A206 aluminum is a high-strength aluminum-copper casting alloy with 4.2 to 5.0% copper and very low iron and silicon (0.10% and 0.05% max). Heat treated to the T7 temper, it reaches roughly 63 ksi (440 MPa) tensile and 50 ksi (350 MPa) yield strength, enough to replace ductile iron in many structural parts at well under half the weight. The tradeoff is a harder casting process: A206 is prone to hot tearing and needs tight foundry control.
A206 is one of the strongest aluminum alloys poured in sand and permanent mold, and it pairs that strength with good toughness and elongation. That combination is why defense, heavy truck, and aerospace programs specify it for structural brackets, suspension parts, and housings that take shock loads.
This guide is for engineers and procurement managers evaluating A206 castings. It covers composition, the T4 and T7 tempers, how A206 compares with A356 and ductile iron, where it’s used, and what to ask a foundry before you place the order. For every alloy LeClaire pours, see our aluminum casting alloys guide.
What is A206 aluminum made of?
A206 gets its strength from copper and its toughness from unusually low iron and silicon. The “A” prefix marks tighter impurity limits than standard 206.
- Copper (4.2 to 5.0%): The main strengthening element. It forms the precipitates that harden the alloy during heat treatment.
- Magnesium (0.15 to 0.35%): Supports the precipitation hardening response.
- Manganese (0.20 to 0.50%): Ties up the small amount of iron present in a less harmful form.
- Titanium (0.15 to 0.30%): Refines grain size, which helps reduce hot tearing during solidification.
- Iron (0.10% max) and silicon (0.05% max): Held very low. This is what separates A206 from 206 and gives it higher ductility and toughness.
A206-T4 vs A206-T7: which temper fits your part?
Choose T4 when the part needs ductility and fatigue endurance. Choose T7 when it needs maximum strength and better resistance to stress corrosion cracking. A206 is always used heat treated.
- A206-T4 (typical): about 56 ksi (390 MPa) tensile and 36 ksi (250 MPa) yield, with high elongation. The casting is solution heat treated, quenched, and naturally aged.
- A206-T7 (typical): about 63 ksi (440 MPa) tensile and 50 ksi (350 MPa) yield. T7 is produced by aging a T4 casting for about 5 hours at 190°C (374°F).
- What aging changes: Going from T4 to T7 typically raises yield strength by about 40% and cuts elongation to one-half or one-third of the T4 value.
- Stress corrosion cracking: Aluminum-copper alloys are sensitive to stress corrosion cracking. The overaged T7 temper is the usual choice when a part will see sustained stress in a corrosive environment.
Temper control matters as much as alloy chemistry with A206. LeClaire performs heat treating in-house, and our heat treatment process guide explains how solution treating and aging work.
How does A206 compare with A356 and ductile iron?
A206 is much stronger than A356 and comes close to ferritic ductile iron in tensile properties, at well under half the weight of iron. It gives up some castability and corrosion resistance to get there.
- Strength vs A356: Sand-cast A356-T6 has an ASTM B26 minimum of 34 ksi tensile and 24 ksi yield. In published comparisons of castings poured in both alloys, 206-T7 showed about 50% higher yield strength than A356-T6, with higher elongation as well.
- Weight vs ductile iron: Aluminum weighs roughly 40% as much as iron, so an A206 part redesigned from ductile iron can cut weight substantially while carrying similar loads.
- Castability: A356 is far easier to pour. A206’s low silicon reduces fluidity, and its long freezing range makes it prone to hot tearing.
- Corrosion resistance: Aluminum-silicon alloys like A356 resist corrosion better. A206 parts in harsh environments are usually painted or coated.
- Cost: A206 costs more to produce than A356 because of tighter chemistry limits, more demanding foundry practice, and higher scrap risk.
Why do military and defense programs use A206?
Defense programs use A206 to take weight out of vehicles, weapon systems, and field equipment without losing the strength and toughness those parts need under shock and vibration. Every pound saved on a military vehicle or a carried system has a direct payoff in mobility and payload.
- Vehicle structural parts: Brackets, mounts, and suspension components converted from iron or steel.
- Weapon and equipment housings: Castings that must survive repeated shock loads.
- Aerospace-type fittings: Structural castings where strength-to-weight drives the design.
LeClaire supports military and defense customers with ISO 9001:2015 certified quality systems and single-source casting and machining. If your part needs the highest strength available and can carry the cost of silver, compare A206 with the silver-bearing alloy in our A201 aluminum guide.
What should you ask a foundry before sourcing A206 castings?
A206 rewards foundries with tight process control and punishes those without it. These questions separate the two.
- How do you prevent hot tearing? Look for solidification simulation, deliberate gating and risering, and core design that lets the casting shrink without restraint.
- How do you control melt quality? Degassing, grain refinement, and chemistry verification should be standard practice.
- Who heat treats, and how is temper verified? In-house heat treating with property testing shortens lead times and removes a handoff.
- What inspection fits this part? Agree on dimensional inspection and any radiographic or other non-destructive testing up front.
- Who machines the casting? A206 machines well, and a single-source supplier keeps casting and machining accountability in one place.
Frequently asked questions
Is A206 the strongest aluminum casting alloy?
A206 is among the strongest aluminum alloys used for sand and permanent mold castings. The silver-bearing A201 alloy reaches higher strength in the T6 and T7 tempers, but A206 avoids the cost of silver and typically offers better toughness.
What is the difference between 206 and A206?
A206 has tighter limits on iron and silicon than standard 206. The lower impurity levels improve ductility and toughness, which is why A206 is the version usually specified for structural castings.
Can A206 aluminum be sand cast?
Yes. A206 can be produced in sand casting and permanent mold casting. Both require careful gating, feeding, and core design to manage hot tearing.
Is A206 aluminum corrosion resistant?
A206 has lower corrosion resistance than aluminum-silicon or aluminum-magnesium alloys because of its copper content. Parts exposed to moisture, salt, or chemicals are usually protected with paint or another coating, and T7 is preferred where stress corrosion cracking is a concern.
Can A206 replace ductile iron?
For many structural parts, yes. A206-T7 approaches the tensile properties of ferritic ductile iron, and most conversions adjust wall thickness and ribbing to suit aluminum rather than requiring a complete redesign.
Get a quote on your A206 castings
A206 aluminum delivers strength close to ductile iron at well under half the weight, which makes it a strong fit for defense and structural parts where every pound counts. LeClaire Manufacturing pours A206 with simulation-backed tooling, in-house heat treating, and in-house machining, so one supplier owns the part from pattern to finished casting. Request a quote to have your A206 part reviewed.