Keywords
Constituent intermixing, Bimetallic structure, Laser powder bed fusion, Diffusion couple, Nanohardness
Abstract
Laser powder bed fusion (LPBF) is a popular additive manufacturing (AM) technique that has demonstrated the capability to produce sophisticated engineering components. This work reports the crack-free fabrication of an SS316L/IN718 bimetallic structure via LPBF, along with compositional redistribution, phase transformations and microstructural development, and nanohardness variations. Constituent intermixing after LPBF was quantitatively estimated using thermo-kinetic coefficients of mass transport and compared with the diffusivity of Ni in the austenitic Fe-Ni system. The intermixing of primary solvents (Ni and Fe) in SS316L/IN718 bimetallic structures was observed for an intermixing zone of approximately 800 µm, and their intermixing coefficient was estimated to be in the order of 10−5 m2/s based on time of 10 ms. In addition, to understand the high temperature behavior, SS316L/IN718 bimetallic structures were annealed at 850, 950, and 1050 °C, for 120, 48, and 24h respectively, followed by water quenching (WQ). Furthermore, to better understand the intermixing of individual components (Ni and Fe) and to predict the varying (maximum) temperatures in LPBF of SS316L/IN718 bimetallic structures, solid-to-solid SS316L vs IN718 diffusion couples were examined at 850, 950, and 1050 °C, for 120, 48, and 24h respectively, followed by WQ. The investigation of SS316L vs IN718 diffusion couples yielded a maximum temperature of approximately 3400 K in the LPBF of SS316L/IN718 bimetallic structures. Finally, compositional redistribution, phase transformations and microstructural development, and nanohardness variations after LPBF of SS316L/IN625 bimetallic structure were also investigated to provide a better understanding of the LPBF process via bimetallic fabrication.
Completion Date
2023
Semester
Fall
Committee Chair
Sohn, Yongho
Degree
Doctor of Philosophy (Ph.D.)
College
College of Engineering and Computer Science
Department
Materials Science and Engineering
Degree Program
Materials Science and Engineering
Format
application/pdf
Identifier
DP0028059
URL
https://purls.library.ucf.edu/go/DP0028059
Language
English
Release Date
December 2023
Length of Campus-only Access
None
Access Status
Doctoral Dissertation (Open Access)
Campus Location
Orlando (Main) Campus
STARS Citation
Mahmud, Asif, "Laser Powder Bed Fusion of Bimetallic Structures" (2023). Graduate Thesis and Dissertation 2023-2024. 30.
https://stars.library.ucf.edu/etd2023/30