On the relationship between laser scan strategy, texture variations and hidden nucleation sites for failure in laser powder-bed fusion

0566031 - ÚJF 2023 RIV GB eng J - Journal Article
Pacheco, V. - Marattukalam, J. J. - Karlsson, D. - Dessieux, L. - Tran, V. K. - Beran, Přemysl - Manke, I. - Kardjilov, N. - Markotter, H. - Sahlberg, M. - Woracek, Robin
On the relationship between laser scan strategy, texture variations and hidden nucleation sites for failure in laser powder-bed fusion.
Materialia. Roč. 26, DEC (2022), č. článku 101614. ISSN 2589-1529
R&D Projects: GA MŠMT EF16_013/0001794
Research Infrastructure: Reactors LVR-15 and LR-0 II - 90120
Institutional support: RVO:61389005
Keywords : Laser powder-bed fusion * Texture * Preferential orientation * Diffraction contrast neutron imaging * Bragg-edge * Inhomogeneous microstructure * Texture control
OECD category: Materials engineering
Impact factor: 3.4, year: 2022
Method of publishing: Open access
https://doi.org/10.1016/j.mtla.2022.101614

While laser powder-bed fusion has overcome some of the design constraints of conventional manufacturing meth-ods, it requires careful selection of process parameters and scan strategies to obtain favorable properties. Here we show that even simple scan strategies, complex ones being inevitable when printing intricate designs, can inadvertently produce local alterations of the microstructure and preferential grain orientation over small areas - which easily remain unnoticed across the macroscale. We describe how a combined usage of neutron imaging and electron backscatter diffraction can reveal these localized variations and explain their origin within cm-sized parts. We explain the observed contrast variations by linking the neutron images to simulated data, pole figures and EBSD, providing an invaluable reference for future studies and showing that presumably minor changes of the scan strategy can have detrimental effects on the mechanical properties. In-situ tensile tests reveal that fracture occurs in a region that was re-melted during the building process.
Permanent Link: https://hdl.handle.net/11104/0337469