7A03 Aluminium Alloy Wire for Rivets and Fasteners
7A03 is a high-strength Al-Zn-Cu-Mg alloy designed specifically for rivets. It is supplied as drawn wire in H14 or T6, and in the T6 condition GB/T 3195 requires a shear strength of at least 285 MPa on small diameters, placing it among the strongest aluminium rivet materials. This guide explains its chemistry, tempers, test requirements, tolerances and where it fits against 2xxx and other 7xxx rivet alloys.
- Alloy
- 7A03 (GB designation)
- Tempers
- H14, T6
- Diameter
- 1.6 – 10 mm
- Standard
- GB/T 3195
What is 7A03?
7A03 is a wrought alloy registered in the Chinese national standard GB/T 3190 (its older designation was LC3). It is not an Aluminum Association registration, so there is no exact ASTM or EN equivalent, although it belongs to the same Al-Zn-Mg-Cu family as 7075 and 7050.
Its composition is tuned for rivets. Compared with 7075, 7A03 has more copper (1.8 – 2.4 %), less magnesium (1.2 – 1.6 %) and a little more zinc. The lower magnesium content keeps the heat-treated alloy ductile enough to drive, so 7A03 rivets can be installed in the solution-treated and aged condition rather than freshly quenched. That gives high joint strength without the cold-storage handling of 2024 "icebox" rivets.
The trade-off is corrosion behaviour. Like other copper-bearing 7xxx alloys, 7A03 needs surface protection (anodising or conversion coating, often with a sealant at installation) and should not be used unprotected in marine or strongly corrosive service.
7A03 chemical composition (wt %)
Limits per GB/T 3190. Single values are maximums. The mill certificate reports the actual analysis.
| Element | Limit | Comment |
|---|---|---|
| Silicon (Si) | ≤ 0.20 | Kept low for ductility |
| Iron (Fe) | ≤ 0.20 | Kept low for headability |
| Copper (Cu) | 1.8 – 2.4 | Higher than 7075; adds strength |
| Manganese (Mn) | ≤ 0.10 | |
| Magnesium (Mg) | 1.2 – 1.6 | Lower than 7075; keeps driven rivets ductile |
| Chromium (Cr) | ≤ 0.05 | Much lower than 7075 |
| Zinc (Zn) | 6.0 – 6.7 | Main strengthening element with Mg |
| Titanium (Ti) | 0.02 – 0.08 | Deliberate grain-refining addition |
| Others, each / total | Per GB/T 3190 | |
| Aluminium (Al) | Remainder |
| Element (wt %) | 7A03 | 7075 | 7050 |
|---|---|---|---|
| Zinc | 6.0 – 6.7 | 5.1 – 6.1 | 5.7 – 6.7 |
| Magnesium | 1.2 – 1.6 | 2.1 – 2.9 | 1.9 – 2.6 |
| Copper | 1.8 – 2.4 | 1.2 – 2.0 | 2.0 – 2.6 |
| Grain control | Ti | Cr | Zr |
Tempers, shear strength and riveting tests
| Supply temper | Test temper | Diameter (mm) | Shear strength requirement |
|---|---|---|---|
| H14 | H14 | 1.6 – 10 | No shear value; riveting (heading) test only |
| T6 | T6 | 1.6 – 4.5 | ≥ 285 MPa |
| T6 | T6 | over 4.5 – 10 | Per GB/T 3195 for the size band |
Shear and riveting tests are carried out to GB/T 3250. Requirements are summarised; the governing table in GB/T 3195 and the certificate apply.
H14 wire is strain-hardened. Fastener makers head it and then solution treat and age the finished parts to T6. T6 wire is already heat-treated, which suits simple heads and rivets that will be driven as supplied.
The riveting test upsets a short sample to a set height relative to its diameter and checks the head for cracks. It is the practical proof that the wire will form heads in production. Larger diameters are tested to a lower upset ratio because they are harder to head without cracking.
Diameter tolerance and surface quality
Rivet wire is drawn to tight tolerances because head volume depends on slug volume. GB/T 3195 offers several tolerance grades, from minus-only classes that guarantee entry into the die to symmetric classes. Precision rivet wire is commonly held to about ±0.02 mm on small diameters. Specify the grade on the order.
| Surface condition | Typical requirement for rivet wire |
|---|---|
| Cracks, seams, laps, peeling, blisters | Not allowed |
| Metallic or non-metallic pick-up pressed into the surface | Not allowed |
| Corrosion spots | Not allowed |
| Light scratches, scuffs or dents | Allowed only if shallower than half the minus diameter tolerance |
| Light oil or drawing lubricant | Allowed; helps cold heading |
Coils should be level-wound with no kinks, and the wire marked with alloy, temper, diameter and lot number. Mixing 7A03 with similar-looking 2xxx or 5xxx wire on the shop floor is a real risk, so clear identification is part of the quality requirement.
7A03 compared with other rivet alloys
| Alloy | Typical rivet condition | Strength level | Main advantage | Main limitation |
|---|---|---|---|---|
| 2A01 / 2117 | T4, driven as received | Medium | Easy to drive, general use | Lower strength |
| 2A10 | T4 | Medium–high | Higher shear than 2A01 | Lower strength than 7xxx rivets |
| 2024 | T4, icebox | High | Proven aircraft rivet | Refrigeration needed |
| 7A03 | T6, driven as received | High | High shear without icebox handling | Needs corrosion protection |
| 7050 | T73, driven as received | High | Good stress-corrosion resistance | Aerospace-controlled supply |
Within Chinese-standard designs, 7A03 is the usual choice for high-strength load-bearing rivets. For international designs, the closest functional alternatives are 7050-T73 and 7075-T73 rivet wire. For lower-load rivets, see 2A01 and 2A10.
Where 7A03 rivets and fasteners are used
- Aircraft structures: load-bearing solid rivets in designs built to Chinese aviation standards
- Spacecraft and launch vehicles: high-strength rivets in aluminium structures
- Rail and road vehicles: riveted aluminium body and frame joints that need high shear strength
- Defence equipment: riveted structures and fasteners for shelters and vehicles
- Special fasteners: pins, screws and bolts headed from wire where steel is too heavy
What to confirm before ordering
- Standard and temperGB/T 3195 (or your equivalent specification), H14 or T6, and the test temper for qualification.
- Diameter and tolerance gradeState both; do not rely on a default.
- TestsShear and riveting tests per GB/T 3250, chemistry, and surface inspection.
- Identification and traceabilityLabels with alloy, temper, size and lot; lot traceability back to the cast.
- Packing and documentsMoisture-protected coils in export cases, EN 10204 3.1 certificate, delivery on EXW, FOB, CIF or DAP terms.
References and standards
- GB/T 3190 – Wrought aluminium and aluminium alloys: chemical composition
- GB/T 3195 – Aluminium and aluminium alloy drawn round wire for rivets
- GB/T 3250 – Shearing and riveting test method of wires and rods for aluminium and aluminium alloy rivets
- ASTM B316 / B316M – Aluminum and Aluminum-Alloy Rivet and Cold-Heading Wire and Rods (international comparison)
7A03 rivet wire: frequently asked questions
What is the international equivalent of 7A03?
There is no exact Aluminum Association or EN equivalent. 7A03 is a Chinese GB designation. Functionally, 7050-T73 and 7075-T73 rivet wire are the closest international alternatives for high-strength rivets.
What is the shear strength of 7A03 rivet wire?
GB/T 3195 requires at least 285 MPa shear strength for 7A03-T6 wire of 1.6 – 4.5 mm diameter. Requirements for other sizes are in the standard and on the certificate.
What is the difference between H14 and T6 7A03 wire?
H14 is strain-hardened and is headed first, then heat-treated to T6. T6 wire is already solution treated and aged and can be headed and driven as supplied for suitable head shapes.
Do 7A03 rivets need refrigeration like 2024 rivets?
No. 7A03 is designed to be driven in the heat-treated T6 condition, which removes the icebox handling needed for 2024-T4 rivets.
Is 7A03 suitable for marine use?
Only with protection. Like other copper-bearing 7xxx alloys it needs anodising or conversion coating and sealing; 5xxx rivet alloys such as 5A06 or 5056 are better for unprotected marine exposure.
Need 7A03 rivet wire?
Send the diameter, temper, tolerance grade and quantity. We will confirm availability, testing and delivery to your plant.
