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Choosing the Right TIG Welding Materials

Last updated:
May 3, 2024
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Table Of Contents

1. Shielding Gas

Tungsten inert gas welding generally uses argon, helium, argon-helium mixed gas, or argon-hydrogen mixed gas as the shielding gas.

(1) Selection of Shielding Gas

The shielding gas suitable for different materials is shown in Table 5-70.

Table 5-70 Shielding Gas Suitable for Different Materials

MaterialApplicable Shielding Gas and Characteristics
Aluminum and Aluminum AlloysArgon: AC welding provides a stable arc and good surface cleaning action

Helium: DC positive connection, produces a stable arc on chemically cleaned materials and has a higher welding speed

Argon-helium mixed gas: Has good cleaning action, higher welding speed and penetration, but the arc stability is not as good as pure argon
BrassArgon: Stable arc with minimal evaporation.
Cobalt AlloysArgon: Stable arc that is easy to control.
Copper-Nickel AlloysArgon: The arc is stable and easy to control, also suitable for welding copper-nickel alloys with steel
Oxygen-Free CopperArgon: Uses DC positive connection, the arc is stable and easy to control

Helium: Has a larger heat input, fast welding speed, and deep penetration

Argon-helium mixed gas: 75% helium, 25% argon. The arc is stable, suitable for welding thin parts
InconelArgon: The arc is stable and easy to control

Helium: Suitable for high-speed automatic welding
Low Carbon SteelArgon: Suitable for manual welding

Ammonia: Suitable for high-speed automatic welding, deeper melting compared to argon protection
Magnesium AlloysArgon: Uses AC welding, has good arc stability and cleaning action
Maraging SteelArgon: Arc is stable and easy to control
Molybdenum-0.5% Titanium AlloyArgon and Helium are both suitable: To obtain weld metal with good plasticity, in addition to enhanced protection, the nitrogen content in the welding atmosphere must be controlled below 0.1% (volume fraction), and the oxygen content controlled below 0.05% (volume fraction)
Monel AlloyArgon: Arc is stable and easy to control
Nickel AlloysArgon: Arc is stable and easy to control

Helium: Suitable for high-speed automatic welding
Silicon BronzeArgon: Can reduce the thermal brittleness of the base material and the weld metal
Silicon SteelArgon: Arc is stable and easy to control
Stainless SteelHelium: Arc is stable and can achieve greater melting depth than argon

Argon: The arc is stable and easy to control
FerroalloyArgon: The arc is stable and easy to control

Helium: Suitable for high-speed automatic welding

(2) Requirements for protective gases

1) Argon.

Requirements for the purity of argon in welded parts are shown in Table 5-71. The composition of domestically produced welding argon is shown in Table 5-72.

Table 5-71 Requirements for the purity of argon in welded parts

Welding MaterialPower Source Type and PolarityArgon Purity (Volume Percentage, %)
Molybdenum, Niobium, Zirconium, Tantalum, and their alloysDC Electrode Positive99. 98
High-temperature Resistant AlloysDC Electrode Positive99. 95

Table 5-72 Composition of domestically produced welding argon (volume fraction, %)

Argon purityN2O2H2CnHmHO
≥99.999≤7 x10-5≤10-5≤5 x10-510 -5≤2 x10-5

2) Helium.

The purity of welding helium generally requires more than 99.8% (volume fraction). The composition of domestically produced welding helium (volume fraction 99.999%) is shown in Table 5-73.

Table 5-73 Composition of Domestic Welding Helium (99.999%) (Volume Fraction, %)

ComponentsNeH2O2 + ArN2COCO2HO

3) Argon-helium mixed gas.

When using argon-helium mixed gas, it is particularly suitable for occasions where weld quality requirements are very high. The typical mixing ratio is (75%~80%) He + (15%~20%) Ar (volume fraction).

4) Argon-hydrogen mixed gas.

Argon-hydrogen mixed gas is mainly used for welding nickel-based alloys, nickel-copper alloys, and stainless steel. Generally, the hydrogen content in the mixed gas should be controlled below 15% (volume fraction).

2. Filler metal

In tungsten inert gas welding, the inert gas only serves a protective role, and the weld composition is mainly adjusted by the filler metal to ensure weld quality. The filler metal is provided by the welding wire, therefore, the content of sulfur, phosphorus, harmful gases, and impurities in the welding wire must be strictly controlled.

Currently, there is no dedicated TIG welding wire standard in China, generally, welding wires for gas metal arc welding or welding steel wires are used. When welding low carbon steel and low alloy high strength steel, welding steel wires are generally selected according to the principle of equal strength, and when welding copper, aluminum, stainless steel, welding wires for gas metal arc welding, gas welding wires, or submerged arc welding wires are generally selected according to the principle of equal composition.

When welding dissimilar steels, if the structures of the two steels are different, the selection of welding wire should consider crack resistance and carbon diffusion issues; if the structures of the two steels are the same but their mechanical properties differ, it is best to choose a welding wire with a composition between the two. Recommended welding wire grades for common steel types are shown in Table 5-74.

Table 5-74 Recommended Welding Wire Grades for Common Steel Types

Steel MaterialSelected Welding Wire Grade
Carbon steelQ235, Q235F, Q235gH08Mn2Si
10g, 15g, 20g, 22g, 25gH05MnSiAlTiZr
Low alloy steelQ345H10Mn2
15MnV, 16MnVCuH08MnMoA
15MnVN, 19Mn5H08Mn2SiA
Low alloy heat-resistant steel18MnMoNb, 14MnMoVH08Mn2SiMo
12CrMo, 15CrMoH08CrMoA, H08CrMo, Mn2Si
20CrMo, 30CrMoAH05CrMoVTiRe
12Cr1MoV, 15Cr1MoV
15Cr1MoV, 20Cr1MoVH08 CrMnSiMoV
G106 steelH10Cr5MoVNbB
Stainless steel06Cr19Ni10, 12Cr18Ni9HOCr18Ni9
Low temperature steel09Mn2VH05Mn2Cu, H05Ni2.5
Low temperature steel3.5Ni, 06MnNb
Different types of steelG102 +12CrMoV 
G102 + 15CrMo
G102+Carbon steelH08Mn2Si
G102 + 1Cr18NiTi 
G102 + G106
Nickel-based welding wire
12Cr1MoV+Carbon steelH08Mn2Si, H05MnSiAlTiZr
12CrMoV +15CrMoH13CrMo, H08CrMoV

3. Electrode Materials

The role of the non-consumable electrode in TIG welding is to conduct electricity, ignite the arc, and maintain normal arc combustion. Its quality greatly affects the stability of the arc and the welding process, as well as the quality of the weld. Generally, non-consumable electrodes should meet the requirements of high allowable current and low consumption.

1) Currently, common electrode materials include pure tungsten, thoriated tungsten, ceriated tungsten, zirconiated tungsten, and lanthanated tungsten. Common tungsten electrode diameters are: 0.5mm, 1.0mm, 1.6mm, 2.0mm, 2.5mm, 3.2mm, 4.0mm, 5.0mm, 6.3mm, 8.0mm, 10.0mm, a total of 11 types, with lengths ranging from 76 to 610mm. The surface of the tungsten electrode should not have defects such as scars, cracks, shrinkage cavities, burrs, or non-metallic inclusions.

2) Domestic tungsten electrodes are usually surface treated by chemical cleaning or mechanical grinding. To improve the stability of the arc, the end of the tungsten electrode needs to be ground into a conical or hemispherical shape depending on the current size.

3) When the tungsten electrode material is the same, different electrode shapes will have a certain impact on the stability of the arc and the formation of the weld. The relationship between common tungsten electrode tip shapes and arc stability is shown in Table 5-75.

Table 5-75 Common Tungsten Electrode Tip Shapes and Their Relationship with Arc Stability

Tungsten Electrode Tip ShapeType of Tungsten ElectrodeCurrent PolarityApplication RangeArc Stability
Ceriated or Thoriated TungstenDirect Current Electrode PositiveHigh CurrentStable
Ceriated or Thoriated TungstenDirect Current Electrode PositiveLow Current
Suitable for welding in narrow gaps and thin plates
Pure Tungsten ElectrodeAlternating CurrentWelding of aluminum, magnesium, and their alloysStable
Ceriated or Thoriated TungstenDirect Current Electrode PositiveContinuous welding with tungsten electrodes smaller than 1mm in diameterGood

4) The current carrying capacity of tungsten electrodes is shown in Table 5-76.

Table 5-76 Tungsten Electrode Current Carrying Capacity

Electrode Diameter/mmDC Current/AAC Current/A
Direct Connection (Electrode -)Reverse Connection (Electrode +)
Pure TungstenThoriated Tungsten, Ceriated TungstenPure TungstenThoriated Tungsten, Ceriated TungstenPure TungstenThoriated Tungsten, Ceriated Tungsten
0.52 ~202 ~202 ~152~15
110 ~ 7510 ~7515 ~5515 ~ 70
1.640 ~13060 ~15010 ~2010 ~3045 ~ 9060 ~125
275 ~ 180100 ~20015 ~2515 ~2565 ~12585 ~160
2.5130 ~ 230160 ~25017 ~3017 ~3080 ~140120 ~ 210
3140 ~ 280200~30020 ~4020 ~ 40100~160140 ~ 230
3.2160 ~310225~33020 ~3520 ~35130 ~190150 ~250
4275 ~ 450350~48035 ~5035 ~50180 ~260240 ~350
5400 ~625500 ~ 64550 ~7050 ~70240 ~ 350330 ~ 460
6500 ~625620 ~ 65060 ~8060 ~80260 ~390430 ~560
6.3550~675650 ~85065~10065~100300~420430 ~ 575
8650 ~830

5) The open-circuit voltage required for commonly used electrode materials is shown in Table 5-77.

Table 5-77 Open-Circuit Voltage Required for Commonly Used Electrode Materials

Electrode TypesElectrode DesignationsRequired No-Load Voltage /V
CopperStainless SteelSilicon Steel
Pure Tungsten ElectrodeW959595
Thoriated Tungsten ElectrodeWTh-10
40 ~65 
50 ~70 
Ceriated Tungsten ElectrodeWCe-2030~35

6) The selection of tungsten electrodes is shown in Table 5-78. Note that some tungsten rods are radioactive (such as thoriated tungsten electrodes), therefore, safety protection must be ensured when grinding tungsten rods. When storing a large quantity of tungsten rods, it is best to keep them in a lead box to prevent radiation from harming the human body.

Table 5-78 Selection of Tungsten Electrodes

Types of Tungsten ElectrodesGradeCharacteristics
Pure TungstenW1、W2Both melting point and boiling point are very high, the disadvantage is that it requires the welding machine to have a higher open-circuit voltage. Long-term operation may result in melting of the tungsten electrode.
Thoriated TungstenWTh7, WTh10,
WTh15, WTh30
By adding a certain amount of oxide needles, the disadvantages of the above pure tungsten electrodes are overcome, but there is a trace of radioactivity.
Ceriated TungstenWCe-20A certain amount of cerium oxide is added to pure tungsten, the advantages are: low arc initiation current, better arc column compression, longer life, and extremely low radioactivity.
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