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Expert Tips: Selecting Parameters for TIG Welding

Last updated:
May 3, 2024
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The main parameters for TIG welding include welding current, arc voltage, welding speed, tungsten electrode diameter and tip shape, nozzle diameter and gas flow, distance from the nozzle to the surface of the workpiece, and the angle of the welding torch.

(1) Selection of manual TIG welding parameters

1) Type of current and polarity.

There are two types of welding currents: direct current and alternating current. Direct current has two different methods of connection: straight and reverse. The choice of current type and polarity mainly depends on the type of material being welded and the requirements for the weld.

To reduce or eliminate current fluctuations caused by changes in arc length, TIG welding requires the use of a power source with steep-drop or constant-current external characteristics. The characteristics and applicable scope of different types of currents and polarity connections in TIG welding are shown in Table 5-80.

Table 5-80 Characteristics and applicable scope of different types of currents and polarity connections in TIG welding

Types of CurrentDirect Current, Electrode PositiveDirect Current, Electrode NegativeAlternating Current
Connection Method
Approximate Ratio of Heat DistributionWorkpiece 70%, Electrode 30%Workpiece 30%, Electrode 70%Workpiece 50%, Electrode 50%
Characteristics of PenetrationDeep and narrowShallow and wideMedium
athodic Cleaning ActionNonePresentPresent (when the workpiece is negative)
ф3.2W Electrode Allowed Maximum Current400A420A250A
Applicable MaterialsBrass, copper alloys, cast iron, stainless steel, dissimilar metals, titanium, silverGenerally not usedAluminum, magnesium, aluminum bronze, beryllium bronze, cast aluminum

2) Welding current.

Welding current is usually selected based on the material, thickness, and position of the weldment. The diameter of the tungsten electrode must be chosen based on the welding current. The allowable welding current range for different tungsten electrode diameters is shown in Table 5-81.

Table 5-81 Allowable welding current range for different tungsten electrode diameters (unit: A)

Electrode Diameter/mmAlternating CurrentDirect Current, Straight PolarityDirect Current, Reverse Polarity
Pure TungstenThoriated Tungsten, Ceriated TungstenTungstenThoriated Tungsten, Ceriated TungstenTungstenThoriated Tungsten, Ceriated Tungsten
0.52~152~152~202~20
115~5515~7010~7510~75
1.645~9060~12540 ~13060~15010~2010 ~20
265~12585~16075~180100~20015~2515~25
2.580~140120~210130~230170~25017~3017~30
3.2140 ~190150~250160 ~310225~33020~3520~35
4180~260240~350275~450350~48035~5035~50
5240~350330~460400~625500 ~ 67550~7050 ~70
6.3300~450430~575550~675650~95060~10065~100

3) Arc voltage.

Arc voltage is the main parameter determining the width of the weld bead. Lower arc voltages are used in TIG welding to achieve good molten pool protection. When welding under helium protection, due to the higher ionization of helium, the same arc length has a higher arc voltage compared to an argon arc.

The arc voltage is related to the angle of the tungsten electrode tip. The sharper the tip of the tungsten electrode, the higher the arc voltage, with a common range of 10~20V.

4) Tungsten electrode diameter and tip shape.

The choice of tungsten electrode diameter depends on the type, polarity, and size of the welding current to be used. At the same time, the sharpness of the tungsten electrode tip affects the depth and width of the weld. See Table 5-82 for tungsten electrode tip shapes and current ranges.

Table 5-82 Tungsten electrode tip shapes and current ranges

Tungsten Electrode Diameter /mmTip Diameter /mmTip Angle / (°)Direct Current Electrode Positive
Constant DC Current /APulse Current /A
10.125122~152~25
10.25205~305~60
1.60.5258~508~100
1.60.83010~7010~140
2.40.83512~9012~180
2.41.14515 ~15015~250
3.21.16020~20020~300
3.21.59025~25025~350

5) Welding speed.

The welding speed of TIG welding depends on the thickness of the workpiece and the welding current. Since the tungsten electrode can withstand lower currents, the welding speed is usually below 20m/h. The maximum welding speed of mechanized TIG welding can exceed 35m/h, but at this time, the effect of welding speed on the laminar shape of the shielding gas must be considered.

6) Nozzle diameter and gas flow.

The minimum gas flow required to effectively protect the welding area is related to the shape and size of the welding torch nozzle. The nozzle diameter depends on the thickness of the workpiece and the type of joint, and as the nozzle diameter increases, the gas flow needs to be correspondingly increased.

The nozzle diameter can be selected according to the following formula:

D=(2.5 ~3.5)d w

In the formula:

  • D—nozzle diameter or inner diameter, mm;
  • w tungsten electrode diameter, mm.

Once the nozzle diameter is determined, the argon flow rate can be calculated as follows:

Q=(0.8 ~1.2)D

Where:

  • Q—argon flow rate, L/min;
  • D—nozzle diameter.

When D is small, take the lower limit for Q; when D is large, take the upper limit for Q.

Generally, when the nozzle aperture is 8~12mm, the protective gas flow rate is 5~15L/min; when the nozzle diameter increases to 14~22mm, the gas flow rate is 10~20L/min. When welding thick plates of aluminum and aluminum alloys, the gas flow rate should reach 25~35L/min.

Additionally, the gas flow rate also depends on the welding environment. When welding in an area with air movement, the gas flow rate should be increased according to the air velocity, and the flow rate can also be selected through trial welding. When the flow rate is appropriate, the color of the weld surface can be used to identify.

The relationship between the color and protective effect of stainless steel welds is shown in Table 5-83.

Table 5-83 Relationship between the color and protective effect of stainless steel welds

Weld Seam ColorsSilver-white, golden-yellowBlueRed-grayGrayBlack
Protection EffectivenessExcellentGoodFairPoorWorst

The relationship between the color and protective effect of titanium and titanium alloy welds is shown in Table 5-84.

Table 5-84 Relationship between the color of titanium and titanium alloy welds and protection effect

Weld Seam ColorsSilver-WhiteGoldPurple-BlueBlue-GrayYellow-White
Protection EffectivenessExcellentGoodFairPoorWorst

See Table 5-85 for argon flow rate, nozzle aperture, and distance to the workpiece.

Table 5-85 Argon flow rate, nozzle aperture, and distance to the workpiece

Welding MethodsAppropriate Argon Flow Rate (L/min)Nozzle Diameter (mm)Distance Between Nozzle and Workpiece (mm)
Tungsten Inert Gas Welding (TIG)3~255 ~205 ~12
Metal Inert Gas Welding (MIG)10~50≤308~15

See Table 5-86 for the relationship between welding current, nozzle diameter, and gas flow rate.

Table 5-86 Relationship between welding current, nozzle diameter, and gas flow rate

Welding Current /ADC WeldingAC Welding
Nozzle Diameter /mmGas Flow Rate / (L/min)Nozzle Diameter /mmGas Flow Rate / (L/min)
10 ~1004~9.54 ~58~9.56~8
101 ~1504 ~9.54~79.5~117 ~10
151~2006~136~811 ~137 ~10
201~3008~138~913 ~ 168 ~15
301~50013 ~169~1216 ~198~15

Note: The maximum allowable welding current for metal nozzles is 500A, and for ceramic nozzles, it is 300A.

(2) Selection of automatic TIG welding parameters

Automatic TIG welding parameters include manual tungsten electrode argon arc welding parameters and wire feed speed. The wire feed speed should match the welding speed and welding current. The impact of TIG welding parameters on weld formation and welding quality is rarely independent in actual production, such as in manual TIG welding processes, only welding current and argon flow rate are specified.

During automatic TIG welding, the welding parameters that need to be controlled include welding current, arc voltage, welding speed, argon flow rate, wire diameter, and wire feed speed. In addition, when welding particularly reactive metals such as titanium, enhanced protection of the high-temperature zone is necessary, and strict protective measures must be taken.

(3) Typical TIG Welding Parameters

1) See Table 5-87 for manual TIG welding parameters for aluminum and aluminum alloys, stainless steel.

Table 5-87 Manual TIG Welding Parameters for Aluminum and Aluminum Alloys, Stainless Steel

MaterialPlate Thickness/mmGroove TypeNumber of Weld Layers (Front/Back)Tungsten Electrode Diameter/mmWelding Wire Diameter/mmPreheat Temperature/°CWelding Current/AArgon Flow Rate/(L/min)Nozzle Aperture/mm
Aluminum and Aluminum Alloys1Beveled EdgeFront 121.645 ~ 607~98
1.5Beveled or I-grooveFront 121.6~2.050~807~98
2I-grooveFront 12 ~32~2.590 ~1208 ~128~12
3Y-grooveFront 132~3150 ~1808~128~12
41~2/143180 ~20010~158~12
51~2/143~4180~24010~1510 ~12
61~2/154240~28016~2014 ~16
82 /154~5100260~32016~2014 ~16
103~4/1~254~5100 ~150280~34016~2014 ~16
123~4/1~25 ~64~5150~200300~36018~2216~20
143 ~4/1~25 ~65~6180~200340~38020~2416 ~20
164~5/1~265~6200 ~220340~38020~2416~20
184~5/1~265~6200~240360~40025~3016~20
204~5/1~265~6200~260360~40025~3020~22
16 ~20X-groove2~3/2~365~6200~260300~38025~3016~20
22~253 ~4/3 ~46 ~75~6200~260360~40030~3520~22
Stainless Steel1Butt Joint121.67~283~412~47
1.2Butt Joint121.6153~425
1.5Butt Joint121.65 ~193~48~32

① Welding speed, in cm/min.

2) See Table 5-88 for manual TIG welding parameters for carbon steel, low alloy steel.

Table 5-88 Manual TIG Welding Parameters for Carbon Steel, Low Alloy Steel

Weldment Thickness/mmWelding Current/AWire Diameter/mmWelding Speed/(mm/min)Gas Flow Rate/(L/min)
0.9100ф1.6300~3704~5
1.2100~125ф1.6300~4504~5
1.5100 ~140ф1.6300~4504~5
2.5140~180ф2 300 ~4505~6
3.2150 ~200ф3250~3005~6

3) See Table 5-89 for manual TIG welding parameters for copper and copper alloys.

Table 5-89 Manual TIG Welding Parameters for Copper and Copper Alloys

MaterialWeld Thickness/mmGroove TypeTungsten ElectrodeElectrode Diameter/mmFiller Wire Diameter/mmWelding Current/ANozzle Diameter/mmGas Flow Rate/(L/min)Preheat Temperature/°C
Copper<1.5Single-VThoriated2.42140-18086-8
2-3Single-VThoriated3.23160-2808-106-10
4-5V-grooveThoriated43-4250-35010-128-12100-150
6-10V-grooveThoriated54-5300-40010-1210-14300-500
Brass1.2Butt jointThoriated3.2160-18087
Tin Brass2Single-VThoriated3.23180-20087
Tin Phosphorus<1.6Single-VThoriated3.21.690-15010-128-12
Bronze1.6-3.2Single-VThoriated3.22-3100-22010-128-12
Aluminum Bronze<1.6Single-VCeriated1.61.625-8010-129-10
3.2Single-VCeriated3.22-3160-21010-1210-12
9.5V-grooveCeriated44210-33010-1212-13
Silicon Bronze1.6Single-VCeriated1.61.6100-12087
3.2Single-VThoriated2.42130-15087
6.4V-grooveThoriated3.23200-250109
9.5V-grooveThoriated3.23230-280109
Nickel Bronze<3.2Single-VThoriated3.22-3250-30012-1412-14
3.2-9.5V-grooveThoriated43280-32012-1412-14

4) Manual TIG welding of titanium and titanium alloys (DC positive connection, butt joint) welding parameters see Table 5-90.

Table 5-90 Titanium and titanium alloy manual TIG welding (DC positive connection, butt joint) welding parameters

Plate Thickness/mmBevel TypeNumber of Weld LayersTungsten Electrode Diameter/mmWire Diameter/mmWelding Current/AArgon Flow Rate/(L/min)Nozzle Diameter/mmNotes
Main NozzleDrag ShieldBack Side
0.5Single-V Bevel11.51.030 ~508~1014~166~810Butt joint gap 0.5mm, titanium may also not be added

Wire gap 1.0mm
112.01.0~2.040~608~1014~166~810
1.512.01.0~2.060~8010~1214~168~1010 ~12
212.0~3.01.0~2.080~11012~1416~2010~1212 ~14
2.512.0~3.02.0110~12012~1416~2010~1212 ~14
3Single-Y Bevel1 ~23.02.0~3.0120~14012~1416~2010~1214 ~18Bevel gap 2~3mm, blunt edge 0.5mm

The back of the weld is lined with a steel backing plate

Bevel angle 60°~65°
3.51~23.0~4.02.0~3.0120~14012~1416~2010~1214 ~18
423.0~4.02.0~3.0130~15014~1620~2512~1418 ~20
423.0~4.02.0~3.020014~1620~2512~1418 ~20
52~34.03.0130~15014~1620~2512~1418~20
62~34.03.0~4.0140~18014~1625~2812~1418~20
72~34.03.0~4.0140~18014~1625~2812~1420~22
83 ~44.03.0~4.0140~18014~1625~2812~1420~22
10Double-Y Bevel4~64.03.0~4.0160~20014~1625~2812~1420~22Bevel angle 60°, blunt edge 1mm

Bevel angle 55°, blunt edge 1.5-2.0mm

Bevel angle 55°, blunt edge 1.5~2.0mm, gap 1.5mm
136~84.03.0~4.0220~24014~1625~2812~1420~22
20124.04.0200~24012~142010~1218
2264.04.0~5.0230~25015~1818~2018~2020
2515~164.03.0~4.0200~22016~1826~3020~2622
3017~184.03.0~4.0200~22016~1826~3020~2622

5) See Table 5-91 for automated TIG welding parameters for aluminum and aluminum alloys.

Table 5-91 Automated TIG welding parameters for aluminum and aluminum alloys

MaterialPlate Thickness/mmNumber of Weld LayersTungsten Electrode Diameter/mmWire Diameter/mmWelding Current/AArgon Flow Rate/(L/min)Nozzle Aperture/mmWire Feed Speed/(cm/min)
Aluminum and aluminum alloys111.5 ~21.6120 ~1605~68~10
2131.6~2180 ~22012 ~148 ~10108 ~117
31~2 42220~24014 ~1810 ~14108~117
41~252~3240~28014 ~1810 ~14117 ~ 125
5252~3280 ~32016 ~ 2012 ~16117 ~ 125
6~82~3 5~63280 ~32018~2414 ~18125~133
8~122~363~4300 ~34018~2414 ~18133 ~142
Stainless steel1.5121.6125 ~1308~10260
2131.6138~1426~8260

6) See Table 5-92 for automated TIG welding parameters for titanium and titanium alloys (DC positive, butt joint).

Table 5-92 Automated TIG welding parameters for titanium and titanium alloys (DC positive, butt joint)

Plate Thickness / mmBevel TypeNumber of Welding LayersDimensions of the Backing Strip in the Forming GrooveTungsten Electrode Diameter / mmWire Diameter / mmWelding Current / AArc Voltage / VWelding Speed / (cm/min)Argon Flow Rate / (L/min)
Width / mmDepth / mmMain NozzleTrailing ShieldBack Side
1I-grove150.51.61.270~10012~1530~378~1012~146~8
1.2I-grove150.721.2100~12012~1530~378~1012~146~8
1.5I-grove150.721.2~1.6120~14014~1637~4010~1214~168~10
2I-grove1612.51.6~2.0140~16014~1633~3712~1414~1610~12
3I-grove171.132.0~3.0200~24014~1632~3512~1416~1810~12
4Single Bevel with 2mm Gap281.323200~26014~1632~3314~1618~2012~14
6Y-Groove 60°343240~28014~1830~3714~1620~2414~16
10Y-Groove 60°343200~26014~1815~2014~1618~2012~14
13Double Y-Groove 60°443220~26014~1833~4214~1618~2012~14

7) See Table 5-93 for TIG welding parameters for austenitic stainless steel pipes (suspended welding).

Table 5-93 TIG welding parameters for austenitic stainless steel pipes (suspended welding)

Thickness/mmBevel ShapeWelding Current/AWelding Speed/(mm/min)Notes
1.5100 ~110460 ~480Used for overhead welding of round and square tubes, with argon gas protection inside the tube to shield the back of the weld.
2120 ~130400 ~410
3190~200300 ~310
Note: Connect to positive DC.

8) See Table 5-94 for the root pass welding parameters of multi-layer welding of stainless steel thick-walled pipes using IG welding.

Table 5-94 Welding parameters for the root pass of multi-layer TIG welding of stainless steel thick-walled pipes

Wire Diameter / mmTungsten Electrode Diameter / mmCurrent PolarityWelding Current / AArc Voltage / VWelding Speed / (cm/min)Weaving MethodShielding Gas
TypesFlow Rate / (L/min)
2.0(1.6)1.6Direct current50~1309~164~14Transverse OscillationArgon purity (volume fraction) greater than 99.9%8~15
2.42.4Tangent
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