Magnetic Field-Assisted Laser Shock Peening of Ti6Al4V Alloy

Laser shock peening is widely used in mechanical property improvements of metallic materials. One concerning factor is the nonuniformity of mechanical properties and microstructures, such as surface hardness and grain refinement. Herein, a new strengthening strategy that integrates femtosecond laser shock peening and pulse magnetic field that can uniformize the performance of metallic materials is proposed. With the magnetic field-assisted laser shock peening (MFLSP), the reduction of preferred-clustering points shows uniform grain refinement with the maximum area fraction of small grains. The fabrication of uniform grain refinement is attributed to the dislocation redistribution by the release of pinning effect. With magnetic field stimulation, dislocation lines are observed to disperse from low-angle grain boundary to the intragranular area. Dislocation behaviors stimulated by magnetic field are attributed to atomic migration. The dispersed dislocations serve as potential glide sources for grain refinement during laser-induced plastic deformation. The enhanced grain refinement results in uniform surface hardening of metallic materials. The application of this integrated strategy with laser processing and external energy field can be used for adjusting mechanical properties of metallic materials with uniform microstructures and surface hardness.