Keywords

Laser powder bed fusion, gas atomization, additive manufacturing, high carbon steel, high entropy alloys, multi-principal element alloys

Abstract

The integration of laser powder bed fusion (LPBF) to produce critical engineering components, aimed at achieving reduced weight and enhanced efficiency, has sparked significant interest in the field of additive manufacturing (AM). LPBF is highly desirable due to its rapid production capabilities, minimized material waste, and its ability to facilitate intricate engineering designs. The ongoing challenges associated with processing metals free of cracks while attaining high relative density remain central to advancing AM technology. This has led to a continued interest in alloy development for LPBF given the limited selection of alloys currently available. This study seeks to evaluate the printability of selected alloys and understand the cracking mechanism through the application of the solidification cracking criterion. An in-house laboratory-scale gas atomizer was employed to produce gas-atomized powders of carbon-bearing steels and eutectic multi-principal element alloys (EMPEAs). The compositions of the carbon-bearing alloys were modulated to yield either austenite or martensite in the as-printed condition to understand the printability and evaluate the applicability of the hot cracking susceptibility criterion. Selected EMPEA compositions were modified in reference to the pseudo-binary phase diagrams to evaluate their printability. Systematic investigations were conducted to assess the effects of processing parameters on the microstructure and flaw formation. Hot cracking in a high carbon-bearing steel is consistent with the hot cracking susceptibility criterion while the observed cracking formation in EMPEAs is driven by thermal residual stress.

Completion Date

2025

Semester

Summer

Committee Chair

Sohn, Yongho

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Materials Science and Engineering

Format

PDF

Identifier

DP0029559

Language

English

Document Type

Thesis

Campus Location

Orlando (Main) Campus

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