Enhancing mechanical properties of Ti–6Al–4V through directed energy deposition-arc by coating with 316L-sodium silicate additive

Additive manufacturing (AM) using directed energy deposition-Arc (DED-Arc) for Ti–6Al–4V alloys often results in coarse columnar grains, leading to anisotropic mechanical properties and thermal cracking. This study explores the use of 316L stainless steel powder and sodium silicate mixtures as additives to enhance grain refinement and mechanical performance in Ti–6Al–4V components. Various mass ratios of 316L powder and sodium silicate were applied during the DED-Arc process, and the resulting samples were analyzed using microscopy and tensile testing. The addition of these mixtures significantly refined the prior β grain structure, promoting a transition to equiaxed grains. A 1:5 mixture of 316L powder and sodium silicate yielded optimal results, increasing tensile strength by 30%–1293 MPa and elongation by 51%–12.1%. However, excessive additive concentrations caused brittle phases and cracking. This work demonstrates a cost-effective approach for improving grain refinement and mechanical properties in Ti–6Al–4V alloys using recycled 316L powder and sodium silicate. Compared to powder-based AM processes, the DED-Arc process offers a more economical method for producing high-performance alloys through multi-element in-situ alloying.