Abstract
A laser surface treatment (LST) which can enhance fatigue resistance of metallic parts has been developed. The LST is useful both for improving the surface microstructure of undamaged specimens, thereby increasing the original fatigue life, and for healing in service metallic parts subjected to cyclic loading. The LST method was applied to three point bend specimens of Ti–6Al–4V alloy at different stages of fatigue life. Results show a significant improvement in fatigue resistance, with a distinct treatment optimum point at about two-thirds of the original lifetime. In addition, changes in the near surface microstructure, including grain size and shape distribution, phase ratios, etc., have been studied. The relative α phase surface area, as well its grain size, decreased considerably, showing large perimeter curvatures and larger total grain border lengths.