Effect of stress ratio on high-cycle fatigue properties of Ti-6Al-4V ELI alloy forging at low temperature

Abstract

Abstract. The effect of the stress ratio R (the ratio of minimum stress to maximum stress) on the high-cycle fatigue properties of Ti-6Al-4V extra-low interstitial (ELI) alloy forging was investigated at 293 and 77 K. At 293 K, the fatigue strength at 10 7 cycles exhibited deviations below the modified Goodman line in the R=0.01 and 0.5 tests. Moreover, at 77 K, larger deviations of the fatigue strength at 10 7 cycles below the modified Goodman line were confirmed in the same stress ratio conditions. The high-cycle fatigue strength of the present alloy forging exhibit an anomalous mean stress dependency at both temperatures and this dependency becomes remarkable at low temperature.

On the Effect of the Stress Ratio on Fatigue Properties of Ti-6Al-4V Produced by Laser Powder Bed Fusion

“…The lower sensitivity reported by Benedetti et al could be explained by the combined effect of a lower surface roughness of the samples and a finer α + β microstructure. In fact, several studies on the mean stress influence on Ti-6Al-4V produced with conventional manufacturing techniques [7,10,23,24] indicate the microstructure morphology as the main factor that changed the material fatigue response when subjected to positive mean stresses.…”

“…Despite the efforts of several researchers all over the world, the state of the art lacks a proper characterisation of the L-PBF Ti-6Al-4V fatigue dependency from the mean stress. Moreover, the literature on conventionally manufactured Ti-6Al-4V fatigue performance reports a variety of mean stress relations [7][8][9][10][11] highlighting the need to extend this research to L-PBF Ti-6Al-4V.…”

Effect of carbon fibres on the static and fatigue mechanical properties of fibre metal laminates

“…Rhymer et al reported a slightly longer fatigue life than that observed in this study. Although the fatigue strength of Ti‐alloy (Ti‐6Al‐4V) was comparable to that observed in this study, as obtained from fatigue data sheets at a stress ratio R of 0, the strength was slightly higher even after considering the effect of the stress ratio . The fatigue performance of IMS60‐Ti was higher than that of Ti‐alloy under shorter fatigue cycles (~10 4 ), and the fatigue performance of IMS60‐Ti was lower higher than that of Ti‐alloy under longer fatigue cycles (10 4 ~).…”

A new method for predicting the fatigue strength at various stress ratios based on damage of metallic materials

“…The relations between C and σ −1 / σ b of the four alloys under the same loading conditions 15,19, 31–35, 38,40, 42–45, 47 . [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…To further analyze the representation of fatigue strength in metallic materials with different stress ratios using the conventional models, supplementary data from steels, 18,20,30,[35][36][37][38][39][40] aluminum alloys, 31,33,41 titanium alloys, 32,34,[42][43][44][45][46] and Ni-base superalloys 15 were utilized, as shown in Table 3. The contrastive diagrams of the above models for the three materials among them at several stress ratios are shown in Figures 5B-D, respectively.…”