Spectroscopic Analysis of Arc-Laser Plasmas during Hybrid Welding

B. Ribic, T.A. Palmer*, and T. DebRoy

Department of Materials Science and Engineering

Pennsylvania State University

University Park, PA

*Applied Research Laboratory

Pennsylvania State University

University Park, PA

Abstract

      During hybrid welding, the interaction between the arc and laser energy sources is believed to create a synergy which enhances the energy transfer efficiency and melting efficiency of the process.  These improvements in the energy transfer contribute to the attractive properties of the process over laser or arc processes performed alone.  However, the properties of the combined arc and laser plasma have not been quantified or characterized in a fundamental way, resulting in a lack of understanding of the mechanisms driving the observed arc/laser plasma synergy.  In this work, emission spectroscopy measurements are performed to analyze the plasma phase formed by the interaction between a gas tungsten arc (GTA) and a high power Nd:YAG laser in an argon shielding gas.  Measurements of the electron temperature, electron density, and densities of various other heavy particles will be performed in order to characterize the plasma phase.  As part of these measurements, the role of metal vaporization from the mild steel substrate material will also be quantified based on a spectroscopic analysis of the metal vapor peaks in the plasma phase.  The properties of the plasma phase formed by the combination of the arc and laser will be compared with those of plasmas formed by the arc and laser individually, providing a straightforward means for characterizing the synergistic effect of the arc-laser combination.