Enigneering, Materials Science
Carnegie Mellon University
Professor Garrison’s primary research interests are in the influence of microstructure on the mechanical behavior of metallic materials with an emphasis on steels. Currently the primary interests are (1) the effects of inclusion distributions and fine-scale microstructure on the toughness of ultra-high strength steels, (2) the effects of composition and heat treatment on the strength and toughness of martensitic precipitation strengthened stainless steels, (3) the effects of fine-scale microstucture and inclusion distributions on the strength and formability of advanced high strength steels for sheet applications and (4) the effects of microstructure and inclusion distributions on the stress corrosion cracking resistance of ultra-high strength steels. The effects of inclusion spacing, of inclusion volume fraction and of void nucleation resistance on toughness have been investigated for a wide range of fine-scale steel microstructures. It has been found that particles of titanium carbosulfide are much more resistant to void nucleation than particles of other sulfide types and that this improved resistance to void nucleation can lead to significant improvements in toughness, particularly in the steels HY180 and AF1410. The effects of cobalt on the strength of precipitation strengthened martensitic stainless steels has been investigated and has led to the development of new ultra-high strength stainless.