types of steel

Steel in its various types is a vital component of the United States economy. As of January 2020, domestic steel production was at 1,928,000 tons — making steel one of the most widely consumed domestic manufacturing products. From buildings to medical equipment and vehicles, the world literally runs on steel products. But not all steel materials are made alike.

There are multiple steel types and alloys that each have unique properties — making them each suited to specific production goals. Some steels are sturdy and heavy, while other steels are ductile and versatile.

Frequently, our customers approach us regarding the best type of steel for their application. We put together this quick guide to help you navigate the language of steel. Of course, you may still have questions regarding the application. Feel free to reach out to us with any unique property needs so that we can help you find the right steel and manufacturer for your needs.

Carbon Steel

Technically, carbon steel is a metal alloy that contains both iron and carbon. But in the manufacturing industry, carbon steel is often defined in multiple ways. Both of the following constitutes a “carbon steel” in the metals market.

  • Steel that contains up to 2% carbon
  • Steel that does not contain any standard amounts of elements that would classify it as an “alloy steel” (e.g., cobalt, nickel, tungsten, molybdenum, titanium, zirconium, vanadium, chromium, etc.)

You may also notice the term “carbon steel” applied to steels with less than 0.4% copper or steels that have certain magnesium to copper contents, though those definitions are contested across industries. For the purposes of this, we’re talking about the first two definitions.

There are three ways that carbon steel is classified — low, medium, and high

Low Carbon Steel

Low carbon steel (or “mild carbon steel” or “plain carbon steel”) refers to carbon steels that have up to 0.30% carbon content. This is, by far, the most common type of steel on the metals market. There are a few reasons for this. For starters, low carbon steel is relatively inexpensive. Also, since the carbon content is lower than medium and high steels, low carbon steel is easy to form and is perfect for applications where tensile strength isn’t an immediate issue, such as structural beams.

Another benefit of low carbon steel is that its properties can be improved relatively easily by adding additional elements, such as magnesium. Low carbon steel is also an ideal choice for carburizing, which improves case hardness without impacting ductility or toughness.

What are some common uses for low carbon steel?

  • Structural components
  • Machinery
  • Pipes
  • Domestic appliances
  • Automobile components
  • Surgical instruments
  • Medical equipment
  • Wires
  • Bolts
  • Stampings
  • etc.

Core properties of low carbon steel:

  • Low cost
  • Low hardness
  • Mild strength
  • High machinability
  • Very high toughness
  • High ductility
  • High weldability

Medium Carbon Steel

Medium carbon steel refers to carbon steels that have between 0.31% and 0.60% carbon content and between 0.31% and 1.60% magnesium. One of the biggest benefits of medium carbon steel is its strength. However, that comes with some tradeoffs. Medium carbon steel has low ductility and toughness — making it more difficult to form and weld.

What are some common uses for medium carbon steel?

  • Machinery parts
  • Pressure structures
  • Cranks
  • Gears
  • Railway tracks

Core properties of medium carbon steel:

  • Low hardenability
  • Medium ductility
  • Average toughness
  • Medium strength
  • Medium weldability
  • Average machinability

High Carbon Steel

High carbon steel refers to carbon steels that have between 0.61% and 1.50% carbon content and between 0.31 and 0.90 magnesium. When it comes to hardness and toughness, high carbon steel is the carbon steel of choice. However, this comes at a tradeoff. It’s very difficult to weld, cut, or form high carbon steel.

What are some common uses for high carbon steel?

  • Railways
  • Bars
  • Spring steel
  • Plates
  • etc.

Core properties of high carbon steel:

  • Low hardenability
  • Low ductility
  • Reduced weldability
  • Low machinability
  • High toughness
  • High strength

Stainless Steel

While carbon steel is typically defined by its carbon content, stainless steel is defined by its 10.5% minimum chromium content. Like carbon steel, stainless steel also contains carbon and iron, but the extra chromium is the key that gives it its unique properties. One of the biggest benefits of stainless steel is that it protects the steel for oxidization — which degrades metals over time. Stainless steel is also identified by its sheen, a property provided by the chromium. You will often see stainless steel utilized in cookware, knives, and medical equipment.

Like carbon steel, there are various types of stainless steel, each with a unique market price and properties.

Austenitic Alloys

Stainless steel austenitic alloys are, by far, the most common types of stainless steel metals on the market. They resist oxidation, provide a unique look, and are non-magnetic (though they can become magnetic in certain circumstances).

There are two common austenitic alloy grades:

  • Grade 304
  • Grade 316

Grades of austenitic alloys also include 301, 302, 303, 309, and 321.

Ferritic Alloys

Stainless steel ferritic alloys are another semi-common stainless steel alloy. Unlike austenitic alloys, they are magnetic — lending them to applications where magnetism is necessary. These are typically the cheapest stainless steel alloys due to their relatively low nickel content.

There are two common ferritic alloy grades:

  • Grade 430
  • Grade 434

Martensitic Alloys

Stainless steel martensitic alloys are the least common stainless steel alloy. These alloys have incredible hardiness and toughness, but they have poor oxidation properties, making them only suited for applications that require incredible hardiness.

There is one common martensitic alloy grade:

  • Grade 420

Alloy Steels

The widest and most diverse range of steel alloys is “alloy steels.” These are made by combining carbon steel with various alloying elements to provide unique properties to each steel. There is an incredibly wide range of alloy steels, but some of the most common include:

  • Chromium
  • Cobalt
  • Molybdenum
  • Nickel
  • Tungsten
  • Vanadium

Due to the incredible variety of alloy steels, you can create steels with almost every possible property using alloy elements. That being said, some of these steels are relatively expensive.

Tooling Steels

The final steel group is tooling steels. These are steels used for tooling activities such as drilling. Commonly made up of molybdenum, vanadium, tungsten, and cobalt, tooling steels are heat-resistant, durable, and strong.

There are 6 grades of tool steel:

  • Air-hardening
  • Water-hardening
  • D-type
  • Hot-working
  • Shock-resisting types
  • Oil-hardening

Do You Need Steel?

Staub Manufacturing offers services using most of the steels listed above. If your company needs best-fit steel parts to manufacture high-quality products, contact us. We’re American ISO 9001:2105 certified manufacturers who are ready to help you deliver superior fabricated steel products.