Ar+CO2 Mixture Effects on GMAW-SP of Mild Steel

When using the spray-transfer mode with GMAW, the most common gas blend for steel applications are mixtures of argon and carbon-dioxide (CO2).  In certain applications, CO2 levels as low as 5% (C5) are preferred, and in other cases blends with up to 15% (C15) or higher are specified. Although this process and these effects have been studied for decades, there are still a variety of opinions and misunderstandings on the selection of the ‘best’ gas for any application.  Too often the effects of the gas mix on welding outcomes are not given proper consideration.

In this presentation the effects of systematically altering this blend will be explored.  The study will examine the effects through various experiments on arc performance, bead-shape and surface appearance, weld penetration profile, deposit microstructure, and microhardness.  This selection can also have broader implications on welding cost and quality in some surprising ways.