ORAL

SESSION: AdvancedMaterialsTueAM-R6	Marquis International Symposium on New and Advanced Materials and Technologies for Energy, Environment and Sustainable Development(3rd Intl Symp. on New and Advanced Materials and Technologies for Energy, Environment and Sustainable Development)
Tue Oct, 24 2017	Room: Condesa IA
Session Chairs: Yail Jimmy Kim; Sandra E. Rodil; Session Monitor: TBA

12:30: [AdvancedMaterialsTueAM04] Invited
The Properties and Microstructure Evolution of Cast Austenite Stainless Steel under Thermal Aging
Fei Xue¹ ; Xiao Jin¹ ; Xiangbing Liu¹ ; Xitao Wang² ; ¹Suzhou Nuclear Power Research Institute, Suzhou, China; ²University of Science and Technology Beijing, Beijing, China;
Paper Id: 142 [Abstract]

In this paper, cast austenite duplex stainless steel from main circulating pipe are aged at 400°C for different times, the properties are studied during aging, and the mechanism of material is investigated by microstructure evolution characterization at same aging time. The results show the tensile strength increased nearly 12%, reduction of area decreased nearly 21%, and impact ductility decreased nearly 50%. The reason lies in the ferrite phase becoming weak and harmful to mechanical properties after aging. Transmission electron microscope (TEM) and three dimensional atom probe (3DAP) are used to study the microstructure evolution during aging, effect of aging on duplex stainless steel by spinodal decomposition in ferrite phase, Cr-rich phase formed from Cr-rich segregated region by the concentration of Cr atoms in it after being aged 3000h, and the size of Cr-rich phase between 5-10nm, and then, the difficulty of increased slipping in dislocation and aggregated dislocations, resulting in the local stress concentration around the Cr-rich phase. The phenomenon of spinodal decomposition is that as the aging time and content of Cr in Cr-rich cluster increases, the more stress is required during the deformation, which causes higher level of stress triaxiality ratio; with this focus, dislocations get across the Cr-rich phase, which disperses in ferrite phase and slipping, the plastic deformation is more easily reached, and leads to the decreased of ductility.

SESSION: AdvancedMaterialsWedAM-R6	Marquis International Symposium on New and Advanced Materials and Technologies for Energy, Environment and Sustainable Development(3rd Intl Symp. on New and Advanced Materials and Technologies for Energy, Environment and Sustainable Development)
Wed Oct, 25 2017	Room: Condesa IA
Session Chairs: Qizhen Li; Kunichi Miyazawa; Session Monitor: TBA

16:00: [AdvancedMaterialsWedAM08] Keynote
Development of Primary Coolant Piping for AP1000 Pressurized Water Reactor
Xitao Wang¹ ; Fei Xue² ; ¹University of Science and Technology Beijing, Beijing, China; ²Suzhou Nuclear Power Research Institute, Suzhou, China;
Paper Id: 127 [Abstract]

Nuclear power is increasing rapidly as an important substitute for coal-fired electricity power in China. Four 3rd generation AP1000 nuclear reactors are under construction. The primary piping is one of the key components for reactor coolant system pressure boundary, which provides a barrier against the release of radioactivity generated within the reactor and is designed to provide a high degree of integrity throughout operation of the plant.
Manufacturing of the world first AP1000 primary piping is a big challenge. According to Westinghouse design, it is forged integrally with nozzles. Ultra-low carbon-nitrogen alloyed stainless steel AISI 316LN is selected. Microstructure and precision shape control are two major goals to fulfill in manufacturing. A number of investigations on the materials and process have been carried out both in lab and full scale. Solidification sequence was observed in-suit to optimize the microstructure of ingot. Hot deformation behavior was studied by a large number of tensile and compression experiments. Constitutional model for flow stress was established. Recrystallization was observed and physical based models for microstructure evolution was obtained. Full scale 3D FEM simulations on forging and bending were performed to optimize grain size and its distribution, as well to ensure the final shape precision.
Based on the laboratory results, full-size hot leg and cold leg piping were trail-manufactured. Both microstructure and property requirements are fulfilled. The final product was granted by authorities.