Aluminum 2A21
GB 2A21
2A21 (LY21) is a heat-resistant Al-Cu rivet alloy from the GB 2000-series family, supplied in O, T4, T6 and T62 and functionally close to 2219.
Reference datasheet — 2A21 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the T4 condition
2A21 tempers and conditions
2A21 is supplied in 4 conditions, soft to hard. T4 is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition for wire drawing, cold heading of large rivets and intermediate processing before solution treatment. | 80 | 175 | 18 | 45 HB | 44 % IACS |
T4Default Solution heat treated and naturally aged | Standard supply condition for rivet wire — driven cold within the specified time window after quenching, then ages in place. | 210 | 350 | 16 | 100 HB | 28 % IACS |
T6, heat treated by the user | Used when parts are formed or machined soft and then re-solution-treated and aged to full heat-resistant strength. | 275 | 390 | 11 | 115 HB | 30 % IACS |
Solution heat treated and artificially aged | Choose when the joint or part must keep strength at 200–250 °C; peak-aged θ' structure is thermally stable but ductility drops. | 290 | 400 | 10 | 118 HB | 30 % IACS |
What is 2A21?
2A21 (LY21) is a heat-resistant Al-Cu rivet alloy from the GB 2000-series family, supplied in O, T4, T6 and T62 and functionally close to 2219. Engineers specify it where riveted joints run hot: the default heat-treated condition gives 350 MPa tensile, 210 MPa yield, 16% elongation and 100 HB, with usable service to 175 °C, and it is normally bought as rivet wire, rod and bar. Conductivity is moderate (116 W/m·K, 28% IACS) and corrosion resistance is low (score 33), so coatings, sealant or alclad faying surfaces are required; 2219 is the nearest broadly stocked substitute. 2A21 has a density of 2.84 g/cm³ (0.103 lb/in³), heavier than 93% of aluminum grades. It melts at 543°C (1,009 °F). 2A21 has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 350 MPa (50.8 ksi) — stronger than 56% of aluminum grades. Elongation at break is 16% and the elastic modulus is 73 GPa (10.6 Msi).
What is 2A21 used for?
- High-temperature aircraft rivets
- Engine mount fasteners
- Firewall and cowling riveted joints
- Riveted splices near heat sources
- Solid rivet wire and rod stock
- Riveted ducting and shroud assemblies
Advantages
- Ductile — tolerates forming and impact — 16%, better than 84% of aluminum grades
- Tough — resists crack growth — 32 MPa·√m (29.1 ksi·√in), better than 83% of aluminum grades
- High service temperature — 175°C (347 °F), better than 83% of aluminum grades
Limitations
- Needs corrosion protection — 33/100, worse than 91% of aluminum grades
- Poor heat conductor — 116 W/m·K (67 BTU/hr·ft·°F), worse than 84% of aluminum grades
- Low electrical conductivity — 28 % IACS, worse than 82% of aluminum grades
2A21 properties
Typical room-temperature values for 2A21-T4; bars are the position among aluminum grades.
Physical3
2A21 has a density of 2.84 g/cm³ (0.103 lb/in³), heavier than 93% of aluminum grades. It melts at 543°C (1,009 °F).
Mechanical13
2A21 has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 350 MPa (50.8 ksi) — stronger than 56% of aluminum grades. Elongation at break is 16% and the elastic modulus is 73 GPa (10.6 Msi).
Thermal6
2A21 is rated for continuous service to 175°C (347 °F). It conducts heat at 116 W/m·K (67 BTU/hr·ft·°F), worse than 84% of aluminum grades. Thermal expansion is 22.3 µm/m·K (12.4 µin/in·°F).
Electrical3
2A21 conducts electricity at 28 % IACS, worse than 82% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (33/100), worse than 91% of aluminum grades.
Sustainability4
Producing a kilogram of 2A21 takes about 210 MJ of energy and emits 12.5 kg of CO₂ — more than 88% of aluminum grades. Typical recycled content is 15%.
Manufacturability7
2A21's machinability is good (58/100, worse than 54% of aluminum grades); weldability good (60/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the aluminum family
Yield strength against density for every aluminum grade FabDigit runs. 2A21 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 2A21
Is 2A21 easy to machine?
Machines like other 2000-series heat-treated Al — sharp uncoated carbide, high speed, generous coolant; T4/T6 chips well, annealed material is gummy.
Can 2A21 be welded?
One of the better-welding 2000-series types (2219-like): GTAW/GMAW with ER2319 filler, no hot-cracking filler needed from 4000 series; post-weld re-solution + age restores strength, do not weld in T6 without requalifying joint properties.
Can 2A21 be formed, bent or molded?
Cold-head or upset rivets in the freshly quenched T4 window (or refrigerate to hold the temper); annealed stock forms readily but requires full re-heat-treatment afterwards.
2A21 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Cumain strengthening element, Al₂Cu/θ' | 5.8 – 6.8 | 6.3 |
| Mn | 0.2 – 0.4 | 0.3 |
| Tigrain refinement | 0.1 – 0.2 | 0.15 |
| Vraises recrystallisation/thermal stability | 0.05 – 0.15 | 0.1 |
| ZrAl₃Zr dispersoids | 0.1 – 0.25 | 0.18 |
| Siimpurity | ≤ 0.2 | |
| Feimpurity | ≤ 0.3 | |
| Mgimpurity | ≤ 0.02 | |
| Znimpurity | ≤ 0.1 | |
| Others (each)total ≤ 0.15 | ≤ 0.05 | |
| Albalance, per GB/T 3190 Al-Cu-Mn-Ti-V-Zr type (2219 analogue) — verify against mill certificate | balance |
What surface finishes work on 2A21?
Chromic or sulfuric anodize plus chromate/primer for corrosion protection — expect a dull yellow-grey film; alclad or wet-installed sealant is standard where joints see moisture, and avoid direct contact with steel or carbon fibre.
Surface treatments FabDigit runs on aluminum parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Equivalent designations
Standards and trade names that resolve to Aluminum 2A21 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- GB (China)
- LY21
How much does 2A21 cost?
2A21 is a premium-cost aluminum ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
2A21 — frequently asked
What is 2A21 used for?
2A21 is typically used for high-temperature aircraft rivets, engine mount fasteners, firewall and cowling riveted joints, riveted splices near heat sources, solid rivet wire and rod stock and riveted ducting and shroud assemblies. In short: best-welding 2000-series rivet alloy; strength to 175 °C; 2219-class rivet stock.
What is the yield strength of 2A21?
2A21 has a typical yield strength of 210 MPa (30.5 ksi) and a tensile strength of 350 MPa (50.8 ksi) — stronger than 56% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 2A21 easy to machine?
Reasonably — machinability is rated good (58/100, worse than 54% of aluminum grades). Machines like other 2000-series heat-treated Al — sharp uncoated carbide, high speed, generous coolant; T4/T6 chips well, annealed material is gummy.
Can 2A21 be welded?
Yes — weldability is rated good (60/100). One of the better-welding 2000-series types (2219-like): GTAW/GMAW with ER2319 filler, no hot-cracking filler needed from 4000 series; post-weld re-solution + age restores strength, do not weld in T6 without requalifying joint properties.
What surface finishes work on 2A21?
Chromic or sulfuric anodize plus chromate/primer for corrosion protection — expect a dull yellow-grey film; alclad or wet-installed sealant is standard where joints see moisture, and avoid direct contact with steel or carbon fibre.
Can 2A21 be formed, bent or molded?
Cold-head or upset rivets in the freshly quenched T4 window (or refrigerate to hold the temper); annealed stock forms readily but requires full re-heat-treatment afterwards.
What is the maximum service temperature of 2A21?
2A21 is rated for continuous use to about 175°C (347 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 2A21-T4 and 2A21-O?
T4 is the default condition — standard supply condition for rivet wire — driven cold within the specified time window after quenching, then ages in place. O: softest condition for wire drawing, cold heading of large rivets and intermediate processing before solution treatment. Yield strength is 210 MPa in T4 versus 80 MPa in O.
How much does 2A21 cost?
2A21 is a premium-cost aluminum ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (2219 data used as analogue) — ASM International (1990)
- MMPDS-17 (2219 property basis) — Battelle/FAA (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.