Cracking in high performance metallic alloys; due to fatigue, stress corrosion, hydrogen embrittlement and elevated temperature; adversely affects the performance of structures in aerospace, transportation infrastructure, military, power generation, and petrochemical technologies. These problems result in important economic losses and performance limitations. Examples include environment-enhanced fatigue cracking in aging aircraft, hydrogen embrittlement in petrochemical pressure vessels, stress corrosion cracking in nuclear plant components, and elevated temperature-oxidation cracking in high strength turbine disks. Such complex failure processes are likely to recur in next generation materials and designs, including amorphous-based metals and micro-electromechanical systems. To counter such problems, it is necessary to develop cracking resistant alloys, as well as new prognosis methods to manage durability and safety. Fundamental understanding of crack tip damage is a foundation element of this damage management.
For the past 30 years, Professor Gangloff has lead research programs in metal fatigue and fracture, focused on understanding cracking behavior of high performance metals and emphasizing the deleterious effect of the surrounding environment. Our overarching objective is to relate cracking properties with microscopic structure of the metal and chemistry of the surrounding environment. We aim to understand causal mechanisms and develop predictive models from this understanding. Our work emphasizes the time-dependent character of environment-chemical reactions, material deformation, and fracture; as well as damage processes localized at the crack tip. This approach provides important inputs to alloy development and methods that scale short-term laboratory data to predict long-term performance of a component. This research is interdisciplinary; involving metallurgy, fracture mechanics, and electrochemistry.
Current research focuses on hydrogen embrittlement, corrosion fatigue, stress corrosion cracking and experimental fracture mechanics of ferrous and aluminum alloys.
Work for the Office of Naval Research is examining the hydrogen embrittlement problem in next generation ultra-high strength steels used in naval aircraft. Research sponsored by the Air Force Office of Scientific Research, Alcoa, NASA-Langley Research Center, and Air Force Aging Aircraft Program Office is investigating several aspects of the corrosion fatigue problem in aluminum alloys. Projects include the effect of exfoliation and pitting corrosion on fatigue crack formation and early growth, new experimental probes and fracture mechanics models of crack tip damage derived from plasticity-hydrogen interaction, and electrochemical methods to mitigate the dominant effect of moist environment on crack growth kinetics. A consortium of 15 petrochemical companies and steel producers supports work on the development of laboratory test methods and fracture mechanics models to predict the fitness-for-service of steel in hydrogen containing pressure vessels.
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Corporate Research and Development Center, General Electric Co., Schenectady, NY:
Metallurgist, 1974 to 1980
Corporate Research Science Laboratories, Exxon Research and Engineering, Annandale, NJ:
Staff Metallurgist, 1980 to 1982
Senior Staff Metallurgist, 1982 to 1986
School of Engineering and Applied Science, University of Virginia, Charlottesville, VA
Associate Professor of Materials Science, 1986 to1990
Professor of Materials Science and Engineering, 1990 to present
Chairman, Department of Materials Science and Engineering, 2003 to 2008
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Jennifer Warner, Sangshik Kim and Richard P. Gangloff, “Molybdate Inhibition of Environmental Fatigue Crack Propagation in Al-Zn-Mg-Cu”, International Journal of Fatigue, in press (2009).
Thorsten Michler, Yongwon Lee, Richard P. Gangloff, and Joerg Naumann, “Influence of Macro Segregation on Hydrogen Environment Embrittlement of SUS 316L Stainless Steel”, International Journal of Hydrogen Energy, Vol. 34, pp. 3201-3209 (2009).
Sangshik Kim, James T. Burns, and Richard P. Gangloff, “Fatigue Crack Formation and Growth from Localized Corrosion in Al-Zn-Mg-Cu”, Journal of Engineering Fracture Mechanics, Vol. 76, pp. 651-667 (2009).
Uday Komaragiri, Sean R. Agnew, Richard P. Gangloff and Matthew R. Begley, “The Role of Macroscopic Hardening and Individual Length Scales on Crack Tip Stress Elevation from Phenomenological Strain Gradient Plasticity”, Journal of Mechanics and Physics of Solids, vol. 56, pp. 3527-3540 (2008).
Yunjo Ro, Sean R. Agnew and Richard. P. Gangloff, “Environmental Fatigue Crack Surface Crystallography for Al-Zn-Cu-Mg-Mn/Zr” Metallurgical and Materials Transactions, A, vol. 39, pp. 1449-1465 (2008).
Yongwon Lee and Richard. P. Gangloff, “Measurement and Modeling of Hydrogen Environment Assisted Cracking of Ultra-High Strength Steel”, Metallurgical and Materials Transactions, A, vol. 38, pp. 2174-2190 (2007).
D. Li, R.P. Gangloff, and J.R. Scully, “Hydrogen Trap States in Ultrahigh-Strength AerMet® 100 Steel”, Metallurgical and Materials Transactions, A, Vol. 35A, pp. 849-864 (2004).
R.P. Gangloff, “Hydrogen Assisted Cracking of High Strength Alloys”, in Comprehensive Structural Integrity, I. Milne, R.O. Ritchie and B. Karihaloo, Editors-in-Chief, J. Petit and P. Scott, Volume Editors, Vol. 6, Elsevier Science, New York, NY, pp. 31-101 (2003). link to paper
R.P. Gangloff, “Environment Sensitive Fatigue Crack Tip Processes and Propagation in Aerospace Aluminum Alloys”, in Fatigue ’02, Anders Blom, Editor, Engineering Materials Advisory Services, West Midlands, UK, pp. 3401-3433 (2002). link to paper
B.P. Somerday, L.M. Young and R.P. Gangloff, “Crack Tip Mechanics Effects on Environment-Assisted Cracking of Beta-Titanium Alloys in Aqueous NaCl”, Fatigue and Fracture of Engineering Materials and Structures, Vol. 23, pp. 39-58 (2000).
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