Allison investiaged the influence of loading rate on the stress corrosion cracking behavior of a Ni-Cu (Monel K-500) and Co-Ni (MP98t) superalloy in marine environments. Her thesis work demonstrated that loading rate effects can significantly contribute to the measured crack growth rate. This result suggests a need to incorporate such effects into SCC test design. Additionally, her work also examined the fundamental contribution of plasticity to false increases in the measured dcPD voltage. This effort resulted in the development of a robust plasticity-correction protocol that should be employed during fracture mechanics testing of moderate strength/high toughness alloys. Allison is currently working at NAS Cherry Point and enjoying living near the beach!
Ryan investigated the effects of NaCl solutions of various concentrations on fatigue properties of the ultra-high strength stainless steel Custom 465. He sought to more precisely explain how increasing the chloride concentration of an aqueous solution results in a decrease in fatigue life. SEM was used to identify load-induced fatigue markings on the fracture surface, providing high fidelity measurement of crack initiation life and growth behavior. It was found that the chloride concentration has the most pronounced effect on the pit-to-crack transition behavior, resulting in a shorter crack initiation life (and thus fatigue life) as chloride levels are increased. This work will be used to inform future linear elastic fracture mechanics codes to improve component lifetime prediction models.
Jennifer examined the effect of high purity water vapor on fatigue crack growth rates (da/dN) in aluminum alloys (AA7075-T651 and AA2199-T86). Her work incorporated using fracture mechanics testing coupled with fractography to characterize fatigue crack growth rates in pertinent airframe environments. The understanding developed in this investigation will be used to better inform protocols in selecting environment appropriate crack growth rates for linear elastic fracture mechanics (LEFM) modeling. Jennifer is currently serving as an officer in the US Navy.
Justin worked on hydrogen environment-assisted cracking (HEAC) of Monel K-500. This included fracture mechanics testing of in-field components coupled with fractography and hydrogen analysis to explore lot-to-lot variation in cracking behavior. Such data will be implemented to refine an engineering-level component SCC lifetime modeling program. Justin now works as a Staff Engineer at Elzly Technology Corporation in Reston, VA.
Kendall studied Mechanical Engineering with a minor in Materials Science and Engineering at the University of Virginia. Her research focused on understanding plasiticy-based false crack growth when measuring crack length using the direct current potential difference technique.
Cameron studied Electrical Engineering and Computer Science as an undergraduate at the University of Virginia. In the lab, he focused on examining the contribution of grain boundary sulfur on hydrogen environment-assisted cracking of Monel K-500.
Fernando studied Mechanical Engineering as an undergraduate at the University of Virginia. His research focused on studying how different corrosion morphologies affect fatigue life and fatigue crack growth in an aluminum alloy..
Richard studied Mechanical and Aerospace Engineering as an undergraduate at the University of Virginia, while also obtaining a minor in Systems Engineering. His research focused on fatigue crack growth behavior of hot corroded Ni-based superalloys.
Sarah studied Electrical Engineering as an undergraduate at the University of Virginia. Sarah's research focused on studying the microscopic morphology of beta particles along the grain boundaries of “sensitized” Al-Mg alloys.
Christina studied Aerospace Engineering and Materials Science as an undergraduate at the University of Virginia. Christina's research focused on lot to lot variations in Monel K500, comparing a low strength and a high strength material lot to Justin Dolph's work.
Douglas studied Materials Science and Physics during his time as an undergraduate at University of Virginia. In the lab, Douglas focused on the study of small crack initiation and fatigue crack growth of corroded samples of 7075Al. His work consisted of developing programs and exposing the samples to fatigue stresses until failure, followed by analysis of the fracture surfaces and crack initiation sites using a number of different microscopy techniques and the AFGROW modeling software.
Sam studied Materials Science during his time as an undergraduate at University of Virginia. In the lab, Sam's research was focused on studying the effect of grain orientation and the degree of sensitization on crack growth in stress corrosion cracking specimens of 5083 and 5456 Al alloys. Testing includes G67 nitric acid testing for DOS diagnosis on sensitized specimens, metallographic analysis with chemical etching, EDS imaging of fractured specimens, and final data analysis of environmentally cracked test pieces.
Mike worked as a postdoc in the Burns group from 2014-2016. He received a Bachelors in Chemical Engineering from Brigham Young University in Provo, Utah before moving to Michigan for his graduate studies. He received his Masters and PhD from the University of Michigan in Nuclear Engineering and Radiological Sciences, studying the effects of radiation on stress corrosion cracking of austenitic stainless steels under Dr. Gary Was. Mike has since moved on to work at the Idaho National Laboratory, returning to his nuclear materials science roots. He and his family are looking forward to hiking and exploring the many beautiful areas around Idaho Falls.