Lower rate
Spring rate is proportional to shear modulus. For the same wire, coil diameter and active coils, a 5056 spring is about one third as stiff as a steel spring, so use thicker wire or fewer coils to reach a target rate.
Spring wire guide
5056-H38 Aluminium Spring Wire
5056-H38 is the strongest work-hardened temper of a 5% magnesium aluminium alloy, and it is the usual aluminium wire for light springs, clips and formed wire parts. It weighs about a third as much as steel, is non-magnetic and resists seawater without plating, but it is far less stiff, so springs must be designed for it. Metline supplies 5056-H38 wire from about 1 to 15 mm in coils, with certificates, to spring and wire-form makers worldwide.
- Alloy
- 5056 (Al-Mg 5)
- Temper
- H38 (also O, H32, H34)
- Diameter
- about 1 – 15 mm
- Typical tensile
- ≈ 415 MPa (H38)
Why 5056-H38 for springs?
5056 contains 4.5 – 5.6 % magnesium, the highest level among common wrought wire alloys. Magnesium in solid solution makes the alloy harden quickly when drawn, and the H38 temper (strain-hardened to full hard and then thermally stabilised) gives a tensile strength of around 415 MPa, about double that of annealed 5056.
That strength, combined with excellent corrosion resistance and no need for heat treatment after coiling, is why 5056-H38 is chosen for aluminium springs, clips, retaining rings, zip-fastener wire and insect-screen wire. The stabilising step in H38 also limits the slow loss of strength (age softening) that unstabilised high-magnesium tempers can show at room temperature.
Aluminium is not a substitute for spring steel in every case. Its elastic modulus is about one third of steel, so an aluminium spring of the same size deflects about three times as much under the same load and stores less energy per unit volume. 5056 springs make sense where weight, corrosion, magnetism or galvanic compatibility with aluminium parts matter more than compactness.
5056 chemical composition (wt %)
| Element | Limit (%) |
|---|---|
| Magnesium (Mg) | 4.5 – 5.6 |
| Manganese (Mn) | 0.05 – 0.20 |
| Chromium (Cr) | 0.05 – 0.20 |
| Silicon (Si) | 0.30 max |
| Iron (Fe) | 0.40 max |
| Copper (Cu) | 0.10 max |
| Zinc (Zn) | 0.10 max |
| Others, each / total | 0.05 / 0.15 |
| Aluminium (Al) | Remainder |
Registered Aluminum Association limits for 5056 (UNS A95056), followed by ASTM B211 and B316.
Mechanical and physical properties of 5056-H38
Typical values for 5056 wire are listed below. Strength in fine wire can be higher than the values shown because of greater cold reduction; the certificate for each lot reports actual results.
| Property | 5056-O | 5056-H38 |
|---|---|---|
| Tensile strength | 290 MPa | 415 MPa |
| Yield strength (0.2 %) | 150 MPa | 345 MPa |
| Elongation | 35 % | about 15 % |
| Shear strength | 180 MPa | 234 MPa |
| Fatigue strength (5×10⁸ cycles) | 140 MPa | 152 MPa |
| Brinell hardness | 65 HB | 100 HB |
Physical properties
- Density
- 2.64 g/cm³ (about 34 % of steel)
- Modulus of elasticity
- about 71 GPa
- Shear modulus
- about 26 GPa (spring steel is about 79 GPa)
- Melting range
- 568 – 638 °C
- Thermal conductivity
- about 112 – 117 W/m·K
- Electrical conductivity
- about 27 – 29 % IACS
- Magnetic
- Non-magnetic
Designing springs in 5056 wire
Stress limits
Keep working shear stress well below the shear strength; many designers start at 35 – 45 % of tensile strength for static springs and lower for cyclic duty.
Fatigue
Aluminium has no true endurance limit. For springs cycled millions of times, design to the fatigue strength at the required life and consider shot peening.
Temperature
Avoid prolonged service above about 65 °C: high-magnesium alloys can become sensitised and lose stress-corrosion resistance, and springs relax faster when warm.
Galvanic fit
A 5056 spring inside an aluminium housing avoids the corrosion cell that a steel or stainless spring would create in wet service.
Coiling
H38 wire coils well on standard machines; allow for greater springback than steel when setting coil diameter.
Sizes, tolerances and supply
5056 spring wire supply
- Diameter
- about 1.0 – 15 mm; fine sizes below 1 mm on request
- Tempers
- H38 for springs; O, H32 and H34 for formed parts and rivets
- Tolerance
- typically ±0.02 mm for drawn sizes; tighter on request
- Form
- Level-wound coils or spools; straight lengths for larger diameters
- Standard
- ASTM B211, EN 573-3 / EN 1301, or customer specification
| Diameter | Typical use |
|---|---|
| 1.0 mm | Small clips and springs for instruments and electronics |
| 1.5 – 2.0 mm | Appliance springs, latches and light wire forms |
| 3.0 – 4.0 mm | Larger compression and torsion springs, retaining rings |
| Above 5 mm | Heavy wire forms, hooks and bent parts |
Finishes for aluminium springs
- Anodising: harder, more wear-resistant surface and optional colour coding; apply after coiling and any stress relief
- Chemical conversion coating: extra corrosion protection and a good base for paint
- Shot peening: introduces compressive surface stress to lift fatigue life of cyclically loaded springs
- Lubricant or wax: for coiling and to prevent galling between coils in service
Where 5056 spring wire is used
- Compression springs in valves, switches and marine fittings where steel would corrode
- Extension and torsion springs for hatches, latches and light hinges
- Clips, retaining rings and wire forms in aircraft interiors and electronics
- Zip-fastener and insect-screen wire, two large uses of 5056 wire
- Non-magnetic parts near compasses, sensors and MRI equipment
Where higher stress is needed in aluminium, heat-treated 7075-T6 or 2024-T4 wire can be used, at the cost of lower corrosion resistance.
5056-H38 compared with spring steels
| Property | 5056-H38 | Music wire (ASTM A228) | Stainless 302 |
|---|---|---|---|
| Density | 2.64 g/cm³ | 7.85 g/cm³ | 7.9 g/cm³ |
| Tensile strength | ≈ 415 MPa | ≈ 1,600 – 2,800 MPa (size dependent) | ≈ 1,300 – 2,200 MPa |
| Shear modulus | ≈ 26 GPa | ≈ 79 GPa | ≈ 69 GPa |
| Corrosion in seawater | Very good | Poor without plating | Good |
| Magnetic | No | Yes | Slightly, after cold work |
| Galvanic fit with aluminium | Ideal | Poor | Fair |
In short: choose 5056 for light loads in corrosive or weight-sensitive assemblies; choose steel when the spring must be small and carry high loads.
References and standards
- ASTM B211 – Aluminum and Aluminum-Alloy Rolled or Cold Finished Bar, Rod and Wire
- EN 573-3 – Aluminium and aluminium alloys: chemical composition of wrought products
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
- ASM Handbook, Vol. 2 – Properties of Wrought Aluminum and Aluminum Alloys: 5056
5056 aluminium spring wire: FAQ
What does the H38 temper mean?
H3x tempers are strain-hardened and then thermally stabilised; the 8 means full hard. Stabilising prevents high-magnesium wire from slowly softening at room temperature, so spring properties stay consistent.
Can an aluminium spring replace a steel spring?
Only if the design allows for aluminium's lower stiffness and strength. A 5056 spring is about one third as stiff as a steel spring of the same geometry, so wire size or coil count must change.
Is 5056 spring wire corrosion resistant?
Yes. With about 5 % magnesium it resists seawater and marine air very well, and it does not create a galvanic cell inside aluminium housings. Avoid long exposure above about 65 °C.
How much lighter is a 5056 spring than steel?
Its density is 2.64 g/cm³ against about 7.85 g/cm³ for steel, so the same volume weighs about 34 % as much.
Can 5056 aluminum springs be anodised?
Yes. Anodising after coiling improves wear and corrosion resistance and allows colour coding. Note that the oxide layer adds a little thickness and slightly reduces fatigue life unless the spring is shot peened first.
What diameters are available?
Typically about 1 to 15 mm in H38, with fine sizes and other tempers on request, supplied in coils with a mill test certificate.
Need 5056-H38 spring wire?
Send the diameter, tolerance, temper, coil size and quantity. We will confirm availability and certification.
