gas metal arc welding gmaw modes of metal transfer spray globular short circuiting pulsed spray gas...

Gas Metal Arc WeldingGas Metal Arc Welding

GMAW Modes of Metal TransferSpray 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

Composition6 = high silicon

AWS Specifications for GMAW Wire

AWS A5.18 - Carbon Steel ElectrodesAWS A5.28 - 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 He CO2

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