Optimization of CoCrFeMnNi/SA203 welded joints for cryogenic environments guided by MD simulations

XY Teng and GQ Chen and Z Lamei and ZH Gan and LK Zhu and XS Leng, MATERIALS CHARACTERIZATION, 230, 115696 (2025).

DOI: 10.1016/j.matchar.2025.115696

The CoCrFeMnNi high-entropy alloy (HEA), known for its exceptional mechanical properties and cryogenic performance, shows promise for applications in cryogenic components. However, its high fabrication cost and challenges in welding have limited its widespread use. To address these issues, this study explores the electron beam welding (EBW) of CoCrFeMnNi HEA and SA203 cryogenic steel, combining the benefits of both materials for cryogenic service. A composition-performance relationship for the Fex(CoCrMnNi)y alloy system was established through molecular dynamics simulations, guiding the development of optimized welding processes. The results show that increasing Fe content in the weld metal degrades mechanical properties, while adjusting beam offset during EBW improves weld composition and microstructure. Optimal beam offset (0.4 mm) maximized joint performance, achieving a tensile strength of 538 MPa (91 % of the base material) and ductile fracture behavior. Microstructural analysis revealed significant lattice distortion, element segregation, and deformation mechanisms such as micro-twinning and secondary twinning, enhancing joint strength and toughness. This study provides a framework for the tailored design of high-performance HEA-based welded joints and advanced materials for cryogenic applications.

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