Process development and quality monitoring of additively manufactured 1.6657 case hardening steel for gear applications.

Abstract Lightweight versions of components made from 1.6657 case-hardening steel could significantly benefit automotive and industrial machinery applications, where this material is valued for its high toughness and fatigue resistance. Although additive manufacturing enables the production of lightweight and complex geometries, the availability of dedicated case hardening steels suitable for this technology remains limited. This paper aims to address that gap by demonstrating the successful production of 1.6657 gears using Powder Bed Fusion with a Laser Beam. This work also proposes to adjust two traditional parameter development tools by, on the one hand, presenting a method to prevent the misuse of volumetric energy density, and on the other hand, by integrating additional material characteristics into the process map beyond density alone. Specifically, it focuses on incorporating pore features relevant to fatigue performance, with the aim of embedding gear performance requirements already in the early stages of parameter development. Finally, this work demonstrates how the proposed development framework enables a strong correlation between melt pool monitoring data and specific porosity types. This correlation supports the use of melt pool monitoring as a reliable tool for detecting pore formation in critical areas of the additively manufactured gears.