What Is 5356 Aluminum?
5356 is an aluminum-magnesium filler alloy. It carries roughly 5% magnesium, which puts its chemistry close to the 5xxx plate and sheet alloys it is designed to join — 5083, 5086, 5056, 5454 and 5456.
That magnesium match is the whole point. When you weld a 5xxx base metal, the weld pool is a mixture of filler and melted parent metal. If the filler is chemically close to the parent, the finished weld behaves like the rest of the part: similar strength, similar corrosion potential, similar response to anodizing. If it is not, the weld becomes the weak link — or the site where corrosion starts.
One clarification that matters for specification: 5356 is registered as a wrought alloy and appears in rod, bar and wire standards, but in practice essentially all of the 5356 produced goes into welding filler. It is not a structural grade. You will not see 5356 specified as structural plate the way you see 5083-H116 or 5456-H116. Where 5356 appears in bar form, it is bar destined to become or feed filler.
Specifications and Equivalent Designations
A “specifications” question should start with the actual specification numbers, because that is what goes on a WPS and a purchase order.
| Standard | Designation |
|---|---|
| AWS A5.10 (USA) | ER5356 |
| EN ISO 18273 (Europe) | S Al 5356 (AlMg5Cr(A)) |
| DIN 1732 (legacy German) | 3.3556 |
| JIS Z 3232 (Japan) | A5356-WY (wire) / A5356-BY (rod) |
| Alloy family | 5xxx, Al-Mg, non-heat-treatable |
Classification society approvals are commonly available on commercial wire from major filler makers — ABS, BV, LR, DNV, TÜV and DB appear on ER5356 datasheets. If your project requires a society-approved consumable, ask for the approval certificate by name rather than assuming the stock wire carries it.
Chemical Composition
Composition limits below are the AWS A5.10 / EN ISO 18273 values for bare solid wire.
| Element | Weight % |
|---|---|
| Silicon (Si) | 0.25 max |
| Iron (Fe) | 0.40 max |
| Copper (Cu) | 0.10 max |
| Manganese (Mn) | 0.05 – 0.20 |
| Magnesium (Mg) | 4.5 – 5.5 |
| Chromium (Cr) | 0.05 – 0.20 |
| Zinc (Zn) | 0.10 max |
| Titanium (Ti) | 0.06 – 0.20 |
| Beryllium (Be) | 0.0003 max |
| Others, each / total | 0.05 / 0.15 |
| Aluminum (Al) | Balance |
Two elements are worth reading closely. Magnesium at 4.5–5.5% is what makes 5356 a good match for high-magnesium base metals — and it is also what creates the temperature limit discussed later in this guide. Titanium at 0.06–0.20% is a deliberate addition: it refines the solidification grain structure of the weld bead and reduces hot-cracking sensitivity.
The silicon cap at 0.25% is equally deliberate. Keeping silicon low limits the formation of Mg₂Si when 5356 is diluted by a silicon-bearing base metal.
Selected physical properties of the filler alloy. These are wire-maker data — AWS A5.10 does not specify them:
| Property | Value |
|---|---|
| Density | 2.68 g/cm³ |
| Melting range | 575 – 633 °C |
| Thermal conductivity | ~120 W/m·K |
| Electrical conductivity | ~29 % IACS |
Product Forms, Diameters, and Packaging
Filler wire is specified by diameter and package, not by H-temper. AWS A5.10 and EN ISO 18273 control composition, diameter tolerance and surface condition; the strain-hardened tempers used for wrought products (H22, H32, H18 and so on) do not appear as filler classifications. A “5356-H32” designation describes as-drawn hardness only — it carries no specification meaning.
What does affect your process is the drawn condition of the wire. MIG wire is normally supplied hard-drawn, and that is beneficial: 5356 is stiffer than the silicon fillers, and that column strength is why it feeds through a MIG gun more reliably than ER4043 does. Softer wire buckles in the liner and birdnests at the drive rolls.
Typical commercial sizes:
| Process | Diameters | Standard packaging |
|---|---|---|
| MIG (GMAW) | 0.8, 1.0, 1.2, 1.6 mm | 7 kg spools; 0.5 kg mini-spools |
| TIG (GTAW) | 1.6, 2.0, 2.4, 3.2 mm | Cut lengths, typically 1000 mm, in 2 kg tubes |
Diameter choice follows section thickness and deposition rate: 0.8–1.0 mm for thin sheet and dip transfer, 1.2 mm as the general-purpose size, 1.6 mm and above for thick plate and spray transfer.
As-Welded Mechanical Properties
These are typical all-weld-metal values for the deposited filler, not for the finished joint. Actual joint strength depends on base metal, dilution, joint design and procedure.
| Property | ER5356 | ER4043 |
|---|---|---|
| Tensile strength, typical | 250 – 300 MPa | 165 – 200 MPa |
| Tensile strength, AWS A5.10 minimum | 240 MPa | 165 MPa |
| Yield strength, typical | 120 – 145 MPa | 55 – 90 MPa |
| Yield strength, AWS A5.10 minimum | Not specified | Not specified |
| Elongation, typical | 18 – 25% | 12 – 20% |
| Shear strength, approximate | 170 – 190 MPa | 110 – 130 MPa |
The 2021 edition of AWS A5.10 introduced a minimum tensile requirement for ER5356 — 240 MPa. Yield and elongation are tested and reported on the certificate but carry no classification minimum, so read those figures as typical wire-maker values rather than a specification floor.
Approximate shear values are derived at roughly 60–65% of tensile strength and should be treated as indicative only. For a structural joint, design against the allowable stresses in the applicable code — AWS D1.2 for aluminum structures in the US, or the relevant EN or class-society rule.
The headline is that 5356 gives roughly 50% more as-welded tensile strength than 4043. That is the reason it is the default structural filler for 5xxx work.
Why 5356 Matches 5xxx Base Metals
Three mechanisms, in order of how often they decide the job.
Corrosion compatibility. The weld bead and the parent plate sit in the same electrolyte. If their corrosion potentials differ, one becomes the anode and corrodes preferentially. Filling a high-magnesium plate such as 5083-H321 with a magnesium-matched filler keeps the weld zone close to the parent in potential, so the joint does not become a built-in corrosion site.
Avoiding brittle intermetallics. Silicon-bearing filler diluted into a high-magnesium base forms Mg₂Si in the weld metal. In quantity it reduces ductility and makes the joint brittle. The low silicon cap on 5356 is there to prevent exactly that.
Anodizing consistency. A magnesium-rich bead anodizes to a light, near-white finish that is close to the 5xxx parent plate. Silicon fillers go dark gray to black. Where appearance is a specification line, this decides the filler on its own.
5356 vs 4043: How to Choose
This is the single most common filler decision in aluminum fabrication. The silicon side of the same decision is covered in our 4043 filler guide.
| Factor | ER5356 | ER4043 |
|---|---|---|
| Filler system | Al-5%Mg | Al-5%Si |
| Best-matched base metals | 5xxx with >3% Mg (5083, 5086, 5456, 5056) | 6xxx (6061, 6063), castings (A356, 319) |
| As-welded tensile | 250 – 300 MPa | 165 – 200 MPa |
| Shear strength | Higher | Lower |
| Hot-cracking resistance | Good | Better |
| Puddle fluidity | Lower — 5356 does not wet out as easily | Higher, easier bead control |
| Solidification range | Wider | Narrower, which is why it cracks less |
| Anodized color | Light, matches 5xxx parent | Dark gray to black |
| Marine corrosion match with 5xxx | Good | Poor — avoid |
| Sustained service above 65 °C | No | Yes |
The working rule: match the filler magnesium level to the base metal. High-magnesium base, ambient service → 5356. 6xxx base → 4043 or 5356 depending on whether crack resistance or anodizing matters more. Castings → 4043. Sustained heat → 4043, or better, a low-magnesium 5xxx filler.
One caution on the marine case. The failure mode people describe — a 4043 weld corroding preferentially on a 5xxx hull — is real and well documented in boat construction, but the polarity of that couple depends on the exact dilution and is not something to state as a universal rule. The safe and defensible statement is that the electrochemical mismatch makes the weld zone the likely attack site in saltwater, and that is reason enough to avoid it.
Other 5xxx Fillers: 5183, 5556, and 5554
5356 is the general-purpose option, not the only one. When you are welding high-magnesium plate, these three come up regularly.
| Filler | Mg % | Mn % | Use it when |
|---|---|---|---|
| ER5356 | 4.5 – 5.5 | 0.05 – 0.20 | Default for 5xxx base metals; best combination of strength, feedability and finish |
| ER5183 | 4.3 – 5.2 | 0.50 – 1.00 | 5083 and similar high-strength marine plate where the WPS calls for a manganese-bearing filler |
| ER5556 | 4.7 – 5.5 | 0.50 – 1.00 | Highest-strength 5xxx filler; specified for 5456 and heavy high-Mg weldments |
| ER5554 | 2.4 – 3.0 | 0.50 – 1.00 | Sustained service above 65 °C — the magnesium stays under the 3% SCC threshold |
The trade-off with ER5554 is strength. It is deliberately weaker, which is the price of staying below the magnesium threshold that makes the other three unsuitable for warm service.
ER4943 is a newer aluminum-silicon-magnesium filler worth knowing about. It is a modification of 4043 developed for higher as-welded strength while keeping 4043-level crack resistance, and it is increasingly specified for 6xxx production welding. Color match after anodizing can be less predictable than with 5356, so test it if appearance matters.
The 65 °C Limit: Stress Corrosion Cracking
This is the limitation that catches people out, and it is the one that should be checked first on any 5356 specification.
Any aluminum alloy containing more than 3% magnesium is susceptible to stress corrosion cracking. That includes the 5xxx base metals such as 5083 and 5086 — and it includes almost all the common 5xxx fillers: 5356, 5183 and 5556 all exceed the threshold.
Four conditions have to line up:
- The alloy contains at least 3% magnesium.
- A tensile stress is present. Weld residual stress is almost always enough.
- An electrolyte is available — salt water, for example.
- The joint has been held above roughly 65 °C (150 °F) long enough for the microstructure to sensitize.
They do not all need to happen at the same time. Once the joint has seen elevated temperature, β-phase (Al₃Mg₂) has precipitated along the grain boundaries and the microstructure is sensitized. Dropping the temperature afterwards does not undo it — given stress and an electrolyte, cracking can still follow.
The practical consequences:
- Do not specify ER5356 for components running continuously above 65 °C. Engine brackets, heat exchangers, exhaust-adjacent parts and warm process lines fall in this category.
- If you need a 5xxx filler at elevated temperature, use ER5554 — it is formulated to stay under 3% magnesium. Accept the lower strength.
- For 6xxx alloys in elevated service, ER4043 is usually the better answer.
- This applies to the base metal too. High-magnesium plate such as 5083 or 5456 should not be used above 65 °C regardless of what it is welded with.
There is a specific trap here that is worth naming because it is easy to walk into. 5454 is selected precisely because it tolerates elevated-temperature service. If you weld 5454 with ER5356 and then put it into warm service, the filler reintroduces the problem the base metal was chosen to avoid. For 5454 vessels or tanks designed to run hot, specify ER5554.
What Welding Does to the Base Metal
Filler strength is only half the joint. The other half is what the arc does to the parent plate, and on non-heat-treatable 5xxx alloys that is a real strength loss.
The heat-affected zone of a welded 5xxx joint is effectively annealed. Strain-hardened tempers — H116, H321, H32 — lose their work hardening in the HAZ, and because the alloy is non-heat-treatable, that strength cannot be brought back by post-weld heat treatment. A 5083-H116 plate carries a specified minimum yield of 215 MPa under ASTM B928 (228 MPa is typical); in the HAZ the yield drops back toward annealed values, a loss of roughly 35–45%.
Design accordingly: use the annealed allowable stresses from AWS D1.2 (or the applicable code) for the HAZ rather than the parent-metal temper values. The same principle applies to 6061-T6, where the HAZ overages and softens even though the filler choice is different.
Practical Welding Notes
Most 5356 problems on the shop floor are feeding and cleanliness issues, not metallurgy.
| Item | Recommendation |
|---|---|
| Shielding gas | 100% argon for most work; argon/helium mixtures for thicker sections |
| Polarity | MIG: DCEP. TIG: AC |
| Drive rolls | U-groove rolls intended for aluminum — V-grooves deform soft wire |
| Liner | Clean Teflon or nylon liner sized for aluminum |
| Contact tip | Oversized tip marked for aluminum; reduces burnback |
| Gun cable | Keep it short and as straight as possible |
| Cleaning | Degrease first, then brush with a stainless brush kept only for aluminum |
| Technique | Stringer beads or a tight step-pause; 5356 does not wet out as readily as 4043, so avoid wide weaving |
| Craters | Always fill craters to avoid crater cracking |
| Storage | Keep dry and sealed in original packaging; aluminum wire picks up moisture and surface contamination |
ER5356 has higher electrical conductivity than steel wire, so burnback into the contact tip is a common complaint. Oversized tips and clean liners address most of it.
Anodizing and Appearance
If the part will be anodized, 5356 is usually the right filler and 4043 is usually the wrong one. A 5356 bead anodizes to a light, slightly gray finish that sits close to a 5xxx parent plate. A 4043 bead goes dark gray to near black, because the silicon in the weld metal does not anodize the way the surrounding aluminum does.
For architectural or decorative work where color match is on the drawing, do not rely on the general rule alone. Run a coupon through the actual anodizing line with the actual filler lot and approve the sample before production.
Go/No-Go: When to Specify 5356
Go — specify 5356 when:
- The base metal is a 5xxx alloy with more than 3% magnesium — 5083, 5086, 5056, 5456 — and service stays below 65 °C.
- The joint sees saltwater or a marine atmosphere, and the weld zone must not become the corrosion site.
- The part will be anodized and the weld has to match the parent plate.
- As-welded strength or shear strength is a design driver and 4043 does not reach it.
- The process is MIG and feedability matters — 5356 feeds more reliably than the softer silicon fillers.
No-go — do not use 5356 when:
- The assembly runs continuously above 65 °C. Use ER5554 or ER4043 instead.
- The base metal is a high-silicon casting such as A356, 356 or 319. ER4043 is the standard repair filler and its silicon content suppresses hot cracking in castings.
- You are running high-volume 6xxx production where puddle fluidity and crack resistance matter more than strength or anodizing. ER4043 or ER4943 fits better.
- Bead cosmetics dominate over strength — 4043 lays a smoother, shinier bead.
- Someone is trying to specify 5356 as structural plate, sheet or bar. It is a filler; the base metal choice is a separate engineering decision.
Where 5356 Is Used
| Sector | Typical joints |
|---|---|
| Marine | Hull plating, decks, superstructure, fuel and water tanks, gangways |
| Road and rail transport | Truck trailers, tanker bodies, chassis and frame welds, rail car bodies |
| Structural fabrication | Frames, scaffolding, platforms, storage tanks at ambient temperature |
| Automotive and cycle | Frames, brackets, roll structures |
| Pressure equipment | 5083 and 5086 vessels and tanks operating at ambient temperature |
Note the qualifier on pressure equipment. 5083 vessels at ambient service are a normal 5356 application. A 5454 vessel intended for elevated-temperature service is not — that one needs ER5554.
Every joint in this table is welded with 5356 aluminum wire, supplied spooled for MIG or cut to length for TIG.
Pros and Limitations at a Glance
| Strengths | Limitations |
|---|---|
| Magnesium-matched to 5xxx base metals | Not for sustained service above 65 °C (SCC risk) |
| Roughly 50% more as-welded tensile strength than 4043 | Lower fluidity and a narrower wetting window than silicon fillers |
| Corrosion match with 5xxx parent metal in marine service | Not the right choice for high-silicon castings |
| Anodizes to a light finish that matches the parent plate | More prone to burnback than steel wire; needs aluminum-specific setup |
| Stiffer wire feeds better through MIG guns | Bead appearance is less smooth than 4043 |
Conclusion
5356 is the default filler for 5xxx aluminum, and the reason is chemistry: at 4.5–5.5% magnesium it matches the plate it is joining closely enough that the weld behaves like the rest of the structure — in strength, in corrosion, and under anodizing. The cost of that magnesium is a hard service ceiling. Above roughly 65 °C the joint becomes susceptible to stress corrosion cracking, and the only fixes are a low-magnesium filler such as ER5554 or a change to a silicon filler. Work through the temperature question before the strength question, and the rest of the selection follows.
We supply 5356 as MIG spool wire and TIG cut-length rod in the diameters and packaging your process needs, and we flag any job where ER5554 would be the safer filler.
Send the base alloy, section thickness, process and service temperature, and we will confirm the filler before you write the WPS.
Frequently Asked Questions
What is the difference between 5356 and 4043 filler?
5356 is a 5% magnesium filler for 5xxx base metals. 4043 is a 5% silicon filler for 6xxx alloys and castings.
- Strength — 5356 deposits roughly 50% more as-welded tensile.
- Corrosion — 5356 matches 5xxx parent metal, while 4043 does not.
- Anodizing — 5356 stays light; 4043 darkens.
- Fluidity — 4043 wets out better and cracks less on 6061.
What is the maximum service temperature for 5356 welds?
Treat 65 °C (150 °F) as the standard ceiling for continuous service.
Above 65 °C, alloys holding more than 3% magnesium — 5356, 5183 and 5556 among them — sensitize and can crack under stress in salt water. For hot service specify ER5554, which stays under 3% magnesium.
Is 5356 suitable for marine welding?
Yes. It is the standard filler for 5xxx marine work.
5083 and 5086 hulls, decks, tanks and superstructure rely on it because the magnesium match keeps weld-zone corrosion potential close to the parent plate. The one exception is warm service: above 65 °C, change to ER5554.
What is the minimum order for 5356 wire, and can you supply test certificates?
Low-MOQ production is available, and every order carries a mill test certificate.
- Stock sizes — standard diameters ship from inventory.
- Non-standard — custom diameters and spool weights run 10–60 days.
- Documents — MTC standard; SGS composition or mechanical reports on request.
