Control of Powder and Process Variations for a Robust and Repeatable Metal Additive Manufacturing

Purpose and goal

The goal of the project is to (1) correlate the laser powder bed fusion (LPBF) process and post process variables to materials properties of tool steels, and (2) provide a guideline for applying additive manufacturing (AM) techniques in a broader category of tools and products. In ROAR-AM, the effect of both main and other LPBF parameters as well as post process were studied. A guideline including design for AM, material development, process parameter development, post process (thermal treatment and machining), quality control, and potential iterations were summarized.

Expected results and effects

The major parameters of LPBF and recoating process were varied and correlated to density, hardness, and/or residual stress of the printed specimens. A couple of rubber extrusion nozzles for HGF were printed in 420s/420 martensitic tool steel. An aluminum extrusion die for Hydro was printed in H13 carbon tool steel. They were processed with the validated thermal treatment respectively and tested in a production or a lab extrusion machine. Two contributions to conferences were made, and one publication on the process parameter development is at the manuscript stage.

Planned approach and implementation

The project was carried out according to the work package plan as below WP1 Characterization and quality assurance of robust powders for AM WP2 Correlation between powder characteristics and AM WP3 Correlation between AM process and mechanical data WP4 Demonstrators and industrial guideline for a robust AM process WP5 Project management, coordination, and dissemination. The printing process and post thermal treatment were tuned and validated to fulfill the requirement of the two use-case, which are two types of demonstrators printed in different carbon tool steels.