There’s something about a fire truck that brings out the kid in us. Maybe it’s the red paint and flashing lights, or perhaps it’s how the sun catches the polished stainless steel bumper. Yes, they are stainless steel and not chrome or aluminum, and we know because we make most of them.
Mild or carbon steel bumpers would be a lot easier to fabricate but they wouldn’t look as good or last as long. Stainless steel isn’t easy to work with, but for some applications, like fire truck bumpers, it’s the only way to go. You may know stainless from your kitchen appliances, cutlery or grill but it has many more uses, especially when given a mirror finish.
Architects are big fans of polished stainless steel, using it in handrails and balustrades as well as building facades. It crops up in aerospace, and is popular in automotive aftermarket applications like replacement running boards and grilles in trucks and RV’s. We even use it in our mirrors here at Wiley Metal and Avionic Structures of Indiana.
Four Reasons for Polished Stainless Steel
- Naturally corrosion-resistant. Carbon steels need a protective finish if they’re not going to rust. That adds cost and requires periodic maintenance. Stainless, thanks to a chromium content of 10% or more, forms a layer of chromium oxide on the surface that stops corrosion.
- More Than Just a Surface Coating. Bright chrome gives a shiny finish but is only a surface coating. Scratch or crack it, (as can happen when a bumper collects a dent,) and moisture can reach the substrate, letting rust gain a toehold. In contrast, stainless is stainless all the way through.
- Mirror Finish Does Not Become Dull. Freshly machined aluminum has a mirror finish but oxidizes and becomes dull very quickly. It is lighter than stainless but also more ductile, so not so good in applications where it might be struck and bent. (Did we mention fire trucks?)
- Stainless is tough. It has a lot of spring-back, which makes it fun to fabricate, (okay, it’s not much fun,) but it means in service it resists impacts, retaining its shape and appearance better than regular steels or aluminum.
Stainless steel comes from the mill in a range of compositions and finishes: the smoother the surface the more mirror-like it is. We use 304 grade stainless because it gives the best combination of corrosion resistance, finish and physical properties that make it suitable for fabrication. Then we add some skilled polishing – make that a lot of skilled polishing – to create a finish almost indistinguishable from bright chrome, but far more durable.
So the next time you see a fire truck in your mirror, admire it’s polished stainless steel bumper, but only AFTER you’ve pulled to the side of the road!