Improving high cycle fatigue performance of gas tungsten arc welded Ti6Al4V titanium alloy by warm laser shock peening

Welded components of titanium alloy used in aviation and aerospace industries were generally vulnerable to alternate cycles of vibrations stress during their service, which were weakest part and highly prone to failure and fracture. To improve the resistance towards vibration failure of weldments, warm laser shock peening (WLSP) technology was successfully applied as a post weld treatment in present work and significant 42.3% increase in high cycle vibration fatigue limit was achieved (from 399 ± 5 MPa to 568 ± 19 MPa). The notable effects of WLSP on the residual stress, microhardness, roughness and microstructure of weldments was investigated to clarify its strengthening mechanism. It is analyzed that the large improvement of fatigue limit was attributed to high amplitude compressive residual stress, high stability of compressive residual stress and surface nanostructure induced by WLSP. Our work indicated that WLSP could be an effective approach for promoting weld quality and fatigue performance over conventional methods of post weld treatment.