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TIG Welding

TIG Welding, also known as Gas Tungsten Arc Welding (GTAW), is a process that joins metals by heating them with an arc between a tungsten electrode (non-consumable) and the work piece. The process is used with a shielding gas and may also be used with or without the addition of filler metal. The primary variables in TIG Welding are arc voltage (arc length), welding current, travel speed and shielding gas composition. The amount of energy the arc produces is proportional to the current and the voltage. The amount of energy transferred per unit length of weld is inversely proportional to the travel speed. Shielding gases are typically inert to protect the electrode from contamination. The use of helium shielding provides more penetration than argon. The arc, established between the tip of the electrode and the work, generates heat to melt the base metal. Once the arc and weld pool are established, the torch is moved along the joint, and the arc progressively melts the surfaces to be joined. If used, filler wire is usually added to the leading edge of the weld pool to fill the joint. The tungsten electrode can be alloyed with small amounts of active elements to increase emissivity of the electrode; this provides quicker arc starting, greater arc stability, and longer electrode life.

Why Use TIG Welding?

  • Can be used to join almost all metals, with superior weld quality, generally free of defects
  • Free from spatter that occurs with other arc welding processes
  • Can be used with or without filler metal as required for the specific application
  • Provides excellent control of root pass weld penetration
  • Can be used to produce inexpensive autogenous (fusion) welds with good penetration
  • Provides for separate control over the heat input and filler metal additions


  • Travel speeds and deposition rates are relatively low, increasing weld cost
  • A high degree of operator skill is required to produce quality welds
  • Process is not easily automated

TIG Welding: How to Improve Results

Tips and TricksTitanium AlloysHigh Nickel AlloysAluminum AlloysCopper AlloysStainless Steel Alloys (300 Series)
With cylinder gas supply, use a high integrity gas delivery system in place of standard rubber diaphragm regulator/flowmeter.XXXXX
Use a gas lens in the TIG torch to support a lamellar gas flow.XXXXX
Use gas flow rates in the 15-20 cfh range.XXXXX
Ascertain both raw material and filler metals are clean before welding.XXXXX
Use a high integrity TIG torch as it utilizes a high integrity gas delivery line which is not permeable to atmospheric gases. The gas line is also separate from the power cable, further enhancing gas purity.XXXXX
Use a high integrity gas supply line from the flowmeter to the gas solenoid on the welder. Conventional rubber hoses may leak.XXXXX
If a central gas supply or distribution pipeline is utilized, use a high flow moisture trap and consider use of an oxygen trap.XXXXX
Use ultra-high purity argon when possible (Grade 5.0 or better), 99.999% purity.XXXXX
With materials grater than 1/8", consider use of an argon/helium shielding gas blend for improved penetration.  XX 
Consider adding controlled amounts of hydrogen to the argon-based shielding gas (<10% H2). A CGA 350 regulator will be required when this gas is selected. The CGA 580 used with pure argon will not fit this cylinder. This mixture is not recommended for joining stainless to carbon steel. It is ideal for stainless-to-stainless joining. X  X
Use post and pre-flow when possible (1 second for each 10 amps of welding current).XXXXX
Use a trailing shielding gas if possible.XXX  
Use a high integrity regulator/flowmeter with a stainless steel diaphragm. X   
Perform inter-pass cleaning with a 300 series stainless steel brush. This will remove surface oxides for improved results. XXX 
Remove surface oxide in the weld zone using a clean stainless steel brush prior to welding.  XXX
On thicker material, set balance control to maximum penetration when possible.  X  
Match filler metal to base metal - consult AWS or CWB guidelines. For stainless to steel, use an E309 filler metal.  XXX
For dissimilar alloy joining, consider silver bearing filler metal. Service temperatures must be below the melting point of the alloy selected (typically <900° F).   X 
If the weld needs to be anodized, use a 5000 series filler metal.  X  
Use an AC square wave power supply when possible.  X  
Use a water-cooled TIG torch to prevent the tungsten from melting and improve the current carrying capacity of the torch when welding thicker material.  XXX
Use a pure tungsten electrode and increase the diameter to compensate for additional heat load at the torch. Less than 3/32" thoriated tungsten electrodes are not recommended for welding aluminum.  X  
Consider using preheat on thick sections. Oxy-acetylene torches work well. Be sure to set a carburizing flame and use a temperature measuring device.  XX 
Be patient on arc starts. Aluminum and copper have high heat conductivity. Materials will not melt for several seconds.  XX 
Use a remote foot or hand control to compensate for the high thermal conductivity of aluminum or copper or with thin stainless steel.  XXX
Use Direct Current Straight Polarity (DCSP) electrode negative when possible. Direct Current Reverse Polarity (DCRP) may be used for very thin sections (<1/16").   XX
To improve surface color match and corrosion resistance, use pulsed current settings.   XX
Use an alloyed tungsten electrode to increase current carrying capacity. If thoriated tungsten is selected, ensure all grinding dust is captured and removed from the operator's breathing zone. Consult MSDS of the electrode manufacturer.   XX
To minimize surface discoloration, maintain close nozzle-to-work distances (maximum 1/2" from work piece).   XX
Rapid cool thin sections to maintain corrosion resistance.    X
Minimize heat input while maintaining sufficient penetration.    X

TIG Welding Parameters for Aluminum

Material Thickness (in)PositionPasses RequiredTravel Speed (ipm)AC (amp)Cup Diameter (in)Cup SizeGas Flow (cfh)Gas Volume per 100 ft of weld (cft)Tungsten Diameter (in)Filler Rod Diameter (in)Pounds Deposited per 100 ft (lb)
1/16H & V18803/8620501/163/321/2
1/8H & V181203/8620503/321/82
3/16H & V181801/2825621/85/324.5
1/4H & V182353/41230753/163/167

Recommended Shielding Gases

  • Praxair HeliStar™ A-75 (25% Helium/75% Argon)
  • Praxair Argon

TIG Welding Parameters for Stainless Steel

Material Thickness (in)PositionPasses RequiredTravel Speed (ipm)DCEN (amp)Cup Diameter (in)Cup SizeGas Flow (cfh)Tungsten Diameter (in)Filler Rod Diameter (in)

Recommended Shielding Gases

  • Praxair Helistar™ A-75 (25% Helium/75% Argon)
  • Praxair Hydrostar™ H-5
  • Praxair Argon
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