Aluminum 7108
AA 7108
7108 is a medium-strength, weldable Al-Zn-Mg extrusion alloy with no significant copper addition, supplied in F, O, T4, T5, T6, T651, T7, T76, T79 and as-welded condition.
Reference datasheet — 7108 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 T6 condition
7108 tempers and conditions
7108 is supplied in 10 conditions, soft to hard. T6 is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition for severe forming or straightening before re-heat-treatment. | 75 | 155 | 20 | 45 HB | 39 % IACS |
As fabricated | Mill state of press-exit material sold for further heat treatment or as non-structural sections. | 150 | 250 | 16 | 70 HB | 34 % IACS |
Solution heat treated and naturally aged | Use when sections must be bent, roll-formed or stretch-bent before final artificial aging. | 175 | 280 | 18 | 80 HB | 30 % IACS |
As-welded deposit | Design basis for welded joints in T6 profiles; strength largely recovers after several weeks of natural aging. | 205 | 290 | 10 | 85 HB | 32 % IACS |
Cooled from hot working and artificially aged | Cheapest strengthened condition for press-quenchable profiles where T6 dimensional accuracy is not required. | 295 | 335 | 11 | 100 HB | 33 % IACS |
Solution heat treated and overaged (stabilized) | Pick for thick welded sections or corrosive/humid service where SCC risk outweighs 10 % strength loss. | 295 | 335 | 13 | 100 HB | 37 % IACS |
Overaged for exfoliation-corrosion resistance | Intermediate overage: better exfoliation/SCC resistance than T6 with most of its strength. | 315 | 350 | 12 | 105 HB | 35 % IACS |
T6Default Solution heat treated and artificially aged | Default stocked condition: maximum strength for welded structural profiles and crash members. | 340 | 370 | 11 | 110 HB | 33 % IACS |
T6, stress relieved by stretching | Choose when machined parts must stay dimensionally stable after heavy stock removal. | 345 | 375 | 10 | 112 HB | 33 % IACS |
Very slightly overaged | Automotive bumper-beam/crash-box temper: near-T6 strength with improved bendability and crash folding behaviour. | 355 | 385 | 12 | 112 HB | 34 % IACS |
What is 7108?
7108 is a medium-strength, weldable Al-Zn-Mg extrusion alloy with no significant copper addition, supplied in F, O, T4, T5, T6, T651, T7, T76, T79 and as-welded condition. It is used for welded structural extrusions where good extrudability is combined with 340 MPa yield, 370 MPa tensile, 11% elongation and 110 HB, and a weldability score of 80 with natural HAZ recovery after welding. Corrosion resistance is moderate (score 50), machinability is average (score 60) and service temperature is limited to about 120 °C, with SCC a concern in sustained short-transverse tension. 7020 is the nearest weldable 7000-series alternative. 7108 has a density of 2.78 g/cm³ (0.1 lb/in³), heavier than 74% of aluminum grades. It melts at 600°C (1,112 °F). 7108 has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 370 MPa (53.7 ksi) — stronger than 82% of aluminum grades. Elongation at break is 11% and the elastic modulus is 70 GPa (10.2 Msi).
What is 7108 used for?
- Welded structural extrusions
- Transport frames
- Ladders
Advantages
- High strength — 340 MPa (49.3 ksi), better than 82% of aluminum grades
- Conducts heat well — 160 W/m·K (92.4 BTU/hr·ft·°F), better than 76% of aluminum grades
Limitations
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
7108 properties
Typical room-temperature values for 7108-T6; bars are the position among aluminum grades.
Physical3
7108 has a density of 2.78 g/cm³ (0.1 lb/in³), heavier than 74% of aluminum grades. It melts at 600°C (1,112 °F).
Mechanical12
7108 has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 370 MPa (53.7 ksi) — stronger than 82% of aluminum grades. Elongation at break is 11% and the elastic modulus is 70 GPa (10.2 Msi).
Thermal6
7108 is rated for continuous service to 120°C (248 °F). It conducts heat at 160 W/m·K (92.4 BTU/hr·ft·°F), better than 76% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7108 conducts electricity at 33 % IACS, worse than 57% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (50/100), worse than 56% of aluminum grades.
Sustainability4
Producing a kilogram of 7108 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 25%.
Manufacturability8
7108's machinability is good (60/100, worse than 51% of aluminum grades); weldability very good (80/100); 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. 7108 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 7108
Is 7108 easy to machine?
Machines well in T5/T6 with sharp polished-flute carbide tools, high speed and generous coolant; O/T4 tempers are gummy and give poor surface finish.
Can 7108 be welded?
Excellent MIG/TIG and FSW behaviour with 5356/5183 filler; HAZ softening is partly recovered by natural aging, but keep the HAZ out of sustained tensile short-transverse stress to avoid SCC.
Can 7108 be formed, bent or molded?
Best formed in T4/T5 (stretch-bending, roll-forming) with generous bend radii; T6/T79 tolerate only mild bends and press-quenching from the extrusion press is standard for thin profiles.
7108 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 |
|---|---|---|
| Si | ≤ 0.1 | 0.06 |
| Femax (7108A allows up to 0.15) | ≤ 0.1 | 0.07 |
| Cumax; Cu-free class for weldability | ≤ 0.05 | 0.02 |
| Mn | ≤ 0.05 | 0.02 |
| Mg | 0.7 – 1.4 | 1 |
| Cr | ≤ 0.05 | 0.02 |
| Zn | 4.5 – 5.5 | 5 |
| Zrrecrystallisation control | 0.12 – 0.25 | 0.16 |
| Ti | ≤ 0.05 | 0.02 |
| Others (each)each | ≤ 0.05 | |
| Others (total)total | ≤ 0.15 | |
| Al | balance |
What surface finishes work on 7108?
Takes clear and hard anodizing well (slightly grey/yellow tint versus 6060/6063), chromate-free conversion coating and powder paint are common for automotive profiles.
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 7108 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- 7108-T6
How much does 7108 cost?
7108 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.
7108 — frequently asked
What is 7108 used for?
7108 is typically used for welded structural extrusions, transport frames and ladders. In short: weldable 7000-series extrusion alloy; HAZ recovers by natural aging; stronger than 6082.
What is the yield strength of 7108?
7108 has a typical yield strength of 340 MPa (49.3 ksi) and a tensile strength of 370 MPa (53.7 ksi) — stronger than 82% of aluminum grades. Strength varies by condition: see the 10 listed tempers.
Is 7108 easy to machine?
Reasonably — machinability is rated good (60/100, worse than 51% of aluminum grades). Machines well in T5/T6 with sharp polished-flute carbide tools, high speed and generous coolant; O/T4 tempers are gummy and give poor surface finish.
Can 7108 be welded?
Yes — weldability is rated very good (80/100). Excellent MIG/TIG and FSW behaviour with 5356/5183 filler; HAZ softening is partly recovered by natural aging, but keep the HAZ out of sustained tensile short-transverse stress to avoid SCC.
What surface finishes work on 7108?
Takes clear and hard anodizing well (slightly grey/yellow tint versus 6060/6063), chromate-free conversion coating and powder paint are common for automotive profiles.
Can 7108 be formed, bent or molded?
Best formed in T4/T5 (stretch-bending, roll-forming) with generous bend radii; T6/T79 tolerate only mild bends and press-quenching from the extrusion press is standard for thin profiles.
What is the maximum service temperature of 7108?
7108 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 7108-T6 and 7108-O?
T6 is the default condition — default stocked condition: maximum strength for welded structural profiles and crash members. O: softest condition for severe forming or straightening before re-heat-treatment. Yield strength is 340 MPa in T6 versus 75 MPa in O.
How much does 7108 cost?
7108 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
- 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)
- ASM Handbook Vol. 13B: Corrosion — Materials (Al-Zn-Mg corrosion & SCC) — ASM International (2005)
- Extrusion alloy data for Al-Zn-Mg automotive profiles (7003/7108 class) — Hydro Aluminium Extrusion (2021)
- EN 755-2 Aluminium and aluminium alloys — Extruded rod/bar, tube and profiles: mechanical properties — CEN (2016)
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.