Development Of ENiCrMo-3 Nickel-based Electrode For Nuclear Power And Study Of The Organization And Properties Of The Deposited Metal

At present,there is still a gap between domestic and international advanced level in the field of nuclear power welding materials,most of the key welding materials for nuclear power construction still rely on foreign imports,but the long delivery cycle of imported welding materials,communication and supervision difficulties in the production process,high prices and other shortcomings,has become one of the main bottlenecks limiting the speed of development of nuclear power in China.In this thesis,based on the research on the R&D technology of nickel-based welding consumables for nuclear power at home and abroad,a nickel-based electrode ENiCrMo-3 for nuclear power was developed through a reasonable core design and slag system selection.The stability of the mechanical properties of the molten metal of different batches of electrodes was analyzed;the influence of the interlayer temperature on the microstructure and mechanical properties of the molten metal was studied;and a comparative analysis of the chemical composition,microstructure and mechanical properties of the molten metal with similar foreign UTP6222 nickel-based electrodes was conducted.The effect of interlayer temperature on the microstructure and mechanical properties of the molten metal was studied.The ENiCrMo-3 nickel-based electrodes developed in this thesis were selected from the Ni-Cr-Mo alloy system with Ca O-Ca F2-Si O2-Ti O2 slag system as the flux crust.The tensile strength and low temperature impact toughness test values of the three batches of electrodes fluctuate within a small range and meet the requirements of ASME standards,indicating good stability of mechanical properties.The chemical composition of domestic ENiCrMo-3 nickel-based electrodes conforms to ASME standards,and the impurity elements are strictly controlled,with S and P content of0.006%;the organization of the deposited metal is mainly austenite in the form of columnar crystal,and there is Nb C precipitation phase;the tensile strength of the deposited metal reaches 815 MPa,the yield strength reaches 512 MPa,and the elongation after break reaches38.25%.The properties are in accordance with the requirements of ASME standards.Five different interlayer temperature of ENiCrMo-3 nickel-based welding electrodes melt metal organization performance research shows that: interlayer temperature of 25 ℃,60 ℃,the melt metal organization is fine austenite columnar crystal,with the interlayer temperature increases,the melt metal organization becomes coarse austenite dendrite,precipitation phase size increases.Interlayer temperature of 25 ℃,the maximum tensile strength of 807.5 MPa,while the interlayer temperature of 200 ℃,the minimum tensile strength of 791.0 MPa;interlayer temperature of 60 ℃,the highest value of hardness and low-temperature impact toughness of the molten metal,the average hardness of 268.6 HV,impact absorption work of 64.0 J;When the interlayer temperature is higher than 100℃,the tensile mechanical properties and low-temperature impact toughness of ENiCrMo-3 nickelbased welding electrodes decrease with the increase of interlayer temperature.Comparative studies with foreign UTP6222 nickel-based electrodes show that: the difference in the organizational properties of the deposited metal is not significant.Domestic ENiCrMo-3 nickel-based electrodes melt metal tensile strength than foreign electrodes,but yield strength and-46 ℃ low-temperature impact absorption work is slightly lower than foreign electrodes;both impact fracture are ductile fracture.