Artigo Acesso aberto Revisado por pares

Statistical fatigue properties and small fatigue crack propagation in bimodal harmonic structured Ti-6Al-4V alloy under four-point bending

2017; Elsevier BV; Volume: 711; Linguagem: Inglês

10.1016/j.msea.2017.11.010

ISSN

1873-4936

Autores

Shoichi Kikuchi, Hiroki Kubozono, Yuhei Nukui, Yoshikazu NAKAI, Akira UENO, Mie Kawabata, Kei Ameyama,

Tópico(s)

Hydrogen embrittlement and corrosion behaviors in metals

Resumo

Small fatigue crack propagation in bimodal harmonic structured titanium alloy (Ti-6Al-4V) with high strength and ductility was examined under four-point bending at a stress ratio of 0.1 in the ambient laboratory atmosphere. The crack profiles were observed using optical microscopy and scanning electron microscopy, and analyzed using an electron backscattered diffraction to examine the mechanism of small fatigue crack propagation. Fatigue crack paths were not influenced by the bimodal harmonic structure, and the crack growth rates, da/dN, in the harmonic structured Ti-6Al-4V were almost the same as those in a material with coarse acicular microstructure for comparable values of stress intensity range, ΔK. In contrast, the harmonic structured Ti-6Al-4V had a higher resistance of fatigue crack initiation due to the grain refinement induced by mechanical milling, which resulted in an increase of the fatigue life and fatigue limit. Furthermore, the statistical fatigue properties of Ti-6Al-4V alloy were analyzed using the stress dependence of Weibull parameters to quantitatively examine the effects of the bimodal harmonic structure on its fatigue life.

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