Numerical Simulation of the Processes of Formation of a Welded Joint with a Pulsed ND:YAG Laser Welding of ZR–1%NB Alloy

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In recent years use of Zr-Nb alloys has increased in nuclear and chemical industry due to its corrosion resistance and enhanced strength compared to tin based ones. Welding of zirconium alloys is one of the most critical manufacturing processes for nuclear assembly production. To select suitable welding parameters to achieve quality weld, understanding of temperature and velocity fields during process in fusion zone and heat affected zone are essential. In the present study the Nd:YAG pulsed laser welding of zirconium alloy E110 was simulated using three-dimensional heat and fluid flow model. The convection mode of heat transfer and Marangoni stresses in fusion zone are two important mechanisms in controlling the heat transfer weld bead size. The calculated heating and cooling rates are of typical in laser welding and useful in microstructure study of fusion and heat affected zones. Experiments were carried with varying peak power, pulse frequency and duration using Nd:YAG pulsed laser on 0.5 mm thick sheets of E110 to form butt joints. The comparison of the results shows that the weld geometry is well matched with the numerical model.