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Welding processes8 GTAW
! "# $# # Arc Characteriscs in Argon and Helium $# % $# % $# &'(() $# &'*+ $# &'*+ & "&,- .,/ &&, ! 0 1& 2 3) 4 5 6% #, ( %'- & An arc Welding process that uses an arc between a tungsten electrode (nonconsumable) and the weld pool. The process is used with a shielding gas and without application of pressure. Filler metal may or may not be used. •. •. 7' •. 7'# "&,- • - -& • , & • -#8 & • , & .,/ • +#1%% • 9%:;'%;&$1 • #$&%/#$ • #<#;#:&: • &'&, • #&##&&$ [...]... tungsten size, nozzle size and gas type (part of a welding procedure) Primary variables are welding current, arc voltage, travel speed, pulsing (if used), upslope and downslope for programmed welding Factors of interests are penetration, bead width or weld reinforcemnt Gas Tungsten Arc Welding 9 Quality Control • • • • Better than any of the arc welding processes Highest quality obtained when all precautions... starting and operates at lower voltage Provides higher voltage and higher heat in the arc (also possible to weld at a higher speed) Gas Tungsten Arc Welding 6 Equipment Gas Tungsten Arc Welding 7 Joint Design • • 8 Mostly the same as for SMAW Related to Design for Welding Process Control • • • • Follow the schedule • • Secondary variable include rod feed speed, torch angles and possibly tungsten angles Currents... taken Cleanliness plays a critical role (joints, worktables, fixtures, filler etc) Welder skill also is critical 10 Suitability For Materials Gas Tungsten Arc Welding 11 Process Variants • • • Pulsed-Currnet GTAW Manual Programmed GTAW Hot Wire GTAW ... • • Filler Metals Shielding Gases Tungsten Electrodes Gas Tungsten Arc Welding 7 Consumables Main Consumables • • Filler Metals • • • AWS Provide specifications for filler metals Uses straight lengths of rods for manual application Automatic applications uses metal wire from coils or spools Tungsten Electrodes Gas Tungsten Arc Welding 7 Consumables Main Consumables • Shielding Gases • • • Must be an...Gas Tungsten Arc Welding 4 Common Applications • Thinner Materials, thin wall tubing and root pass in pipes • 5 High Precision work due to extreme control Consumables Main Consumables • • • Filler Metals Shielding Gases Tungsten Electrodes Gas Tungsten Arc Welding 6 Common Applications • Thinner Materials, thin wall tubing and root pass