Laser-based powder bed fusion of niobium with different build-up rates

Abstract

Niobium is an important material for high temperature applications, in space, in superconductors or in chemical process constructions. Laser-based powder bed fusion of niobium (PBF-LB/M/Nb) offers new opportunities in design, though it is still an expensive technique. The build-up rate is an important factor for economical manufacturing using PBF-LB/M/Nb. It is largely influenced by variation of process parameters, affecting the heat flow during the manufacturing process. In this work, an empirical model for PBF-LB/M/Nb is developed. Based on this model, manufacturing parameter sets using different volume build-up rates are predicted and confirmed. They enable the manufacture of parts with homogeneous and crack-free microstructure with more than 99.9% relative density. Tensile and hardness tests of specimens, which were manufactured using different parameter sets, are performed to determine the effects of the build-up rate—and thus the heat flow during manufacturing—on different mechanical properties. The ultimate tensile strength and yield strength of as-manufactured specimens reach values up to 525 MPa and 324 MPa, respectively, while the elongation at break ranges between approximately 8 and 16%. The Vickers hardness of all specimens was in the range of 149 ± 8 HV0.1. In addition, the microstructure of the manufactured samples is investigated by means of light as well as scanning electron microscopy.

Investigations of Microstructure and Mechanical Properties in Wire + Arc Additively Manufactured Niobium–Zirconium Alloy

“…Microstructure characterization showed the presence of columnar grain extending along the build direction and the presence of higher dislocation density when compared with annealed Nb sheet. In another research, Griemsmann et al [ 26 ] manufactured Nb using laser‐based powder bed fusion (LPBF) considering different build‐up rates. They were successfully able to manufacture a crack‐free structure with 99.9% relative density.…”

Integrated Process and Materials Modeling for Development of Additive Manufacturing of Refractory Materials for Critical Applications

“…Such properties make refractory metals and alloys suitable for applications such as aerospace propulsion (thrusters, nozzles, thrust augmenter flags) [3][4][5] and energy generation (nuclear reactors [6], nuclear space power, gas turbines, fusion, and light water reactors [7]). Additionally, refractory materials find applications in the biomedical sector as bio-inert materials [8][9][10], electronics industry as capacitors [11,12] and superconductors [13], and in chemical process industries due to their chemical stability [14].…”

“…Among the AM techniques, laser powder-bed-fusion (LPBF), laser powder-directed energy deposition (LP-DED), and electron beam powder-bed-fusion (EB-PBF) have been most commonly employed for refractory metals and alloys [20]. Griemsmann et al [10] examined LPBF of pure Nb with different parameters of laser power, scan speed, and hatch spacing and their effect on part quality. Terrazas et al [21] performed studies on AM of pure Nb using EB-PBF.…”