Magnetic Field-Assisted Ultrasonic Nanocrystal Surface Modification of Titanium Alloy

Metallic materials with poor plasticity are usually difficult to get effective surface strengthening. To solve this problem, an innovative surface deformation technology called magnetic-assisted ultrasonic nanocrystal surface modification (MA-UNSM), was used to process Ti64 alloy in this study. It has been demonstrated that MA-UNSM leads to higher hardness, deeper plastic deformation layer, and residual stresses with higher magnitude and greater depth compared with UNSM. Specifically, the external magnetic field increased the hardness from 427.6 HV for traditional UNSM to 493.8 HV for MA-UNSM and the surface compressive residual stress (CRS) from 641 MPa to 757 MPa. It is believed that by lowering the resistance between dislocations and pinning obstacles, the magnetic field enhances the plasticity of the material, and thus more effective surface hardening.