Date of Award

2024-05-01

Degree Name

Master of Science

Department

Materials Science And Engineering

Advisor(s)

Francisco Medina

Abstract

This study examines the microstructure and mechanical properties (tensile, hardness, and fatigue endurance) of laser powder-directed energy deposition (LP-DED) printed specimens with varying deposition parameters. Five samples with power inputs ranging from 350 to 2620W, all of similar thicknesses, were evaluated to enable a direct comparison. The varying specimens were heat treated, including stress relief, hot isostatic pressing, solution, and two-step aging. The resulting microstructures and their corresponding hardness values were compared at each heat treatment stage. The fully heat-treated specimens' tensile properties and fatigue life were also examined and compared. Key findings of this study indicate that complete heat treatment will recrystallize and homogenize the microstructures of specimens printed, regardless of the varying parameters. This transformation shifts the microstructure from a predominantly dendritic structure to an austenitic one, incorporating annealing twins and increasing its hardness correspondingly. This heat treatment schedule produced nearly comparable tensile and fatigue properties, irrespective of the parameter variations. This investigation reveals that samples produced at the lowest laser power (350W) demonstrated a finer microstructure, improving overall mechanical properties. This research provides an efficient post-processing HT schedule for LP-DED Inconel 718 for aerospace applications. It contributes to the material's characterization and the printing process's standardization.

Language

en

Provenance

Received from ProQuest

File Size

124 p.

File Format

application/pdf

Rights Holder

Dana Victoria Godinez

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