Gas Metal Arc Welding

GMAW Modes of Metal Transfer Spray Globular Short Circuiting Pulsed Spray Gas Metal Arc Welding

GMAW Filler Metal Designations ER - 70S - 6 Electrode Rod (can be used with GMAW) Minimum ultimate tensile strength of the weld metal Solid Electrode Composition 6 = high silicon

AWS Specifications for GMAW Wire AWS A Carbon Steel Electrodes AWS A Low Alloy Steel Electrodes

Shielding Gas Shielding gas can affect –Weld bead shape –Arc heat, stability, and starting –Surface tension –Drop size –Puddle flow –Spatter Ar Ar-He HeCO 2 Gas Metal Arc Welding

GMAW Advantages Deposition rates higher than SMAW Productivity higher than SMAW with no slag removal and continuous welding Easily automated Gas Metal Arc Welding

Quality Spatter –Droplets of electrode material that land outside the weld fusion area and may or may not fuse to the base material Porosity –Small volumes of entrapped gas in solidifying weld metal Gas Metal Arc Welding

Limitations Equipment is more expensive and complex than SMAW Process variants/metal transfer mechanisms make the process more complex and the process window more difficult to control Restricted access –GMAW gun is larger than SMAW holder Gas Metal Arc Welding