Numerical investigation of the effect of shot peening parameters on the titanium alloy

A new revolution in the manufacturing industry has been brought about by the tremendous advancements in metal additive manufacturing technologies in recent years. This technology has made it simpler and more affordable to make components that would be difficult and expensive to produce using conventional methods. It has also made it possible to produce open-pore parts with complex geometry. These benefits are particularly significant in high-strength titanium alloy applications, which are common in the aerospace and biomedical industries. Some of the most prominent and rapidly evolving technologies in this sector are those related to metal additive manufacturing, including electron beam melting (EBM) and selective laser melting (SLM). However, due to the lower surface quality and more internal structure defects of the parts produced with additive manufacturing technology, the lower fatigue life compared to the workpieces produced by traditional methods poses a significant problem. Therefore, shot peening is typically used to enhance the fatigue characteristics of high-strength titanium alloys such as Ti-6Al-4V produced by additive manufacturing methods. To improve process efficiency and predictability of the results, it is important to identify the ideal shot peening process parameters. In this study, the residual stresses resulting from the shot peening process applied to titanium metal and Ti-6Al-4V alloy produced with different manufacturing methods were examined using the finite element method. By creating a finite element model consisting of a single ball shot, the relationship between different parameters of the shot peening process, including shot speed, shot diameter and shot angle, and the residual stress profile of the workpiece was analyzed. As a result of this study, it was determined that using a lower shot speed was sufficient to obtain the same residual stresses as the titanium material in the Ti-6Al-4V alloy. Moreover, it was concluded that in order for the Ti-6Al-4V alloy produced by the EBM method to have the same increase in the normalised residual stress as the Ti-6Al-4V alloy produced by traditional methods after shot peening process, the ball diameter should be 2 mm instead of 1 mm. Additionally, the shot speed should be increased from 50 m/s to 125 m/s in Ti-6Al-4V alloy and from 50 m/s to 75 m/s in titanium material to obtain same improvement in maximum compressive residual stress. This study forms the basis for research aimed at determining the parameters that can improve the fatigue life of Ti-6Al-4V alloy and titanium material produced with classical production methods and metal additive manufacturing technology to the desired extent. Moreover, the findings presented in this study can be used in the design and production of high-strength parts in the aerospace and biomedical industries. Additionally, the design through the application of key parameters and precise modeling techniques allows the shot peening process to be implemented more efficiently, resulting in increased productivity.