Comparative Numerical Analysis of Tool Tilt Effects in Friction Stir Processing of AZ91: Exploring SPH Applications

Abstract A comparative investigation is carried out on the impact of TTA on the FSP of AZ91 using a novel mesh-free SPH technique. The main objective is to interpret thermo-mechanical behavior by examining temperature distribution, material flow, and microhardness within the SZ. Comparing FSP with and without tool tilt revealed that the 2.5° TTA results in higher and more uniform temperatures throughout the SZ. A minimal % difference of 0.93% and a maximum of 7.86% were noticed when the temperature distribution at the shoulder edge was compared between both cases. It also causes increased material flow, zero surface defects, and a more refined and uniform microstructure. The 2.5° TTA increased overall microhardness compared to the BM and 0° TTA, with the advancing side showing higher microhardness. Around 13% improvement in the microhardness than the 0° TTA was observed due to the strengthening phenomena such as grain boundary strengthening. Thus, the application of SPH has precisely captured the thermal and mechanical characteristics for the impact of TTA on the FSP of AZ91 and proved that employing SPH in numerical simulations provides valuable insights and can further aid in optimizing process parameters to reach desirable microstructural and mechanical characteristics.

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