Control of Density and Grain Structure of a Laser Powder Bed-Fused Superelastic Ti-18Zr-14Nb Alloy: Simulation-Driven Process Mapping

Abstract

This study focuses on the control of density and grain structure of a superelastic Ti-18Zr-14Nb (at. %) alloy subjected to laser powder bed fusion. It starts with the production and characterization of a Ti-18Zr-14Nb powder feedstock and printing of a series of calibration specimens. These specimens are next subjected to chemical, structural, phase and texture analyses in order to collect experimental data needed to build simulation-driven processing maps in the laser energy density–material build rate coordinates. The results of this study prove that, once calibrated, the simulation-driven processing maps can be used to relate the main LPBF parameters (laser power, scanning speed, hatching distance and layer thickness) to the density and grain structure of the printed material, and the process productivity (build rate). Even though this demonstration is made for a specific material–system combination (TiNbZr & TruPrint 1000), such a process mapping is feasible for any material–system combination and can, therefore, be exploited for the process optimization purposes and for manufacturing of functionally graded materials or parts with intentionally seeded porosity.

Shape Memory Alloys 2020

“…Against this background and paying attention to the latest developments, Ewald et al [5] innovatively applied laser powder bed fusion to produce crack-free samples of a low-cost Fe-based SMA and achieved a good shape recovery by means of an optimized heat treatment route. Applying a different approach to achieve optimized materials, Brailovski et al [6] demonstrated that simulation-driven processing maps can be used to relate the main laser powder bed fusion parameters to the control of density and grain structure of superelastic Ti-18Zr-14Nb alloys. To complete this section of the Special Issue, NiTi, as the most successful SMA, also produced via additive manufacturing could not be absent.…”