THE INFLUENCE OF LASER SHOCK PEENING ON THE BEHAVIOR OF Ti6Al4V TITANIUM ALLOY UNDER GIGACYCLE FATIGUE CONDITIONS

This study investigates the gigacycle fatigue behavior of Ti6Al4V titanium alloy – a critical aerospace material – following laser shock peening (LSP). While prior work by the authors demonstrated LSP enhances fatigue life by up to 8 times in stress-concentrated samples, the present research reveals a paradoxical deterioration under gigacycle conditions ( N =10 10 using ultrasonic testing (Shimadzu USF-2000). Contrary to established LSP benefits, treated specimens exhibited a significant reduction in fatigue limit compared to as-received material. Infrared thermography confirmed substantially higher energy dissipation in LSP-processed specimens, while fractography showed a complete transition in failure origin: cracks invariably initiated centrally in LSP specimens versus near-surface initiation in untreated counterparts. These findings are attributed to tensile residual stresses in the specimen core and microstructural alterations induced by LSP.