Abstract
Vibratory stress relief (VSR) is a highly efficient and low-energy consumption method to relieve and homogenize residual stresses in materials. Thus, the effect of VSR on the fatigue life should be determined. Standard fatigue specimens are fabricated to investigate the fatigue life of Ti-6Al-4V titanium alloy treated by VSR. The dynamic stresses generated under different VSR amplitudes are measured, and then the relationship between the dynamic stress and vibration amplitude is obtained. Different specimen groups are subjected to VSRs with different amplitudes and annealing treatment with typical process parameters. Residual stresses are measured to evaluate the stress relieving effects. Finally, the fatigue behavior under different states is determined by uniaxial tension–compression fatigue experiments. Results show that VSR and annealing treatment have negative effects on the fatigue life of Ti-6Al-4V. The fatigue life is decreased with the increase in VSR amplitude. When the VSR amplitude is less than 0.1 mm, the decrease in fatigue limit is less than 2%. Compared with specimens without VSR or annealing treatment, the fatigue limit of the specimens treated by VSR with 0.2 mm amplitude and annealing treatment decreases by 10.60% and 8.52%, respectively. Although the stress relieving effect is better, high amplitude VSR will lead to the decrease of Ti-6Al-4V fatigue life due to the defects generated during vibration. Low amplitude VSR can effectively relieve the stress with little decrease in fatigue life.
Highlights
Residual stresses exist in many fabricated structures due to plastic deformation from thermal and mechanical operations during manufacturing [1]
The stress relieving effect is better, high amplitude Vibratory stress relief (VSR) will lead to the decrease of Ti-6Al-4V fatigue life due to the defects generated during vibration
Their experimental results show that the fatigue life of machined components can be increased if compressive residual stress and high hardness within surface layer can be induced by a cutting process
Summary
Residual stresses exist in many fabricated structures due to plastic deformation from thermal and mechanical operations during manufacturing [1]. The presence of residual stresses in engineering components and structures significantly affect the fatigue behavior [2], strength [3], and dimensional stability [4]. Many studies have been conducted to investigate the effects of residual stress on the fatigue life of different materials [5,6,7]. The effects of residual stress and surface hardness on the fatigue life under different cutting conditions of 0.45%C steel were studied by Sasahara [8]. Their experimental results show that the fatigue life of machined components can be increased if compressive residual stress and high hardness within surface layer can be induced by a cutting process. Pouget and Reynolds [10] determined that fatigue crack propagation in friction stir-welded AA2050 was strongly linked with the presence of residual stresses, and compressive residual stresses in the heat affected zone were responsible for the apparent improvement of fatigue behavior when the crack approached the weld
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