Summary
This paper summarizes the results of some recent research on a thermomechanical method of refining the grain size in precipitation hardenable aluminum alloys and illustrates the infuence of grain refinement on several material properties. Grain refinement is achieved by deliberately introducing a large number of nucleation sites for recrystallization and by controlling grain growth after recrystallization. Recrystallization to a relatively small and equiaxed grain size has been achieved in a number of commercial aluminum alloys using these concepts. The influence of the fine recrystallized grain size on such properties as superplastic deformation, room temperature tensile properties, fatigue life, and exfoliation corrosion resistance is discussed. The results show that refinement to a grain size of 8–14 µm is sufficient to develop extensive superplasticity and to yield a small increase in tensile properties in alloys such as 7075 and 7475.
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Dr. Paton received his bachelors and masters degrees in engineering from the University of Auckland in New Zealand, and his PhD in materials science from Massachusetts Institute of Technology. He is the author of numerous publications on metallurgy and mechanical properties of high-strength materials with emphasis on titanium and aluminum alloys. His recent interests have been centered on high-temperature deformation and fracture. Dr. Paton is a member of The Metallurgical Society of AIME.
Dr. Hamilton received his MS in mechanical engineering from the University of Southern California and PhD in metallurgy from Case Western Reserve University. He has directed program efforts in the development of superplastic forming, diffusion bonding, concurrent superplastic forming and diffusion bonding, and manufacturing methods to produce metal-matrix composites. He has developed numerous analytical models to describe forming and diffusion bonding processes. Dr. Hamilton is a member of The Metallurgical Society of AIME.
Dr. Wert received his BS in physics from Cornell University and MS and PhD in materials science from the University of California, Berkeley. He has published a number of papers in the areas of precipitation, recrystallization, and grain size control. He is a member of The Metallurgical Society of AIME.
Mr. Mahoney received his BS from the University of California, Berkeley and MS from UCLA, both in physical metallurgy. His research has included the successful demonstration of superplasticity in a number of structural alloys including 7000 series aluminum alloys, Inconel 718, and titanium aluminides. He is the author of a number of publications on fatigue, creep, impurity embrittlement,and stress corrosion in a variety of structural materials.
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Paton, N.E., Hamilton, C.H., Wert, J.A. et al. Characterization of Fine-Grained Superplastic Aluminum Alloys. JOM 34, 21–27 (1982). https://doi.org/10.1007/BF03338068
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DOI: https://doi.org/10.1007/BF03338068