Overview of 7A04 aluminum round bar
7A04 is a high-strength aluminum alloy in the Al-Zn-Mg-Cu system, known in China as a "super-duralumin" grade. In the T6 temper it reaches a tensile strength of 530 MPa or more and a yield strength around 400 MPa, placing it in the same strength class as 7075-T6. It is the domestic Chinese standard choice for parts that need the highest strength-to-weight ratio available from aluminum.
7A04-T6 round bar is produced as an extruded product and inspected to GB/T 3191 (extruded bars) with composition to GB/T 3190. Its strength comes from heat treatment rather than cold work, so it machines cleanly in the T6 condition and holds tight tolerances after precision turning.
Chemical composition of 7A04 aluminum round bar
The composition below follows GB/T 3190 for 7A04. The high zinc and copper content is what gives the alloy its strength; the small chromium and manganese additions help control grain structure.
| Element | 7A04 (GB/T 3190), wt% |
|---|---|
| Silicon (Si) | ≤ 0.50 |
| Iron (Fe) | ≤ 0.50 |
| Copper (Cu) | 1.4 – 2.0 |
| Manganese (Mn) | 0.20 – 0.60 |
| Magnesium (Mg) | 1.8 – 2.8 |
| Chromium (Cr) | 0.10 – 0.25 |
| Zinc (Zn) | 5.0 – 7.0 |
| Titanium (Ti) | ≤ 0.10 |
| Other impurities (each / total) | ≤ 0.05 / ≤ 0.15 |
| Aluminum (Al) | remainder |
Mechanical properties of 7A04-T6 aluminum round bar
The values below are the minimum requirements from GB/T 3191-2019 for extruded 7A04-T6 bar. Thinner bars (≤22 mm) are slightly lower in strength because of the faster quench; thicker sections meet the higher values. As with all heat-treated aluminum, the actual certificate values may exceed the minima.
| Temper | Diameter (mm) | Tensile strength (MPa) | Yield strength (MPa) | Elongation (%) |
|---|---|---|---|---|
| T6 | ≤ 22 | ≥ 490 | ≥ 370 | ≥ 7 |
| T6 | 22 – 75 (≤150) | ≥ 530 | ≥ 400 | ≥ 6 |
| O (annealed) | all | ≤ 235 | ≤ 95 | ≥ 25 |
Typical physical properties: density about 2.85 g/cm³, modulus of elasticity about 71 GPa, hardness about 150 HB in T6. The alloy keeps most of its strength down to low temperatures, but its resistance to stress-corrosion cracking is lower than that of 5xxx or 6xxx grades, which is why it is used where maximum strength matters more than corrosion exposure.
Tempers and sizes of 7A04 aluminum bar
The standard supply condition is T6. The tempers below are offered depending on the forming and service requirement:
T6 - solution heat-treated and artificially aged. Highest strength; the default for structural and tooling use.
O - annealed, soft and formable. Used where the bar must be bent or heavily formed before final heat treatment.
T74 / T73 - overaged tempers with improved stress-corrosion resistance, available on request where long-term durability in a stressed condition is critical.
Export sizes: round bar in diameters 10 – 75 mm, supplied in standard 2 – 6 m lengths and cut to order. Larger diameters above 75 mm are not offered for export (see compliance note). Square and hexagonal sections can be quoted on request.
Dimensions and tolerances of 7A04 aluminum round bar
Dimensional tolerances follow ANSI H35.2(M). 7A04 is not 6063, so the "other alloys" column applies for extruded bar. A cold-finished (drawn) version is offered where a tighter diameter is needed.
| Diameter (mm) | Extruded dia. tolerance (±, mm) | Cold-finished dia. tolerance (mm) |
|---|---|---|
| 6.30 – 12.50 | 0.18 | 0.040 |
| 12.50 – 25.00 | 0.23 | 0.050 |
| 25.00 – 50.00 | 0.30 | 0.08 |
| 50.00 – 75.00 | 0.61 | 0.15 |
Length tolerance (extruded, ANSI H35.2(M) Table 10.2): plus 4 to 7 mm for lengths up to 5,000 mm, plus 7 to 9 mm for 5,000 – 10,000 mm. Straightness: 1 mm per metre for bar in the T-temper. Surface condition is as-extruded; peeling and precision turning are available as services.
Applications of 7A04 aluminum round bar
7A04-T6 is chosen where strength per kilo is the priority and the environment is not severely corrosive. Common, verified uses include:
Aircraft and aerospace structural components - spars, fittings, brackets and other primary-structure parts where the high strength-to-weight ratio is required.
High-strength tooling and mold bases - blow-molding molds, jigs, fixtures and CNC machining stock that must stay dimensionally stable under load.
High-performance bicycle and light-vehicle components - frames and structural parts where weight saving matters.
Heavy-duty machinery shafts, gears and structural members - where a strong, light part replaces steel.
Because of its stress-corrosion tendency, 7A04 is not a good choice for long-term marine or continuously wet service. For those conditions, 5083 or 6061 is the practical alternative.
Export compliance and orders for 7A04 aluminum bar
Export-control note: 7A04 is a high-strength alloy subject to China's dual-use export control. GNEE supplies 7A04-T6 round bar in diameters up to 75 mm, which sits below the large-diameter high-strength control threshold (tensile strength ≥ 460 MPa with outside diameter greater than 75 mm) and can be exported after routine export-license screening. Diameters above 75 mm that meet the high-strength / large-diameter threshold are not offered for export. GNEE does not supply sanctioned parties or destinations.
| Item | Typical range or option |
|---|---|
| Alloy / temper | 7A04 - T6 (O, T74/T73 on request) |
| Product form | Extruded round bar, 10 – 75 mm diameter |
| Standards | GB/T 3191 (bar), GB/T 3190 (composition); dims per ANSI H35.2(M) |
| Mill certificate | EN 10204 3.1; 3.2 and third-party inspection on request |
| Export control | Dual-use screening required; diameters ≤75 mm exportable; >75 mm not offered |
| MOQ | Flexible - small lots negotiable |
| Lead time | 15 – 30 days |
| Incoterms | FOB / CIF |
| Payment | T/T, L/C |
About GNEE
GNEE has supplied aluminum mill products since 2008 and ships to more than 100 countries and regions.
Common sizes of high-strength and standard alloys are kept in stock, and small orders are accepted alongside full mill runs.
Every order ships with an EN 10204 3.1 mill certificate; 3.2 certificates and third-party inspection can be arranged.
Our technical team helps buyers select the right temper and size for the actual service condition, including export-control screening for controlled grades.
MOQ is flexible and typical lead time is 15 – 30 days, with FOB/CIF terms and T/T or L/C payment.
FAQ
What is 7A04 aluminum and how does it compare with 7075?
7A04 is a Chinese GB high-strength aluminum alloy in the Al-Zn-Mg-Cu family, often called super-duralumin. In the T6 temper its tensile strength (≥530 MPa for diameters above 22 mm) and yield strength (≥400 MPa) are in the same range as 7075-T6, so it is used as a domestic alternative where that strength class is required. It is a distinct GB grade (not an AA number) and is produced to GB/T 3191 rather than ASTM B211.
What tempers are available for 7A04 aluminum round bar?
The standard supply temper is T6 (solution heat-treated and artificially aged), which gives the highest strength. O (annealed) is available for severe forming. Overaged tempers such as T74/T73, which improve stress-corrosion resistance, can be arranged on request. Cert values for each temper are stated on the EN 10204 3.1 mill certificate.
Can 7A04-T6 aluminum bar be welded?
7A04-T6 has poor fusion-weldability: welded joints lose most of the parent strength and the heat-affected zone is prone to stress-corrosion cracking. For structures that must be welded, select a weldable grade such as 5083 or 6061. 7A04 parts are normally joined by mechanical fastening, machining, or bonding. Spot welding is acceptable for non-structural assemblies.
What diameters, lengths and tolerances does GNEE supply?
We supply 7A04-T6 round bar in diameters from 10 mm to 75 mm and lengths up to 6 m (cut to order). Diameter tolerance follows ANSI H35.2(M): ±0.23 mm for 12.50–25.00 mm, ±0.30 mm for 25.00–50.00 mm, ±0.61 mm for 50.00–75.00 mm (extruded, other-alloy column). Length tolerance is plus 4 to 7 mm up to 5,000 mm and plus 7 to 9 mm up to 10,000 mm. A cold-finished (drawn) option is offered for tighter diameter control.
Is 7A04-T6 aluminum bar exportable, and what is its export-control status?
7A04 is a high-strength alloy subject to China's dual-use export control. GNEE supplies 7A04-T6 round bar in diameters up to 75 mm, which sits below the large-diameter high-strength control threshold (tensile strength ≥460 MPa with outside diameter greater than 75 mm) and can be exported after routine export-license screening. Diameters above 75 mm that meet the high-strength/large-diameter threshold are not offered for export. GNEE does not supply sanctioned parties or destinations.
What certificate and test documentation do you provide?
Every shipment is delivered with an EN 10204 3.1 mill certificate showing heat number, composition and mechanical test results. Third-party inspection and 3.2 certificates can be arranged on request. Ultrasonic testing, sawing, peeling and precision turning are available as additional services.
