Arc Length Behaviour and Welding Voltage Analysis for Aluminum GMAW

The heat input is a key component of a welding procedure, which is dependent on several fall voltages that compose the total voltage fall. As current practice is primarily reliant on trial and error to determine voltage settings for a desired heat input, having a means to predict voltage fall is of interest to welding practitioners. Here, a series of welds using ER4043 were analyzed with synchronized data (voltage, amperage, and high-speed videography) to confirm the expected arc lengths for a given range of parameters as well as the individual contributors to overall voltage fall. The Lincoln Procedure Handbook was leveraged to determine the resulting arc lengths for a range of desired settings. The sum of the anode and cathode fall voltages were found to be approximately independent of current and can be considered constant with a value of 18.3±0.4 V and a total contribution of 64±3% to the total voltage fall. Arc column potential was found to be 0.62±0.05 V mm-1 with 34±3% overall voltage contribution at the arc column for a desired weld. This work provides a clear and practical expected voltage contribution for each fall voltage constituent. Results for carbon steel will also be discussed for comparison.