High temperature high strength austenitic steel fabricated by laser powder-bed fusion

Sebastien Dryepondt; Peeyush Nandwana; Kinga A. Unocic; Rangasayee Kannan; Patxi Fernandez Zelaia; Fred A. List

doi:10.1016/j.actamat.2022.117876

High temperature high strength austenitic steel fabricated by laser powder-bed fusion

Sebastien Dryepondt, Peeyush Nandwana, Kinga A. Unocic, Rangasayee Kannan, Patxi Fernandez Zelaia, Fred A. List

Research output: Contribution to journal › Article › peer-review

25 Scopus citations

Abstract

Extremely fast cooling rates during laser powder-bed fusion (LPBF) can result in materials with unique microstructures. For LPBF 316L stainless steel, the formation of sub-grain cellular structures with high dislocation density has been linked to superior tensile properties at room temperature. This cellular structure offers also a new route for the development of high temperature LPBF steels with the nucleation of nano-size strengthening carbides in the cell walls. HK30Nb steel (Fe-25Cr-20Ni-Nb-C) was, therefore, fabricated by LPBF to evaluate its potential for high temperature applications. Optimization of the fabrication parameters yielded material with density greater than 99.7%, with nano Nb-rich precipitates in the cell walls. Annealing at 800 °C for 5h resulted in the nucleation and growth of additional precipitates mainly in the cell walls and at grain boundaries. The high dislocation density led to yield strength at 20–900 °C two to three times higher than yield strength for cast HK30Nb and the nano carbides in the cell walls significantly improved the cellular structure stability at 800 °C.

Original language	English
Article number	117876
Journal	Acta Materialia
Volume	231
DOIs	https://doi.org/10.1016/j.actamat.2022.117876
State	Published - Jun 1 2022

Funding

The authors would like to thank K. Carver, K. Hedrick, C.S. Hawkins, T. M. Lowe and V. Cox for assistance with the experimental work, and M. Romedenne and J. Jun for reviewing the manuscript. This research was sponsored by the US Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office, Propulsion Materials Program, under contract DE-AC05-00OR22725 with UT-Battelle LLC and performed in partiality at the Oak Ridge National Laboratory Manufacturing Demonstration Facility, an Office of Energy Efficiency and Renewable Energy user facility. Notice of Copyright . This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

Keywords

Austenitic steel
Cellular structure
HK30Nb
Laser powder bed fusion (LPBF)
Nano carbides
Tensile

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.actamat.2022.117876

Cite this

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title = "High temperature high strength austenitic steel fabricated by laser powder-bed fusion",

abstract = "Extremely fast cooling rates during laser powder-bed fusion (LPBF) can result in materials with unique microstructures. For LPBF 316L stainless steel, the formation of sub-grain cellular structures with high dislocation density has been linked to superior tensile properties at room temperature. This cellular structure offers also a new route for the development of high temperature LPBF steels with the nucleation of nano-size strengthening carbides in the cell walls. HK30Nb steel (Fe-25Cr-20Ni-Nb-C) was, therefore, fabricated by LPBF to evaluate its potential for high temperature applications. Optimization of the fabrication parameters yielded material with density greater than 99.7%, with nano Nb-rich precipitates in the cell walls. Annealing at 800 °C for 5h resulted in the nucleation and growth of additional precipitates mainly in the cell walls and at grain boundaries. The high dislocation density led to yield strength at 20–900 °C two to three times higher than yield strength for cast HK30Nb and the nano carbides in the cell walls significantly improved the cellular structure stability at 800 °C.",

keywords = "Austenitic steel, Cellular structure, HK30Nb, Laser powder bed fusion (LPBF), Nano carbides, Tensile",

author = "Sebastien Dryepondt and Peeyush Nandwana and Unocic, {Kinga A.} and Rangasayee Kannan and {Fernandez Zelaia}, Patxi and List, {Fred A.}",

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doi = "10.1016/j.actamat.2022.117876",

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AU - Dryepondt, Sebastien

AU - Nandwana, Peeyush

AU - Unocic, Kinga A.

AU - Kannan, Rangasayee

AU - Fernandez Zelaia, Patxi

AU - List, Fred A.

PY - 2022/6/1

Y1 - 2022/6/1

N2 - Extremely fast cooling rates during laser powder-bed fusion (LPBF) can result in materials with unique microstructures. For LPBF 316L stainless steel, the formation of sub-grain cellular structures with high dislocation density has been linked to superior tensile properties at room temperature. This cellular structure offers also a new route for the development of high temperature LPBF steels with the nucleation of nano-size strengthening carbides in the cell walls. HK30Nb steel (Fe-25Cr-20Ni-Nb-C) was, therefore, fabricated by LPBF to evaluate its potential for high temperature applications. Optimization of the fabrication parameters yielded material with density greater than 99.7%, with nano Nb-rich precipitates in the cell walls. Annealing at 800 °C for 5h resulted in the nucleation and growth of additional precipitates mainly in the cell walls and at grain boundaries. The high dislocation density led to yield strength at 20–900 °C two to three times higher than yield strength for cast HK30Nb and the nano carbides in the cell walls significantly improved the cellular structure stability at 800 °C.

AB - Extremely fast cooling rates during laser powder-bed fusion (LPBF) can result in materials with unique microstructures. For LPBF 316L stainless steel, the formation of sub-grain cellular structures with high dislocation density has been linked to superior tensile properties at room temperature. This cellular structure offers also a new route for the development of high temperature LPBF steels with the nucleation of nano-size strengthening carbides in the cell walls. HK30Nb steel (Fe-25Cr-20Ni-Nb-C) was, therefore, fabricated by LPBF to evaluate its potential for high temperature applications. Optimization of the fabrication parameters yielded material with density greater than 99.7%, with nano Nb-rich precipitates in the cell walls. Annealing at 800 °C for 5h resulted in the nucleation and growth of additional precipitates mainly in the cell walls and at grain boundaries. The high dislocation density led to yield strength at 20–900 °C two to three times higher than yield strength for cast HK30Nb and the nano carbides in the cell walls significantly improved the cellular structure stability at 800 °C.

KW - Austenitic steel

KW - Cellular structure

KW - HK30Nb

KW - Laser powder bed fusion (LPBF)

KW - Nano carbides

KW - Tensile

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High temperature high strength austenitic steel fabricated by laser powder-bed fusion

Abstract

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Keywords

UN SDGs

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