Aluminum 7A77 · temper
Aluminum 7A77-T6
Properties of the T6 condition, compared with the other 7A77 tempers.
Standard delivery condition for structural AM parts — gives strength close to wrought 7075-T6; least resistant to stress-corrosion cracking.
What is 7A77-T6?
7A77-T6 is 7A77 in the T6 temper — standard delivery condition for structural AM parts — gives strength close to wrought 7075-T6; least resistant to stress-corrosion cracking. 7A77-T6 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 545 MPa (79 ksi) — stronger than 95% of aluminum grades. Elongation at break is 5% and the elastic modulus is 70 GPa (10.2 Msi). 7A77-T6 has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 477°C (891 °F). As Printed is the default condition FabDigit quotes; T6 is available on request or by drawing note.
Advantages
- High strength — 480 MPa (69.6 ksi), better than 95% of aluminum grades
- Easy to machine — 72/100, better than 80% of aluminum grades
Limitations
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
- Needs corrosion protection — 40/100, worse than 75% of aluminum grades
7A77-T6 properties
Typical room-temperature values for 7A77-T6 — 17 properties are specific to this condition; the rest are grade-level values shared by every 7A77 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
7A77-T6 has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 477°C (891 °F).
Mechanical14
7A77-T6 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 545 MPa (79 ksi) — stronger than 95% of aluminum grades. Elongation at break is 5% and the elastic modulus is 70 GPa (10.2 Msi).
Thermal6
7A77-T6 is rated for continuous service to 120°C (248 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7A77-T6 conducts electricity at 33 % IACS, worse than 57% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), worse than 75% of aluminum grades.
Sustainability4
Producing a kilogram of 7A77-T6 takes about 215 MJ of energy and emits 13 kg of CO₂ — more than 92% of aluminum grades. Typical recycled content is 5%.
Manufacturability8
7A77-T6's machinability is very good (72/100, better than 80% of aluminum grades); weldability poor (25/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 7A77 tempers and conditions
7A77 is also supplied in 5 other conditions. The full side-by-side table is on the 7A77 overview.
- As PrintedDefaultBaseline condition straight off the LPBF machine; crack-free equiaxed structure but supersaturated and residually stressed — use only for form/fit or before heat treatment.310 MPa yield · 110 HB
- HIP+T6Best overall combination for flight-type hardware: densified by HIP then aged to peak strength, giving T6 strength with better ductility and fatigue scatter.485 MPa yield · 152 HB
- T6Standard delivery condition for structural AM parts — gives strength close to wrought 7075-T6; least resistant to stress-corrosion cracking.480 MPa yield · 150 HB
- T73Pick when the part sees sustained tensile stress in humid or marine service; roughly 10–15 % lower strength than T6 but far better SCC and exfoliation resistance.400 MPa yield · 135 HB
- Stress RelievedChoose when distortion control during plate removal and machining matters more than peak strength; strength drops slightly as precipitates coarsen.270 MPa yield · 100 HB
- HIPUse for fatigue- or leak-critical parts: HIP collapses gas/lack-of-fusion porosity and raises ductility, but the slow cool leaves the alloy soft until re-aged.250 MPa yield · 95 HB
Working with 7A77-T6
Is 7A77 easy to machine?
Machines like 7075 — sharp uncoated carbide, high speed, generous coolant; expect springy thin walls and beware of subsurface porosity opening up on finish passes.
Can 7A77 be welded?
Fusion welding of 7xxx is still discouraged (hot cracking, HAZ softening); use mechanical joints, adhesive, or friction stir welding, and re-age after any thermal joining.
Can 7A77 be formed, bent or molded?
Built by laser powder bed fusion (typically 30–60 µm layers, N₂/Ar, preheated plate); Zr nucleant suppresses solidification cracking, but supports and low-angle overhangs still need care, and powder must be kept dry.
What surface finishes work on 7A77?
Blast/tumble then machine critical faces; clear or hard anodize is standard (colour is darker and less even than 6xxx), chromate/Ti-Zr conversion + primer for corrosion-critical parts, HIP first if a sealed anodic film is required.
7A77 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 |
|---|---|---|
| Zn7075 base composition | 5.1 – 6.1 | 5.6 |
| Mg | 2.1 – 2.9 | 2.5 |
| Cu | 1.2 – 2 | 1.6 |
| Zrnanoparticle nucleant added to the powder surface (7A77 functionalization); level is proprietary/process-dependent | 0.5 – 2 | 1 |
| Cr | 0.18 – 0.28 | 0.23 |
| Feimpurity max | ≤ 0.5 | 0.2 |
| Siimpurity max | ≤ 0.4 | 0.1 |
| Mnimpurity max | ≤ 0.3 | 0.05 |
| Tiimpurity max | ≤ 0.2 | 0.03 |
| Al | balance | — |
7A77-T6 — frequently asked
What is 7A77-T6 used for?
7A77-T6 is typically used for aerospace primary and secondary structures, defence hardware and weapon mounts, high-load fittings and lugs, missile and UAV structural components, motorsport chassis brackets and topology-optimised replacements for machined 7075. In short: aerospace 7000-series LPBF.
What is the yield strength of 7A77-T6?
7A77-T6 has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 545 MPa (79 ksi) — stronger than 95% of aluminum grades. Strength varies by condition: see the 6 listed tempers.
Is 7A77-T6 easy to machine?
Yes — machinability is rated very good (72/100, better than 80% of aluminum grades). Machines like 7075 — sharp uncoated carbide, high speed, generous coolant; expect springy thin walls and beware of subsurface porosity opening up on finish passes.
Can 7A77-T6 be welded?
Not readily — weldability is rated poor (25/100). Fusion welding of 7xxx is still discouraged (hot cracking, HAZ softening); use mechanical joints, adhesive, or friction stir welding, and re-age after any thermal joining.
What surface finishes work on 7A77-T6?
Blast/tumble then machine critical faces; clear or hard anodize is standard (colour is darker and less even than 6xxx), chromate/Ti-Zr conversion + primer for corrosion-critical parts, HIP first if a sealed anodic film is required.
Can 7A77-T6 be formed, bent or molded?
Built by laser powder bed fusion (typically 30–60 µm layers, N₂/Ar, preheated plate); Zr nucleant suppresses solidification cracking, but supports and low-angle overhangs still need care, and powder must be kept dry.
What is the maximum service temperature of 7A77-T6?
7A77-T6 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 7A77 As Printed and 7A77-T6?
As Printed is the default condition — baseline condition straight off the LPBF machine; crack-free equiaxed structure but supersaturated and residually stressed — use only for form/fit or before heat treatment. T6: standard delivery condition for structural AM parts — gives strength close to wrought 7075-T6; least resistant to stress-corrosion cracking. Yield strength is 310 MPa in As Printed versus 480 MPa in T6.
Can FabDigit make parts in 7A77-T6?
Yes — 7A77-T6 is available for 3D printing with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- 7A77.60L nanofunctionalized aluminium powder for additive manufacturing — HRL Laboratories (2021)
- 3D printing of high-strength aluminium alloys (Martin, Yahata, Hundley et al.) — Nature 549, 365–369 (2017)
- Aluminum Standards and Data / Teal Sheets — alloy 7075 registration — The Aluminum Association (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials — 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.