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What are the Four Types of Steel?

Steel is the world’s most important engineering and construction material. It is used in every aspect of our lives; in cars and construction products, refrigerators and washing machines, cargo ships, surgical scalpels, Oil Rigs, etc. It can be recycled over and over again without loss of property.

Although Steel consists of more than 3500+ Grades they are fundamentally broken down into four foundational types:

1. Carbon Steel

Carbon steels make up about 90% of all steel production in the world.

Carbon steel is an iron-carbon alloy containing up to 2.1 wt.% carbon. For carbon steels, there is no minimum specified content of other alloying elements, however, they often contain manganese. The maximum manganese, silicon, and copper content should be less than 1.65 wt.%, 0.6 wt.% and 0.6 wt.%, respectively.

Types of Carbon Steel:

  • High-carbon steel - Low hardness and cost. High ductility, toughness, machinability, and weldability.

  • Medium-carbon steel - Low hardenability, medium strength, ductility, and toughness.

  • Low-carbon steel - High hardness, strength, and low ductility.

2. Stainless Steel

There are over 100 grades of stainless steel, making it an incredibly versatile, customizable material.

Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals, and metals to obtain other desired properties. Stainless steel's resistance to corrosion results from chromium, which forms a passive film that can protect the material and self-heal in the presence of oxygen.

Types Of Stainless Steel

  • Martensitic alloys: Toughness is a hallmark of martensitic alloys, but they’re prone to corrosion. They’re formed by a rapid-cooling process that makes them ideal for heat treatment and is found in medical instruments, cutlery, and pliers.

  • Ferritic alloys: These are less-expensive steels with low amounts of carbon and nickel. Automotive applications are common final destinations for ferritic alloys because of their chromium-induced strength and sheen.

  • Austenitic alloys: Austenitic alloys have higher chromium and nickel contents, improving their resistance to corrosion and causing them to become non-magnetic. They’re present in commercial kitchen appliances and are popular because they’re durable and easy to clean.

  • Duplex alloys: A combination of austenitic and ferritic alloys results in a duplex alloy that inherits the properties of both whilst doubling strength. They’re also ductile and corrosion-resistant due to their fairly high chromium content.

Stainless steel variants, when used in the construction industry, are prized for their corrosion resistance and strength. They’re well-suited for a variety of building applications, as well as storage functions for hazardous construction materials.

3. Alloy Steel

Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low alloy steels and high alloy steels. The difference between the two is disputed.

Alloy steel as a grouping includes a diverse range of alloys with an equally diverse range of properties. Shipping containers use a complex alloy that combines multiple elements to produce a durable and lasting product. Silicon isn’t often thought of as a component of steel, but its magnetic properties make it a perfect component of most large machinery. Aluminum is versatile and used in revolutionary building materials that are both lightweight and extremely durable.

Some of the elements that combine with iron and carbon to produce alloys are also found in tool steels — cobalt, tungsten, and molybdenum, for example, are ultra-hard metals that are desired for their impact resistance and cutting abilities.

Types Of Alloy Steel

  • Aluminum: Lightweight, heat-resistant steel that’s ductile and easy to work with and is often used in hot exhaust systems and power generators.

  • Copper: Corrosion-resistant steel that conducts heat very efficiently, making it a great choice for electrical wiring and industrial heat exchangers.

  • Manganese: Impact-resistant steel that’s extremely tough. It can be found in bulletproof cabinets, anti-drill plates, and high-strength safes.

  • Molybdenum: Weldable, corrosion-resistant steel that performs under high pressure, making it well-suited for underwater construction or oil and gas pipelines.

  • Silicon: Soft-natured steel that’s malleable and highly magnetic, and creates strong permanent magnets that are used in electrical transformers.

  • Vanadium: High-impact steel that’s shock-absorbent and vibration-resistant, and often found in automotive parts like springs and shocks.

Their downright versatility makes alloys a common occurrence in many construction projects. Copper and aluminum alloy varieties are particularly popular for their low weight and heat-working properties.

4. Tool Steel

Tool steel is any of various carbon steels and alloy steels that are particularly well-suited to be made into tools and tooling, including cutting tools, dies, hand tools, knives, and others. Their suitability comes from their distinctive hardness, resistance to abrasion and deformation, and their ability to hold a cutting edge at elevated temperatures. As a result, tool steels are suited for use in the shaping of other materials, for example in cutting, machining, stamping, or forging.

Types of Tool Steel

Different types of tools require different types of tool steel in production. Tool steel is used in a variety of ways to best serve the production requirements of a particular tool. Added elements will determine which particular applications it’s suited for.

  • Air-hardening: The high chromium content in this steel allows it to be exposed to high temperatures without distorting.

  • Water-hardening: This steel is water-quenched during use; it’s the most affordable tooling type and is used to make common tools.

  • Oil-hardening: This oil-quenched steel is exceptionally wear-resistant from slipping, and is used to produce knives and shears.

  • High-speed: High-speed steel is highly abrasive and impact-resistant. It’s found in drill bits and power saws.

  • Hot-working: The name gives it away, but this steel can withstand extreme heat and is used in forging and casting.

  • Shock-resisting: Small amounts of carbon, silicon, and molybdenum harden this steel and suit it for punches and riveting tools.

These types can be further separated by the industry they’re used in, as well as their hardness and toughness.

What Are the Different Grades of Steel?

Steel is notably complicated due to its many properties and applications. Two comprehensive grading systems have been developed to accurately categorize a particular type, even within subgroups. These systems are standardized across industries so that material integrity can be insured. The two grading systems are:

  • ASTM (American Society for Testing and Materials): Alphanumeric classification that denotes the steel’s overall categorization and specific attributes.

  • SAE (Society of Automotive Engineers): Four-digit numerical classification that highlights steel type and carbon content along with the presence of other alloying elements.

You can find steel everywhere, materialized in different forms to suit various needs. It is an essential component of many building materials, home appliances, and even tools used to make other tools. By combining the right elements, an exact steel match is available for almost any application.


In 1967, the world made only 500 million tons of steel. However, in 2016, that number rose to over 1,600 million. In addition to that, according to The World Steel Association, 55% of a typical car’s weight is a result of steel. With this reality, it is hard to imagine a world without steel in it. With more than 3,500 different steel grades, the possibilities for its usage are seemingly endless for what it can do. From manufacturing, and fabrication, to CNC machining steel, each type has its perfect place and characteristics to accommodate just about every need. In the end, the different steel properties stem from using different steel alloys and break down into the four types that we see today. If you're thinking about Steel we would suggest you buy the right type of Steel based on the properties suitable for your requirement


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