アルミニウム合金7075-T6および2017-T4におけるモードII型進展破面

概要

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A fractographic investigation on mode II fatigue crack growth has been made on 7075-T6 and 2017-T4 aluminum alloys. Not like in mode I growth which is known to show a stage I-stage II transition, no transition has been observed in mode II growth but there has been a gradual change in fracture appearance with an increase in ΔK_<II>, whose growth is characterized by crystallographic growth in the lower ΔK_<II> region while in the higher ΔK_<II> region the smooth curved surface which seems to be formed by glide plane decohesion becomes dominant. Another characteristic pattern, which is often observed regardless of the magnitude of ΔK_<II> is what looks like piled-up thin lamellas. Stress ratio R and superimposed static K_I have no influence on the appearance of mode II growth. Mode II growth rate depends on the range of the stress for both cases of R-0 and-1. A model which is to explain these characteristics of mode II growth has been proposed.
社団法人日本材料学会の論文
1983-04-15