Grade Guide: A36 Steel

Steel is one of the most common metals used for structural applications. It is strong, tough, ductile, formable and weldable. As there are many different types of steel available, each with unique chemical and mechanical properties, it is important to know some of the key attributes of A36 steel.

Chemical Composition

A36 is a low carbon steel. Low carbon steels are classified by having less than 0.3% carbon by weight. This allows A36 steel to be easily machined, welded, and formed, making it extremely useful as a general-purpose steel. The low carbon also prevents heat treatment from having much of an effect on A36 steel. A36 steel usually has small amounts of other alloying elements as well, including manganese, sulfur, phosphorus, and silicon. These alloying elements are added to give A36 steel its desired chemical and mechanical properties. Since A36 does not contain large amounts of nickel or chromium, it does not have excellent corrosion resistance.

Designation

Unlike most AISI grades such as 1018, 1141, or 4140, American Society for Testing and Materials (ASTM) A36 steel is not designated by chemical composition. Instead, A36 is designated by mechanical properties. This means that while most grades must have added alloys that fit between certain percentages, A36 must meet specific mechanical standards. For example, steel bars and plates must have a minimum yield strength of 36,000 pounds per square inch. While there are some chemical composition requirements that A36 steel must adhere to, the most important characteristic is the yield strength requirement.

Other Mechanical Properties

A36 steel can have ultimate tensile strengths from 58,000 to 79,800 psi. The exact ultimate tensile strength is determined by a variety of factors such as chemical composition and forming method. A36 is relatively ductile and can elongate to around 20% of its original length when tensile testing. Its ductility and strength also give it excellent impact strength at room temperature.

How A36 is Made

A36 is made in a fashion similar to most carbon steels. First, iron ore and coal are combined in a furnace. Impurities are burned away and alloying elements are added to the molten steel. Once the chemical composition of the A36 steel is achieved, it is solidified in into a rectangular ingot. A36 steel is normally hot rolled. This means that it is formed to its final dimensions in using rollers while the ingot is at an elevated temperature.

Common Uses of A36

A36 steel is used in many different industries for a variety of applications because of its relatively low cost. Also, as mentioned, the mechanical properties make it particularly suited for structural applications. Many bridges are constructed with A36 steel. Likewise, buildings are frequently created with A36 steel because of its high strength and toughness. A36 steel is also used for components in the automotive, construction, heavy equipment, and oil and gas industries.

Don’t have time to read the blog? You can check out our Grade Guide video below which takes a closer look at this commonly used type of steel: