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Four Types of SteelWith exceptional strength and mechanical properties, steel offers you a versatile material option for construction and building projects. While there are different classifications or grades of steel, all steels 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 types of steel are categorized and how each type of steel can work for your project requirements.
Carbon SteelAs a general-purpose steel, carbon steel is available with varying elements of carbon.Low carbon (mild) steel includes 0.30% or less carbon
- Medium or mid carbon steel includes 0.30%-0.60% carbon
- High carbon steel includes more than 0.60%-1.5% carbon
Stainless SteelOften used for hygienic applications, stainless steel comprises of 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.
Alloy SteelWith a mix of aluminum, copper, nickel, and other elements such as titanium or manganese, alloy steel is a cost-efficient steel that includes at least 5% alloying elements. Often used for pipes, alloy steel is easily machinable and provides good corrosion resistance.
Tool SteelUsed for toolmaking and drilling equipment, tool steel is an abrasion resistant material option. Tool steel is characterized by its extreme hardness as well as its ability to hold a cutting edge at high temperatures. Tool steel often contains varying levels of cobalt, tungsten, molybdenum, or vanadium.
Steel Grades and Identification MethodsSteel grade classification includes ASTM and AISI/SAE standards for identification.
The ASTM grading system utilizes letters as designators for the metal category and a sequential number. For example, ASTM A36 reflects a 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 quality and performance based steels that will 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 reflects the concentration of elements. The last two digits reflect the carbon concentration in each steel. For example, AISI/SAE 1018 reflects a low carbon steel.
- 1XXX – Carbon steels
- 2XXX – Nickel steels
- 3XXX – Nickel-chromium steels
- 4XXX – Molybdenum steels
- 5XXX – Chromium steels
- 6XXX – Chromium-vanadium steels
- 7XXX – Tungsten-chromium steels
- 9XXX – Silicon-manganese steels
Steel Surface AppearanceWhile surface finishes vary among steel types, there are surface finishing options for each steel type.
- Hot rolled steel can be oiled and pickled
- HR steel results in a rough surface finish
- Cold rolled steel provides a smooth surface finish
- Surface finish is smoother than HR steel due to the carbon content
- Aesthetically pleasing shiny surface finish due to levels of chromium
- A higher chromium content will result in a highly reflective surface
- Often used for decorative or architectural purposes
- Can be found with brushed finishes
- Often hot-dipped with a thicker layer of zinc
- Zinc plated
- Raw dipped
Galvanized steel offers you a thick layer of zinc offering exceptional corrosion resistance.
- Surface finish of galvanized steel is a matte finish