CO2, MAG & MIG Welding: Optimal Current, Wire Diameter & Plate Thickness

1. The relationship between the commonly used steel manual arc welding current and the diameter of the welding rod, and the applicable range of plate thickness. Types of Steel Types of Welding Rods Welding Rod Model Diameter of the welding rod Types of Power Supply Polarity φ2.5 φ3.2 φ4 φ5 φ6 Carbon Steel Low Alloy […]

CO2, MAG & MIG Welding Optimal Current, Wire Diameter & Plate Thickness

Table Of Contents

1. The relationship between the commonly used steel manual arc welding current and the diameter of the welding rod, and the applicable range of plate thickness.

Types of SteelTypes of Welding RodsWelding Rod ModelDiameter of the welding rodTypes of Power Supply Polarity
Carbon Steel

Low Alloy Steel

Acid Welding RodsE4303(J422)

30-70A60-140A80-220A140-260A180-320ADual-use for AC and DC
Alkali Welding RodsE5015(J507)

30-60A50-120A80-180A120-220A160-260ADirect Current Reversal
Applicable Plate Thickness(mm)2~64~126~20010~20020~200
Carbon Steel

General Low Carbon Steel

Large Diameter Pipe

(Vertical Down Welding)

(Root Welding)
40-120A50-140A90-200A120-250ADirect Current Connection

60-140A80-200A100-240A140-280ADirect Current Reversal
Applicable Wall Thickness(mm)4~66~188~228~30
Austenitic Stainless Steel

Acid Welding RodsAustenite 102

Austenite 312
25-65A40-120A70-140A90-180ADirect Current Reversal
Alkali Welding RodsAustenite 137

Austenite 317
25-55A40-110A70-120A90-150ADirect Current Reversal
Applicable Plate Thickness(mm)2~64~106~4010~60
Copper & Copper Alloys

(Pure Copper)
Alkali Welding RodsT10780-140A100-180ADirect Current Reversal
Applicable Plate Thickness(mm)4~106~20


  1. Low-alloy steels include heat-resistant steels and low-temperature steels (such as 15CrMo, 16MnDR).
  2. For thicknesses greater than 4mm, a bevel should be opened, adopting a multi-layer, multi-pass welding process.
  3. Low alloy steel plates thicker than 28mm should undergo a preheating process to prevent the formation of cold cracks.
  4. The purple copper plate must be preheated to 400~600℃ before welding.
  5. For direct current, the workpiece is connected to the positive terminal, and for reverse polarity, the workpiece is connected to the negative terminal.
  6. For root welding, a cellulose welding rod is used with direct positive connection, while for hot welding, filler welding, and cover welding, a direct reverse connection is used.
  7. The general welding speed range for manual arc welding is 2~15cm/min.

2. The relationship between the commonly used carbon arc gouging current and the carbon rod, as well as the applicable range for plate thickness.

Type of Carbon RodRound BarDiameter of the Carbon Rodφ
Applicable Current(A)150-180150-200250-250180-300200-350250-400350-450350-500
Applicable Plate Thickness(mm)4~64–84~105~106~128~2010~3012~50
Flat BarSpecifications(mm)3×124×84×125×105×125×155×185×20
Applicable Current(A)180-220200-260220-280240-300250-380280-450300-500350-600
Applicable Plate Thickness(mm)4~86~106~128~128~168~2010~30≥20


  1. Carbon arc gouging is used for the gouging of carbon steel, common low-alloy steel (such as 16Mn, 15MnV, etc.), stainless steel, heat-resistant steel, and low-temperature steel. It is a process for beveling, cleaning the back of welds, and removing welding defects.
  2. Carbon arc gouging should use a direct current reverse polarity power supply (the workpiece is connected to the negative).
  3. The general planing speed ranges from 500 to 1200 cm/min.
  4. Generally, for low-alloy steel plates with a thickness of ≥30mm, a preheating process must be adopted before planing to prevent the steel from forming hardened structures and developing cold cracks.

3. The relationship between the welding current and tungsten electrode diameter in commonly used material manual tungsten inert gas (TIG) arc welding, and the applicable range of plate thickness.

Material CategoryPower Supply
Type of Polarity
Tungsten electrode diameterφ1.6φ2.0φ2.5φ3.2φ4φ5
Current ProfileConstant flowPulseConstant flowPulseConstant flowPulseConstant flowPulseConstant flowPulseConstant flowPulse
Carbon Steel and Low Alloy SteelDirect Current ConnectionPermissible Current (A)4-504-1008-908-18015-15015-25020-20020-30030-25030-35060-50060-650
Applicable Sheet Thickness(mm)0.3-2.50.3-2.50.5-40.5-41–61–82–122–144–224–266–306–30
Stainless SteelDirect Current Forward ConnectionPermitted Current(A)4-504-1008-908-18015-15015-25020-20020-30030-25030-35060-50060-650
Applicable Plate Thickness(mm)0.3-20.1-20.5-30.3-41–60.5-62–102–124–204–246–306–30
Aluminum and Aluminum Alloys

Magnesium and Magnesium Alloys
Alternating Current
Permissible Current(A)20-10010-13050-15030-18050-20050-25080-22080-300120-260120-360180-400180-420
Applicable Sheet Thickness(mm)0.5-20.5-30.5-40.5-62–62–104–124–166–186–208–208–24
Copper and Copper Alloys

(Pure Copper)
Direct Current Forward Connection
Permissible Current(A)8-908-18015-15015-25020-22020-32030-28030-38060-50060-650
Applicable Sheet Thickness(mm)0.3-0.50.1-0.50.5-20.3-21–31–42–41–54–204–20
Titanium and Titanium AlloysDirect Current Forward ConnectionPermissible Current(A)4-504-1008-908-18015-15015-25020-20020-30030-25030-35060-45060-550
Applicable Sheet Thickness(mm)0.5-20.3-21–30.5-42–41–42–62–84–204–226–306–30


  1. The types of tungsten electrodes are thoriated and ceriated with a tip diameter of φ0.5, at an angle of 30 degrees. For AC welding, the tip diameter of the tungsten electrode is φ1.5, at an angle of 90 degrees.
  2. For sheet metal thickness >4mm, a bevel should be opened, adopting multi-layer and multi-pass welding process. Preheating process should be applied for aluminum sheets with thickness >8mm and copper sheets with thickness >4mm. The welding speed for thin sheets is 15~55cm/min, and the automatic welding speed is 15-100cm/min.
  3. TIG welding is suitable for flat, vertical, horizontal, and overhead all-position welding.

4. The relationship between CO2/MAG/MIG welding current and wire diameter, as well as the applicable range for sheet thickness.

Material CategoryType of GasTungsten Electrode Diameterφ0.8φ1.0φ1.2φ1.6
Droplet transition formCO2MAGCO2MAGCO2MAGCO2MAG
Carbon Steel

Low Alloy Steel
1. CO2
2. 80%Ar+20%CO2
3. 80%Ar+15%CO2+5%O2
Welding Current Range (A)50-15030-15070-18050-30080-35060-440140-500120-550
Arc Voltage Range (V)18-2217-2218-2218-3219-3419-3520-3819-40
Applicable Sheet Thickness (mm)0.9-40.4-62–122–202–2520-504-804-100
Austenitic Stainless Steel1. 95%Ar+5%CO2
2. 98%Ar+2%O2
Welding Current Range (A)30-12050-30060-440120-500
Arc Voltage Range (V)17-2418-3419-3524-40
Applicable Plate Thickness (mm)0.4-61–122–204-50
Ar(99.9%)Welding Current Range (A)Short circuitJettingShort circuitJetting
Aluminum and Aluminum Alloys100-200220-400140-220240-500
Arc Voltage Range (V)16-2222-3417-2224-36
Applicable Plate Thickness (mm)2–242–304-506-80


  1. Short circuit transition is applicable for flat, horizontal, vertical, and overhead welding positions; spray transition (droplet transition) is suitable for flat welding and fillet welding.
  2. Low-alloy steel and austenitic stainless steel utilize flux-cored welding wire, resulting in good internal and external weld quality.
  3. For plates thicker than 6mm, bevel edge welding is applied, utilizing multi-layer and multi-pass welding techniques. The maximum weldable thickness is 100mm.
  4. Pre-heating techniques should be applied to low alloy steel plates with a thickness of 28mm or more, and for aluminum and aluminum alloy plates with a thickness of 34mm or more.
  5. The general welding speed range for Gas Metal Arc Welding is 12-90cm/min.:12-90cm/min .

5. Recommended Method for Striking an Arc and Adjusting Thrust Current in a Direct Current Arc Welding Machine.

Welding Machine ModelType of Welding RodWelding current rangeArcing current
Thrust Current
Process CharacteristicsWeld seam appearance
Ordinary Acidic Welding RodI≤50A1/31/3Arc initiation is easy, no stickingGood, aesthetically pleasing.
I>50AUnaddedUnaddedThe arc is gentle and very stable, no sticking, minimal spatterAesthetically pleasing, no jagged edges.
Low Hydrogen Alkaline Welding RodI≤70A1/21/3Arc initiation is easy, no stickingGood, aesthetically pleasing.
I>70AUnaddedUnaddedThe arc is gentle, no sticking, minimal spatterAesthetically pleasing, no jagged edges.
AT400Cellulose Welding Rod20-400A1/21/3-1/2Arc initiation is easy, no sticking, no arc interruption, high arc stiffness, high blow force, slight spatterGood.


  1. The SS300, SS400, SS630 welding machines, and the AT315 welding machine do not have an arc initiation current knob.
  2. The TR315 tungsten electrode argon arc welding machine, when used for manual arc welding, allows for the adjustment of arc initiation and thrust current.
  3. The numerical value of the arc thrust current (1/2, 1/3) indicates the clockwise rotation position of the knob.
  4. The thrust current regulation is too high, causing the arc noise to be slightly louder and the spatter of molten droplets to increase. It can be adjusted to zero when the rod is not sticking.

6. The actual load sustainability of various arc welding processes under different operating modes.

Process MethodMode of OperationWelding Operation MethodsContinuous Load Factor
Gas Tungsten Arc Welding

Semi-automatic Hand WeldingShort weld seams, intermittent operations.40%
Small batch workpieces, continuous operation.60%
Large-scale, continuous operation of workpieces.80%
Fully AutomatedSmall batch workpieces, continuous operation.80%
Large-scale, continuous operation of workpieces.100%
Non-melting electrode inert gas shielded welding

Manual Tungsten Inert Gas WeldingShort weld seam, intermittent operation.20%
Long welding seams, small batches, continuous operations.40%
Long weld seams, large quantities, continuous operation.60%
Fully AutomatedLong weld seam, small batch, continuous operation.60%
Long weld seams, large quantities, continuous operation.80%
Manual Arc Welding

Manual WeldingShort weld seams, intermittent operation.20%
Small batch workpieces, continuous operation.40%
Large-scale, continuous operation of workpieces.60%
Gravity WeldingSmall batch workpieces, continuous operation.60%
Large-scale, continuous operation of workpieces.80%
Carbon Arc GougingHandheld Pneumatic PlanerShort weld seam root cleaning, intermittent operation.40%
Long weld seam cleaning, continuous operation.60%
Automatic Air PlanerContinuous air planing of long weld groove.80%


  1. The selection of a welding machine is based on the thickness of the welded part, the welding position, and the diameter of the welding material, to choose the maximum actual welding current value.
    Confirm the operation method and estimate the actual load duration. When the actual load duration exceeds the rated load duration, the actual welding current should be lower than the rated current of the welding machine for normal use, to avoid damage to the welding machine.
  2. For a CO2 welding machine rated at 200KR, the rated current is 200A when the duty cycle is 60%. When used for small batch continuous semi-automatic welding, the actual duty cycle is 60%, with a maximum welding current of 200A. During automated large batch continuous operations, the maximum allowable current value is 155A, which still satisfies the welding production of workpieces with a thickness of 6mm.
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Founder of MachineMFG

As the founder of MachineMFG, I have dedicated over a decade of my career to the metalworking industry. My extensive experience has allowed me to become an expert in the fields of sheet metal fabrication, machining, mechanical engineering, and machine tools for metals. I am constantly thinking, reading, and writing about these subjects, constantly striving to stay at the forefront of my field. Let my knowledge and expertise be an asset to your business.

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