What TIG Filler Rod Should I Use for What?
A beginner's guide to choosing filler metal without getting overwhelmed.
The 3 most commonly welded metals are
- Carbon Steels
- Stainless Steels
- Aluminum Alloys
Within these 3 different metal categories there are many different alloys and grades.
There are also many other metals that are tig welded like titanium and nickel alloys but the top 3 listed above are the most common.
Washington alloys and few other sites have FREE filler metal selection charts that guide you on which filler rod works best for certain applications.
For TIG welding Aluminum, use this:
ALUMINUM FILLER METAL SELECTION GUIDE
For TIG welding Stainless, use this:
STAINLESS STEEL FILLER METAL SELECTION GUIDE
For TIG welding Carbon steel: use ER70S-2 or ER70S-6
You could stop right here and you would have enough information to get started.
But lets keep going…
ER70S-2 or ER70S-6 are the 2 main tig rods for tig welding plain carbon steel and also chromoly.
I usually prefer ER70S-6 filler rod for TIG welding carbon steel.
ER70S-2 is usually a bit easier to find at local welding supply stores but both rods are easy enough to order online. Weldmonger.com has both ER70S-2 or ER70S-6 in 1 lb tubes.
If you are just getting started TIG welding, you might not even see any difference in ER70S-2 and ER70S-6 so don’t get all hung up on which one to get.
Stainless steel: ER308L, ER309L, and ER316L.
There are several different grades of stainless steels but the most common ones are the 300 series:
I have found this stainless steel filler metal selection chart from Washington alloys to be helpful
301 - work hardened grade that comes in 1/4 hard, half hard, full hard. Less corrosion resistance than most other 300 series. loses some strength and corrosion resistance in heat affected zone when welded. Commonly Tig welded using 308L, 309, or 312 filler rod. Best choice is usually 308L rod.
303 - free machining grade usually bar stock or round stock. Free machining stainless usually comes in bar stock or round and contains sulphur. It’s not really recommended for welding for anything structural but can be welded for light duty applications using 308L, 309, or 312 filler rod.
304L - This is the most commonly welded grade of stainless by far. 308L is the best choice for a filler rod.
316L- is specified for high corrosion resistance in marine environments as well as other applications where corrosion resistance is the main reason for choosing a stainless steel.
316L is the main filler rod used to maintain corrosion resistance along with controlled heat input and post weld treatment like passivation or electropolishing with a machine like the EasyKleen.
321 - is known as a stabilized stainless and is used mostly in motorsports and aerospace applications due to its resistance to carbide precipitation. It is commonly welded using 347 filler rod.
There are many other grades of stainless steels but the ones listed above are by fare the most common.
Aluminum: just like other metals, there are numerous grades of aluminum alloys.
Fortunately, there are some pretty good filler metal charts for aluminum. This aluminum filler metal chart from Washington alloy is extremely helpful in selecting the best filler rod for a specific aluminum alloy and also for joining aluminum alloys of different compositions.
ER4043 and ER5356 are by far the most commonly used filler metals because they can be used on so many different aluminum alloys.
Applications for ER4043 TIG Filler Rod
ER4043 is one of the most commonly used aluminum TIG filler rods. It contains approximately 5% silicon and is an excellent choice for many general-purpose aluminum welding applications.
The silicon helps the molten filler metal flow smoothly, improves wetting, and reduces the tendency for weld cracking in many aluminum alloys.
1. Common applications for 4043 TIG rod
|
Application |
Why 4043 works well |
|
6061 aluminum tubing |
Good crack resistance and smooth weld appearance |
|
6063 aluminum extrusions |
Excellent for frames, brackets, and fabricated assemblies |
|
3003 aluminum sheet |
Good weldability for sheet metal projects |
|
Cast aluminum repairs |
Often suitable for weldable aluminum-silicon castings |
|
Aluminum tanks |
Useful on compatible alloys when service requirements permit |
|
Aluminum brackets |
Good for general-purpose fabrication |
|
Aluminum automotive components |
Useful for certain castings, housings, and fabricated parts |
|
6061 aluminum plate |
Good for lap joints, tee joints, and butt joints |
2. Aluminum alloys commonly welded with 4043
- 6061: One of the most common applications. Frequently used for tubing, plate, and structural fabrications.
- 6063: Common for extrusions, frames, and architectural aluminum.
- 3003: Used for sheet metal, tanks, and general fabrication.
- 5052: Sometimes used with 4043, but 5356 or 5554 may be preferable depending on service conditions and specifications.
- 356.0 and A356.0 cast aluminum: Common applications for 4043, provided the casting is weldable and properly prepared.
3. When 4043 is not the best choice
- Anodized aluminum: 4043 welds typically turn dark gray after anodizing. 5356 generally provides a better color match.
- Higher-strength fillet welds: 5356 or 4943 may provide better strength.
- High-magnesium alloys: Avoid 4043 on alloys such as 5083 and 5086.
- Applications requiring high ductility or toughness: 5356 is often a better choice.
These distinctions are supported by Hobart’s aluminum filler selection guide.
There are hundreds of different aluminum alloys.
So then how do you know how to select the right filler metal for each alloy and also different combinations?
Fortunately, there are Aluminum Filler metal charts that can guide you to the right tig rod choice.
3 Aluminum Filler Rod chart resources that can be easily found and downloaded for free are:
https://www.hobartbrothers.com/downloads/aluminum_selecti_1lOo.pdf
https://www.washingtonalloy.com/wp-content/uploads/2020/12/aluminum-selection-chart-.pdf
With any filler metal selection chart, it is important to read all the footnotes. ( a good practice with all technical documents, codes, and specifications)
TIG rods don't always match the base metal exactly.
TIG filler metal is often designed using a slightly different chemistry than the base metal they are intended for. Small tweaks in the chemistry can make certain TIG rods less crack sensitive than an exact chemistry match would be.
A great example of this that you will notice on an aluminum filler metal chart is 6061.
6061 is almost never welded using matching 6061 filler metal. f
There are several aluminum filler rods that can be used to weld 6061.
4043 and 5356 are the main two choices. But the footnotes instruct you to use 4043 if service temperature is above 150F. and 5356 if the part will be anodized after welding.
Sometimes filler metal is determined by a welding procedure or other document.
But other times filler metal selection is a matter of personal preference.
The aluminum filler metal charts listed above can be very helpful
HERE’S A PRACTICAL, SHOP-FLOOR WAY TO LOOK AT ALUMINUM FILLER METALS — NOT METALLURGY THEORY, JUST WHAT YOU’D REALISTICALLY REACH FOR AND WHY.
Aluminum TIG Filler Metals – Practical Applications
ER4043 – The “Default” Aluminum Filler
Personality: Flows easy, forgiving, smooth puddle.
Practical Uses: can be used for 6061, 3003, as well as common grades of cast aluminum and…
- General aluminum repairs
- Thin sheet metal
- Automotive parts
- Some Motorcycle and bicycle components
- Small brackets and tabs
- Practice beads and training
- Cast aluminum repairs (most of the time)
Why You’d Choose It
- Very smooth flow
- Less crack-prone than many rods
- Beginner-friendly
- Good for unknown alloys
- Produces shiny, attractive beads
Downsides
- Not as strong as 5356
- Not ideal for anodizing color match
- Slightly lower ductility in some structural uses
- Can result in a grainy looking bead if cooling rate is too slow
Rule of thumb:
If you don’t know what rod to grab, 4043 is the safest starting point.
ER5356 – The “Stronger Structural” Filler
Personality: Stiffer puddle, stronger weld, more resistant to saltwater.
Practical Uses
- Boat and marine components
- Trailer frames
- Structural brackets
- Handrails and railings
- Load-bearing aluminum parts
- Outdoor equipment
Why You’d Choose 5356
- Higher tensile strength than 4043
- Better corrosion resistance in marine environments
- Better color match if anodizing
- Good combination of ductility and strength for many structural applications
Downsides
- Doesn’t flow as smoothly as 4043
- Slightly harder for beginners
- Can be more crack-sensitive on some cast alloys
- Higher melting range
Rule of thumb:
If the part needs strength, sees outdoor/marine exposure, or will be anodized after welding… think 5356.
ER4943 – The “Best of Both Worlds” Modern Option
Personality: Flows like 4043, strength closer to 5356.
Practical Uses
- Automotive structural repairs
- Performance parts
- Shop fabrication where both strength and appearance matter
- Mixed-alloy fabrication
- Professional repair shops
- Aerospace and higher-spec fabrication environments
Why You’d Choose It
- Higher strength than 4043
- Very smooth flow
- Reduced cracking tendency
- Good for multi-alloy compatibility
- Attractive bead appearance
Downsides
- Not as widely available as 4043/5356
- Slightly higher cost
- Color match after anodizing still not pleasing
- Many beginners simply don’t know about it yet
Rule of thumb:
If you want 4043 puddle behavior with better strength, 4943 is a smart upgrade.
ER4047 – The “High-Silicon / Cast Specialist” Filler
Personality: Extremely fluid, excellent crack resistance, very low shrinkage.
Practical Uses
- Cast aluminum repairs
- Engine blocks and heads
- Transmission housings
- Porous or contaminated castings
- Thin cast sections
- Heat-sink type components
- Situations where cracking keeps happening
Why You’d Choose It
- Very high silicon content lowers melt point and reduces cracking
- Extremely fluid puddle
- Excellent for filling gaps
- Great wetting action on dirty castings
- Lower shrinkage stress
Downsides
- Lower strength than 4043/5356
- Not ideal for structural parts
- Very fluid puddle can be hard to control for beginners
- Color mismatch if anodized
Pro Tip:
If cast aluminum keeps cracking or fighting you, 4047 often fixes the problem.
Lets boil it down
- 4043 = Easy & forgiving but won’t anodize well
- 5356 = Strong & marine + anodizes well
- 4943 = Smooth + strong
- 4047 = Castings, less porosity & crack-resistant
If you only stocked two rods in a small shop, a very practical combo would be:
4943 + 5356
And if you do a lot of cast aluminum repairs:
Add 4047 to your list.
What size TIG filler Rod should I buy?
Choose a filler diameter that matches the job.
- Small-diameter rods for small welds and thin material.
- Larger diameters for larger welds and higher deposition.
Choosing the right filler diameter makes puddle control easier.
Rule of thumb for thin sheet metal tig welding up to .063”
There are a lot of situations where using a tig rod diameter that is approximately the same as the thickness of sheet metal welded works great.
It doesn’t have to be exact…just approximate.
Example .050” thickness can be tig welded using either .063” or .045”.
From .063” to .125” you will probably want to use either 1/16” or 3/32” tig rod.
1/8” is usually for thicker metal.
Using a filler rod that's too large can cool the puddle excessively when dipped.
Comparing three sizes on the same joint.
.045", 1/16", and 3/32" on 11-gauge cold-rolled steel.
