propagation rate is controlled by the small crack growth law; dl/dN=Cσ^nl(σ : stress amplitude, l : crack length, C and n : constants) .
一般社団法人日本機械学会の論文
1992-12-25