Effect of rare earth metal on plasma properties in GMAW using CO 2 shielding gas

Gas metal arc welding (GMAW) process, the effect of welding polarity and rare earth metal (REM) elements on physical properties was investigated through the observation of the plasma characteristics using the optical emission spectroscopy method which is suitable respectively to the O plasma region and the Fe plasma region. At the present experimental conditions, the MG-50 wire electrode and KC-500 wire electrode (REM-added electrode) were used for welding with 100% CO2 shielding gas. The results of the KC-500 wire electrode with DCEN polarity showed that the maximum temperature of the O plasma region was around 13,000–13,500 K. The maximum occurs at the region apart from the arc axis. The effect REM elements can cause high current density and electromagnetic pinch force at the tip of electrode. Meanwhile, the metal droplet diameter became smaller like spray transfer during arc with DCEN polarity.