A method to manipulate non-steady-state columnar-to-equiaxed transition in powder bed fusion additive manufacturing using an electron beam

Site-specific control of solidification grain structure is one the largest attractiveness manufacturing metallic parts with powder bed fusion additive manufacturing. In this study, we manufacture non-weldable superalloy Alloy713ELC using an electron beam (PBF-EB) and achieve various bulk structures, i.e. near fully equiaxed structure, interlocked zigzag columnar structures widths, through controlling process parameters under a line order scan strategy. An analytical transient model, which capable simulating heat transfer in PBF-EB single-layer melting experimental conditions, established validated by compared to numerical models computational fluid dynamics finite element method single-track melting. The evolutions are rationalized microstructural characterization simulations based on models. It found that mechanisms refinement columnar-to-equiaxed transition (CET) related Walton Chalmers selection effect, governed spatial temporal variations direction, effect convection within mushy zone. Based evolution mechanisms, propose manipulate CET or novel PBF-EB.