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Balancing strength and ductility is crucial for structural materials, yet often presents a paradoxical challenge. This research focuses on crafting a unique bimetallic structure, combining non-magnetic, stainless steel 316L (SS316L) with limited strength but enhanced ductility and magnetic, martensitic 17-4 PH with higher strength but lower ductility. Utilizing a powder-based laser-directed energy deposition (L-DED) system, two vertical bimetallic configurations (SS316L/17-4 PH) and a radial bimetallic structure (SS316L core encased in 17-4 PH) were fabricated. Monolithic SS316L, 17-4 PH, and a 50% SS316L/50% 17-4 PH mixture were printed. The printed samples' phase, microstructure, room temperature mechanical properties, and fracture morphology were examined in as-printed conditions. Bimetallic samples exhibited both phases, with a smooth grain transition at the interface. Radial bimetallic samples demonstrated higher mechanical strength than other compositions, except 17-4 PH. These findings showcase the potential of the L-DED approach for creating functional components with tailored mechanical properties.
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This content will become publicly available on June 1, 2026
The role of grain size in achieving excellent properties in structural materials
Advanced structural materials are expected to display significantly improved mechanical properties and this may be achieved, at least in part, by refining the grain size to the submicrometer or the nanocrystalline range. This report provides a detailed summary of the role of grain size in the mechanical properties of metals. The effect of grain size on the high temperature behavior and the development of superplasticity is illustrated using deformation mechanism maps and the development of exceptional strength through grain refinement hardening at low temperatures is also discussed. It is shown that the deformation mechanism of grain boundary sliding, as developed theoretically, can be used to effectively predict both the high and low temperature behavior of metals having different grain sizes. This analysis explains the increase in strain rate sensitivity in ultrafine-grained metals with low and moderate melting points and the ability to increase both the strength and ductility of these materials to thereby overcome the strength-ductility paradox. The recent development of hybrid materials is also reviewed and it is demonstrated that, although these hybrids have received only limited attention to date, they provide a potential for making significant advances in the production of new structural materials.
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- Award ID(s):
- 2051205
- PAR ID:
- 10643547
- Publisher / Repository:
- ELSEVIER
- Date Published:
- Journal Name:
- Journal of Materials Research and Technology
- Volume:
- 30
- ISSN:
- 2238-7854
- Page Range / eLocation ID:
- 3448-3462
- Subject(s) / Keyword(s):
- Grain boundary sliding Hybrids Severe plastic deformation Superplasticity Ultrafine grains
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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