There are many different types of steel available for different applications in construction, industry, and aesthetic design. If you don't work with steel regularly, knowing what type of steel you need can be a challenge. Each type has specific strengths and weaknesses that make them a better or worse choice for a certain job. When buying steel for the first time, choosing the specific steel type is important, and the first decision you need to make is whether to look into steel that is cold rolled or hot rolled, and then make even more specific decisions from that point.
Understanding Steel Numbers
When you start shopping for steel, you will realize that there are different numbers assigned to steel types. Steel is made when carbon is mixed with iron, and the numbers that are assigned to steel types show the alloying ingredients and how much carbon is present in the metal. For example, a common type of cold rolled steel is 1018, which ideally has 0.18 percent carbon content, but it can vary from 0.15 to 0.2. Carbon content matters because as carbon increases, the overall strength of the metal also goes up, but other properties, like malleability and luster, decrease. Higher-carbon steels are more difficult to weld and to machine into different shapes. Sometimes, steel numbers have letters, which also indicate alloying ingredients.
Hot Rolled Steel
Hot rolling is a refining process used to produce steel products. The process heats the steel above crystallization points, which makes the steel easy to form into shapes or to roll into large sheets. However, because the heating and cooling of the steel causes expansion and contraction, the final product is less attractive and does not keep a specific shape or form as easily. It is cheaper to produce hot rolled steel because it takes less time, machinery, and precision. Hot rolled steel products are used in building applications where appearance and specific shapes are not needed. For example, the steel rebar used in pavement would be made from hot rolled steel.
The most common and affordable type of hot rolled steel to consider is A36 steel. A36 steel is a low carbon steel that is used to make small beams and rods. The surface finish is rough, and the metal is malleable. Galvanized hot rolled steel (A653) is often used in construction applications as well, to protect against rust.
Cold Rolled Steel
Cold rolled steel has wider use in the world, because the cold rolled steel does not shrink or change its shape. The finish of cold rolled steel is smooth and beautiful. The cold rolling process takes hot rolled steel and refines it even further with a series of processes to refine imperfections and to increase alloy strength. Depending on the final purpose, cold rolled steel goes through:
- drawing, which is the process that increases tensile strength.
- turning, which helps to improve the appearance of the steel surface.
- grinding, which helps to restrict size tolerance.
- polishing, which finishes the surface.
Cold rolled steel is sued for car surfaces, carefully machined parts and hardware, stainless steel countertops and work surfaces. Cold rolled steel sheets are easier to work with than hot rolled sheets, and cold rolling helps to increase carbon content in the alloy and allow the metal to still be workable in an industrial or construction setting. Generally, if your project requires finishing and precision, cold rolled products are the best choice.
The most common type of cold-rolled steel currently used in 1018 steel. It has a good balance of strength, ductility, and relative ease to machine in comparison to other types of cold-rolled products. It has a relatively low carbon content, making it easier to weld and work with in a design application.
For more information contact a company that supplies steel.
