Laser dissimilar weldability of cast and rolled CoCrFeMnNi high-entropy alloys for cryogenic applications

Abstract

This study investigates the effects of welding velocity on weldability of dissimilar cast/rolled high-entropy alloys and the applicability of cryogenic temperatures. Cast HEA side of dissimilar weld metal (WM) indicates a larger dendrite packet and dendrite arm spacing (DAS) than rolled WM. Size difference is associated with epitaxial growth from each base metal (BM). As the welding velocity increases (6–10 m min⁻¹), shrinkage voids and DASs decreases. Dissimilar welds show tensile properties comparable to cast BM, where there are tensile fractures of dissimilar welds. Cryogenic properties of dissimilar welds are superior to those of room-temperature welds, because deformation twins and dislocation densities are significantly formed at 77 K. Therefore, dissimilar welds can be applied to the production of cryogenic products.

KEYWORDS:

• High-entropy alloys
• dissimilar welds
• microstructure
• mechanical properties
• deformation twins
• dislocation density
• cryogenic property

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Hyunbin Nam http://orcid.org/0000-0003-3152-9567

Eun-Joon Chun http://orcid.org/0000-0002-0358-2603

Hyoungseop Kim http://orcid.org/0000-0002-3155-583X

Youngsang Na http://orcid.org/0000-0002-7634-7225

Namhyun Kang http://orcid.org/0000-0002-9460-5128

Additional information

Funding

This work was supported by the Future Material Discovery Project of the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (MSIP) of Korea (NRF-2016M3D1A1023534), and by NRF grant funded by the Korea government (MSIT) through GCRC-SOP (No. 2011-0030013).