Aluminum 7A77
GB 7A77
7A77 is an additive-manufacturing version of 7075 (Al-Zn-Mg-Cu) whose powder surfaces are functionalised with zirconium-based nanoparticles, developed by HRL Laboratories as powder grade 7A77.60L.
Values for the As Printed condition
7A77 tempers and conditions
7A77 is supplied in 6 conditions, soft to hard. As Printed is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot isostatic pressed | Use 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 | 350 | 10 | 95 HB | 33 % IACS |
low-temperature anneal to remove build residual stress | Choose when distortion control during plate removal and machining matters more than peak strength; strength drops slightly as precipitates coarsen. | 270 | 360 | 7 | 100 HB | 30 % IACS |
As PrintedDefault laser powder bed fusion, as-built (no post heat treatment) | 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. | 310 | 400 | 5 | 110 HB | 26 % IACS |
Solution heat treated and overaged for stress-corrosion resistance | Pick 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 | 470 | 8 | 135 HB | 40 % IACS |
Solution heat treated and artificially aged | Standard delivery condition for structural AM parts — gives strength close to wrought 7075-T6; least resistant to stress-corrosion cracking. | 480 | 545 | 5 | 150 HB | 33 % IACS |
hot isostatic pressed, then solution treated and aged | Best overall combination for flight-type hardware: densified by HIP then aged to peak strength, giving T6 strength with better ductility and fatigue scatter. | 485 | 550 | 8 | 152 HB | 33 % IACS |
What is 7A77?
7A77 is an additive-manufacturing version of 7075 (Al-Zn-Mg-Cu) whose powder surfaces are functionalised with zirconium-based nanoparticles, developed by HRL Laboratories as powder grade 7A77.60L. The nucleants seed fine equiaxed grains in the laser melt pool instead of columnar growth, eliminating the solidification cracking that normally prevents 7000-series powder bed fusion; after solution treatment and artificial ageing the strength approaches wrought 7075-T6, with 310 MPa yield, 400 MPa tensile, 5 % elongation and 110 HB. Limits are high powder cost, elongation and fracture toughness below wrought stock, a 100 °C service ceiling and the weldability and stress-corrosion behaviour typical of 7000 series; T73 is on file where SCC resistance matters. 7A77 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). 7A77 has a yield strength of 310 MPa (45 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 78% of aluminum grades. Elongation at break is 5% and the elastic modulus is 70 GPa (10.2 Msi).
What is 7A77 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
- Topology-optimised replacements for machined 7075
Advantages
- High strength — 310 MPa (45 ksi), better than 78% of aluminum grades
Limitations
- Limited service temperature — 100°C (212 °F), worse than 91% of aluminum grades
- Poor heat conductor — 105 W/m·K (60.7 BTU/hr·ft·°F), worse than 91% of aluminum grades
- Low electrical conductivity — 26 % IACS, worse than 90% 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 properties
Typical room-temperature values for 7A77-As Printed; bars are the position among aluminum grades.
Physical3
7A77 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 has a yield strength of 310 MPa (45 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 78% of aluminum grades. Elongation at break is 5% and the elastic modulus is 70 GPa (10.2 Msi).
Thermal6
7A77 is rated for continuous service to 100°C (212 °F). It conducts heat at 105 W/m·K (60.7 BTU/hr·ft·°F), worse than 91% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7A77 conducts electricity at 26 % IACS, worse than 90% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), worse than 75% of aluminum grades.
Sustainability4
Producing a kilogram of 7A77 takes about 215 MJ of energy and emits 13 kg of CO₂ — more than 93% of aluminum grades. Typical recycled content is 5%.
Manufacturability8
7A77's machinability is good (65/100, better than 62% of aluminum grades); weldability poor (25/100); formability poor (20/100).
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. 7A77 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 7A77
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 7000 series 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.
Manufacturability
The process limits FabDigit's quote engine applies to 7A77. Design inside these and the part quotes instantly; outside them it routes to an engineer.
3D printing
| Technologies | DMLS |
|---|---|
| Layer height | 20 – 60 µmdefault 30 µm |
| Minimum wall / feature | 0.5 / 0.3 mm |
| Build envelope | 250 × 250 × 325 mm |
| Supports | Yes |
| Anisotropy | Mild |
| Mandatory post-processing | heat treatment |
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 |
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 6000 series), chromate/Ti-Zr conversion + primer for corrosion-critical parts, HIP first if a sealed anodic film is required.
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
Metal Finish
How much does 7A77 cost?
7A77 is a specialty-cost aluminum ($$$$$), pricier than about 99% 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.
7A77 — frequently asked
What is 7A77 used for?
7A77 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?
7A77 has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 78% of aluminum grades. Strength varies by condition: see the 6 listed tempers.
Is 7A77 easy to machine?
Reasonably — machinability is rated good (65/100, better than 62% 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 be welded?
Not readily — weldability is rated poor (25/100). Fusion welding of 7000 series 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?
Blast/tumble then machine critical faces; clear or hard anodize is standard (colour is darker and less even than 6000 series), chromate/Ti-Zr conversion + primer for corrosion-critical parts, HIP first if a sealed anodic film is required.
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 is the maximum service temperature of 7A77?
7A77 is rated for continuous use to about 100°C (212 °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.
How much does 7A77 cost?
7A77 is a specialty-cost aluminum ($$$$$), pricier than about 99% 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.
Can FabDigit make parts in 7A77?
Yes — 7A77 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; 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.