Use of an Abrasive Water Cavitating Jet and Peening Process to Improve the Fatigue Strength of Titanium Alloy 6A-l4V Manufactured by the Electron Beam Powder Bed Melting (EBPB) Additive Manufacturing (AM) Method

Metal components made by additive manufacturing have large inherent surface roughness, and as such, their strength and fatigue life can be reduced significantly vs. wrought products. In order to improve these properties, a novel mechanical surface treatment that introduces compressive residual stress while simultaneously reducing the surface roughness is proposed. The proposed treatment uses water cavitation peening combined with an abrasive slurry. The impact of the kinetic energy charged abrasive particles, induced by water cavitation vapor bubbles collapsing, produces compressive residual stress, while the abrasive reduces the surface roughness. Plane bending fatigue tests were done to determine the effectiveness of this treatment on the fatigue life and strength of titanium alloy Ti6Al4V manufactured by electron beam melting. It was demonstrated that the fatigue strength of an as-built specimen was improved from 169 MPa to 280 MPa by the proposed treatment.