What’s the actual difference between normal and stainless steel?



I keep hearing the phrase ‘stainless steel’ and I’m still not sure why it’s such a selling point compared to regular steel. Is it just for aesthetic purposes?

In: Technology

There are many different grades of steel such as carbon steel, tool steel, damascus steel, and of course stainless steel. Stainless steel has chromium mixed in to prevent rusting and keep the shine for a long period of time. While aesthetics is one aspect, prevention of rust is a much more major one, as rust can compromise structural stability. Also, not rusting means that stainless steel is very light on maintainence, so it’s used for parts which are hard to conduct maintainence on. It’s also arguably cheaper in the long-term due to lack of maintainence required.

Normal steel is essentially carbon added to iron, which makes it hard and strong. Strong as in it has high tensile strength.

Stainless steel has a relatively high chromium content in addition to iron and carbon. The chromium forms a layer at the surface, and since chromium is a relatively more inert metal (i.e., less reactive) it doesn’t react as readily with oxygen and other corrosive agents in the environment. Hence, it doesn’t rust as easily (hence stainless) and lasts longer.

Edit:- Chromium is more reactive than iron, but the oxide it forms can protect the bulk material from further oxidation, as opposed to iron oxide which is permeable. Thanks to u/SoulWager for correcting me

Okay imagine steel is a shirt. If you spill something on your shirt it’s going to absorb it and possibly even stain it. Now imagine you waterproof your shirt. When you spill something on it, it’ll be repelled and it won’t stain or absorb whatever you spilled onto it and it will be easier to clean. Very convenient don’t you think? What shirt would you rather have?

Steel is an alloy and there are different types of steel but I will not go into detail. Basically non-stainless steel has no protective coating while stainless does, making it much more easier to clean and it also looks much nicer.

Typical stainless steel is “18/8”, which means 18% Chromium and 8% Nickel.

It’s more expensive and harder to work than normal “mild steel”, so you won’t see car bodies made of the stuff, but it is highly resistant to corrosion, so it has a lot of applications.

You have to match the steel to the job. Stainless doesn’t rust significantly but is more difficult to machine and it lacks “toughness” (it cracks instead of deforms.) Mild steel rusts but is very workable and difficult to break. Other flavors of steel are very hard or very flexible or very something else. It comes down to what you need the steel to do.