Towards understanding the surface strengthening mechanism in negative rake angle cutting of additively manufactured stainless steel

Abstract

The design of lightweight transmission units highlights the importance of additive manufacturing (AM) techniques in gear production; however, it suffers from a limited understanding of the cutting induced surface enhancement mechanism subjected to inevitable negative rake angle cutting (NRAc). This work applies the NRAc method to process hardened AM-produced 17-4PH stainless steel made with 0°, 67°, and 90° hatching strategies, elucidating subsurface alteration mechanisms in distinct crystallographic textures. In-depth microstructural analysis and machinability evaluation revealed that the compressive stress-induced material removal process promotes a refinement-dominated deformation mode, leading to surface strengthening via grain refinement and martensitic phase transition.