Aluminum 5A12-O (Annealed)
Temper · default condition
GB 5A12
Most commonly stocked condition: maximum ductility for forming, bending and welding of high-Mg sheet/plate.
Values for the O condition
Other 5A12 tempers and conditions
5A12 is listed in 5 conditions; see the grade overview at 5A12.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Forging stock, billet and rough extrusion supplied without guaranteed mechanical properties, for subsequent working and annealing. | 205 | 395 | 15 | 95 HB | 25 % IACS |
ODefaultThis page Annealed | Most commonly stocked condition: maximum ductility for forming, bending and welding of high-Mg sheet/plate. | 210 | 400 | 18 | 95 HB | 25 % IACS |
Strain hardened from hot working only | Thick plate and extruded shapes supplied as hot-worked with guaranteed properties; used for machined aerospace structural parts. | 230 | 410 | 15 | 100 HB | 25 % IACS |
Strain hardened, half hard | Cold-rolled half-hard sheet when higher strength and stiffness of thin skins is needed and only mild forming is required. | 350 | 460 | 8 | 120 HB | — |
Strain hardened, full hard | Fully cold-worked strip/sheet for flat, high-strength, non-formed parts; lowest ductility and highest SCC sensitivity. | 440 | 520 | 4 | 140 HB | 24 % IACS |
What is 5A12-O?
5A12-O is 5A12 in the O temper — most commonly stocked condition: maximum ductility for forming, bending and welding of high-Mg sheet/plate. 5A12-O has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 56% of aluminum grades. Elongation at break is 18% and the elastic modulus is 69 GPa (10 Msi). 5A12-O has a density of 2.6 g/cm³ (0.0939 lb/in³), lighter than 97% of aluminum grades. It melts at 565°C (1,049 °F).
Advantages
- Ductile — tolerates forming and impact — 18%, better than 86% of aluminum grades
- Forms and bends easily — 65/100, better than 80% of aluminum grades
- Tough — resists crack growth — 30 MPa·√m (27.3 ksi·√in), better than 76% of aluminum grades
Limitations
- Limited service temperature — 65°C (149 °F), worse than 97% of aluminum grades
- Low electrical conductivity — 25 % IACS, worse than 92% of aluminum grades
- Poor heat conductor — 105 W/m·K (60.7 BTU/hr·ft·°F), worse than 91% of aluminum grades
- Difficult to machine — 42/100, worse than 77% of aluminum grades
5A12-O properties
Typical room-temperature values for 5A12-O; 12 are specific to this condition. Other listed values are 5A12 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
5A12-O has a density of 2.6 g/cm³ (0.0939 lb/in³), lighter than 97% of aluminum grades. It melts at 565°C (1,049 °F).
Mechanical13
5A12-O has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 56% of aluminum grades. Elongation at break is 18% and the elastic modulus is 69 GPa (10 Msi).
Thermal6
5A12-O is rated for continuous service to 65°C (149 °F). It conducts heat at 105 W/m·K (60.7 BTU/hr·ft·°F), worse than 91% of aluminum grades. Thermal expansion is 25 µm/m·K (13.9 µin/in·°F).
Electrical3
5A12-O conducts electricity at 25 % IACS, worse than 92% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), better than 67% of aluminum grades.
Sustainability4
Producing a kilogram of 5A12-O takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 20%.
Manufacturability8
5A12-O's machinability is fair (42/100, worse than 77% of aluminum grades); weldability very good (72/100); formability good (65/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 5A12-O
Is 5A12 easy to machine?
Machine with sharp polished-flute carbide tools, high rake, high speed and generous flood coolant/lubricant; annealed material is gummy and forms built-up edge, cold-worked tempers cut cleaner.
Can 5A12 be welded?
Readily GTAW/GMAW welded with 5356 or 5556 (high-Mg) filler under clean argon; avoid 4000 series Si fillers (brittle Mg2Si) and keep interpass temperature low to limit sensitization; as-welded HAZ strength ≈ O temper.
Can 5A12 be formed, bent or molded?
Form in the O temper — the alloy work-hardens very fast; use generous bend radii (≥2–3 t), warm forming 200–250 °C for severe shapes, and intermediate anneal ~340–380 °C with slow cool.
What surface finishes work on 5A12?
Responds well to clear sulphuric/chromic anodizing and chromate/trivalent conversion coatings; alkaline etch times must be short because of high Mg; not furnace-brazeable, mechanical polish then anodize for decorative finish.
5A12 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 |
|---|---|---|
| Mgprimary solid-solution strengthener | 8.3 – 9.6 | 9 |
| Mngrain-structure control | 0.4 – 0.8 | 0.6 |
| Tigrain refiner | 0.05 – 0.15 | 0.1 |
| Siimpurity | ≤ 0.3 | — |
| Feimpurity | ≤ 0.3 | — |
| Cuimpurity | ≤ 0.05 | — |
| Znimpurity | ≤ 0.2 | — |
| Bemelt oxidation control (optional addition) | ≤ 0.01 | 0 |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
5A12-O — frequently asked
What is 5A12-O used for?
5A12-O is typically used for aerospace structural components, high-strength welded assemblies, airframe sheet and plate parts, welded frames and brackets, riveted structural fittings and highly loaded lightweight covers. In short: highest-strength Al-Mg grade; hardest 5000 series in library; limited availability, low formability.
What is the yield strength of 5A12-O?
5A12-O has a typical yield strength of 210 MPa (30.5 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 56% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is 5A12-O easy to machine?
Not especially — machinability is rated fair (42/100, worse than 77% of aluminum grades). Machine with sharp polished-flute carbide tools, high rake, high speed and generous flood coolant/lubricant; annealed material is gummy and forms built-up edge, cold-worked tempers cut cleaner.
Can 5A12-O be welded?
Yes — weldability is rated very good (72/100). Readily GTAW/GMAW welded with 5356 or 5556 (high-Mg) filler under clean argon; avoid 4000 series Si fillers (brittle Mg2Si) and keep interpass temperature low to limit sensitization; as-welded HAZ strength ≈ O temper.
What surface finishes work on 5A12-O?
Responds well to clear sulphuric/chromic anodizing and chromate/trivalent conversion coatings; alkaline etch times must be short because of high Mg; not furnace-brazeable, mechanical polish then anodize for decorative finish.
Can 5A12-O be formed, bent or molded?
Form in the O temper — the alloy work-hardens very fast; use generous bend radii (≥2–3 t), warm forming 200–250 °C for severe shapes, and intermediate anneal ~340–380 °C with slow cool.
What is the maximum service temperature of 5A12-O?
5A12-O is rated for continuous use to about 65°C (149 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 5A12-O and 5A12-H18?
O is the default condition — most commonly stocked condition: maximum ductility for forming, bending and welding of high-Mg sheet/plate. H18: fully cold-worked strip/sheet for flat, high-strength, non-formed parts; lowest ductility and highest SCC sensitivity. Yield strength is 210 MPa in O versus 440 MPa in H18.
Sources
- ASM Handbook Vol.2: Properties and Selection — Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol.13B: Corrosion — Materials (Al-Mg sensitization/SCC) — ASM International (2005)
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.