Tig Welding 3/8 Inch (0.375″) Aluminum

Aluminum is a non-ferrous silvery white metal with 1220°F melting point. Aluminum is a very popular metal because of its lightweight feature. From frames of bike to trailers of truck, aluminum is used everywhere.

Welding an aluminum plate is possible and you can do that with Tig, Mig or plasma welding. Tig welding with DC current flow is popular while it comes to welding thicker aluminum.

Today we will cover the machine settings for Tig welding 3/8″aluminum plate. Lets start-

Joints for 3/8 inch aluminum

We all know that there are multiple types of joint in welding. We will use discuss Butt, Lap, Corner & fillet joint in this case & also will find the machine settings.

Butt Joint 3/8″Aluminum

Butt joint is normal joint types where a piece of metal is welded to other placing them side by side.

butt joint 0.375 inch plate
Tungsten ElectrodeYou may use 3.32 mm diameter or 1/8 inch diameter tungsten electrode. Use 2% thoriated electrode for better penetration.
Torch CupYou may use ceramic cup for less than 200amp but need to use water cooled torch for more than 250amps machine
Filler Metal4043 filler metal of 1/8″ (3.2mm) is ok for the project
PolarityFor thicker metal you should use DC polarity
AmperageRanging from 110 to 260amp. It depends on pass you are employing. For root pass you must use 3/32 filler @ 220-260amp and for cover pass 1/8 @ 110 to 130amp.
GasFor thicker metal you may use Argon and for better result use argon & helium mix for deep penetration. Gas flow should be 29cft.
Above settings are approximated. Can differ depending on application and machine catalogue.

Lap Joint 3/8″ Aluminum

Lap joint is another type of joint where two pieces of metal are welded overlapping each other.

Lap Joint 0.375 aluminum
MachineUse high amperage machine more than 125amps.
Tungsten ElectrodeUse 1/8inch 2% ceriated tungsten
Torch CupUse 5/8″ water cooled torch cup
AmperageRanging from 230 to 250amp
Gas & Flow RateUse argon/helium mixture at 29cft for better weld
Other settings are similar to butt joint

Corner Joint

Corner joint is welding two pieces corner side by side as shown in the picture bellow

Corner Joint 0.375 aluminum
AmperageRanging from 130 to 260 in 3 passes. 1st root pass @230-260amp, 2nd cover(1)@ 130-160amp and 3rd cover(2)@130-160amp.
Tungsten ElectrodeSame as butt and lap joint requirements
Gas & flow rateSame as lap joint requirement
Filler DiameterSame as butt joint requirement

Fillet Joint

Fillet joint is welding two pieces of metal one over another perpendicularly or in 90 degree angle.

fillet joint 0.375 aluminum
AmperageRanging from 240 to 270amp
Torch CupSame as butt and lap joint requirement
Tungsten ElectrodeSame as but and lap joint
Gas & Flow RateSame as butt and lap joint
Other requirements are same as butt and lap

Check Out Some 6061 Aluminum Plates For Projects

Important Notes

For Tig welding thicker aluminum you must pre-heat the aluminum and raise the temperature to at least 130°F. Doing so would make the aluminum ready for perfect welding and the penetration would be better.

Tig welding 3/8inch aluminum requires you to travel the torch slowly with steady hands. The benefit of tig welding 3/8inch aluminum is it produces less spatter and slags than other welding methods.


It is not that difficult to weld thicker metal with tig welder if the correct settings are followed. Besides, if you have prior experience then it would be a piece of cake to tig weld aluminum. However, take necessary precautions before starting the welding and make sure you wear helmet and gloves.


  • James Smith

    This is James Smith, a Hobbyist welder, welding since my 15th birthday. My father was a professional welding mechanic at a garage and used to take me to garage. My love for welding started then and I learnt basics from my father. At my 15th, my father gifted me a stick welder and my journey to become a welder began. Gradually I accustomed to welding and mastered at tig welding.

Leave a Comment