Effect of machine hammer peening on the structural phase state and mechanical properties of Ti–6Al–4V in layer-by-layer electron beam additive manufacturing

Electron beam 3D printing is a method of modern high-performance additive manufacturing of titanium alloy products. There are well-known problems with the formation of equiaxed primary grains suitable for providing the required level of mechanical characteristics that call for searching technological approaches to improve the quality of printing products used in critical industries. Machine Hammer Peening (MHP) has proven itself as the most effective method of interlayer material work hardening in additive manufacturing. The article examines the possibility of controlling the structural-phase state and mechanical properties of Ti–6Al–4V titanium alloy by using the interlayer machine hammer peening with different intertreatment intervals. The data obtained during experimental studies indicate that the greatest improvement in strength and microhardness is provided by machine hammer peening after depositing each 4 layers. Machine hammer peening contributes to the formation of a more uniform structure, the columnar prior grain refinement, elimination of columnar grains, and a decrease in the thickness of the α‑lath width. The results of the research confirm the effectiveness of using machine hammer peening in layer-by-layer electron beam additive manufacturing of the Ti–6Al–4V alloy for improving mechanical properties.