Material selection is one of the most consequential decisions in aerospace component design. The right material balances strength, weight, corrosion resistance, temperature performance, and machinability — while the wrong choice can lead to premature failure, unnecessary cost, or manufacturing difficulties that delay your program.
Aluminum Alloys: The Workhorse
Aluminum remains the most widely used material in aerospace machined components, and for good reason. It offers an excellent strength-to-weight ratio, machines easily, and is readily available at reasonable cost.
Common Aerospace Grades
- 6061-T6: Good all-around alloy with excellent machinability and corrosion resistance. Widely used for structural brackets, housings, and non-critical structural components. Lower cost than other aerospace aluminums.
- 7075-T6: Significantly higher strength than 6061, approaching some steels. The go-to choice for structural aerospace components where strength matters. Slightly more difficult to machine and less corrosion-resistant than 6061.
- 2024-T3: Excellent fatigue resistance, making it ideal for components subject to cyclic loading. Common in fuselage and wing structures. Poor corrosion resistance — typically requires surface treatment.
Best for: Structural brackets, housings, mounting plates, and any application where weight is critical but temperatures remain below 150°C.
Titanium: When Strength and Temperature Matter
Titanium offers the highest strength-to-weight ratio of common aerospace metals, with excellent corrosion resistance and temperature capability up to approximately 315°C. The trade-off is cost — both material and machining costs are significantly higher than aluminum.
Key Grades
- Grade 5 (Ti-6Al-4V): The most widely used titanium alloy in aerospace, accounting for over 50% of all titanium used. Excellent strength, good fatigue resistance, and proven track record in flight-critical applications.
- Grade 2 (Commercially Pure): Lower strength than Grade 5 but excellent corrosion resistance and better formability. Used in fluid system components, exhaust hardware, and marine-adjacent aerospace applications.
Best for: Engine components, landing gear hardware, fasteners, and structural components where aluminum is not strong enough or temperatures exceed aluminum limits.
Inconel: Extreme Temperature Performance
Inconel alloys (primarily 625 and 718) maintain their mechanical properties at temperatures where other metals weaken or fail — up to 700°C for Inconel 718. This makes them essential for hot-section components in jet engines and other extreme-temperature applications.
Inconel is challenging to machine. It work-hardens rapidly, generates significant heat during cutting, and is abrasive to tooling. This means longer cycle times, more frequent tool changes, and higher machining costs. However, for applications that demand extreme temperature resistance, there is often no substitute.
Best for: Turbine hardware, exhaust components, combustion chamber parts, and any application with sustained temperatures above 315°C.
Stainless Steel: Corrosion Resistance with Strength
Stainless steels offer a middle ground — stronger and more temperature-resistant than aluminum, more affordable and easier to machine than titanium, with excellent corrosion resistance.
- 303: The most machinable stainless steel. Used for non-critical components where corrosion resistance is needed but strength requirements are moderate.
- 304/316: Excellent corrosion resistance for fluid handling components, fittings, and hardware exposed to harsh environments.
- 17-4 PH: Precipitation-hardened stainless with high strength (up to 190 ksi). Used for high-strength fasteners, shafts, and structural components where corrosion resistance and strength are both critical.
Best for: Fluid system components, fasteners, shafts, and applications requiring both corrosion resistance and moderate-to-high strength.
Making the Right Choice
Material selection should be driven by the functional requirements of your application — not habit or preference. Consider these factors in order of priority:
- Operating temperature — eliminates options that cannot perform
- Strength requirements — defines the minimum material capability
- Weight constraints — favors aluminum and titanium
- Corrosion environment — may require specific alloys or treatments
- Cost and availability — practical considerations that affect lead time
At Tru-Tech Precision, our engineering team works with all of these materials daily. We can help you evaluate trade-offs and recommend the best material for your specific application. Our complimentary DFM review includes material selection guidance based on your performance requirements and budget. Contact us to get started.