Mechanical behaviour and subsurface characteristics of Ti-6Al-4V subjected to electropulsing-assisted multiple laser shock processing impacts.

Electropulsing (EP)-assisted laser shock peening (LSP), involving the synchronous application of EP and LSP to Ti-6Al-4V samples, represents an innovative surface strengthening technology. A comprehensive series of evaluations and examinations were conducted to thoroughly investigate the effects of EP-assisted multiple laser shock processing impacts on the mechanical behaviour and subsurface characteristics of the Ti-6Al-4V sample. The strength and ductility properties, fatigue performance, microstructure features in subsurface regions and deformation characteristics at various depths of the treated Ti-6Al-4V samples were investigated. The results revealed that as the number of impacts increased, a prominent multilayered structure, including a remelting layer, a severe plastic deformation region, and a plastic deformation-affected zone in the subsurface developed. The observed increase in strength can be attributed to grain refinement, an increase in dislocation density and the presence of high-density nanotwins within the subsurface layer. A high fatigue life was achieved by EP-assisted multiple LSP, with a ∼328.1 % increase compared with that of the as-received sample.The improvement in durability is mainly related to the enhanced subsurface structure acted as a barrier to crack propagation. • Electropulsing assisted multiple laser shock peening at low pulse energy can improve the mechanical properties of Ti-6Al-4V. • An multilayered structure is formed, including a remelting layer, a deformation region, and a deformation-affected zone within the subsurface. • Electropulsing-assisted multiple laser shock processing impacts improve the fatigue life of Ti-6Al-4V samples by 3.28 times. • The finer grains, high-density dislocations and nanotwins significantly contribute to the enhanced fatigue performance. [ABSTRACT FROM AUTHOR]