What Is Carbon Steel? (Everything You Need to Know About Carbon Steel)

I know we talk about carbon steel a lot in our blog. We say buy carbon steel woks or carbon steel pans etc.

But what is carbon steel? How is it formed, and how many variations of carbon steel are there?

I know all we compare is carbon steel and stainless steel, but there is actually more to it.

Ready to find out? Wear your nerdy outfit and join me because this is going to be a bit rocky.

Table of Contents

What is carbon steel?

steel-pans-and-spoons

This is a kind of steel that contains carbon and iron. The amount of carbon in the steel determines what grade of carbon steel it is.

Low carbon steel has 0.25% of carbon, medium carbon steel has 0.25-0.50% carbon, while any other kind of carbon steel is very high-carbon steel.

We will be expounding more on each of these carbon steels later on the blog post and where each of them is applicable.

Let’s dive right in.

Low Carbon Steel

This is probably the most common form of carbon steel. As I mentioned earlier, it has a carbon percentage of 0.25%, and it can’t be hardened using heat treatment like other levels of carbon steel. Therefore, this is done through cold work.

Low carbon steel is neither too brittle nor too ductile; it’s a good balance, explaining why it’s used in multiple industries.

Another reason why this grade of steel is everywhere is because it’s versatile and its manufacturing cost is very low.

Some of the common uses of low carbon steel include.

  • Cookware. There is a big market for stainless steel knives and pans. However, there is also a market for carbon steel knife cookware. Low carbon steel is more preferred because it stays sharper for longer and it doesn’t rust easily. It’s also great because of the high-temperature limit, which makes it non-stick once it’s treated. 
steel-frying-pan
  • Pipelines. Low carbon steel is used to transport beer, natural gases, and water because they are ductile and don’t crack under pressure.
  • Steel frame buildings. It works perfectly for building frames because it meets wind requirements and it also cannot be damaged by fire or insects, and it doesn’t rust.
  • Machinery parts. It works well in the machinery because it can be molded, shaped, pressed without breaking.
  • Fencing/ Metal Gates. There are many reasons that this steel is good for metal gates because of its aesthetic appearance. It’s also strong, so it doesn’t break easily, and it can be painted for longevity and preventing corrosion.

Medium Carbon Steel

This carbon steel contains 0.25 – 0.60 wt.% carbon and 0.60 – 1.65 wt.% manganese. Its mechanical properties are improved through heat treatment that involves austenitizing, quenching, and tempering, which gives it a martensitic microstructure.

When treatment can only be done on thin sections, additional alloys like nickel, molybdenum, and chromium improve the steels’ ability to treat and harden it.

Hardened medium carbon steel is stronger than low carbon steel, but its ductility properties aren’t as good as low carbon steel.

Here are some of the uses of medium carbon steel.

  • Railway applications. Rails, railway wheels, and other parts associated with rail cars are mostly made using this kind of steel. This is because the high tensile strength allows it to withstand the changing force on the rails.
  • Pressured structures. Thanks to its ductility, it’s easily shaped into plates for broilers and other tanks. However, since it’s brittle and prone to breaking, it can’t be used for gasses or cold liquids; for these cases, high carbon steels and stainless steel are the best.
  • Structural steel. This works perfectly for structures like bridges because this steel has high tensile strength. However, the steel must be properly insulated against extreme heat or cold as it can affect the martensite structure.
  • Shafts & gearing. Most gearing plates, axle shafts, and crankshafts are all made from medium carbon steel. Its ductility allows the steel to be molded or toothed while retaining its tensile strength.
pieces of steel

High Carbon Steel

Any steel with a carbon content of 0.55% or higher is high carbon steel; pushing the carbon content past 2% makes it very brittle. This is how all carbon cookware and wood stoves are made.

High carbon steel has extreme hardness, high strength, moderate elasticity, and is resistant to wear.

Since this steel can maintain a very sharp edge, it’s used in cutting tools and masonry nails.

Besides the high carbon steel, there is another category that contains a carbon content of 0.8%. This type of steel is known as tool-carbon steel. The latter is very hard, and they’re mostly used in shearing blades, punch awls, razors, and knives.

Benefits of Using Carbon Steel

If I had to write all the pros of using carbon steel over traditional steel, I would need to dedicate a whole blog post to that.

However, in a nutshell, here are some of the greatest benefits of using carbon steel.

  • It’s durable. Carbon steel is both shock-resistant and it’s extremely strong. This makes it a perfect choice for piping, construction and supporting modern roads. This type of steel is also corrosion-resistant compared to other metals.
  • It’s safer compared to other metals. Carbon steel is safe to handle and build homes that can survive fires, earthquakes, hurricanes, and tornadoes.
  • It’s Green. Carbon steel can be recycled, which helps in reducing clutter in the environment.
  • It’s economical. Carbon steel manufacturing is cost-friendly as it uses carbon and iron. Also, it’s used in pipes because it can be made very thin, which is cheaper than copper wires.
  • It makes healthy and long-lasting cookware. Knives and pots made from carbon steel are healthy and safe to cook with compared to aluminum cookware. The latter reacts with food that can cause health issues. Carbon steel cookware also lasts longer than aluminum, and it’s prone to scratches and dents.

Disadvantages of Using Carbon Steel

While carbon steel has so many advantages, it also has its cons, and it’s only fair that I let you in.

Here are the setbacks of using carbon steel.

  • It’s prone to rust. Unlike stainless steel, carbon steel doesn’t have chromium that reacts with oxygen to form a coat and prevent rusting. This means you need to be careful with maintenance practices.
detail-of-rusty-metal-showing-rust
  • It can’t be molded into various shapes. Since carbon steel is strong, it’s hard to bend, which limits its usage.
  • It reacts with acidic foods. Although it’s safer than aluminum, it reacts with acidic foods such as wine sauces and tomatoes.
  • It’s hard to get. Unlike other utensils, knives or pans made using carbon steel are hard to come by. You’ll have to explore unknown companies and dig deeper to get carbon steel cookware.
  • It lacks an aesthetic appearance. Although you can still paint carbon steel for better finishing, it doesn’t offer a very good finishing.

Frequently Asked Questions

Here are the commonly asked questions regarding carbon steel.

Is Carbon Steel Better than Mild Steel?

The question of whether carbon steel is better than mild steel is a grey area. Some people also wonder if they mean the same thing. Well, the thing is, mild steel is a category of carbon steel. They’re just carbon steels that have different carbon levels. Whether they are great or not depends on how you’re applying them.

Is carbon steel stronger than stainless steel?

Carbon steel is stronger and harder than stainless steel. This is why it’s commonly used for bladed instruments and knives. On the other hand, it’s more prone to rust as the iron reacts with moisture to form iron oxide.

What Is Carbon Steel? (Final Thoughts)

In addition to cast iron, Carbon steel is a big name in all industries. In the cookware industry, it’s used to make carbon steel pans and knives.

However, carbon steel is a major category divided into low-carbon steel, high-carbon steel, and medium-carbon steel.

The difference between this steel is the level of carbon in them. This affects their ductility, strength, and, subsequently, their uses.

I hope my blog post gave you a bit of clarity on what carbon steel is and how it’s used.

What else would you love to know about carbon steel?

Colin Matthews

Colin is a passionate chef by trade and a kitchen nerd on the side. Growing up in the kitchen, Colin has always had a passion for learning the absolute best way to cook a dish. He quickly realized most kitchens have duplicate cookware and small appliances and had to decide which ones were going to be the “keepers” – causing him to take a closer look at all his products.

As it turns out, small differences make a big impact on the experience. Whether it’s how hard you have to press a microwave button, to how long a cast iron skillet stays warm after you turn off the heat, these little difference changed everything.