In 1939, Dr. Troiano accepted a position as assistant professor in the Department of Metallurgy at Notre Dame University; he was promoted to associate professor in 1941 and professor in 1945. He was department head from 1947 to 1949. During his years at Notre Dame, he continued to pursue his interest in phase transformations and made significant advances in our understanding of grain-size effects on the martensite transformation, produced a series of time-temperature-transformation diagrams in the iron-chromium-carbon system that advanced the concept of the incomplete reaction associated with the decomposition of austenite to bainite, and studied the martensite transformation in cobalt and the sigma phase in stainless steels.

During World War II, as an inspection engineer for munitions production, he was involved directly in manufacturing for the war effort. He was instrumental in revising standards and procedures to ensure the quality of components being shipped to the field, and, at the same time, he learned a great deal about the quenching techniques used to impart residual stresses into cannon barrels. This direct exposure to manufacturing influenced the rest of his career.

After the war, Professor Troiano, by now well established in the metallurgical community, joined the Department of Metallurgy at Case Institute of Technology as professor in 1949 and department head from 1953 to 1967, when he was awarded the Republic Steel Corporation distinguished professorship. Upon retirement from the Republic Steel chair in 1979, he remained active in research at Case Western Reserve University as senior research scientist and Republic Steel professor emeritus until his death on June 12, 2002.

While at Case, he initiated programs in mechanical properties, with a focus on the metallurgical aspects of embrittlement, which led to programs in slack quenching and the end-quench test, 500°F embrittlement of quenched and tempered steels, the mechanical properties of carburized steels, hydrogen embrittlement and delayed failure, and eventually stress-corrosion phenomena. He also continued to pursue his interest in phase transformations, with an emphasis on the