The strongest common aluminum alloy. 7075-T6 delivers ultimate tensile strength approaching mild steel at roughly one-third the density — the reason it dominates aerospace structural parts, high-stress tooling, and firearms components. Trade-offs: higher cost, poorer corrosion resistance than 6061, and a tendency to work-harden if feeds are too conservative.
There are exactly three reasons to choose 7075 over 6061: strength, strength-to-weight, and fatigue life under cyclic loading. At 572 MPa ultimate tensile strength, 7075-T6 is roughly 80% stronger than 6061-T6, approaching the tensile strength of many structural steels while weighing a third as much. In fatigue-critical aerospace structures — wing spars, bulkheads, missile components — this strength ratio is why 7075 has been a staple since the B-29 fuselage in 1943.
But the trade-offs are real. 7075 costs 1.5–2× more than 6061 at the mill. It cannot be welded conventionally (the heat-affected zone loses most of its strength). Its corrosion resistance is only "fair" — in marine or humid environments, 7075 parts must be anodized, painted, or used only in the clad variant (Alclad 7075) where a thin layer of pure aluminum protects the core. And because 7075 is so strong, it generates higher cutting forces: tooling wears faster, and thin-wall parts require more careful fixturing to avoid deflection.
If your application is not fatigue-critical and not weight-critical, specify 6061-T6. You will get functionally equivalent performance for 40–50% less material cost and slightly better machining yields. 7075 is the right choice only when you genuinely need the strength — over-specification is the single most common way procurement teams inflate aluminum part costs.
7075 is an Al-Zn-Mg-Cu alloy. The high zinc content (5.1–6.1%) is what drives its strength via precipitation hardening during T6 aging.
| Element | Min % | Max % | Role |
|---|---|---|---|
| Zinc (Zn) | 5.1 | 6.1 | Primary strengthening element |
| Magnesium (Mg) | 2.1 | 2.9 | Forms MgZn₂ precipitates during aging |
| Copper (Cu) | 1.2 | 2.0 | Further strength, reduces corrosion resistance |
| Chromium (Cr) | 0.18 | 0.28 | Stress-corrosion cracking resistance |
| Iron (Fe) | — | 0.50 | Impurity, limited |
| Silicon (Si) | — | 0.40 | Impurity, limited |
| Manganese (Mn) | — | 0.30 | Impurity, limited |
| Titanium (Ti) | — | 0.20 | Grain refinement |
| Aluminum (Al) | balance | Matrix | |
| Property | Metric | Imperial | Test method |
|---|---|---|---|
| Ultimate tensile strength | 572 MPa | 83,000 psi | ASTM E8 |
| Yield strength (0.2%) | 503 MPa | 73,000 psi | ASTM E8 |
| Elongation at break | 11% | 11% | ASTM E8 |
| Brinell hardness | 150 HB | — | ASTM E10 |
| Shear strength | 331 MPa | 48,000 psi | ASTM B769 |
| Fatigue strength (5×10⁸ cycles) | 159 MPa | 23,000 psi | ASTM E466 |
| Modulus of elasticity | 71.7 GPa | 10.4×10⁶ psi | ASTM E111 |
| Density | 2.81 g/cm³ | 0.102 lb/in³ | — |
| Thermal conductivity | 130 W/m·K | — | ASTM E1461 |
| Max service temperature | ~120°C | ~250°F | Above this, T6 temper degrades |
Higher cutting forces than 6061 — expect 25–30% more spindle load at equivalent MRR. Carbide tooling with polished flutes and high helix angles recommended. Flood coolant or MQL to evacuate the long, stringy chips 7075 tends to produce.
| Operation | Surface speed (m/min) | Feed per tooth (mm) | Depth of cut | Tool |
|---|---|---|---|---|
| Face milling (rough) | 400–700 | 0.15–0.30 | 3–5 mm | Carbide, 5–7 teeth |
| Face milling (finish) | 600–1000 | 0.08–0.15 | 0.2–0.5 mm | PCD insert |
| End milling (rough) | 300–500 | 0.08–0.20 | 1–2× diameter | Solid carbide, high-helix |
| End milling (finish) | 400–700 | 0.05–0.10 | 0.1–0.3 mm | Polished flute, 3-flute |
| Drilling | 80–150 | 0.15–0.30/rev | — | Parabolic flute HSS-Co or carbide |
| Tapping | 15–25 | — | — | Spiral-flute, TiN-coated |
| Turning (rough) | 200–400 | 0.20–0.40/rev | 2–4 mm | Carbide CCMT/CNMG |
| Turning (finish) | 300–600 | 0.05–0.15/rev | 0.2–0.5 mm | PCD insert |
Wing ribs, bulkheads, fuselage frames, landing gear components. 7075-T73 or T7351 temper often specified for stress-corrosion resistance.
Upper/lower receivers, match-grade rifle components, optic mounts. Hard anodized finish standard.
Frames, stems, triple clamps, suspension components. Strength-to-weight that 6061 can't match.
Jigs, fixtures, molds where reduced weight enables faster handling. Not for molds exceeding 150°C.
Carabiners, ice axes, rifle rails — anywhere load capacity per gram is the design driver.
High-acceleration arms where inertia matters. 7075 gives stiffness at lower mass than 6061.
| Property | 6061-T6 | 7075-T6 | Winner |
|---|---|---|---|
| Ultimate tensile strength | 310 MPa | 572 MPa | 7075 (+85%) |
| Yield strength | 276 MPa | 503 MPa | 7075 (+82%) |
| Machinability | 100% (baseline) | 70% | 6061 |
| Weldability | Excellent (TIG/MIG) | Poor — HAZ loses strength | 6061 |
| Corrosion resistance | Good | Fair — requires coating | 6061 |
| Cost (raw material) | Baseline | 1.5–2× 6061 | 6061 |
| Anodizing cosmetics | Excellent, consistent | Can show streaking on large surfaces | 6061 |
| Fatigue life (high cycles) | Lower | Higher | 7075 |
Full comparison in our 6061 vs 7075 decision guide.
Raw material is 1.5–2× more, tooling wears faster, and parts almost always need post-process coating (anodize or chromate). Budget accordingly — don't let engineering specify 7075 without procurement visibility.
If your assembly needs to be welded, use 6061 or 5052 instead. Welding 7075 typically reduces strength by 50% in the heat-affected zone, defeating the reason for choosing it. Use mechanical fasteners or adhesive bonding.
7075-T6 is standard, but 7075-T73 (overaged) gives much better stress-corrosion cracking resistance at the cost of ~10% strength. For aerospace structures, T73 or T7351 is often preferred. Not interchangeable — your drawing must call out the temper.
Higher cutting forces mean thin-wall flex is 25–30% worse than on 6061. Minimum wall for standard machining: 1.0 mm. Below that, expect quality escapes or custom fixturing costs.
Bare 7075 pits and corrodes in salt spray within months. Type III hard anodize is the default for defense work; Type II is sufficient for most consumer applications. Never leave 7075 bare if it will see moisture.
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