Page 94 - MSAM-4-3

Materials Science in

Additive Manufacturing

ORIGINAL RESEARCH ARTICLE
Enhanced strength of A131 steel via

heterostructures induced by laser-directed
energy deposition

Yuchao Bai 1,2,3 , Silu Zhang 1,2,3 , Qi Yan 1,2,3 * ,Cuiling Zhao 1,2,3 * ,
and Jiaming Zhan 4
1 Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robots,
Harbin Institute of Technology, Shenzhen, Guangdong, China
2 Key University Laboratory of Mechanism and Machine Theory and Intelligent Unmanned Systems
of Guangdong, Harbin Institute of Technology, Shenzhen, Guangdong, China
3 School of Robotics and Advanced Manufacture, Harbin Institute of Technology, Shenzhen,
Guangdong, China
4 School of Advanced Manufacturing, Sun Yat-sen University, Shenzhen, Guangdong, China
(This article belongs to the Special Issue: Metallic Additive Manufacturing)

Abstract

The trade-off between strength and plasticity has posed a challenge to the broader
application of conventional metallic structural materials in high-speed, heavy-load,
and extreme service environments. Heterogeneous structure designs could potentially
*Corresponding authors:
Qi Yan overcome these limitations with their inherent superior combination of strength and
(galaxy.yanqi@gmail.com) plasticity. To harness this potential, this study employed a directed energy deposition
Cuiling Zhao additive manufacturing (AM) technology to fabricate a novel heterostructure in
(zhaocuiling@hit.edu.cn) as-built (AB) A131 steel, consisting of alternating coarse and fine-grain layers along
Citation: Bai Y, Zhang S, Yan Q, the building direction. In addition, a heat treatment process was applied to fabricate a
Zhao C, Zhan J. Enhanced strength near-homogeneous microstructure, allowing for the investigation of the role of crystal
of A131 steel via heterostructures
induced by laser-directed energy misorientation in tensile anisotropy. Compared to the performance of commercial
deposition. Mater Sci Add Manuf. hot-rolled ASTM A131 steel (yield strength [σ ]: 346.5 MPa; ultimate tensile strength
YS
2025;4(3):025220038. [σ ]: 545.0 MPa), the AB A131 steel achieved significant enhancements of 168.3%
UTS
doi: 10.36922/MSAM025220038 and 78.0% in σ and σ , respectively, when maintaining a comparable elongation
YS
UTS
Received: May 27, 2025 of 24.6% along the deposition direction similar to the ASTM A131 standard.
Comprehensive experimental characterizations, combined with molecular dynamics
Revised: June 14, 2025
simulations, were conducted to investigate the underlying formation mechanism of
Accepted: June 16, 2025 the heterostructure and the origins of mechanical anisotropy. It was found that single-
Published online: July 21, 2025 pass deposition produced three distinct microstructure regions with different grain
sizes owing to dendrite growth. With repeated thermal cycles, these evolved into a
Copyright: © 2025 Author(s). layered heterostructure consisting of alternating fine crystals and coarse-columnar
This is an Open-Access article
distributed under the terms of the grains. This heterostructure remarkably contributed to an exceptional improvement
Creative Commons Attribution in strength, accompanied by only a minor reduction in plasticity. These findings
License, permitting distribution, present an efficacious avenue for substantially augmenting the mechanical properties
and reproduction in any medium,
provided the original work is of conventional iron-based alloys, offering useful references for overcoming the
properly cited. strength-plasticity trade-off in other alloys fabricated by AM.
Publisher’s Note: AccScience
Publishing remains neutral with Keywords: Additive manufacturing; A131 steel; Heterostructure; Mechanical
regard to jurisdictional claims in
published maps and institutional performance; Molecular dynamics
affiliations.

Volume 4 Issue 3 (2025) 1 doi: 10.36922/MSAM025220038