The Role of Dislocation Type in the Thermal Stability of Cellular Structures in Additively Manufactured Austenitic Stainless Steel

Journal Article (2024)
Author(s)

Dayong An (Shanghai Jiaotong University)

Yao Xiao

Junshi Yu

Xu Zhang

Zan Li

Yan Ma (Max-Planck-Institut für Eisenforschung)

Rui Li

Xianhong Han

Xifeng Li

Jun Chen

Stefan Zaefferer (Max-Planck-Institut für Eisenforschung)

Affiliation
External organisation
DOI related publication
https://doi.org/10.1002/advs.202402962
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Publication Year
2024
Language
English
Affiliation
External organisation
Issue number
33
Volume number
11

Abstract

The ultrafine cellular structure promotes the extraordinary mechanical performance of metals manufactured by laser powder‐bed‐fusion (L‐PBF). An in‐depth understanding of the mechanisms governing the thermal stability of such structures is crucial for designing reliable L‐PBF components for high‐temperature applications. Here, characterizations and 3D discrete dislocation dynamics simulations are performed to comprehensively understand the evolution of cellular structures in 316L stainless steel during annealing. The dominance of screw‐type dislocation dipoles in the dislocation cells is reported. However, the majority of dislocations in sub‐grain boundaries (SGBs) are geometrically necessary dislocations (GNDs) with varying types. The disparity in dislocation types can be attributed to the variation in local stacking fault energy (SFE) arising from chemical heterogeneity. The presence of screw‐type dislocations facilitates the unpinning of dislocations from dislocation cells/SGBs, resulting in a high dislocation mobility. In contrast, the migration of SGBs with dominating edge‐type GNDs requires collaborative motion of dislocations, leading to a sluggish migration rate and an enhanced thermal stability. This work emphasizes the significant role of dislocation type in the thermal stability of cellular structures. Furthermore, it sheds light on how to locally tune dislocation structures with desired dislocation types by adjusting local chemistry‐dependent SFE and heat treatment.

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