Mississippi State University
El Kadiri, Haitham
McClelland, Zackery B.
Date of Degree
Graduate Thesis - Open Access
Master of Science (M.S.)
James Worth Bagley College of Engineering
Department of Mechanical Engineering
Intercritically annealed medium manganese steels are a promising third-generation advanced high-strength steel candidate, relying on large fractions of Mn-enriched retained austenite for excellent strength-ductility combinations. The present study proposes a novel cyclic intercritical annealing to promote nucleation and efficient stabilization of austenite in a medium Mn microstructure. Design of the heat treatment is driven by the hypothesis that the distribution of ductile austenite is key in mitigating the strain incompatibility that accelerates failure in these steels. Development and preliminary testing of the heat treatment are first detailed and compared with literature results for equivalent isothermal annealing. The effects of cyclic annealing parameters on the amount and stability of retained austenite are also explored through diffraction methods and mechanical testing. Finally, steps are taken towards quantifying austenite formation during the cyclic treatment, and recommendations are made for adapting the designed heat treatment to thicker gauges.
Van Iderstine, Dawn, "Effects of cyclic intercritical annealing on strength-ductility combinations in medium manganese steels" (2022). Theses and Dissertations. 5534.
Available for download on Tuesday, August 15, 2023