Aerospace Metal Selection: Choosing Aluminum, Titanium & Stainless for Aircraft Parts

In aerospace, material selection is never just “pick the strongest.” Every gram costs fuel, every part faces millions of fatigue cycles, and the wrong alloy in the wrong place can crack, corrode, or simply weigh too much. The engineer’s job is to match the metal to the load, the environment, and the fatigue life — and sometimes that means choosing a weaker alloy because it lasts longer.

This guide walks through the metals that build aircraft structures and brackets: the three aluminum workhorses, when titanium or stainless earns its place, and the trade-offs that actually drive the decision.

Why Aluminum Dominates

Aluminum makes up approximately 60% of a commercial aircraft’s weight — for good reason. It offers an excellent strength-to-weight ratio at moderate temperatures, superior machinability, and far lower cost than exotic alloys. Aircraft-grade aluminum like 7075-T6 is more than twice as strong as a common grade like 5052, and nearly six times stronger than pure aluminum — strong enough to replace heavier steel or titanium in many structures while cutting weight.

But “aluminum” isn’t one material. Three alloys do most of the work, and they’re not interchangeable.

The Three Aluminum Workhorses

7075 — Maximum strength

The strongest common aluminum alloy, using zinc as the primary alloying element. With a tensile strength around 572 MPa and yield around 503 MPa, it’s the go-to for high-stress structural parts — aircraft frames, wing structures, landing gear, and load-bearing brackets where strength-to-weight is critical.

The trade-offs: 7075 has lower corrosion resistance than 6061 and is more difficult to weld. It’s also less formable (needs larger bend radii) and harder to machine (machinability ~50% vs 6061’s 100%). You choose 7075 when you need maximum strength and will manage its quirks.

2024 — Best fatigue resistance

A high-strength copper-based alloy with excellent tensile and, crucially, fatigue strength. Tensile is around 470 MPa — lower than 7075 — but its fatigue performance is its standout. This makes it the standard for aircraft skins, wing tension members, and fuselage structures that survive millions of vibration cycles.

The classic example: Boeing uses 2024-T3 for the 747’s wing lower panels rather than the stronger 7075 — precisely because that location sees repeated pressure cycles, and 2024’s superior fatigue life proves more reliable over decades. It’s also more machinable than 7075 (~70%). This is the perfect illustration that “strongest” ≠ “best.”

6061 — The versatile all-rounder

Medium strength, but excellent corrosion resistance and weldability, plus great formability and machinability. Density ~2.70 g/cm³ (slightly lighter than 7075’s 2.81). It’s the default for general structural components, avionics brackets, and parts where versatility, corrosion resistance, or welding matters more than maximum strength.

Quick comparison

Property	7075	2024	6061
Primary element	Zinc	Copper	Mg-Si
Tensile strength	~572 MPa (highest)	~470 MPa	Medium
Fatigue	Good	Best	Moderate
Corrosion resistance	Lower	Lower	Excellent
Weldability	Difficult	Difficult	Good
Machinability	~50%	~70%	100% (baseline)
Best for	High-stress structure	Skins, fatigue parts	Versatile, corrosion

Beyond Aluminum: When to Step Up

Titanium (Ti-6Al-4V) — the strength-to-weight champion

Titanium offers a superior strength-to-weight ratio at elevated temperatures, better corrosion resistance, and higher fatigue strength than aluminum. Ti-6Al-4V reaches 120–170 ksi (830–1,172 MPa) — substantially stronger than 7075.

The catch is weight and cost: titanium’s density (~4.43 g/cm³) makes it about 60% heavier than 7075 for the same volume, and it’s far more expensive and harder to process. You use titanium where its high-temperature performance and strength justify it — engine parts, landing gear, and critical airframe structures — not for a simple bracket that aluminum can handle. When the released scope is a cut, formed or welded sheet component, the custom titanium fabrication page explains the drawing, shielding and inspection inputs needed for an RFQ review.

Stainless steel (17-4PH, 15-5PH) — strength and fire resistance

Precipitation-hardening stainless grades like 17-4PH and 15-5PH deliver high strength, and stainless is chosen for high-strength fittings and fire-resistant parts. Heavier than aluminum, so used selectively where its properties are needed.

AMS: Why Aerospace Materials Are Special

Here’s something that separates aerospace from general fabrication: AMS (Aerospace Material Specifications), maintained by SAE International. AMS standards tighten the composition and property ranges beyond commercial specs.

For example, AMS 4027 (6061) tightens the allowable magnesium and silicon ranges versus commercial ASTM, ensuring predictable strength and spring-back batch to batch — commercial 6061-T6 can vary between batches, while AMS material won’t. AMS 4037 (2024) lowers iron content to improve fatigue crack-growth resistance. When a part is flight hardware, the AMS callout matters as much as the alloy number — it guarantees the consistency that aerospace demands.

The Decision Framework

Choose 7075 if: you need maximum strength in the aluminum family — high-stress structural brackets and frames — and can manage its lower corrosion resistance and tougher forming.

Choose 2024 if: the part sees high cyclic/fatigue loading — skins, tension members — where fatigue life beats raw strength.

Choose 6061 if: you need versatility, good corrosion resistance, or weldability — avionics brackets and general structures. The default for most sheet metal aerospace brackets.

Choose titanium if: you need the best strength-to-weight at high temperature — engine, landing gear, critical structure — and the budget supports it.

Choose stainless (17-4PH/15-5PH) if: you need high strength in steel or fire resistance.

Always specify the AMS where the part is flight hardware — it guarantees the consistency the application requires.

A Note on Sheet Metal Brackets

For formed sheet metal brackets specifically, the choice usually lands between 6061 (the versatile default — formable, corrosion-resistant) and 7075 (when the bracket is structural and needs maximum strength, accepting larger bend radii). 2024 appears where fatigue dominates. The forming behavior matters as much as the strength: 7075 needs generous bend radii and controlled forming to avoid cracking. (See our aluminum grades guide for the broader alloy picture.)

How DRAmetal Helps

We fabricate aerospace sheet metal parts in the right alloy, to the right spec:

• Aerospace aluminum — 5052, 6061, and 7075, plus 2024 by arrangement — matched to your strength, fatigue, and forming needs
• Stainless options — 304/316 and PH grades for high-strength or fire-resistant parts
• AMS-spec sourcing with full mill-to-part traceability and EN 10204 3.1 certs
• Forming expertise — springback-controlled bending that keeps high-strength 7075 crack-free
• AS9102-format first-article inspection for flight hardware

Related customer project: Aerospace Bracket: Vibration and Mounting Stability. Related resources: aerospace sheet metal brackets · aluminum grades guide · aerospace certifications overview.

Selecting material for an aerospace part? Tell us your loads, environment, and fatigue requirements. The initial response target is within 24 working hours; material recommendations, DFM and quotation timing depend on the submitted evidence and engineering scope.