Reactive additively manufactured 6061 aluminum alloy by LP-DED: Effects of laser type and powder reuse on anisotropic tensile and fatigue behaviors

• ● Effects of laser type and powder reuse on LP-DED A6061-RAM2 were investigated. • ● Reuse increased part roughness due to poor flowability and particle agglomeration. • ● Reuse reduced ductility and fatigue life due to increased part surface roughness. • ● Green laser specimens had higher strength and longer fatigue lives than infrared ones. • ● Specimens perpendicular to build direction showed greater tensile and fatigue strengths. This study evaluated the influence of laser type (green and infrared) and powder reuse cycle (zero-time- to four-times-used) on the anisotropic tensile and fatigue behaviors of Ti/B 4 C inoculated 6061 aluminum alloy (A6061-RAM2) fabricated via laser powder directed energy deposition. All the specimens were subjected to hot isostatic pressing followed by solution treatment and aging prior to testing. Among the specimens produced with virgin powder, those produced using the green laser had lower surface roughness than those produced using the infrared laser. Repeated powder reuse caused morphological changes in powder particles, such as reduced circularity. Surface roughness increased in infrared laser-fabricated specimens with subsequent powder reuse due to particle agglomeration, decreased flowability, and inefficient powder delivery, which led to inconsistent powder deposition, variations in layer thickness, and formation of higher peaks and deeper valleys on the surface. Mechanical behavior showed anisotropy primarily in fatigue performance, with specimens excised perpendicular to the building direction (perpendicular specimens) consistently exhibiting longer fatigue lives than those excised along the building direction (parallel specimens), while yield and ultimate tensile strengths remained comparable between both orientations. In both orientations, the green laser-fabricated specimens exhibited greater yield and ultimate tensile strengths, and fatigue resistance compared to the infrared ones due to differences in effective load-bearing area. Fatigue resistance decreased with increasing powder reuse due to the formation of deeper surface valleys and irregularities that acted as crack initiation sites and promoted early crack formation.