Abstract
Owing to its potential application prospect in novel accident tolerant fuel, molybdenum alloys and their welding technologies have gained great importance in recent years. The challenges of welding molybdenum alloys come from two aspects: one is related to its powder metallurgy manufacturing process, and the other is its inherent characteristics of refractory metal. The welding of powder metallurgy materials has been associated with issues such as porosity, contamination, and inclusions, at levels which tend to degrade the service performances of a welded joint. Refractory metals usually present poor weldability due to embrittlement of the fusion zone as a result of impurities segregation and the grain coarsening in the heat-affected zone. A critical review of the current state of the art of welding Mo alloys components is presented. The advantages and disadvantages of the various methods, i.e., electron-beam welding (EBW), tungsten-arc inert gas (TIG) welding, laser welding (LW), electric resistance welding (ERW), and brazing and friction welding (FW) in joining Mo and Mo alloys, are discussed with a view to imagine future directions. This review suggests that more attention should be paid to high energy density laser welding and the mechanism and technology of welding Mo alloys under hyperbaric environment.
Highlights
Molybdenum (Mo) and Mo alloys show characteristics such as high melting point, good high-temperature strength, high wear resistance, high thermal conductivity and low resistivity, low coefficient of linear expansion, high elastic modulus, and good corrosion resistance [1]
The results show pore with thickness mm.welded pore defects are serious when welding heatthat input is defects are serious when welding heat input is large
Compared with the columnar crystal during welding without deflection, the microstructure of the weldof zone an equiaxed when weldingbeam without beam deflection, the microstructure thetransforms weld zoneinto transforms into crystal an equiaxed welding with welding a 0.6 mmwith beama offset to Kovar
Summary
Molybdenum (Mo) and Mo alloys show characteristics such as high melting point, good high-temperature strength, high wear resistance, high thermal conductivity and low resistivity, low coefficient of linear expansion, high elastic modulus, and good corrosion resistance [1]. Such a fuel system needs new fuel system, that is, accident tolerant fuel (ATF) needs to be developed [6,7] Such a fuel system to be able to withstand severe accident conditions and slow and down the rate of the deterioration over a long needs to be able to withstand severe accident conditions slow down rate of deterioration period of time, to provide valuable time for people take emergency and greatly over a long period of time,more to provide more valuable timetofor people to take measures emergency measures reduce the risks of leakage of radioactive materials. A lot of new progress has been achieved in recent years
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