Aluminum 2098-T84
Precip hard
AA 2098 · UNS A92098
T84 = solution heat treated, cold worked and artificially aged
Slightly de-rated ageing practice used when damage tolerance and toughness are traded against a small strength loss.
Values for the T84 condition
Other 2098 tempers and conditions
2098 is listed in 8 conditions; see the grade overview at 2098.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition for maximum forming or intermediate mill processing before re-solution treatment. | 140 | 265 | 17 | 70 HB | 38 % IACS |
T3, stress relieved by stretching | Stress-relieved plate/sheet stock for machining or forming ahead of final artificial ageing; low residual stress and stable dimensions. | 290 | 400 | 15 | 112 HB | 29 % IACS |
Solution heat treated, cold worked and naturally aged | Sheet condition supplied for forming/stretch operations that will be finished by artificial ageing to a T8 temper. | 300 | 410 | 14 | 115 HB | 28 % IACS |
T851Default T8, stress relieved by stretching | Default aerospace plate condition: low residual stress for heavy machining of bulkheads and ribs with peak-aged strength. | 490 | 525 | 8 | 150 HB | 30 % IACS |
T84This page Solution heat treated, cold worked and artificially aged | Slightly de-rated ageing practice used when damage tolerance and toughness are traded against a small strength loss. | 495 | 535 | 9 | 150 HB | 31 % IACS |
Solution heat treated, cold worked and artificially aged | Standard peak-strength sheet temper for fuselage skins and panels where strength plus fatigue-crack-growth resistance dominate. | 505 | 545 | 8 | 155 HB | 30 % IACS |
Solution heat treated, cold worked and artificially aged | Choose when maximum yield strength in thin sheet is required and toughness demands are moderate. | 520 | 555 | 7 | 158 HB | 32 % IACS |
Solution heat treated, cold worked and artificially aged | Highest-strength registered sheet condition; used where static strength governs and ductility/toughness margins are large. | 535 | 570 | 6 | 165 HB | 33 % IACS |
What is 2098-T84?
2098-T84 is 2098 in the T84 condition — slightly de-rated ageing practice used when damage tolerance and toughness are traded against a small strength loss. 2098-T84 has a yield strength of 495 MPa (71.8 ksi) and a tensile strength of 535 MPa (77.6 ksi) — stronger than 96% of aluminum grades. Elongation at break is 9% and the elastic modulus is 76 GPa (11 Msi). 2098-T84 has a density of 2.7 g/cm³ (0.0975 lb/in³), lighter than 59% of aluminum grades. It melts at 545°C (1,013 °F). T851 is the default condition FabDigit quotes; T84 is available on request or by drawing note.
Advantages
- High strength — 495 MPa (71.8 ksi), better than 96% of aluminum grades
- Tough — resists crack growth — 36 MPa·√m (32.8 ksi·√in), better than 93% of aluminum grades
Limitations
- Poor heat conductor — 100 W/m·K (57.8 BTU/hr·ft·°F), worse than 93% of aluminum grades
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
2098-T84 properties
Typical room-temperature values for 2098-T84; 20 are specific to this condition. Other listed values are 2098 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
2098-T84 has a density of 2.7 g/cm³ (0.0975 lb/in³), lighter than 59% of aluminum grades. It melts at 545°C (1,013 °F).
Mechanical13
2098-T84 has a yield strength of 495 MPa (71.8 ksi) and a tensile strength of 535 MPa (77.6 ksi) — stronger than 96% of aluminum grades. Elongation at break is 9% and the elastic modulus is 76 GPa (11 Msi).
Thermal6
2098-T84 is rated for continuous service to 120°C (248 °F). It conducts heat at 100 W/m·K (57.8 BTU/hr·ft·°F), worse than 93% of aluminum grades. Thermal expansion is 22.3 µm/m·K (12.4 µin/in·°F).
Electrical3
2098-T84 conducts electricity at 31 % IACS, worse than 68% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (44/100), worse than 65% of aluminum grades.
Sustainability4
Producing a kilogram of 2098-T84 takes about 215 MJ of energy and emits 13.5 kg of CO₂ — more than 93% of aluminum grades. Typical recycled content is 5%.
Manufacturability7
2098-T84's machinability is good (64/100, better than 58% of aluminum grades); weldability poor (25/100); formability poor (22/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 2098-T84
Is 2098 easy to machine?
Machines like 2024-T851 with sharp carbide, high speed and flood coolant; Li/Zr constituents are mildly abrasive and thin machined webs can distort unless a stress-relieved (T351/T851) plate is used.
Can 2098 be welded?
Fusion welding is crack- and porosity-sensitive because of Li oxidation; friction-stir welding or mechanical fastening (rivets/bolts) is the normal joining route.
Can 2098 be formed, bent or molded?
Form in T3/T351 then age to T8-type tempers; peak-aged material has limited bend ductility and marked anisotropy between L and LT directions.
What surface finishes work on 2098?
Alkaline clean and deoxidize, then chromic/sulfuric or tartaric-sulfuric anodize plus epoxy primer; conversion coating alone is inadequate for chloride service and bare surfaces should not be left unprotected.
2098 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 |
|---|---|---|
| Cu | 3.2 – 3.8 | 3.5 |
| Liprincipal density-reducing addition | 0.8 – 1.3 | 1.05 |
| Mg | 0.25 – 0.8 | 0.5 |
| Agpromotes fine T1/Ω-type precipitation | 0.25 – 0.6 | 0.4 |
| Zrgrain-structure control | 0.04 – 0.18 | 0.11 |
| Mn | ≤ 0.35 | — |
| Zn | ≤ 0.35 | — |
| Fe | ≤ 0.15 | — |
| Si | ≤ 0.12 | — |
| Ti | ≤ 0.1 | — |
| Others (each)others total 0.15 max | ≤ 0.05 | — |
| Al | balance | — |
2098-T84 — frequently asked
What is 2098-T84 used for?
2098-T84 is typically used for aircraft plate for machined structure, structural fittings, wing skin and rib components, machined bulkheads and frames, lightweight aerospace brackets and fuselage substructure plate. In short: third-generation Al-Cu-Li plate; high strength-to-weight ratio; machines like 2024-T851.
What is the yield strength of 2098-T84?
2098-T84 has a typical yield strength of 495 MPa (71.8 ksi) and a tensile strength of 535 MPa (77.6 ksi) — stronger than 96% of aluminum grades. Strength varies by condition: see the 8 listed tempers.
Is 2098-T84 easy to machine?
Reasonably — machinability is rated good (64/100, better than 58% of aluminum grades). Machines like 2024-T851 with sharp carbide, high speed and flood coolant; Li/Zr constituents are mildly abrasive and thin machined webs can distort unless a stress-relieved (T351/T851) plate is used.
Can 2098-T84 be welded?
Not readily — weldability is rated poor (25/100). Fusion welding is crack- and porosity-sensitive because of Li oxidation; friction-stir welding or mechanical fastening (rivets/bolts) is the normal joining route.
What surface finishes work on 2098-T84?
Alkaline clean and deoxidize, then chromic/sulfuric or tartaric-sulfuric anodize plus epoxy primer; conversion coating alone is inadequate for chloride service and bare surfaces should not be left unprotected.
Can 2098-T84 be formed, bent or molded?
Form in T3/T351 then age to T8-type tempers; peak-aged material has limited bend ductility and marked anisotropy between L and LT directions.
What is the maximum service temperature of 2098-T84?
2098-T84 is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 2098-T851 and 2098-O?
T851 is the default condition — default aerospace plate condition: low residual stress for heavy machining of bulkheads and ribs with peak-aged strength. O: softest condition for maximum forming or intermediate mill processing before re-solution treatment. Yield strength is 490 MPa in T851 versus 140 MPa in O.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- MMPDS Metallic Materials Properties Development and Standardization (Al-Li alloy chapters) — Battelle/FAA (2023)
- Third-generation Al-Li plate and sheet product data — Alcoa / Arconic / Constellium (2020)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.