Electronic Theses and Dissertations

Date

2022

Document Type

Thesis

Degree Name

Master of Science

Committee Chair

Amir Hadadzadeh

Committee Member

Gladius Lewis

Committee Member

Ebrahim Asadi

Abstract

In the current study, cylindrical rods of Fe-Cr-Ni-Al maraging steel (with the brand name CX) are fabricated using the laser-powder bed fusion (L-PBF) technique. The material is then analyzed using the differential scanning calorimetry (DSC) technique under continuous heating at different heating rates. The DSC results are employed to identify the heat flow peaks associated with the precipitation and austenite reversion phase transformations. The peaks are then analyzed and processed to determine the onset, peak, and end temperatures associated with each phase transformation. These results are used to calculate the degree of phase transformation under non-isothermal conditions and to evaluate the activation energy of transformation through the Kissinger method. In the next step, the modified Johnson-Mehl-Avrami-Kolmogorov(JMAK) model is employed to model the kinetics of phase transformations during non-isothermal heating. The validated model is then used to predict the kinetics of precipitation and austenite reversion phase transformations under isothermal aging heat treatments. The results of the current study propose a new heat treatment regime for L-PBF-CX to reduce the level of reverted austenite that can enhance the strength of the material.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest

Notes

Open Access

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