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What is Medium Carbon Steel?

Allan Robinson
Allan Robinson

Steel is an alloy of metals that consists primarily of iron and contains 0.2 to 2.1 percent carbon. All steel contains carbon, but the term “carbon steel” applies specifically to steel that contains carbon as the main alloying constituent. Medium carbon steel is carbon steel that contains between 0.30 and 0.60 percent carbon. It also has a manganese content between 0.6 and 1.65 percent. This type of steel provides a good balance between strength and ductility, and it is common in many types of steel parts.

Iron consists of a crystal lattice of iron atoms that allow the atoms to slide past each other, making pure iron relatively soft. The carbon in steel reduces this tendency, making medium carbon steel harder than iron. Additional elements such as chromium, manganese, tungsten and vanadium can also act as hardening agents in steel. The precise proportion of these elements determines the specific properties of the steel.

Medium carbon steel pipes.
Medium carbon steel pipes.

Additional carbon makes the steel harder but also more brittle, so manufacturing carbon steel requires a balance between hardness and ductility. The most common uses of medium carbon steel are in heavy machinery, such as axles, crankshafts, couplings and gears. Steel with a carbon content between 0.4 and 0.6 percent is commonly used in the railroad industry to make axles, rails and wheels.

The axles and wheels on rail cars are made of medium carbon steel.
The axles and wheels on rail cars are made of medium carbon steel.

The treatment of medium carbon steel with heat significantly changes the mechanical properties, such as ductility, hardness and strength. Heat treatment of steel slightly affects other properties such as its ability to conduct heat and electricity as well. A variety of methods exist for treating steel with heat.

The carbon and manganese content in medium carbon steel make quenching and tempering the most common method of heat treatment for this type of steel. This process generally involves repeatedly heating the steel to less than 1,333°F (about 723°C), and cooling it rapidly by quenching it in a liquid such as oil or water. The temperature and time of this process allows the manufacturer to precisely control the final properties of the steel.

Case hardening is a process for hardening steel that only affects the exterior of the steel. This produces a hard, water-resistant exterior with a more ductile interior. Carbon steel is frequently case-hardened because it’s difficult to harden a thick carbon steel part completely. Steel with more alloying agents than that of medium carbon steel has a greater ability to be hardened and may not need to be case-hardened.

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Discussion Comments


Can anyone tell me the maximum shear stress of medium carbon steel?


I know that carbon comes in a variety of forms from graphite to diamonds, but what is used in this process? Is there some type of solid carbon that can be mined or manufactured that is added to the steel? I was thinking it might also be possible to use carbon dioxide from the air and separate the carbon to join with the iron. Does anyone know?


What is done to produce stainless steel? I would have to assume that there is some element that is thrown into the mix to make the steel rust resistant. I don't know of any metals that are resistant to oxidation, though. Is it something about the chemical reaction between the metals that eliminates rust?

Along the same lines of adding materials to steel: What would happen if you put more than 2.1 percent of carbon in with steel? My guess is that the metal would be too brittle to be used for anything, but I could be wrong.


@cardsfan27 - Your question got me interested, so I took a second to look around for some examples. From what I can find, the sky's the limit for carbon steel uses. In general, it seems like the strength of high carbon steel is useful for cutting tools or anything that will be involved in high impact uses. Medium and low carbon steel often seem to be in the same types of things like sheet metal, tools, and machine parts.

If you're interested in the subject, there are quite a few websites I found that give much more detailed descriptions of the different types of steel alloys and their uses.

Unfortunately, I didn't find anything about price. I was curious about that as well. I doubt most types of steel would be worth much. I think iron usually costs about as much to carry away as a scrap yard will pay you for it.


What are some of the various uses for medium carbon steel, or all of the types of carbon steel, for that matter? Is there some way to visibly tell the difference between carbon steel and something like stainless steel or some other alloy?

I know you can buy steel pipe, and sheet metal is always available. I could go on naming hundreds of items, but I wouldn't have any idea what type of steel each was. I know stainless steel is resistant to rust, and is used for things like silverware.

I think it would also be interesting to know about some of the properties of each type of steel. For example, is one type of steel easier to weld, or which steel prices are the highest?


How does the density of carbon steel change depending on the composition? Since carbon is lighter than iron, my initial guess would be that high carbon steel would be less dense than low carbon steel. That also seems to go with what the article says about high carbon steel being more brittle. On the other hand, though, it seems like high carbon steel should be heavier than low carbon steel.

Going with the article, I'm assuming more carbon ends up with stronger steel, but maybe I'm wrong if it ends up being brittle. How does the manufacturing process overcome the high carbon steel being brittle? Is it just through case hardening, or similar techniques? Thanks in advance for any explanations you guys can give.

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    • Medium carbon steel pipes.
      Medium carbon steel pipes.
    • The axles and wheels on rail cars are made of medium carbon steel.
      By: Dmitriy Sladkov
      The axles and wheels on rail cars are made of medium carbon steel.