Comparison of a new, high precision, energy efficient welding method with the conventional Gas Metal Arc Welding on high carbon steel base metal

Abstract: CMT+P welding is less susceptible to hot cracking than the MAG welding process due to use of low heat input properties. Solidification cracking was found in all weld specimens that had greater 0.39KJ/mm heat inputs. Cracking occurs because of the contraction stresses generates during cooling. Hydrogen cracking is found in HAZ with low heat input parameters, this type of cracking occurred because of very rapid cooling and therefore not enough time to allow the hydrogen to dissipate from the specimen. To eliminate this type of cracking the experiment could be repeated by adding heating during welding to control and reduce the cooling rate. Due to high carbon content in the steel and very fast cooling the microstructure of the weld is martensitic in the base metal as well as the HAZ. Microstructure in the weld and base metal is martensitic due to high carbon con-tent and rapid cooling. At low heat inputs dilution is less and therefore lower carbon content in weld pool. Better weld appearance and weld quality is achieved with CMT+P welding process than the conventional GMA welding processes because of the new wire movement technology during welding