THERMAL EFFICIENCY OF ARC-WELDING PROCESSES

A study was conducted on the arc and melting efficiency of the plasma arc, gas tungsten arc, gas metal arc, and submerged arc welding proces ses. The results of this work are extended to develop a quantitative m ethod for estimating weld metal dilution in a companion paper. Arc eff iciency was determined as a function of current for each process using A36 steel base metal. Melting efficiency was evaluated with variation s in arc power and travel speed during deposition of austenitic stainl ess steel filler metal onto A36 steel substrates. The arc efficiency d id not vary significantly within a given process over the range of cur rents investigated. The consumable electrode processes exhibited the h ighest arc efficiency (0.84), followed by the gas tungsten are (0.67) and plasma arc (0.47) processes. Resistive heating of the consumable G MAW electrode was calculated to account for a significant difference i n arc efficiency between the gas metal arc and gas tungsten arc proces ses. A semi-empirical relation was developed for the melting efficienc y as a function of net arc power and travel speed, which described the experimental data well. An interaction was observed between the arc a nd melting efficiency. A low arc efficiency factor limits the power de livered to the substrate which, in turn, limits the maximum travel spe ed for a given set of conditions. High melting efficiency is favored b y high arc powers and travel speeds. As a result, a low arc efficiency can limit the maximum obtainable melting efficiency.