Exploring Fe–Mn–Al–C lightweight steels via in-situ alloying in direct energy deposition

This study explores the feasibility of in-situ alloying via direct energy deposition (DED) to tailor microstructures and strength-ductility balance of Fe–Mn–Al–C lightweight steels (LWSs) with independently varied composition of 8–12 wt% Al and 20–25 wt% Mn. As the Al content increased, the matrix p...

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Main Authors: Seungjin Nam, Chahee Jung, Hyun Chung, Heechan Jung, Young Mok Kim, Hyoung Seop Kim, Hyunjoo Choi, Seok Su Sohn
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:Journal of Materials Research and Technology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2238785425014668
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author Seungjin Nam
Chahee Jung
Hyun Chung
Heechan Jung
Young Mok Kim
Hyoung Seop Kim
Hyunjoo Choi
Seok Su Sohn
author_facet Seungjin Nam
Chahee Jung
Hyun Chung
Heechan Jung
Young Mok Kim
Hyoung Seop Kim
Hyunjoo Choi
Seok Su Sohn
author_sort Seungjin Nam
collection DOAJ
description This study explores the feasibility of in-situ alloying via direct energy deposition (DED) to tailor microstructures and strength-ductility balance of Fe–Mn–Al–C lightweight steels (LWSs) with independently varied composition of 8–12 wt% Al and 20–25 wt% Mn. As the Al content increased, the matrix phase was transformed from austenitic (8Al) to ferritic (10Al and 12Al), accompanied by the formation of secondary phases. The in-situ alloyed LWSs exhibited a reduced density (6.5–7.0 g/cm3) while exhibiting an exceptional strength-ductility synergy. Specifically, 20Mn8Al LWS exhibited an ultimate tensile strength of 883 MPa and an elongation of 43.8 %, resulting in a product of strength and elongation of 39 GPa∙%. It also achieved a weight reduction of 10 % compared to conventional stainless steel. Strengthening was primarily governed by pre-existing dislocations and solid-solution strengthening effects, while deformation twinning in 20Mn8Al enhanced strain hardening and delayed necking. These findings highlight the potential of in-situ alloyed LWSs for lightweight structural applications, offering a superior combination of mechanical properties and density reduction. Furthermore, this study establishes DED-based in-situ alloying as a versatile strategy for microstructural and mechanical property optimization in additive manufacturing of advanced steels.
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spelling doaj-art-b798908147fc4f63b9036c5dfb52686d2025-08-20T02:31:12ZengElsevierJournal of Materials Research and Technology2238-78542025-07-013741743110.1016/j.jmrt.2025.06.044Exploring Fe–Mn–Al–C lightweight steels via in-situ alloying in direct energy depositionSeungjin Nam0Chahee Jung1Hyun Chung2Heechan Jung3Young Mok Kim4Hyoung Seop Kim5Hyunjoo Choi6Seok Su Sohn7Department of Materials Science and Engineering, Korea University, Seoul, 02841, Republic of KoreaDepartment of Materials Science and Engineering, Korea University, Seoul, 02841, Republic of KoreaDepartment of Materials Science and Engineering, Korea University, Seoul, 02841, Republic of KoreaDepartment of Materials Science and Engineering, Korea University, Seoul, 02841, Republic of KoreaDepartment of Materials Science and Engineering, Korea University, Seoul, 02841, Republic of KoreaGraduate Institute of Ferrous and Eco Materials Technology, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea; Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai, 980-8577, Japan; Institute for Convergence Research and Education in Advanced Technology, Yonsei University, Seoul, 03722, Republic of KoreaDepartment of Materials Science and Engineering, Kookmin University, Seoul, 02707, Republic of Korea; Corresponding author.Department of Materials Science and Engineering, Korea University, Seoul, 02841, Republic of Korea; Corresponding author.This study explores the feasibility of in-situ alloying via direct energy deposition (DED) to tailor microstructures and strength-ductility balance of Fe–Mn–Al–C lightweight steels (LWSs) with independently varied composition of 8–12 wt% Al and 20–25 wt% Mn. As the Al content increased, the matrix phase was transformed from austenitic (8Al) to ferritic (10Al and 12Al), accompanied by the formation of secondary phases. The in-situ alloyed LWSs exhibited a reduced density (6.5–7.0 g/cm3) while exhibiting an exceptional strength-ductility synergy. Specifically, 20Mn8Al LWS exhibited an ultimate tensile strength of 883 MPa and an elongation of 43.8 %, resulting in a product of strength and elongation of 39 GPa∙%. It also achieved a weight reduction of 10 % compared to conventional stainless steel. Strengthening was primarily governed by pre-existing dislocations and solid-solution strengthening effects, while deformation twinning in 20Mn8Al enhanced strain hardening and delayed necking. These findings highlight the potential of in-situ alloyed LWSs for lightweight structural applications, offering a superior combination of mechanical properties and density reduction. Furthermore, this study establishes DED-based in-situ alloying as a versatile strategy for microstructural and mechanical property optimization in additive manufacturing of advanced steels.http://www.sciencedirect.com/science/article/pii/S2238785425014668Direct energy depositionLightweight steelsAlloy explorationIn-situ alloyingMechanical behaviors
spellingShingle Seungjin Nam
Chahee Jung
Hyun Chung
Heechan Jung
Young Mok Kim
Hyoung Seop Kim
Hyunjoo Choi
Seok Su Sohn
Exploring Fe–Mn–Al–C lightweight steels via in-situ alloying in direct energy deposition
Journal of Materials Research and Technology
Direct energy deposition
Lightweight steels
Alloy exploration
In-situ alloying
Mechanical behaviors
title Exploring Fe–Mn–Al–C lightweight steels via in-situ alloying in direct energy deposition
title_full Exploring Fe–Mn–Al–C lightweight steels via in-situ alloying in direct energy deposition
title_fullStr Exploring Fe–Mn–Al–C lightweight steels via in-situ alloying in direct energy deposition
title_full_unstemmed Exploring Fe–Mn–Al–C lightweight steels via in-situ alloying in direct energy deposition
title_short Exploring Fe–Mn–Al–C lightweight steels via in-situ alloying in direct energy deposition
title_sort exploring fe mn al c lightweight steels via in situ alloying in direct energy deposition
topic Direct energy deposition
Lightweight steels
Alloy exploration
In-situ alloying
Mechanical behaviors
url http://www.sciencedirect.com/science/article/pii/S2238785425014668
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