The effects of process variables on the bead width of submerged-arc weld deposits

Abstract

The results of bead-on-plate weld measurements are presented to determine the effects of the process variables on the bead width for the submerged-arc welding process, at a heat input of 3 kJ/mm. It is found that bead width is affected by the electrode polarity, electrode diameter, electrode extension, welding current, welding voltage and welding speed. A positive electrode polarity, a large electrode diameter, a small electrode extension and a high welding voltage encourages a large bead width in most cases. For a particular electrode diameter and extension, it is found that the bead width initially increases as the current and the welding speed increase. The bead width reaches a peak value, and then decrease as the welding current and speed are further increased. It has been suggested in a recent tungsten-inert-gas welding investigation that heat input could be used as an independent parameter for predicting bead width. However, the present work suggests that heat input alone is not sufficient for predicting bead width in submerged-arc welding. The bead width is not affected significantly by the power source, constant voltage or constant current, when an acidic fused flux is used. However, when a basic fused flux is used, constant-current operation gives somewhat larger bead widths. It is found also that basic fused flux welds have a somewhat larger bead width than acidic fused flux welds. Regression equations are presented for computing bead width from the welding parameters, the analysis including both linear and curvilinear multiple-regression analysis techniques. Surprisingly, the correlation coefficients of the linear multiple-regression equations were found to be somewhat better than those of the curvilinear analysis.