A201 aluminum is an aluminum-copper-silver casting alloy and the highest-strength aluminum alloy commonly produced in sand and permanent mold. It contains about 4 to 5% copper and 0.4 to 1.0% silver, and 201-type alloys in the T7 temper are specified at minimums of 60 ksi tensile and 50 ksi yield strength for sand castings under ASTM B26. Silver raises the cost and the alloy is difficult to cast, so A201 is used for weight-critical parts where a lower-strength alloy won’t carry the load.
A201 sits at the top of the aluminum casting strength chart, with typical T6 values around 70 ksi tensile. It shares most of its chemistry with A206, and the silver addition is what pushes its strength higher. That makes the A201 vs A206 decision one of the first questions in any high-strength aluminum casting program.
This guide is for engineers and procurement managers specifying high-strength castings for defense, aerospace, and other demanding applications. It covers A201 composition, tempers and properties, how it compares with A206, where it’s used, and what to ask a foundry. For every alloy LeClaire pours, see our aluminum casting alloys guide.
What is A201 aluminum made of?
A201 is an aluminum-copper alloy with a deliberate silver addition and very low impurities. The “A” prefix marks tighter iron and silicon limits than standard 201.
- Copper (about 4 to 5%): The main strengthening element, as in A206.
- Silver (0.4 to 1.0%): Works with magnesium to produce a finer, denser distribution of strengthening precipitates during aging. This is the source of A201’s strength advantage.
- Magnesium, manganese, and titanium (small additions): Magnesium supports hardening, manganese controls iron-bearing phases, and titanium refines grain size.
- Iron and silicon (held to about 0.10% and 0.05% max): Kept very low to protect ductility and toughness.
What are A201’s properties by temper?
A201 must be heat treated, and the temper choice trades peak strength against stress corrosion resistance and dimensional stability.
- T7, sand cast (ASTM B26 minimum for 201): 60 ksi (414 MPa) tensile, 50 ksi (345 MPa) yield, 3% elongation.
- T6 (typical published values for 201): about 70 ksi (485 MPa) tensile and 63 ksi (435 MPa) yield. This is peak strength.
- T7 (typical published values for 201): about 67 ksi (460 MPa) tensile and 60 ksi (415 MPa) yield. The overaged T7 temper gives up a little strength for better resistance to stress corrosion cracking and better dimensional stability.
- T4 and T43: Lower-strength tempers used when ductility and toughness take priority.
Because A201’s value comes from its heat treat response, temper control is part of the alloy decision. LeClaire handles heat treating in-house. Our heat treatment process guide covers what T4, T6, and T7 mean.
A201 vs A206: which high-strength alloy should you choose?
Choose A201 when maximum strength justifies the cost of silver. Choose A206 when you need high strength and toughness at a lower cost. For many structural parts A206 is enough, and A201 is reserved for designs that need every ksi.
- Strength: A201 is stronger. Typical T7 tensile strength runs about 67 ksi for 201 compared with about 63 ksi for A206, and the gap is larger in yield strength.
- Cost: A201 costs more because silver is an alloying element. Remelt and scrap handling also have to keep silver-bearing material separate.
- Ductility and toughness: A206 generally offers higher elongation, especially in the T4 temper.
- Castability: Both alloys are prone to hot tearing and pour less easily than aluminum-silicon alloys. Neither suits a foundry without strong process control.
- Stress corrosion cracking: Both are sensitive, and T7 is the usual choice for both when a part will see sustained stress in a corrosive environment.
- Typical use: A206 is common in structural vehicle and equipment parts. A201 is more common in aerospace and defense castings where strength-to-weight is the deciding factor.
For A206 tempers, properties, and its use as a ductile iron replacement, see our A206 aluminum guide.
Where is A201 aluminum used?
A201 is used where a casting has to carry the highest loads aluminum can handle and weight savings justify the material cost. Defense and aerospace are the main markets.
- Military vehicle and weapon components: Structural castings, mounts, and housings that take high loads and shock.
- Aerospace structural fittings: Castings where strength-to-weight drives the design and the alloy replaces heavier materials.
- Gear and transmission housings: Housings that must stay rigid under high torque loads.
- High-performance equipment: Parts where a lower-strength alloy would force thicker walls and added weight.
LeClaire supports military and defense programs with ISO 9001:2015 certified quality systems, in-house tooling, and casting and machining under one roof.
What should you ask a foundry before sourcing A201 castings?
A201 is one of the least forgiving aluminum alloys to cast, so supplier capability matters as much as the alloy choice.
- How do you design tooling to prevent hot tearing? Solidification simulation, gating and risering strategy, and core design all affect whether the casting tears as it shrinks.
- How do you handle silver-bearing material? Ask how the foundry segregates A201 returns and scrap and verifies chemistry on every heat.
- Who controls heat treatment? In-house solution treating and aging with property testing is the best way to hit T6 or T7 targets consistently.
- What inspection will the part get? Agree on dimensional checks and any radiographic or other non-destructive testing before production.
- Who machines the casting? A single-source supplier removes the handoff between foundry and machine shop.
Frequently asked questions
Why does A201 aluminum contain silver?
Silver changes how strengthening precipitates form during aging, producing a finer and denser distribution than copper and magnesium alone. That raises strength above A206 and other aluminum-copper casting alloys.
Is A201 the strongest aluminum casting alloy?
Yes. Among aluminum alloys commonly produced in sand and permanent mold, A201 reaches the highest strength, with typical T6 tensile strength around 70 ksi. Its cost and casting difficulty keep it limited to parts that need that strength.
What is the difference between 201 and A201?
A201 has tighter limits on iron and silicon than standard 201. Lower impurities improve ductility and toughness in the finished casting.
Is A201 more expensive than A206?
Yes. The silver content raises material cost, and silver-bearing returns must be handled separately. Programs that don’t need A201’s extra strength usually choose A206.
Does A201 need heat treatment?
Yes. A201 reaches its useful properties only after solution heat treatment and aging. T7 is the common choice for parts exposed to stress and corrosion, and T6 is used when peak strength matters most.
Get a quote on your A201 castings
A201 aluminum is the strongest aluminum alloy commonly sand and permanent mold cast, and the right choice when a defense or aerospace part needs more strength than A206 can deliver. LeClaire Manufacturing reviews high-strength parts for castability before tooling is built, then pours, heat treats, and machines them in one facility. Request a quote to have your A201 part reviewed.