Alloy , Designation, and Composition
5A06 is a Chinese-designated aluminum-magnesium alloy registered in GB/T 3190 (chemical composition) and GB/T 3880 (plate, sheet, and strip). Its defining feature is the high magnesium content of 5.8-6.8%, the highest of the common 5xxx anti-rust alloys, which gives it outstanding strength, fatigue resistance, and corrosion resistance without heat treatment.
Internationally, 5A06 is broadly comparable to ISO AlMg6; the nearest European registration is EN AW-AlMg6 in EN 573-3. There is no exact ASTM or UNS equivalent, so buyers should specify 5A06 plus the governing Chinese standard in the contract and accept ISO AlMg6 as the closest cross-reference for design purposes.
Chemical Composition per GB/T 3190
| Element | Composition limit (weight %) |
|---|---|
| Magnesium Mg | 5.8 - 6.8 |
| Manganese Mn | 0.50 - 0.80 |
| Silicon Si | 0.40 max |
| Iron Fe | 0.40 max |
| Copper Cu | 0.10 max |
| Zinc Zn | 0.20 max |
| Titanium Ti | 0.02 - 0.10 |
| Beryllium Be | 0.0001 - 0.005 |
| Others (each / total) | 0.05 / 0.15 |
| Aluminum | Remainder |
The manganese addition refines the grain structure and raises strength, while the controlled beryllium content reduces oxidation during melting and welding. Like all 5xxx alloys, 5A06 is not heat-treatable; its strength comes from solid-solution hardening and cold work, which keeps the alloy stable and immune to quench-related distortion.
Mechanical Properties per GB/T 3880
Typical guaranteed values for 5A06 plate in the O and H112 tempers are a tensile strength Rm of 315 MPa, a 0.2% proof stress Rp0.2 of 155 MPa, and elongation of 16% (values differ slightly with thickness range). H112 is the as-fabricated temper for plate, with mechanical properties close to O. For thin sheet, H22, H24, H26, and H28 strain-hardened tempers provide progressively higher strength with reduced formability.
| Property | 5A06-O | 5A06-H112 |
|---|---|---|
| Thickness | 0.5 - 4.5 mm | 4.5 - 10 mm |
| Tensile strength Rm | 315 MPa | 315 MPa |
| Yield strength Rp0.2 | 155 MPa | 155 MPa |
| Elongation | 16% | 16% |
| Hardness | about 85 HB | about 85 HB |
Weldability and Fabrication
5A06 is one of the most weldable high-magnesium alloys. Argon-shielded processes - TIG, MIG, electron beam, plasma arc, and friction stir welding - all give sound joints, with welded joint strength typically reaching 90-95% of the parent metal, far better than heat-treatable alloys. The alloy also has excellent deep-drawing formability in the O condition for low-load parts such as fuel tanks and conduits. Note that in heavily strain-hardened tempers the alloy has lower plasticity, and machined surfaces benefit from sharp tools and adequate lubrication.
Applications
Aerospace and defense: launch vehicle body structures, missile parts, armor, and aircraft weldments, where the combination of high fatigue strength, light weight, and weldability is decisive. Marine: ship hull components, superstructures, and fittings exposed to seawater. Transport and pressure equipment: liquid tank trucks, refrigerated trucks, refrigerated containers, and pressure vessels requiring fire resistance, plus TV towers, drilling equipment, and subway light-rail structures. Formed parts: fuel tanks, gasoline and lubricating-oil conduits, and deep-drawn containers operating in liquid or gaseous media.
Supply Forms, Packaging, and Transport
5A06 is supplied as sheet (0.2-6 mm thick), plate (6-200 mm), and forged block (200-500 mm), in widths from 900 to 2650 mm and lengths up to 6 m, with cut-to-size and custom film (black, white, blue, or transparent, 50 or 80 microns) options. Surface treatments include mill finish, bright, polished, hairline, brush, sandblast, checkered, embossed, and etched.
Export packaging uses fumigated wooden pallets or crates with a fumigation certificate. Plates must be kept dry, separated from moisture and chemically active goods, padded at the bottom with at least 100 mm of dunnage, covered with waterproof cloth, and handled carefully to avoid collision damage during loading.
Frequently Asked Questions
Can 5A06 strength be increased by heat treatment? No. 5A06 is a non-heat-treatable alloy; artificial aging and quenching have no strengthening effect. Strength is developed through magnesium content, manganese, and cold work. Specify H1xx or H2xx tempers when higher strength is required in thin sections.
What is the difference between 5A06 and 5083? 5A06 carries more magnesium (5.8-6.8% vs 4.0-4.9% for 5083) and is generally stronger and harder, with slightly lower as-welded elongation. 5083 is more widely stocked internationally and has an extensive track record in shipbuilding under ASTM and EN standards.
Is 5A06 suitable for welded pressure vessels? Yes, within the design rules of the applicable pressure-vessel code. Its high welded joint efficiency (90-95% of parent strength) and corrosion resistance make it a standard choice for cryogenic and fire-resistant liquid transport equipment in the Chinese and CIS markets.
What welding filler is recommended for 5A06? Matching 5A06 filler wire is standard practice for maximum joint strength and color match. ER5356-type fillers can be used for many joints; for design-critical welds, qualify the procedure and filler against the governing specification.
Does 5A06 corrode in seawater? 5A06 has excellent resistance to seawater and marine atmospheres. Like other 5xxx alloys with more than about 3% magnesium, it must not be held for long periods at 65-175C in service, where sensitization could reduce stress-corrosion performance. Ambient marine service is fine.
Which standards govern 5A06 plate supply? Chemical composition follows GB/T 3190; plate, sheet, and strip follow GB/T 3880.2; and forging stock follows YS/T 479 and GB/T 4437 series. ISO AlMg6 and EN AW-AlMg6 are the closest international designations for cross-reference.
