Ti-6Al-4V合金のクリープおよびクリープ・疲労挙動に及ぼす微視組織の影響

概要

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The effect of microstructure on creep and creep-fatigue behavior at elevated temperature was studied in Ti-6Al-4V alloy having three different microstructures. The three types of microstructure were prepared with different heat treatment conditions; that is, equiaxed α structure, lenticular α structure and bimodal (mixed of equiaxed α and lenticular α)structure. Creep test was carried out under constant load condition at 773K in air. Creep-fatigue test was carried out under total strain controlled condition using trapezoidal wave form with the hold time of 2 min and 10 min at 773K in air. The following conclusions were obtained. (1)The creep rupture strength of equiaxed α structure was similar to that of lenticular α structure and was larger than that of bimodal structure.(2)The number of cycles to failure under creep-fatigue condition of lenticular α structure was smaller than those of other structures.(3)The effect of microstructure on crack propagation life was small as compared with crack initiation life under creep-fatigue condition.(4)The fracture mode of equiaxed α and bimodal structures was transgranular fracture under creep-fatigue condition. On the other hand, crack of lenticular α structure was initiated and propagated at the interface between α layer precipitated at grain boundary and lenticular α structure.
社団法人日本材料学会の論文
1997-05-15