Twin-related grain boundary engineering of additively manufactured 316L stainless steel

Published

December 1, 2025

Author(s)

Chenglu Tang, Jingfan Yang, Fan Zhang, Joseph Aroh, Ernest Porterfield, Barton Prorok, Xiaoyuan Lou

Abstract

Twin-related grain boundary engineering (GBE) enhances the boundary-related degradation of materials, such as intergranular corrosion by incorporating a high density of twin boundaries. Conventional GBE typically requires one or multiple thermomechanical cycles and is limited to materials with simple geometries, such as plates and sheets. While additive manufacturing (AM), particularly laser powder bed fusion (LPBF), enables the fabrication of net-shape components with complex geometries, a complete twin-related GBE for AM 316L stainless steel (SS) has not yet been achieved. In this study, we demonstrated for the first time that a complete GBE of LPBF AM 316L SS with twin boundary fraction exceeding the best practice of conventional GBE wrought 316L SS can be achieved by phase transformation engineering and post-AM annealing. Two 316L SS compositions favoring either austenite to ferrite (AF) transformation and ferrite to austenite (FA) transformation were studied. Results indicate that AF316L showed negligible twin boundaries in the as-built condition, and direct annealing failed to produce a well-developed GBE twin microstructure. In contrast, FA316L exhibited a higher fraction of twin boundaries in its as-built condition, which increases significantly after annealing, forming high-density twin-related GBE microstructure. Using in-situ melting high-speed synchrotron X-ray diffraction, quasi-in-situ EBSD characterization, and electron microscopy, we reveal how the solidification mode influences the development of twin-related microstructure during laser solidification and twin evolution mechanisms during post-AM annealing to eventually achieve large twin-related domains (TRDs). These results demonstrate the potential of leveraging phase transformation engineering to achieve deformation-free GBE in AM 316L SS, offering a promising strategy for improving a variety of properties of AM SS components.

Citation

Acta Materialia

Volume

301

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.actamat.2025.121503

Local Download

Keywords

additive manufacturing, grain boundary engineering, stainless steel, phase transformation, high-speed X-ray diffraction

Citation

Tang, C. , Yang, J. , Zhang, F. , Aroh, J. , Porterfield, E. , Prorok, B. and Lou, X. (2025), Twin-related grain boundary engineering of additively manufactured 316L stainless steel, Acta Materialia, [online], https://doi.org/10.1016/j.actamat.2025.121503, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=960189 (Accessed December 6, 2025)