Effects of cooling rate and stabilization annealing on fatigue behavior of β-processed Ti-6Al-4V alloys

Impact of Cryogenic Treatment on HCF and FCP Performance of β-Solution Treated Ti-6Al-4V ELI Biomaterial

“…The improvement in the HCF property, reflected in terms of the increased number of cycles to failure, had happened due to a combined effect of a decrease in the size of prior β grain, formation of massive α patch and its subsequent transformation into ultra-fine α and β during the soaking period at −196 • C. Improvement in HCF performance with a reduction in the size of the prior β grain has also been reported earlier in different research studies [41][42][43]. Fractography using scanning electron microscopy was done to have further insight into the nature of failure and analysis of fractured surface.…”

“…The random orientation of martensite α' within prior β grain also leads to the generation of secondary cracks reflected in terms of river like slipping as shown in Figure 7b. Bifurcations of macrocracks into secondary microcracks and severe deflections of cracks in β heat treated Ti-6Al-4V has also been reported by earlier research studies [41,43,44]. The net effect of crack deflection is to disperse the strain field energy of the macroscopic crack into multiple secondary microcracks resulting in a significant reduction in fatigue crack growth [44].…”

Notch fatigue and crack growth resistance of Ti-6Al-4V ELI additively manufactured via selective laser melting: A critical distance approach to defect sensitivity

“…It was not possible to find from the same source information about plain fatigue limit and crack threshold. The only data available in the literature [34] for water quenched wrought Ti-6Al-4V reports an unrealistic crack threshold of 20…”

“…For this purpose, the data reported in Fig. 11 was estimated from the fatigue limit assessed in [34] to be equal to 220 MPa at R=0.1, while the crack threshold at the same stress ratio was taken equal 3 MPa m 0.5 , indicated in [35] as the upper bound value displayed by Ti-6Al-4V in its various microstructural conditions. This value is in good agreement with that found in the present paper for the AMed material at R=0.1.…”

“…This value is in good agreement with that found in the present paper for the AMed material at R=0.1. Equation ( 1) was then used to estimate the critical defect size ar ea max of the material tested in [34], obtaining a value of 6 m, which is reasonable considering the fine acicular microstructure and the absence of porosity.…”