Heat treatment of laser powder-bed-fused Co-28Cr-6Mo alloy to remove its microstructural instability by massive FCC→HCP transformation

0546228 - FZÚ 2022 RIV NL eng J - Journal Article
Roudnická, Michaela - Kubásek, J. - Pantělejev, L. - Molnárová, Orsolya - Bigas, J. - Drahokoupil, Jan - Paloušek, D. - Vojtěch, D.
Heat treatment of laser powder-bed-fused Co-28Cr-6Mo alloy to remove its microstructural instability by massive FCC→HCP transformation.
Additive Manufacturing. Roč. 47, Nov. (2021), č. článku 102265. ISSN 2214-8604. E-ISSN 2214-7810
R&D Projects: GA MŠMT LM2018110; GA MŠMT(CZ) EF16_019/0000760
Grant - others:OP VVV - SOLID21(XE) CZ.02.1.01/0.0/0.0/16_019/0000760
Institutional support: RVO:68378271
Keywords : Co–28Cr–6Mo * additive manufacturing * laser powder bed fusion * elevated temperatures operation * heat treatment
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 11.632, year: 2021
Method of publishing: Limited access
https://doi.org/10.1016/j.addma.2021.102265

Laser powder bed fusion of Co–28Cr–6Mo alloy is a powerful tool for many engineering applications but one has to be familiar with its microstructural instability in the as-produced state. In our previous study, we depicted the phenomenon of this instability when exposing the material to temperatures above 673 K. In the present study, we follow up by revealing the effect of this hardening on mechanical properties in tension and show the beneficial effect of heat treatment on removing the observed instability. Hardening associated with increasing the proportion of HCP ε-phase and with the precipitation of σ-phase has a detrimental effect on material plasticity. We thus applied a two-stage heat treatment comprising solution annealing at 1473 K/2 h and aging at 1173 K/5 h. Not only it induced material stability but also increased the material strength with not such a detrimental decrease in material plasticity as was brought by direct aging at 1173 K/5 h.

Permanent Link: http://hdl.handle.net/11104/0322803