Effect of laser shock peening and heat‑treated on surface hardness of Ti–6Al–4V

Ti-6Al-4V (TC4) titanium alloys have been extensively used in aviation due to their good comprehensive mechanical properties. However, TC4 has low hardness and poor wear resistance, which cannot meet the increasingly stringent working environment requirements of aerospace. Thus, it is necessary to enhance their performance by posttreatment. Laser shock peening (LSP) is an advanced surface treatment technology that improve the hardness and fatigue life of the metal material by ultra-high plastic strain. However, laser shock peening has limits to improve the surface hardness of workpiece. And heat treatment can effectively improve the performance of titanium alloys. Therefore, the combination of heat treatment and laser shock peening is used to improve the surface hardness of TC4. In this study, the Ti-6Al-4V (TC4) samples were subjected to one and two LSP impacts, respectively. Heat treatment was performed on the sample that has been subjected to one impact, and one of the heat-treated samples was subjected to one impact again. The surface hardness was measured by a Vickers hardness tester meter. The fracture morphologies were observed by scanning electron microscope (SEM) and phase characterization was measured by X-ray diffractometer (XRD). The effect of laser shock peening and heat treatment on the surface hardness of TC4 samples was experimentally investigated. The results showed that the maximum surface hardness of the treated sample was increased by 56.8% compared with original sample. Therefore, the combination of laser shock peening and heat treatment can greatly increase the surface hardness of the TC4.