5456-H321 Aluminum
A 5000-series Al-Mg-Mn alloy, stronger than 5083
Typical values for the temper in the title
5456 contains about 5.1% magnesium, more than 5083, which makes it one of the strongest in the 5000 series. In H321 its tensile strength is about 317 MPa. It is not heat treatable; its strength comes from magnesium and cold work.
It is used in welded marine structures that need more strength than 5083, and in light armor for vehicles (to MIL-DTL-46027). Like all magnesium-rich 5000-series alloys, it is not suited to prolonged service at elevated temperature.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 317 MPa | |
| Yield strength Rp0.2 | 228 MPa | |
| Elongation A | 16% | |
| Hardness | 75 HB | |
| Modulus of elasticity E | 71 GPa | |
| Density ρ | 2.66 g/cm³ | |
| Machinability | 50% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Mg magnesium | 4.7–5.5 | gives the strength |
| Mn manganese | 0.50–1.0 | adds strength and controls the grains |
| Cr chromium | 0.05–0.20 | controls the grain structure |
| Fe iron | max 0.40 | |
| Si silicon | max 0.25 | |
| Zn zinc | max 0.25 | |
| Ti titanium | max 0.20 | |
| Cu copper | max 0.10 | |
| Al aluminum | balance |
Common tempers
Marine and armor uses need tempers that have been corrosion tested.
| Temper | Properties | When to choose it |
|---|---|---|
| O / H111 | minimum strength | for forming |
| H116 / H321 | Rm ≈ 317 MPa, Rp0.2 ≈ 228 MPa | strain hardened and stabilized, tested for intergranular and exfoliation corrosion (ASTM B928) |
Applications
- High-strength welded marine structures
- Light armor and combat vehicle hulls
- Hulls of fast craft
- Pressure vessels and welded structures
- Structures where 5083 is not enough
Fabrication
Welding
Welds well. To keep joint strength, ER5556 filler is usual, being stronger than ER5356.
Heat and corrosion
Excellent seawater resistance, but in prolonged service above about 65 °C it becomes sensitized and vulnerable to intergranular corrosion and stress corrosion cracking.
Machining
Soft and prone to smearing. Use sharp tools with a positive rake.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 5083-H111 | 275–350 / 125–200 MPa | Excellent — ER5356 | more available and easier to work, at slightly lower strength · material page |
| 5059-H116 | 380 / 260 MPa | Excellent — ER5183 | even higher strength in welded structures · material page |
| 5454-H32 | 248 / 193 MPa | Excellent | for elevated-temperature service · material page |
Common mistakes
Using 5456 at elevated temperature
Above about 65 °C over time it becomes sensitized. For hot service, choose 5454.
Welding with ER5356 and expecting full strength
The filler is weaker than the base metal. For high joint strength, use ER5556.
Ordering without a marine temper
Marine service needs H116 or H321, which are corrosion tested.
Equivalents, standards and supply
| ASTM | 5456 |
|---|---|
| MIL | DTL-46027 |
| Standards | ASTM B209 / MIL-DTL-46027 |
| Forms | plate · marine structure |
| Producers | Novelis · Aleris · UACJ · Alcoa · Kaiser |
Learn more
Values are typical and for comparison only. For design, rely on the standard and on the mill certificate. Sources: Aluminum Association (composition), ASM and MatWeb data sheets, and the METAL HUB materials database.
Updated: October 31, 2026