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Microstructures and Grain Refinement upon Shot Peening of Stainless Steels
KeesamShin
School of Nano and Advanced Materials Engineering, Changwon National University,
Changwon 51140, Korea
时间:周三(3月1日)下午2:00pm
地点:固体所三层大会议室
     In this talk, various ferritic (T91, X20) and austenitic stainless steels (SS304, TP347H and super 304H), which are widely used as the heat exchanger materials in power plants, were shot peened with the objectives on the enhancement of high temperature corrosion resistance and global properties.
     The typical microstructures of ferritic SS are amounts of carbide (M23C6, ~200 nm) embedded in ferritic (a, ~400 nm) matrix. The austenitic SS304 only has the coarsegrain. The TP347H has the extra distribution of NbC within the coarseggrain. However, the super 304H, in addition to the NbC, the solute Cu will be precipitated as the nanosized Cu-particles during the afterword heating, which will provide the strain induced precipitation hardening during service (SIPH). Therefore, the objectives were focused on the effect of carbides on the deformation microstructures during shot peening and post-aging (to simulate the service condition).
     Our works show that the dominant deformation structure in ferritic SS are the dense dislocation walls, which transfer to high angle grain boundaries, and hence refined the original coarse grain. In case of the austenitic stainless steels, the main deformation structure is the deformation twin and martensitic transformation (a¢- ande¢-martensite), which refined the original coarse grain structure. Here, the carbides (M23C6 or NbC) accelerated the grain refinement.
Professor Keesam Shin
- Professor, School of Nano and Advanced Materials,
Changwon National University, Changwon 48516, Korea
- keesamgg@gmail.com
- +82-10-2406-4992
1. Education
  • Jan. 1991- Dec. 1994

Ph.D.in Metallurgical Engineering, Dept. of Materials Science and Engineering
University of Wisconsin - Madison, Wisconsin 53705, U.S.A.
Advisor: Professor Thomas F. Kelly
Ph.D. Thesis:An Electron Microscopy Study of Microstructural Stabilization and Mechanical Property Improvement in Inert-Gas Atomized Superalloy A-286
  • Sept. 1987- Jan. 1991

M.S.in Metallurgical Engineering, Dept. of Materials Science and Engineering
University of Wisconsin - Madison, Wisconsin 53705, U.S.A.
Advisor: Professor Thomas F. Kelly
M.S. Thesis:A Transmission Electron Microscopic Study of the Microstructure of Fe-40%Ni Alloys with and without Niobium and Carbon Additions
  • Mar. 1979 - June 1982, Mar. 1985 – Feb.1986

B.S.in Metallurgical Engineering, Dept. of Metallurgical Engineering
Inha University, Incheon, Korea
2. Experiences
Years
Institutions
Positions
1987. 8. ~ 1995. 4.
University of Wisconsin-Madison
Research/Teaching Assistant
1995. 4. ~ 1996. 9.
Aeronautical Materials Research Center, Pohang University of Science and Technology
Post Doctor
1996. 9. ~ 1999. 2.
Korea Electric Power Research Institution
Staff Researcher
1999. 3. ~ Present
ChangwonNational University
Professor
2003. 9. ~ 2005. 3.
Research Institute for Interdisciplinary Sciences
Tohoku University
2004. 9. ~ 2005. 3.
Institute for Materials Research
Tohoku University
Visiting Professor
2011.5. ~ 2013. 2.
International Affairs Office
Changwon National University
Director
2016.1.~Present
Korean Society of Microscopy
President

3. Area of Scientific Interests
Interest
  • Applications of analytical electron microscopy for development and evaluation of materials

  • Superconductors/alloy development; application of superalloys

  • Nano-materials/superalloy/composite materials

  • Strengthening of materials; effect of microstructures and solutes

  • Powder metallurgy; effect of processing conditions on mechanical properties and micro

  • Interface behavior of electronic materials

Current Research
  • Surface modification of alloys using various shot peening techniques,

  • Electron microscopy characterization of advanced high temperature materials for power plants

  • Electron microscopy characterization of LED devices

  • Determination of the strengthening and corrosion mechanism of complex corrosion resistant steel for flue gas desulfurization