Microstructural Evolution of Dissimilar Metal Welds involving Grade 91 Steel
Department: Materials Science and Engineering
Advisor: John DuPont
Fossil fuel and nuclear power plants that involve steam power generation use hundreds of dissimilar metal welds to join metals used in low-temperature regions to the metals used for high-temperature steam vessels. Dissimilar metal welds involving Grade 91 steel are failing prematurely in power plant steam vessel applications. A power plant outage caused by weld failures can cost power plants hundreds of thousands of dollars per day. Failure in these dissimilar metal welds has been shown to occur within a narrow carbide-free region on the ferritic side of the partially mixed zone. Little is understood about the nature of this region, including when and why the carbide-free region forms. The long-term research objective is to determine why the carbide-free region forms so that this failure mechanism can be prevented in the future. In the short term, a fundamental understanding of the microstructural evolution near the interface is being developed to determine when this region forms. Detailed numerical simulations, microscopy, and hardness indentation mapping are being applied to a series of aged weld passes containing various filler metals to examine the evolution of dissimilar metal welds over time with the ultimate objective of preventing premature failure.
About Michelle Kent:
Michelle Kent is a junior pursuing a B.S. in Materials Science and Engineering with a minor in Science, Technology, and Society at Lehigh University. Michelle has worked in Dr. John N. DuPont’s lab since January 2017. Most recently, her research has focused on the performance of dissimilar metal weld systems operating in high-temperature conditions. Outside of academics, Michelle is involved with the running club and cycling team at Lehigh. Michelle was recently named a Clare Boothe Luce Research Scholar, an award for high-achieving women engineers with interest in research.