STUDY ON METAL TRANSFER IN GMAW UNDER THE INFLUENCE OF SHIELDING GAS

Abstract

This paper investigates the effect of shielding gas on metal transfer behavior in gas metal arc welding (GMAW) using a conventional solid wire electrode. Welding experiments were carried out with three shielding gases, including pure Ar, an Ar + 20% CO₂ mixture, and 100% CO₂, at three welding currents of 220, 250, and 280 A. Under pure Ar shielding, the transfer mode gradually changed from projected droplet transfer to streaming transfer as the welding current increased. When the CO₂ content in the shielding gas increased to 20%, the metal transfer mode evolved from globular transfer to projected droplet transfer as the current increased from 220 A to 280 A. In contrast, under 100% CO₂ shielding, globular transfer was observed at all three current levels. These experimental observations clarify the fundamental differences in the mechanisms governing metal transfer as influenced by the shielding gas during GMAW.