Study On Mechanical Properties Of The Future Fusion Reactor Vacuum Vessel And Port Stub Welded Joints

The China Fusion Engineering Test Reactor(CFETR)is the key to China's development of future commercial fusion reactors.The tailored welding technology was adopted to the forming of the fusion reactor vacuum vessel.Port stubs distribute on each 1/8 sector of the vacuum vessel(VV)for installation,maintenance of internal components and auxiliary heating and diagnosis.The port is connected to the VV with a port stub,and the materials of VV and port stubs are 316 L stainless steel.The Narrow Gap Tungsten Inert Gas Welding(NG-TIG)is used to connect the VV and the port stubs,but the port stubs are formed by Electron Beam Welding(EBW).In this dissertation,the welded joints of the NG-TIG and EBW were studied.The main contents are:(1)Reasonable processes of NG-TIG and EBW were organized to weld 50 mm 316 L stainless steel plate.The phased array ultrasonic nondestructive testing was applied to the welding test plate to evaluate the welding quality of NG-TIG and EBW.The microstructure difference between the two welded joints was observed and analyzed by a metallographic examination;(2)The Vickers hardness test was carried out and the empirical formula for hardness and strength was used to establish a multi-material finite element model of the welded joints with non-uniformity.The error of the finite element model was analyzed by comparing the tensile tests of the welded joint samples taken from the welded test plates.The results have shown that the finite element model can predict the static strength of welded joints accurately;(3)The influencing factors of static strength and stress distribution of NG-TIG and EBW welded joints were analyzed by the finite element model of welded joints established above;(4)The static strength and stress concentration of the NG-TIG and EBW joints were analyzed numerically.The equations were obtained and the accuracy was verified according to the simulation results;Useful theoretical support was provided by this research for the design of fusion reactor VV welding process.The research results can be used as the basis for optimizing the welding process parameters of fusion reactor VV and port stubs.