How to Choose the Right Metal for Your Part
Material decides more about a part than almost any other choice you make. It sets the strength, the weight, whether the part survives outdoors, how it finishes, and a large part of the cost. This guide walks through how to choose, starting from what the part actually has to do, and points you to the deeper article for each material.
Everything below is drawn from what ACP keeps in stock, so the material you pick prices instantly. For the full shelf, see the Stocked Materials list.
Start with what the part has to do
Before you compare metals, answer five questions about the part. The answers point straight at a material:
- Load. Does it carry weight or take stress, or is it a cover and a bracket?
- Environment. Indoors, outdoors, wet, salty, or around chemicals?
- Weight. Does saving weight matter, or is it bolted to a wall?
- Finish. Painted, powder coated, anodized, bare, or clear?
- Budget. Is this cost driven, or does performance win?
The metals ACP stocks, side by side
| Material | Strength | Formability | Corrosion resistance | Stock range |
|---|---|---|---|---|
| Carbon steel | High | Good | Low, rusts bare | 0.024″ to 1″ |
| G90 galvanized | High | Good | Medium, zinc coated | 18 to 11 gauge |
| 5052-H32 aluminum | Medium | Excellent | Very good | 0.040″ to 1/4″ |
| 6061-T6 aluminum | High | Fair | Very good | 0.032″ to 1″ |
| 304 stainless | High | Good | Excellent | 0.030″ to 1/2″ |
| 316 stainless | High | Good | Best, marine grade | 0.060″ to 1/2″ |
| Clear acrylic | Brittle | Cut only | Plastic, inert | 1/8″ to 1/2″ |
Formability describes how the material takes a bend. Acrylic is cut, not formed.
Choose by requirement
| If you need | Reach for |
|---|---|
| Tight bends, formed enclosures | 5052 aluminum, or a softer carbon steel |
| Strength and stiffness | 6061 aluminum, or carbon steel |
| Light weight | 5052 or 6061 aluminum |
| Outdoor or wet, low cost | Galvanized, or coated carbon steel |
| Marine, medical, or chemical | 316 stainless |
| General corrosion resistance | 304 stainless, or aluminum |
| Lowest cost, structural | Carbon steel |
| A clean anodized finish | 6061 aluminum |
| Clear or see through | Cast acrylic |
Aluminum: 5052 or 6061
These two aluminums cover most work and are good at nearly opposite things. 5052 bends tight without cracking, so it wins on formed enclosures and chassis. 6061 is stronger, machines and anodizes cleanly, but wants a generous radius when bent. The full breakdown is in 5052 vs 6061 aluminum.
Stainless: 304 or 316
304 is the default and handles most indoor and general outdoor use. 316 adds molybdenum for far better resistance to salt and chemicals, so it is the marine, medical, and chemical choice. See 304 vs 316 stainless for when the extra cost is worth it.
Steel and the rust question
Carbon steel is the strongest value in the shop, but it rusts bare. If the part lives outdoors or gets wet, either move up to galvanized, plan on a coating, or switch to stainless or aluminum. The options are laid out in how to keep cut steel parts from rusting.
How material affects cutting and forming
The metal you pick also shapes how the part is made:
- Thick or heat sensitive material favors the waterjet, which cuts cold with no heat affected zone. See why waterjet leaves no heat affected zone and cutting thick metal.
- Stainless springs back more than mild steel when formed, so bends need a bit more allowance and a slightly larger radius.
- Thickness is nominal and follows mill tolerance, and the same gauge is a different thickness per material. Call it out in decimals, see the gauge chart.
What it costs, roughly
As a rule of thumb, carbon steel is the least expensive, aluminum sits in the middle, and stainless costs the most, with 316 above 304. That order is a starting point, not a quote; thickness, quantity, and operations move the real number. The fastest way to compare is to price the same part in two materials in the quote portal.
Quick chooser
- Formed enclosure that bends a lot: 5052 aluminum
- Strong, light, gets anodized: 6061 aluminum
- Cheapest structural part, indoors or coated: carbon steel
- Outdoor on a budget: galvanized or coated steel
- Corrosion resistance, general: 304 stainless
- Marine, medical, or chemical: 316 stainless
- Clear part: cast acrylic
- Thick or heat sensitive: cut it on the waterjet