Effect of Heat Flow Condition in Analysis of Electron Beam Welding

Electron Beam welding (EBW) is modeled using a basic Kaplan keyhole formation as in laser beam welding. As high penetration depth to width ratios can be obtained in this process, researchers and engineers are working to enhance this vacuum based technology of component joining. This welding technique has several applications in fusion reactor fabrication of various components like vacuum vessel and test blanket modules with different types of steels. This study is focused on simulating and modeling EBW in terms of the heat flux flow with surface heat on bead area in the form of Gaussian distribution. When the beam forms keyhole plasma, the heat flow conducted to the base metal is modeled as a frustum distribution. Unlike laser beam welding, in EBW, a portion of the heat would leave out to ambience through the lower end of the bead, where this amount of heat is to be apportioned. Heat flow mechanism is calculated using Peclet number from where the empirical formulae power distribution is determined. Peclet number variation is calculated as a function of radial distance, penetration depth and distance from wall. The values obtained may not be directly used in analysis but a correlation is obtained which assists in formulating a finite element analysis. The welding process is evaluated using temperature profile distributions in Weld Zone (WZ) and Heat Affected Zone (HAZ) using Ansys software. SS304 weld material is used and temperature dependent thermal and structural properties are considered. The output obtained is the thermal isotherms around the weld to estimate the surface heat flux distribution on the surface and through the keyhole. The scope of applications where the heat flow distributed in % contribution would provide guidance in structural joints as in nuclear reactor fabrication applications.