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Steel is graded as a way of classification and is often categorized into 4 groups:

  • Carbon Steels only contain trace amounts of elements besides carbon and iron. This group is the most common, accounting for 90% of steel production. Carbon Steel is divided into three subgroups depending on the amount of carbon in the metal: Low Carbon Steels/Mild Steels (up to 0.3% carbon), Medium Carbon Steels (0.3–0.6% carbon), and High Carbon Steels (more than 0.6% carbon).

  • Alloy Steels contain alloying elements like nickel, copper, chromium, and/or aluminum. These additional elements are used to influence the metal’s strength, ductility, corrosion resistance, and machinability.

  • Stainless Steels contain 10–20% chromium as their alloying element and are valued for their high corrosion resistance. These steels are commonly used in medical equipment, piping, cutting tools, and food processing equipment.

  • Tool Steels make excellent cutting and drilling equipment as they contain tungsten, molybdenum, cobalt, and vanadium to increase heat resistance and durability.

Structural Mild Steel

In the UK, we follow the a grading system introduced by the EU.

  • ‘S’ denotes the fact that it is structural steel;

  • ‘235’ which relates to the minimum yield strength of the steel (tested at a thickness of 16mm);

  • ‘J2’, ‘K2’, ‘JR’, and ‘JO’ all demonstrate the material toughness in relation to the Charpy impact or ‘V’ notch test methodology;

  • ‘W’ is weathering steel (atmospheric corrosion-resistant);

  • ‘Z’ represents structural steel with improved strength perpendicular to the surface, and

  • ‘C’ is cold-formed.

Depending on the manufacturing process, chemical composition and relevant application, further letters and classifications might be used to reference particular grades or products of structural steel.

See the images to see how grade names correspond across the pond.

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Engineering Mild Steel

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MATERIAL GRADES
EXPLAINED

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