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19 March 2026 at 19:53 • 5 mins read
With exceptional strength and mechanical properties, steel delivers a versatile material option for a wide range of construction and building projects. While there are different classifications or grades of steel, all steel grades are comprised of iron and carbon. The varying composition of each type of steel differentiates the four basic steel categories.
The four main types of steel include carbon steel, stainless steel, alloy steel, and tool steel. Learn how the different kinds of steel are categorized and how each type can work for your project requirements.
As general-purpose steel, carbon steel is available with varying elements of carbon. Low carbon (mild) steel includes 0.30% or less carbon
From construction to manufacturing, carbon steel is widely used throughout a wide range of industries.
Often used for hygienic applications, stainless steel comprises 10%-20% of chromium, nickel, or molybdenum. Ideal for medical equipment, food processing equipment, appliances, and structural purposes, stainless steel offers you strength and corrosion resistance in addition to low maintenance upkeep.
With a mix of aluminum, copper, nickel, and other elements such as titanium or manganese, alloy steel is cost-efficient and includes at least 5% alloying elements. Often used for pipes, alloy steel is easily machinable and provides good corrosion resistance.
Used for toolmaking and drilling equipment, tool steel is an abrasion-resistant material option. Tool steel is characterized by its extreme hardness and ability to hold a cutting edge at high temperatures. Tool steel often contains varying levels of cobalt, tungsten, molybdenum, or vanadium.
Steel grade classification includes ASTM and AISI/SAE standards for identification.
The ASTM grading system utilizes letters and a sequential number
as designators for the metal category. For example, ASTM A36
reflects low-carbon structural steel. It has a yield strength of
36,000 psi. The “A” reflects that it is a ferrous metal, and the
“36” reflects the mechanical properties.
ASTM standards reflect
classifications based on material, mechanical, chemical, and
metallurgical properties. Steel products that abide by ASTM
standards reflect the quality and performance-based standards that
meet your material needs.
The AISI/SAE grading system uses a four-digit system to identify different steels. The first digit reflects carbon steels. The second digit demonstrates the concentration of elements. The last two numbers reflect the carbon concentration in each steel. For example, AISI/SAE 1018 reflects low-carbon steel.
While surface finishes vary among steel types, there are surface finishing options for each steel type.
Mild or low-carbon steel is the most common form of steel in
existence. Mild steel is less expensive than other steel forms, and
due to its carbon content of .05-.025%, it is highly malleable and
ductile. Mild steel is also machinable and weldable.
On the other
hand, stainless steel contains 10-20% chromium, along with silicon,
nickel, manganese, and carbon, providing high corrosion resistance
levels for various applications. Stainless steel is available in
several alloy options, including 304 and 316.
What separates IMS from other metals companies? With an abundance of metal options and customer service that is second to none, IMS has you covered with the following advantages:
Industrial Metal Supply is your trusted supplier of premium in-stock steel products, including stainless steel bar, sheet, and plate, as well as tubing, pipe, and structural shapes. Get in touch with our sales team for world-class metal products and services today.