Preparation And Metallurgical Mechanism Research Of Nuclear Grade Ⅰ Domestic E2209-15 Electrode

This paper was based on the current research situation of domestic and foreign nuclear grade welding materials. In accordance with ASME SFA-5.4 standard, AWS D1.6 standard, national standard GB/T 983 and pressurized water reactor demonstration project requirements of Shandong Nuclear Power Equipment Manufacturing Co., Ltd. Shanghai Atlantic welding Materials Co.,Ltd was designed and fabricated nuclear grade I E2209-15 electrode, and the chemical composition, mechanical properties and biphasic proportion of deposited metal was analyzed and tested. Domestic nuclear grade I E2209-15 electrode was used, and the welding heat input was affected on the microstructure, mechanical properties, chemical composition, biphasic proportion and phase composition of welded joint. The effect of mechanism with different heat input was revealed. 2205 duplex stainless steel was welded by domestic and foreign typical E2209-15 electrode. The microstructure, mechanical properties and biphasic proportion of welded joint were analyzed, and the electrode with optimal overall performance was determined.The results of deposited metal test indicated that the development of nuclear grade I E2209-15 electrodes was met ASME SFA-5.4 standard, AWS D1.6 standard, and national standard GB/T 983 requirements. C, Cr element content of Nuclear grade I E2209-15 electrode deposited metal was 0.03% and 23.10% respectively, and the S, P and other impurities content was controlled better. Tensile and yield strength of deposited metal was 779 MPa, 540 MPa respectively.The elongation was 32%. The impact absorbed energy was 61 J, 55 J and 45 J at room temperature, 0℃ and-40 ℃ respectively. That was in line with the requirements of ASME standard. No defects of bending test results were found, Vickers hardness value of weld metal was 233 HV.Welding heat input had a significant impact on the microstructure and mechanical properties of domestic nuclear grade I E2209-15 electrode. Welding heat input was 6.6-9.5kJ/cm, and biphasic ratio of welded joint was closest to 50%. Ferrite and austenite of the weld center was distributed alternately. The matrix was ferrite, and the strip and feathery microstructure was austenite. Mechanical properties, the proportion of two-phase and corrosion resistance of welded joints were the best. The tensile and yield strength of welded joint was 779 MPa, 514 MPa respectively.Yield ratio was 0.66. Percentage elongation after fracture was 35%.-40 ℃ low temperature impact energy of welded joint, located at weld center, the heat affected zone and base material was 94 J, 64 J and 76 J respectively. The impact toughness of weld center was better than high welding heat input.The comparative results revealed that 2205 duplex stainless steel was welded by domestic and foreign typical E2209-15 electrode. The tensile strength of welded joint with domestic nuclear grade I E2209-15 electrode was higher than domestic and foreign E2209-15 electrode. But the impact toughness was met the requirements of standard, and was slightly lower than domestic and foreign E2209-15 electrode. Different E2209-15 electrode was used, and the morphology of impact specimen fracture was dimple mainly. Futhermore domestic nuclear grade I E2209-15 electrode was used. The grain size of weld center and heat affected zone with welded joint was finer than domestic and foreign E2209-15 electrode, and was distributed evenly.