In-situ three-dimensional X-ray investigation on micro ductile fracture mechanism of a high-Mn steel with delayed necking effect

Liang-Jiu Jia; Rui Zhang; Chang-Feng Zhou; Tian-Yu Gu; Tao Liu; Jin-Bao Xie; Man-Chao He; Min Xia; Bo Chen

Journal of Materials Research and Technology (May 2023)

In-situ three-dimensional X-ray investigation on micro ductile fracture mechanism of a high-Mn steel with delayed necking effect

Liang-Jiu Jia,
Rui Zhang,
Chang-Feng Zhou,
Tian-Yu Gu,
Tao Liu,
Jin-Bao Xie,
Man-Chao He,
Min Xia,
Bo Chen

Affiliations

Liang-Jiu Jia: College of Civil Engineering, Tongji University, Shanghai, 200092, China; State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai, 200092, China
Rui Zhang: College of Civil Engineering, Tongji University, Shanghai, 200092, China; Key Laboratory of Advanced Civil Engineering Materials (Ministry of Education), School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China
Chang-Feng Zhou: College of Civil Engineering, Tongji University, Shanghai, 200092, China
Tian-Yu Gu: College of Civil Engineering, Tongji University, Shanghai, 200092, China
Tao Liu: College of Civil Engineering, Tongji University, Shanghai, 200092, China
Jin-Bao Xie: College of Civil Engineering, Tongji University, Shanghai, 200092, China
Man-Chao He: College of Civil Engineering, Tongji University, Shanghai, 200092, China; Corresponding author.
Min Xia: Institute of Powder Metallurgy and Advanced Ceramics, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China; Corresponding author.
Bo Chen: Key Laboratory of Advanced Civil Engineering Materials (Ministry of Education), School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China; Corresponding author.

Journal volume & issue: Vol. 24
pp. 1076 – 1087

Abstract

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This study investigates the micro ductile fracture mechanism of a high-Mn steel with delayed necking effect (DN-HMn steel) under monotonic tension. A random-oriented micro-grain structure cooperating with intragranular twins in the DN-HMn steel contributes to its high tensile strength of 880 MPa and high uniform elongation of over 55%, accounting for 92.8% of the total elongation. Three-dimensional (3D) visualization of the ductile fracture process is presented, and characteristics of void evolution are identified. It was observed that voids distribute and grow uniformly during deformation, with larger voids forming a double-helix spatial distribution pattern at high strain levels, which fits the principal shear stress trajectory. The number and volume of voids in the DN-HMn steel showed a significant increase, with the porosity increasing from 0.071‰ (initial state) to 1.580‰ (before fracture). Intervoid necking was found to be the mode of void coalescence, which occurred close to the necking strain of the sample. The DN-HMn steel demonstrated a significant volume expansion of 4.58% throughout the elongation process, which breaks the volume conservation law of classical metal plasticity theory. This study opens new perspectives for understanding the ductile fracture mechanism of this steel.

Published in Journal of Materials Research and Technology

ISSN: 2238-7854 (Print); 2214-0697 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Technology: Mining engineering. Metallurgy
Website: https://www.journals.elsevier.com/journal-of-materials-research-and-technology/

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