A36 Steel: A Grade Guide

The global market for structural steel is enormous, valued at 100 billion dollars USD yearly. It’s easy to see why steel is such an appealing choice for construction due to its qualities: high strength, toughness, formability and ease in welding. And among the many types of structural steels, grade A36 stands above the crowd.

Key Attributes of A36 Steel

A36 is a low carbon steel, which means its composition contains less than 0.3% carbon by weight. At its most basic, steel is formed when alloying iron with carbon. Carbon grants more strength and hardness to the alloyed metal in comparison to pure iron. However, as the percentage of carbon in the steel grows larger, the hardness can become brittle. That same hardness also produces steel with lower ductility and less workability.

In contrast, low carbon steels like A36 are relatively soft and not quite as strong compared to other steels. But their greatest attribute is ductility: that same softness means low carbon steel is much more formable and malleable. This makes low carbon steel an excellent choice for machining and welding. So it’s not surprising to learn that this category is the most widely used type of carbon steel – and A36 is the most utilized type of low carbon steel.

A36 steel is unique in its grading: unlike many other steels whose number is determined by their chemical composition, A36 is designated by its mechanical properties. What this means is that most grades have alloys that must be added in specific percentages in order to qualify as that steel type; meanwhile, A36 steel must meet the set mechanical standards for its grade. So while it does need to conform to certain chemical composition standards, the most important characteristic of A36 steel as established by ASTM International is its yield strength. In order to be graded as A36, the steel must meet a minimum yield strength requirement of 36,000 pounds per square inch. The metal must be able to withstand that amount of pressure with only 0.2% or less deviation to its shape under stress.

A36 is also a relatively ductile steel, able to elongate to around 20% of its original length during tensile testing. Along with its yield strength, this ductility gives A36 steel a high degree of impact strength at room temperature. This toughness helps prevent the metal from fracture and other damage.

Uses for A36 Steel

As you might tell from its attributes, A36 is quite a versatile material. It comes in a variety of shapes suited for riveted, bolted, and welded construction. Many of these shapes are designed for structural applications such as bridges and buildings. Wide flange beams (shaped like an “H”) are used as columns or beams. Tee bars (formed in a “T” shape) can be found used as beams or bracing. Angles are generally used as bracing or finishing elements. However, its uses are not limited to large construction projects. The versatility of A36 steel lends itself to other uses such as ship building, heavy equipment manufacturing, and automotive parts.  Whatever its purpose, it’s clear why grade A36 steel is so popular: tough, strong, easily welded…and all this at a relatively low cost!

Hot Rolled vs Cold Rolled, So much to know

Is one a better choice for your project?

What type of rolled steel would make the better choice for your project? It’s important to understand the fundamental differences between hot and cold rolled steel in order to select the best one for your needs.

Rolling is a metalworking process where the metal is passed through one or more pairs of rolls, which reduces thickness and makes the material uniform throughout the roll. Imagine the steel as if rolling dough through a pasta-maker, flattening and thinning it out until you have an even, smooth product.  The two types of rolling are hot and cold, which is determined by the metal’s temperature during processing. Hot rolling occurs when the metal is heated above its recrystallization temperature. Cold rolling is when the metal is processed while below the recrystallization point.

Hot Rolled Steel

Hot rolling involves rolling the steel at a temperature point above its recrystallization temperature, typically around or above 1700 degrees F. This means the steel can be shaped and formed easily, including producing much larger sizes. Since the manufacturing can be done without pauses or delays in the process, this means hot rolled steel is typically cheaper than cold rolled steel.

Because of the high processing temperature, the hot rolled steel will have a rougher, scaly finish and will also shrink slightly as it cools. This means the finished product can vary in its size and shape dimensions, and at a lower price point than the same item produced through cold rolling. Hot rolled steel is best suited for uses like welding, railroad tracks or construction, where precise shapes and tolerances may not be required.

Cold Rolled Steel

Cold rolled steel is manufactured below its recrystallization temperature. Essentially, it’s hot rolled steel with additional processing in cold reduction mills. Because it is typically produced around room temperature, the process allows for closer dimensional tolerances and a wider range of surface finishes for the steel.

‘Cold rolled’ is often mistakenly used to describe all steel products, but it refers specifically to the rolling of flat rolled sheet and coil products. For other steel shapes produced below the recrystallization temperature, the accurate terminology is “cold finishing”. For instance, a cold finished steel bar is produced by cold drawing (pulling) the metal, then turning, grinding and polishing. This produces a much more precise end product with four advantages:

  • Increased yield and tensile strength
  • Fewer surface imperfections due to the turning process
  • Grinding gives closer size accuracy and precise shapes
  • Polishing improves the surface finish

The exception is cold rolled sheet versus hot rolled sheet. For this particular product, the cold rolled steel has a low carbon content and is typically annealed (heat treatment to increase ductility). This means cold rolled sheet will be softer than hot rolled sheet.

Overall, cold rolled and cold finished steel is superior to hot rolled steel in finish, straightness and tolerance, and comes at a higher price point. It would be the recommended choice when visual appeal is a priority for your project. Typical uses include building materials for sheds and garages, metal furniture, and home appliances.

Buy Hot Rolled or Cold Rolled Steel

Here at FastMetals we offer a range of Hot Rolled and Cold Rolled steel products – we offer great quality product, reasonable pricing and fast shipping – shop online at FastMetals.com or call us toll free at (833) 327-8685.