Influence of Ultrasonic Surface Rolling Process and Shot Peening on Fretting Fatigue Performance of Ti-6Al-4V

Ning Wang,Jinlong Zhu,Bai Liu,Jiamin Zhang,Shantung Tu,Xiancheng Zhang

doi:10.1186/s10033-021-00611-1

Abstract

At present, there are many studies on the residual stress field and plastic strain field introduced by surface strengthening, which can well hinder the initiation of early fatigue cracks and delay the propagation of fatigue cracks. However, there are few studies on the effects of these key factors on fretting wear. In the paper, shot-peening (SP) and ultrasonic surface rolling process (USRP) were performed on Ti-6Al-4V plate specimens. The surface hardness and residual stresses of the material were tested by vickers indenter and X-ray diffraction residual stress analyzer. Microhardness were measured by HXD-1000MC/CD micro Vickers hardness tester. The effects of different surface strengthening on its fretting fatigue properties were verified by fretting fatigue experiments. The fretting fatigue fracture surface and wear morphology of the specimens were studied and analyzed by means of microscopic observation, and the mechanism of improving fretting fatigue life by surface strengthening process was further explained. After USRP treatment, the surface roughness of Ti-6Al-4V is significantly improved. In addition, the microhardness of the specimen after SP reaches the maximum at 80 μm from the surface, which is about 123% higher than that of the AsR specimen. After USRP, it reaches the maximum at 150 μm from the surface, which is about 128% higher than that of AsR specimen. It is also found that the residual compressive stress of the specimens treated by USRP and SP increases first and then decreases with the depth direction, and the residual stress reaches the maximum on the sub surface. The USRP specimen reaches the maximum value at 0.18 mm, about − 550 MPa, while the SP specimen reaches the maximum value at 0.1 mm, about − 380 MPa. The fretting fatigue life of Ti-6Al-4V effectively improved after USRP and SP. The surface integrity of specimens after USRP is the best, which has deeper residual compressive stress layer and more refined grain. In this paper, a fretting wear device is designed to carry out fretting fatigue experiments on specimens with different surface strengthening.

Highlights

Ren et al [15] studied the effects of different surface ultrasonic rolling process parameters on the fretting wear properties of high strength and high toughness titanium alloy, and the experiments showed that the process parameters had the best wear resistance when the rolling times were 30 times and the vibration amplitude was 7 μm
It is found that the different surface treatments on Ti-6Al-4V can effectively improve the fretting fatigue life [18]
It can be seen that the surface roughness of Ti-6Al-4V is significantly improved after ultrasonic surface rolling process (USRP)

Summary

Introduction

A large number of studies have shown that surface strengthening improves the fatigue resistance of materials mainly due to the introduction of residual compressive stress. Compared with traditional surface strengthening technologies, it can make the material surface produce a denser plastic deformation layer [22], higher surface roughness, better wear resistance and introduce a deeper residual compressive stress layer [23,24,25,26].

Results

Conclusion