In situ characterization of additive manufactured 316L stainless steel and copper

Teng, Wanxuan (2025). In situ characterization of additive manufactured 316L stainless steel and copper. University of Birmingham. Ph.D.

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Abstract

Additive manufacturing, particularly laser powder bed fusion (L-PBF), has revolutionized the metal manufacturing industry by offering enhanced design flexibility, reduced material waste, and accelerated production capabilities. L-PBF metals exhibit enhanced strength, hardness, and corrosion resistance, but their durability is still limited by porosity and residual stress. This study aims to determine the underlying deformation mechanisms, deepen understanding of the relationship between microstructure and properties, and improve the reliability of L-PBF metals with heat treatment, specifically focusing on 316L stainless steel and copper. Advanced in situ synchrotron techniques provide a real-time insight of the relationships between microstructural evolution and material properties. The superior strength, ductility, and strain hardening ability of L-PBF 316L stainless steel, is shown to be attributed to its specific microstructural features such as high dislocation densities and crystallographic orientations. Furthermore, the impact of varying heat treatment temperatures on the mechanical behavior and fracture toughness of L-PBF metals is systematically examined. Extending the analysis to L-PBF copper, the study investigates microstructural changes and physical properties post heat treatment. It identifies grain coarsening, twinning phenomena, and improvements in ductility, with high electrical and thermal conductivity achieved after heat treatment. Finally, the nucleation and propagation mechanisms of cracks are revealed.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):