Investigation on thermal inertia of GMAW-P welding on Al alloy

Abstract

Thermal inertia relates to the rate at which the plasma cools and heats, which plays important role in improving the arc stability at base time of pulsed gas metal arc welding (GMAW-P). A three-dimensional (3D) transient model is established to investigate the thermal inertia due to current rapid variation of GMAW-P. The model is validated by comparison of measured and predicted arc profile and voltage. Thermal inertia increases as the current decent rate improves at the same current difference. Two high thermal inertia zones exist in arc region, one locates right under the wire tip, and another is above molten pool surface. The arc region with high temperature is broadened due to thermal inertia compared to constant current, which is more obvious as the current decent rate increases. The results show that thermal inertia remarkably influences the arc temperature and stability while current decent rate is higher than 130 A ms⁻¹.