What Is 1018 Carbon Steel?

cuts a metal blank a grinderHave you stumbled upon a piece of 1018 steel and wondered if it’s good enough for knives? It will be astonishing if you actually find a commercially produced knife made with 1018 steel. It’s not really meant for modern knives at all. But it can work for many other purposes, and beginner bladesmiths can even use it for practice to perfect their forging techniques.

With this guide, you’ll get a much closer look at what 1018 steel is all about, and find out what really makes it tick. Every likely question you have about 1018 steel will be answered, and you’ll even get a close inspection of its chemical composition. When you finish this guide, you’ll realize why it’s not meant for knives, and discover what it’s really good for.

What is 1018 Carbon Steel?

alloy mild steel1018 carbon steel is low alloy mild steel. This means that its iron content is quite high, with the alloying elements not making up more than 5% of the total. It also doesn’t contain a lot of carbon at all. It may be carbon steel, but it’s low carbon steel. Some don’t even regard it as proper carbon steel at all, because the carbon content is so low.

With the low carbon content, it doesn’t harden enough to make it a good choice for knife blades. But it’s quite useful for some industrial components. It’s easy enough to work with, especially for budding bladesmiths who want to improve their knifemaking techniques.

It can be available in cold finished bars, and it’s very easy to weld, form, machine, and fabricate. It’s cheap and easily available, which makes it perfect for smithing practice. It’s very popular not just because of the price and availability, but also because it’s easy to machine and offers a nice balance of strength and a bit of ductility.

Common Uses of 1018 Steel

No, it’s not meant for knives. But it is easy to work with and affordable to boot, making it a great choice for high volume parts. These include:

  • Anchor bolts
  • Fasteners
  • Gears
  • Pins
  • Ratchets
  • Rods
  • Structural parts
  • Tool Holders

This is also great for practicing smithing techniques and other metalworking processes.

1018 Steel Chemical Composition

As the 1018 steel is low alloy steel, this means that the elements other than iron aren’t all that much. In fact, the 1018 steel contains very few elements other than iron.

  • Carbon, 0.15% to 0.20%
  • Manganese, 0.60% to 0.90%
  • Sulfur, 0.05%
  • Phosphorus, 0.04%

Carbon, 0.15% to 0.20% at the most: It usually contains an average of 0.18% carbon, which explains the 18 in its name. Most experts regard carbon as the most crucial component in a knife blade’s composition, and you have to notice that there’s very little carbon here. Some experts define proper carbon steel as having at least 0.40% carbon, and the 1018 steel doesn’t meet that standard at all.

Carbon generally defines the hardness of the steel, and the tiny amount of carbon here makes the 1018 steel too soft for knives.

Manganese, 0.60% to 0.90% at the most: Manganese tends to have somewhat the same effects of carbon, so much so that it’s almost as important as carbon itself. It boosts tensile strength and hardenability, but too much of it lowers the ductility. It’s also a deoxidant, as it takes out oxygen and sulfur out of the melt.

Sulfur, 0.05% at the most: The manganese content is at least 10 times that of sulfur, to make the alloy easier to weld. While manganese tends to take out sulfur because too much sulfur reduces notched impact toughness and transverse ductility. But the tiny amount of sulfur here helps in improving the machinability of 1018 steel.

Phosphorus, 0.04% at the most: This is also normally regarded as an unwanted impurity, since too much of it makes the steel brittle. But here you have just enough phosphorus to improve the tensile strength and machinability of the steel.

1018 Steel Hardness

With the low carbon content, 1018 steel isn’t really all that hard. In fact, you can compare its quality to primitive iron. When you shape into thin knife blades, the hardness level you get is only at 42 HRC or so.

That’s clearly insufficient for knives, though it can suffice for other uses. With knives, you usually get a hardness rating of 52 HRC on average.

Does 1018 Steel Rust?

Yes, it will rust, as it’s a ferrous metal. That means it contains lots of iron and iron can rust. The 1018 steel has very low corrosion resistance levels, and it can rust very easily. It doesn’t contain any of the famous alloying elements for corrosion resistance, like chromium.

If you leave the 1018 steel wet, or even use it extensively in humid environments, then rust is inevitable.

Properties of 1018 Steel

the 1018 steel is great for productionThese are the properties you can expect from 1018 steel:

Very Affordable and Readily Available

You don’t have to go far to find 1018 steel. In fact, you don’t even have to go online and order from special manufacturers. Just head on over to any hardware store, and you can get it for cheap. In fact, you can find it easily enough in any scrap pile too.

If you’re using this for metalsmithing practice, then the low cost and easy availability are both definitive advantages. You can get a lot of practice in.

If you’re in to manufacturing, then the 1018 steel is great for production, especially for high volume manufacturing. You can cut down on costs and delays, since you can easily get the 1018 steel for cheap.

Heat Treatments

You want to practice doing heat treatments on steel samples? You can do that with 1018 steel. The heat treatment processes you can try out include:

  • Normalizing
  • Forging
  • Tempering
  • Annealing
  • Stress relieving
  • Case hardening
  • Core refining
  • Carburizing

Easy to Work With

If you’re using the 1018 steel to make your components, then it’s great. This is even true for cold finished bars. The 1018 steel is easy to fabricate, machine, weld, and form. It’s no trouble to get it to whatever design you want.

You can even weld it without any sort o pre-heating preparation or post-heating treatment. It can be welded in an instant, by all the conventional welding processes. Just keep in mind that welding may not be a good idea if your 1018 steel is carbonitrided and carburized.

1018 Equivalent Steels or Alternative

Close-up master grinds the knife on a belt grinder and many sparks are producedThe 1018 steel is popular and widely used, though not for knives. How does it compare with somewhat similar steels? These direct comparisons should give you a clearer idea of what the 1018 steel is all about.

1018 Steel vs a36 Steel

This can seem like a fair comparison, as the A36 steel is also widely popular. They can be both cold drawn or hot rolled, though normally they’re available in hot rolled form. Their chemical compositions are very similar, though the A36 has a bit more carbon (0.26% to 1018’s 0.18%).

However, the 1018 steel has better chemical and mechanical properties, along with a better surface finish. It’s not just stronger than A36 steel, but also easier to machine. But A36 is much cheaper, and it’s a better choice if you don’t need the superior strength, surface finish, and machinability of the 1018 steel.

1018 Steel vs 1020 Steel

The 1020 steel is considered a lesser grade of steel compared to 1018 steel. They do have the same levels of sulfur and phosphorus. The 1020 steel does have a bit higher carbon content (0.20% to 1018’s 0.18%). But its manganese level is considerably less at 0.3% to 0.6%. You get 0.6% to 0.9% manganese with the 1018 steel.

The 1018 steel is more commonly used, since the 1020 steel isn’t as readily available.

1018 Steel vs 1215 Steel

These 2 alloys also have similar chemical compositions, and they’re both available in different forms and sizes. The 1215 steel is more expensive than 1018 steel, but its use can reduce overall costs by as much as 25% to 40%.

You should go with the 1018 steel if the part you’re making requires welding, bending, or the case hardening process. The 1215 is better for low-stress uses, like for couplings, bushings, and fittings.

1018 Steel vs 4140 Steel

These are somewhat the same, but the 4140 steel contains chromium, molybdenum, and silicon. You also get more carbon and manganese with 4140 steel. It’s very versatile, due to its fatigue strength, toughness, and resistance to impact and abrasion. But the 4140 steel can cost more than twice that of 1018 steel, and the 1018 steel may be easier to work with.

Is 1018 Steel Good for Knives?

No, it’s not. The low carbon content reduces the cutting performance and especially the edge retention. It’s so soft that you’d be sharpening the knife blade almost constantly.

Of course, you can use the 1018 steel to make a primitive iron knife, or at least its equivalent. It will be better than bronze knives, but it sure as heck won’t compare with even the cheapest commercial knives today.

There are simply a lot of steels out there that are just better than 1018 steel for knives. But you can use the 1018 steel for practice if you’re a newbie metalsmith, as it’s very cheap and readily available.

Pros & Cons of 1018 steel

  • Very affordable
  • Easily available
  • Easy to weld
  • Can be used for many heat-treatment processes
  • Can be welded instantly using all regular welding processes
  • Great for metalsmithing practice
  • Good for high-volume manufacturing
  • Doesn’t allow for acceptable edge retention
  • Low corrosion resistance


For tool manufacturers, the 1018 steel represent a good cost-savings measure in the production of various industrial components. It’s cheap, easy to buy anywhere, and inexpensive and easy to work with. Newbie metalsmiths like it to for practice.

It’s just that you won’t really find the 1018 steel used for commercial knives. It’s just too soft for that purpose. It may be good for budding knifemakers, but it’s no good at all for knife users.

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