How to Select a Shielding Gas

There are a variety of gas blends that can be chosen for MIG, TIG, or Flux Cored Welding applications.

To make a well-informed selection, a number of approaches can be used, but all are based on a basic understanding of the requirements for the finished weldment.

Questions that need to be answered first may include:

How important is weld appearance?
Is spatter near the weld area a concern?
Is deep penetration required or should penetration be limited to minimize burn- through of the joint?
Is there a concern about the amount of welding fume generated and should it be reduced?

Depending on the requirements for the finished weld, a number of other questions might be asked as well.

To select a gas blend, the following four-step process can be followed:

Consider the material type – carbon steel, stainless steel, aluminum, nickel alloys, copper alloys or other non-ferrous materials
Know the base material thickness and understand its condition – clean, oily, scaled, etc.
Determine the welding position as this will impact the type of process/metal transfer you plan to utilize. Process selection may be further impacted by the availability of equipment, operator skills and desired productivity.
Review the requirements of the job. Consult the selection chart to determine the gas blend that provides the best performance for the application at hand.

Simple, isn’t it? This selection process should help you make a good first attempt at matching the best shielding gas to your application. Refinement may be needed depending on the specific equipment and skills available. Other needs may have to be identified as work progresses. For further information on Linde's Star™ family of shielding gases, please consult your local Linde representative.

Gas Metal Arc Welding (GMAW or MIG)

Material Type	Thickness	Condition	Transfer Mode	Shielding Gas Recommended	Travel Speed	Weld Appearance	Penetration	Spatter Reduction	Fume Reduction
Mild Steel	22 to 10 ga (0.9-2.5mm)	clean	short-circuit	StarGold C-25	G	E	E	E	G
Mild Steel	22 to 10 ga (0.9-2.5mm)	minor scale/oil	short-circuit	StarGold C-25, Stargon	G	E	E	G	G
Mild Steel	22 to 10 ga (0.9-2.5mm)	clean	pulsed	MIG Mix Gold, StarGold C-25	E	E	G	E	E
Mild Steel	1/8" - 1/2" (3.2-12.7mm)	clean	short & spray	Stargon, MIG Mix Gold, StarGold C-10 to C-15	E	E	G	G	E
Mild Steel	1/8" - 1/2" (3.2-12.7mm)	minor scale/oil	spray	StarGold C-10 to C-15, HeliStar CS	G	G	G	E	G
Mild Steel	1/8" - 1/2" (3.2-12.7mm)	clean	pulsed	StarGold C-5, MIG Mix Gold	E	E	G	E	E
Mild Steel	1/8" - 1/2" (3.2-12.7mm)	clean	spray & pulsed	StarGold O-5	E	G	F	E	E
Mild Steel	Over 1/2" (12.7mm)	clean	spray & pulsed	StarGold C-10* to C-15	E	G	G	E	E
Mild Steel	Over 1/2" (12.7mm)	light scale/oil	spray & pulsed	HeliStar CS*	E	E	E	G	G
Mild Steel (coated)	22-16 ga (0.9-1.6mm)	galvanized	short arc	StarGold C-25**	G	G	G	F	P
Mild Steel (coated)	22-16 ga (0.9-1.6mm)	galvanized	spray* Si-bronze only	Argon	E	E	F	E	F
Stainless Steel	16-10 ga (1.6-2.5mm)	clean	short-circuit	HeliStar A-1025, HeliStar SS	G	G	E	G	F
Stainless Steel	11 ga - 1/2" (2.3-12.7mm)	clean	spray	HeliStar SS, StarGold C-2, C-5	E	E	G	G	G
Stainless Steel	11 ga - 1/2" (2.3-12.7mm)	clean	spray & pulsed	StarGold O-2	E	F	F	G	G
Stainless Steel	16 ga - 1/2" (1.6-12.7mm)	clean	pulsed	HeliStar SS	G	E	G	E	G
Low Alloy Steel	16 ga - 1/2" (1.6-12.7mm)	clean	short-circuit	Stargon, MIG Mix Gold	G	G	G	G	G
Low Alloy Steel	16 ga - 1/2" (1.6-12.7mm)	clean	spray & pulsed	Stargon, MIG Mix Gold, StarGold C-5 to C-10	E	E	E	E	G
Low Alloy Steel	16 ga - 1/2" (1.6-12.7mm)	clean	pulsed	StarGold O-5	G	G	F	E	E
Aluminum Alloys	All Thicknesses	clean	pulsed	Argon	G	G	F	E	G
Aluminum Alloys	All Thicknesses	clean	spray	Argon, HeliStar A-25, A-50, A-75	E	E	E	G	F
Copper Alloys	All Thicknesses	clean	pulsed & spray	Argon	G	F	F	G	E
Copper Alloys	All Thicknesses	clean	pulsed & spray	HeliStar A-25, A-50	E	G	G	G	G
Nickel Alloys	All Thicknesses	clean	pulsed, spray mechanized	HeliStar A-25, A-50, SS	E	E	G	G	G

Performance Measures: E=Excellent, F=Fair, G=Good, P=Poor

* 0.045 to 0.063 wire diameter recommended

** ER70S3 wire recommended

Flux-Cored & Metal-Cored Arc Welding

Material Type	Thickness	Condition	Transfer Mode	Shielding Gas Recommended	Travel Speed	Deposition Efficiency	Weld Appearance	Penetration	Spatter Reduction	Fume Reduction*
Mild Steel	14 - 10 ga (1.8-2.5mm)	clean	globular	StarGold C-25, C-40, C-50	E	G	E	G	G	G
Mild Steel	14 - 10 ga (1.8-2.5mm)	some oxide	globular	StarGold C-25, C-40, C-50	G	G	G	G	G	F
Mild Steel	1/4" - 1/2" (6.4-12.7mm)	clean	globular	StarGold C-25, C-40, C-50	E	G	E	G	G	G
Mild Steel	1/4" - 1/2" (6.4-12.7mm)	clean	globular	CO₂	G	G	G	E	F	P
Mild Steel	1/4" - 1/2" (6.4-12.7mm)	clean	spray**	StarGold C-10 to C-15, MIG Mix Gold	E	E	E	F	E	E
Mild Steel	1/4" - 1/2" (6.4-12.7mm)	some oxide	globular	StarGold C-25, C-50	E	G	G	G	G	G
Mild Steel	1/4" - 1/2" (6.4-12.7mm)	some oxide	globular	CO₂	G	F	G	E	F	P
Mild Steel	1/4" - 1/2" (6.4-12.7mm)	some oxide	spray**	StarGold C-10 to C-15, MIG Mix Gold	E	E	G	F	E	E
Mild Steel	over 1/2" (12.7mm)	clean	globular	StarGold C-25, C-50	G	G	E	G	G	G
Mild Steel	over 1/2" (12.7mm)	clean	globular	CO₂	G	F	G	E	F	P
Mild Steel	over 1/2" (12.7mm)	clean	spray**	StarGold C-10 to C-15, MIG Mix Gold	G	E	E	F	E	E
Mild Steel	over 1/2" (12.7mm)	some oxide	globular	StarGold C-25, C-50	F	F	G	G	F	F
Mild Steel	over 1/2" (12.7mm)	some oxide	globular	CO₂	F	F	F	E	F	P
Mild Steel	over 1/2" (12.7mm)	some oxide	spray**	StarGold C-10 to C-15, MIG Mix Gold	F	E	G	F	E	G

Performance Measures: E=Excellent, F=Fair, G=Good, P=Poor

* Welding fume varies with wire chemistry selected.

** Metal-cored wire recommended.

Gas Tungsten Arc Welding (GTAW or TIG)

Material Type	Condition	Transfer Mode	Shielding Gas Recommended	Travel Speed	Penetration	Color Match	Fume Reduction	Arc Stability
Mild Steel	clean	manual	Argon	F	G	G	E	E
Stainless Steel	clean	manual	Argon	P	G	F	E	E
Stainless Steel	clean	mechanized	HeliStar A-25	F	G	G	E	G
Austentic SS (300 Series)	slight oxide	manual	HydroStar H-2, H-5	F	G	E	E	G
Austentic SS (300 Series)	slight oxide	mechanized	HydroStar H-5, H-10	G	G	E	E	G
Aluminum Alloys	clean	manual	Argon, HeliStar A-75	F	E	E	E	G
Aluminum Alloys	clean	mechanized	HeliStar A-25, A-50	G	E	E	E	F
Copper Alloys	clean	manual	Argon	F	F	G	E	E
Copper Alloys	clean	mechanized	HeliStar A-25, A-50	G	G	G	E	G
Nickel	clean	manual	Argon	P	G	F	E	E

Performance Measures: E=Excellent, F=Fair, G=Good, P=Poor

Note: Thickness foil to 1/8". Base metal thickness greater than 1/8" can be more effectively joined with MIG.