Posted by Ben Wiley on Apr 4, 2016 9:30:00 AM

Selecting an Alloy for Your Custom Metal Fabrication Project

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There are more metal alloys than Ben & Jerry have flavors of ice cream and it's not always obvious which works best for any given custom metal fabrication project. Sometimes the more expensive alloy might work out cheaper overall by virtue of being more durable, stronger, lighter or easier to work with. In other cases the cheapest may well be the best choice. This Tiki Talk covers the main points to consider and summarizes the pros and cons of some common fabrication metal alloys.

Why talk about alloys?

In their elemental state most metals aren't particularly useful. They oxidize quickly and are too soft or brittle to form into complex fabrications, so they are mixed, or “alloyed” with other materials. Steel for instance is an alloy of iron and carbon. Aluminum is usually alloyed with other materials to change its ductility or corrosion resistance. Just about every metal we use is, technically speaking, an alloy.

Three considerations

Alloy selection should be dictated by the performance or function and durability needed. Cost is always important, but we advise looking at the total or lifetime cost of alloy selection. Here's what to think about:

  1. Performance. What qualities will the metal fabrication need? Strength is important in load-bearing pieces, but less so when the main role is aesthetics. Perhaps appearance is the top concern, in which case decide if the metal will be coated or left bare. In many vehicle applications it's essential to keep weight down, which might lead you to aluminum.

  2. Durability. How long do you want the fabrication to last, and what will you do to maintain it? It's often said that steel starts out as iron ore and seems in a hurry to get back to that state. If a fabrication will see wet conditions, especially salt, a corrosion-resistant metal alloy is probably best. Conversely, if it will live indoors it might be enough just to paint a regular steel alloy.

  3. Cost. Regular mild steel is about the least expensive alloy, so it tends to be the default choice. Unfortunately, while it fabricates well it must be corrosion-protected. Coating processes add cost, both initially and down the road in terms of maintenance. A corrosion-resistant alloy not only looks good but will last almost forever. On the other hand, some, like stainless-steel, are not so easily fabricated into complex shapes. Others are difficult to weld or lack strength. An inexpensive metal alloy might be an expensive choice.

Fabrication alloy pros and cons

There are a lot of alloys to choose from. Here's a review of the three most common types.

  • Steel. Consider this the baseline, pros are: good to cut, bend and weld, reasonable tensile strength, inexpensive. Con: it will rust so must be coated.

  • Stainless-steel. Pros: Looks great uncoated and won't rust, thanks to a self-healing skin, so may not need coating. Has good tensile strength. Cons: harder to fabricate into complex shapes, not so easily welded, heavy, more expensive.

  • Aluminum: Pros: corrosion-resistant, looks good, lightweight, a joy to cut to shape. Cons: some grades are hard to form, low tensile strength, hard to weld, more expensive than stainless.

Ask us

Every metal fabrication project should start with alloy selection. Here we've outlined the main points to consider but it's a complicated subject. Even if you know your materials we'd encourage you to talk to us about what will work best in your project. We might even be able to save you some money

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Topics: Metal Fabrication, Custom Metal Assembly