Doctoral Dissertations
Keywords and Phrases
Fe-Mn-Al; Martensite; NiAl; Strain accumulation; Tempered Martensite Embrittlement; Tempering
Abstract
"A martensite-based and an austenite-based Fe-Mn-Al steels were investigated aiming the pilot-scale production of steels that meet military specifications for Rolled Homogeneous Armor (RHA) and High-hardness Armor (HHA) plates. Each material underwent specific thermomechanical processes and the following hardness, Charpy V-notch (CVN) impact toughness at -40 °C and room-temperature tensile properties were correlated with the resulting microstructures.
Specimens of the martensitic steel were austenitized at 1010 °C, quenched and tempered at 150, 175, 200, 225 and 250 °C for times up to four hours. As for the Fe-Mn-Al steel, its hot rolling schedule was design to promote strain accumulation in the as-rolled matrix, which is conducive to the precipitation of NiAl during annealing heat treatments. Specimens of this steel were annealed at 700, 750, 800 and 900 °C for times up to one hour.
The results show evidence of tempered martensite embrittlement (TME) in the martensite-based steel, especially when tempered for four hours at the investigated temperature range.
Regarding the Fe-Mn-Al steel, electron backscattered analyses (EBSD) revealed strain accumulation in the as-rolled austenitic matrix. Annealing at 750 °C for 30 min. strengthened the steel through intra-granular precipitation of NiAl. It was followed by a drop in the CVN impact toughness. Nevertheless, literature review showed that the investigated material outperformed similar austenite-based Fe-Mn-Al steels strengthened through k-carbide"--Abstract, p. iv
Advisor(s)
Bartlett, Laura
Committee Member(s)
Chandrashekhara, K.
Buchely, Mario F.
O'Malley, Ronald J.
Gu, Yijia
Department(s)
Materials Science and Engineering
Degree Name
Ph. D. in Materials Science and Engineering
Publisher
Missouri University of Science and Technology
Publication Date
Spring 2025
Pagination
xv, 131 pages
Note about bibliography
Includes_bibliographical_references_(pages 41, 74, 119 and 125-130)
Rights
©2024 Rogerio Antao Cardoso , All Rights Reserved
Document Type
Dissertation - Open Access
File Type
text
Language
English
Thesis Number
T 12454
Recommended Citation
Cardoso, Rogerio Antao, "Effect Of Thermomechanical Processing And Heat Treatment On The Microstructure And Mechanical Properties Of Ultra-High Strength Steels" (2025). Doctoral Dissertations. 3359.
https://scholarsmine.mst.edu/doctoral_dissertations/3359
