Heat Flow In Argon Tungsten Arcs And Workpiece Thermal Response At Pressures Up To 6 Mpa

For the control of a mechanised or automised dry underwater welding process the arc characteristics, the heat quotation in the electrode, the arc column and the weld have been measured during argon tungsten arc welding at pressured between 0.1 and 6 MPa, arc currents between 50 and 200 A and arc length between 2 and 10 mm. Based on calorimetric measurements a calculational procedure has been developed to determine the arc efficiency as well as the average heat flux to the weld; these parameters have been used in combination with a modified version of the finite difference heat conduction code HEATING5 to model the dry hyperbaric welding process. In a parametric study the spatial and temporal temperature distributions in a workpiece have been calculated leading to a first estimate of the welding result, i.e. geometry and cooling behaviour as well as maximum temperature of the weld, as a function of ambient pressure, arc current and length.