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TIG welding parameters by material

Current and Electrode Parameters by Material

Section titled “Current and Electrode Parameters by Material”

The recommended current ranges for TIG welding vary depending on the material type and its thickness, with 40‑80 A being the typical value for 1.5 mm carbon steel. The following presents the base parameters for the most common metals using direct current electrode negative (DCEN) unless otherwise indicated.

Material Thickness (mm / in) Amperage Range (A) Tungsten Type (AWS Color) Polarity
Carbon steel 1.5 mm / 0.06 in 40‑80 EWTh‑2 (red) or EWLa‑1.5 (gold) DCEN
Carbon steel 3.0 mm / 0.12 in 80‑130 EWTh‑2 (red) or EWLa‑1.5 (gold) DCEN
Carbon steel 6.0 mm / 0.24 in 150‑250 EWTh‑2 (red) or EWLa‑1.5 (gold) DCEN
Stainless steel 304 1.5 mm / 0.06 in 35‑75 EWLa‑1.5 (gold) or EWG DCEN
Stainless steel 304 3.0 mm / 0.12 in 70‑120 EWLa‑1.5 (gold) or EWG DCEN
Aluminum (5000/6000 series) 1.5 mm / 0.06 in 60‑100 EWP (green) or EWLa‑1.5 (gold) AC
Aluminum (5000/6000 series) 3.0 mm / 0.12 in 120‑200 EWP (green) or EWLa‑1.5 (gold) AC
Titanium (commercially pure) 1.5 mm / 0.06 in 40‑90 EWLa‑1.5 (gold) DCEN
Titanium (commercially pure) 3.0 mm / 0.12 in 90‑160 EWLa‑1.5 (gold) DCEN
Copper‑nickel (alloy) 1.5 mm / 0.06 in 70‑110 EWTh‑2 (red) or EWLa‑1.5 (gold) DCEN
Magnesium (AZ31B) 1.5 mm / 0.06 in 50‑90 EWP (green) AC

Shielding Gas Flow Rate and Types of Shielding

Section titled “Shielding Gas Flow Rate and Types of Shielding”

The optimum shielding gas flow rate in TIG is around 8 L / min (17 CFH) for thin thicknesses, increasing to 14 L / min (30 CFH) for more reactive materials or at high currents. The following table summarizes the recommended combinations.

Material Shielding Gas Flow Rate (L / min / CFH) Nozzle Size (mm / in)
Carbon steel 100 % Argon 8‑12 L / min / 17‑25 CFH 8 mm / 0.31 in
Stainless steel 100 % Argon or Argon + 1‑3 % H₂ 8‑12 L / min / 17‑25 CFH 8 mm / 0.31 in
Aluminum 100 % Argon 10‑14 L / min / 21‑30 CFH 10 mm / 0.39 in
Aluminum (thickness > 6 mm) 75 % Helium + 25 % Argon 12‑18 L / min / 25‑38 CFH 12 mm / 0.47 in
Titanium 100 % UHP Argon 12‑15 L / min / 25‑32 CFH (trailing cup) 12 mm / 0.47 in with gas lens
Copper‑nickel 100 % Argon 10‑14 L / min / 21‑30 CFH 8 mm / 0.31 in
Magnesium 100 % Argon 10‑14 L / min / 21‑30 CFH 10 mm / 0.39 in

Weldability of Common Materials in TIG

Section titled “Weldability of Common Materials in TIG”

Weldability with TIG (gas tungsten arc welding process) is classified using the 1 to 10 scale from the eFunda source, where 10 represents excellent and 1 very limited use. The following table translates these values into a qualitative criterion for representative materials.

Material Weldability (scale 1‑10) Qualitative Rating
Carbon steel, low alloy 10 Excellent
Stainless steel 10 Excellent
Nickel and nickel alloys 10 Excellent
Aluminum 7 Good
Magnesium 7 Good
Copper and copper alloys 7 Good
Titanium 7 Good
Cast iron 7 Good (requires preheating)
Zinc 7 Good (caution due to low melting point)
Lead 7 Good (strict heat control)

Advantages and Limitations of the Process

Section titled “Advantages and Limitations of the Process”

Advantages

  • Precise heat control: thicknesses from 0.5 mm / 0.02 in up to 6 mm / 0.24 in can be welded in a single pass without excessive distortion.
  • Zero spatter and slag, reducing post-weld cleaning work by 70‑90 % compared to shielded metal arc welding.
  • Ideal for reactive metals (aluminum, titanium, magnesium) thanks to inert gas shielding that maintains residual oxygen below 0.002 %.
  • The heat-affected zone is limited to 1‑3 mm / 0.04‑0.12 in in width, preserving the mechanical properties of the base material.
  • Suitability for autogenous welding (without filler) on sheets up to 2 mm / 0.08 in.

Limitations

  • Low deposition rate: typically 0.2‑0.8 kg / h (0.44‑1.76 lb / h), making it up to 60 % slower than MIG welding on the same thicknesses.
  • Sensitive to drafts: wind speeds above 1 m / s (3.3 ft / s) can disturb gas coverage and cause porosity.
  • Requires greater operator skill; shop productivity is 2‑4 linear meters per hour in difficult positions.

Parameters Selection Guide

Section titled “Parameters Selection Guide”

Quick parameter selection is based on material and thickness, always starting with a reference current range of 30‑40 A per millimeter of thickness for steels and 40‑50 A per millimeter for aluminum. For carbon and stainless steel, DCEN and alloyed tungsten (gold, red, gray) are used. With aluminum and magnesium, switch to alternating current (AC) and green or gold tungsten. The argon flow rate is set at a base value of 10 L / min (21 CFH) and adjusted ±20 % according to nozzle size and travel speed. In demanding applications (titanium, superalloys) adopt ultra-high purity argon (99.999 %) with a trailing cup or inert chamber to maintain the oxygen level below 10 ppm. Always verify the compatibility of the filler rod (base metal series) and edge preparation: for thicknesses greater than 3 mm / 0.12 in a V-groove of 60‑75° with a root face of 1.5‑2 mm / 0.06‑0.08 in is recommended.

Frequently Asked Questions (FAQ)

Section titled “Frequently Asked Questions (FAQ)”
Section titled “What is the recommended amperage for welding aluminum 3 mm?”

A range of 120‑200 A in alternating current (AC) is recommended for aluminum of 3 mm / 0.12 in, using a green tungsten electrode (EWP) of 2.4 mm / 3/32 in.

What argon flow rate is needed for welding stainless steel 1.5 mm?

Section titled “What argon flow rate is needed for welding stainless steel 1.5 mm?”

The optimum flow rate is 8‑12 L / min (17‑25 CFH) with a standard 8 mm / 0.31 in nozzle; flow rates below 6 L / min (12.7 CFH) cause lack of shielding.

Which materials can be welded autogenously?

Section titled “Which materials can be welded autogenously?”

Autogenous TIG welding is feasible on stainless steel and titanium up to 2 mm / 0.08 in, provided the fit-up between parts is less than 0.25 mm / 0.01 in.

What tungsten diameter should I use for a current of 150 A?

Section titled “What tungsten diameter should I use for a current of 150 A?”

At 150 A a 2.4 mm / 3/32 in electrode is recommended; for currents between 80‑150 A a 1.6 mm / 1/16 in can also be used, although the larger diameter reduces the risk of contamination.

Can copper alloys be welded with TIG without preheating?

Section titled “Can copper alloys be welded with TIG without preheating?”

For thicknesses less than 3 mm / 0.12 in it is generally not necessary, but for more than 3 mm a preheat of 150‑300 °C / 302‑572 °F with argon‑helium is applied to improve fluidity.

How much does a poor gas flow rate affect weld quality?

Section titled “How much does a poor gas flow rate affect weld quality?”

Insufficient flow rate (< 6 L / min / 12.7 CFH) can raise porosity to 15‑20 % of the weld area, while excessive flow creates turbulence that draws in oxygen and doubles the risk of oxidation.

References

Section titled “References”