Mechanical and Microstructural Effects of Thermal Aging on Cast Duplex Stainless Steels by Experiment and Finite Element Method
Cast duplex stainless steel piping in light water nuclear reactors experience thermal aging embrittlement during operational service. Interest in extending the operational life to 80 years requires an increased understanding of the microstructural evolution and corresponding changes in mechanical behavior. We analyze the evolution of the microstructure during thermal aging of cast CF-3 and CF-8 stainless steels using electron microscopy and atom probe tomography. The evolution of the mechanical properties is measured concurrently by mechanical methods such as tensile tests, Charpy V-notch tests, and instrumented nanoindentation. A microstructure-based finite element method model is developed and utilized in conjunction with the characterization results in order to correlate the local stress-strain effects in the microstructure with the bulk measurements. This work is supported by the DOE Nuclear Energy University Programs (NEUP), contract number DE-NE0000724.
KeywordsStainless steel Thermal aging Mechanical testing Microstructure Finite element method
This work is funded by the U.S. Department of Energy Nuclear Energy University Program (DOE-NEUP); technical monitor Dr. Jeremy T. Busby, Oak Ridge National Laboratory; contract number DOE-NE0000724. Mr. Schwarm would like to acknowledge the Department of Energy: Office of Nuclear Energy (DOE-NE) Integrated University Program (IUP) fellowship program for support. Ms. Sarah Mburu is partially supported by the National Science Foundation (NSF) Louis Stokes Alliances for Minority Participation (LSAMP) under Grant No. 0833018. We would also like to thank Dr. Robert Bonenberger and Dr. Aldo Ponce of the Modern Engineering Materials Instructional Laboratory (MEMIL) at the University of Maryland for access and assistance with the nanoindenter and sample preparation equipment. The APT experiments were conducted using EMSL, a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research located at PNNL.
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