Material Selection Guide

6061-T6: the workhorse aluminum. Best all-around machinability, weldability, and strength-to-weight ratio. Yield strength 40 ksi. Excellent anodizing response. Use for: structural components, enclosures, frames, brackets, bike parts, aerospace non-critical. Avoid when: highest strength needed, temperatures over 300°F sustained, or when cost must be minimized (6061 is moderately priced).

7075-T6: highest-strength common aluminum. Yield strength 73 ksi — approaching mild steel at 1/3 the weight. Poor weldability. Excellent for highly stressed aerospace and structural applications. More expensive than 6061. Avoid when: welding required or corrosion resistance needed without coating.

2024-T3: high strength, excellent fatigue resistance, poor corrosion resistance. Classic aerospace aluminum for aircraft skins and structural members. Requires cladding or coating for corrosion protection.

5052-H32: best corrosion resistance of common aluminums. Excellent for marine, outdoor, and chemical environments. Lower strength than 6061. Best for sheet metal applications, tanks, and panels in corrosive environments.

1018 mild steel: the most common low-carbon steel. Excellent machinability, weldability, and formability. Low strength (yield 54 ksi) but adequate for most structural applications. Low cost. Rusts without coating. Use for: brackets, frames, weldments, machine components, anything that will be painted or powder coated.

4130 chromoly: alloy steel with good strength (yield 97 ksi normalized, higher when heat treated) and excellent weldability. Used in aircraft structure, motorsport chassis, bicycle frames, pressure vessels. Commonly specified in MIL-SPEC applications.

4140 chromoly: higher strength than 4130, excellent hardenability. Used for shafts, gears, bolts, tooling, and high-stress components. Heat treatable to very high hardness. Common aerospace and industrial alloy.

A36 structural: the standard structural steel for weldments, beams, plates. Lower cost than 1018, slightly lower machinability. The default for fabricated structural components.

304 stainless: the most common stainless steel. Excellent corrosion resistance, good formability and weldability, non-magnetic (in annealed condition). Used in food processing equipment, kitchen equipment, chemical handling, architectural. Not hardenable by heat treatment.

316 / 316L stainless: superior corrosion resistance to 304, especially in chloride environments (marine, seawater, medical). More expensive than 304. Required for marine applications and aggressive chemical environments. The L designation (low carbon) improves weldability.

303 stainless: free-machining grade of 304. Best machinability of common stainless grades. Not weldable. Use when machining ease matters more than weldability.

17-4 PH stainless: precipitation-hardening stainless — combines high strength (190 ksi yield in H900 condition) with good corrosion resistance. Used in aerospace, medical, pump shafts, and high-stress applications requiring both strength and corrosion resistance.

Grade 5 Titanium (Ti-6Al-4V): the most common titanium alloy. Yield strength 130 ksi at roughly half the density of steel. Excellent strength-to-weight ratio, good corrosion resistance, biocompatible. The standard for aerospace structure, medical implants, motorsport. Expensive and requires expertise to machine and weld.

C110 Copper: highest conductivity copper for electrical and thermal applications. Soft, easily formed. Use for electrical busbars, heat exchangers, terminals.

C360 Brass: free-machining brass — the best machinability of any metal. The standard for turned components, fittings, valves, and anything requiring high-volume precision machining. Not for structural applications.

C932 Bearing Bronze: the standard bearing bronze. Excellent wear resistance and embeddability for bushings and bearings.

Nylon (PA6, PA66): excellent strength, stiffness, and wear resistance. Good for gears, bushings, structural plastic components. Absorbs moisture (affects dimensional stability). Most common engineering plastic for mechanical components.

Acetal (Delrin, POM): dimensionally stable (low moisture absorption), excellent machinability, good chemical resistance, low friction. The preferred material for precision plastic components, gears, bushings, and food contact applications.

PEEK: the premium engineering plastic. High continuous service temperature (up to 480°F), excellent chemical resistance, high strength and stiffness, biocompatible grades available. Used in aerospace, medical, oil/gas, and any application requiring plastic performance approaching metals. 10-20x more expensive than nylon.

Carbon Fiber (CFRP): highest stiffness-to-weight ratio of any structural material. Used in aerospace structure, motorsport, high-performance sports equipment. Expensive material and processing.