ALUMINUM FILLER METAL SELECTION
FILLER METAL IN STOCK NOW AT WELDMONGER.COM
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://esab.com/index.cfm/_api/render/file/?method=inline&fileID=7FEFED6B-E635-42AB-9B2D928603B0E235
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
Rule of thumb:
If cast aluminum keeps cracking or fighting you, 4047 often fixes the problem.
Simple Memory Anchors
- 4043 = Easy & forgiving
- 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 repairs:
Add 4047.
