Article
Looking through a manufacturer’s online enclosure catalog recently, I came across a term I hadn’t heard before. Now, I’m not a contractor, so I likely haven’t seen as many of these listings as you might have. But I am a journalist who has covered the construction industry for several decades, and the term “mild steel” stuck out to me when it showed up as a material option for the maker’s broad range of enclosure offerings.

What Makes Steel “Mild” – Ironing Out Your Metal Material Options

Chuck Ross
Looking through a manufacturer’s online enclosure catalog recently, I came across a term I hadn’t heard before. Now, I’m not a contractor, so I likely haven’t seen as many of these listings as you might have. But I am a journalist who has covered the construction industry for several decades, and the term “mild steel” stuck out to me when it showed up as a material option for the maker’s broad range of enclosure offerings. This ended up taking me down a wormhole of internet searches when I realized I really didn’t know much about how steel is actually made. It turns out there are differences at the molecular level between various steel types that have big implications on long-term performance, depending on where the steel is put into service.

The word “mild” in this case refers to how easy steel products fabricated using very low amounts of carbon can be to work with. All steel is basically iron ore with varying degrees of carbon added to it in the form of coal in the blast furnace. The carbon adds durability, but it also creates a more brittle material at higher amounts. Mild steel is also called low-carbon steel because carbon amounts to only 0.05% to 0.25% of the finished product, by weight.

While mild steel is easier to machine and weld than other varieties, it also rusts more easily because it has no other ingredients to inhibit corrosion. However, its strength and lower cost makes it a material of choice for structural steel, automobile frames, fencing and nails – oh, and also many electrical enclosures. In these products, it’s usually powder coated to help protect against moisture that could lead to rust.

Galvanization is another option to help prolong a mild steel product’s lifespan. Galvanized steel has been run through molten zinc, which creates a rust-proof coating to help prevent oxidation and corrosion.

Stainless steel, however, gets its severe-conditions survivability from the inside out. In addition to carbon at varying quantities, protective and strengthening additions of chromium and nickel are added to the molten iron to manufacture an inherently corrosion-resistant material. Thus, there are no coatings or galvanized zinc that can fail over time with stainless steel. This is why stainless steel can be an option of choice for enclosures where high-temperature washdowns are required or where corrosive chemicals or other conditions prevail.
Photo courtesy of nVent|Hoffman
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