Numerical Simulation Of Welding Distortion In Pulsed Laser Welding Of Hastelloy C-276Thin Sheet

The world is facing an unprecedented energy crisis since the last few years. As the most advanced third-generation nuclear power plants in the world, the API000has wide application prospects. The canned reactor pumps are designed for the AP1000. The cans are using ultra-thin, large aspect ratio structures. In the nuclear reactor coolant pump manufacturing prosess, it is the key technology to precise welding the cans. As a precise welding process, laser welding has been widly used in industrial areas. Using laser welding, it is effctive to reduce the area of the weld and the heat affected zone and improve the welding quality. However, with the local heating by the laser beam, non-uniform stress and strain are induced in the material heating, melting and cooling process. Further welding distortion is producted and has a negative effect on the welding quality and the dimensional accuracy of the cans. In order to meet the required presion of the cans, the subject focuses on the laser welding distortion, reveals the welding distortion law and provides the theory basis for the control of the welding distortion.In this paper, the elesto-plastic finite element method is used to simulate the laser welding. The three-dimensional finite element model is established in ANSYS software. The welding temperature field and the stress-strain field are obtained. The buckling distortion and the shrinkage distortion induced by welding process are investigated. The Hastelloy C-276laser welding experiments are carried out. The laser displacement sensor is used to measure the welding distortion. The experimental results have a good agreement with the simulation results, and the reliability of the finite element model is validated. The research focuses on and results are as follows:(1) The Hastelloy C-276pulsed laser welding finite element model is established. The model includes the changes of material physical properties and mechanical properties at elevated temperatures. The welding temperature field and the stress-strain field are obtained by the model. The welding distortion is measured in the welding experiment. The experiment results have a good agreement with the simulation results, and the reliability of the finite element model is validated.(2) The buckling distortion in the welding is investigated. The dynamic process of the local buckling and the global buckling are analysed and the buckling distortion mechanism is revealed. The effect of welding processing parameters and sheet dimensions on the buckling distortion is discussed.(3) The shrinkage distortion in the welding is investigated. The mechanism of the shrinkage producing is revealed. The effect of the deflection distortion on the transverse shringkage distortion is considered in the simulation and experiment. The simulation and experiment results are amended. The effect of welding processing parameters on the shrinkage distortion is discussed.