Knowing the type of steel to use on a project can help avoid wastage of raw materials, time, and any potential unnecessary additional processing costs. It also helps to know the process when dealing with your steel supplier.
To really get your head around the different types of steel, it’s important firstly to understand the difference between Hot Rolled, Cold Rolled and Cold Drawn steel.
Each of these different types of steel are produced with a different process with their own unique advantages and disadvantages.
What is the Rolling Process?
The rolling process can be an enigma for the uninitiated, but it plays a significant part of the steel industry. It is important to understand the basic concept of the rolling process when communicating with your steel supplier.
Rolling is a fabrication process whereby steel may be passed through rolls. There are two types of rolling: flat rolling and profile rolling. Flat rolling typically results in a steel sheet. Profile rolling results in a product typically in the shape of a rod or a bar.
The process of rolling can be dated back to late 18th century. The temperature by which the steel is rolled also plays a significant result in the end product – it can either be Hot Rolled or Cold Rolled.
Hot Rolled Steel
What is Hot Rolled Steel?
Hot Rolled Steel involves extremely high temperatures in excess of 500° C. These temperatures are above the recrystallization temperature for most variants of steel. At these temperatures, steel is extremely malleable. Although easier to shape, compared with cold rolled steel it is slightly weaker.
Once heated and moulded, Hot Rolled Steel is cooled at room temperature. The finished product is slightly more tensile than Cold Rolled Steel products. The internal stresses of the quenching and hardening processes involved in Cold Rolled Steel are also important to consider.
Hot Rolled Steel is inherently more malleable and able to be cast in various shapes. It makes a good choice for sheet metals and structural components.
Hot Rolled Steel is often chosen over Cold Rolled Steel simply because of the low cost involved in producing it, particularly when surface finish is not a major concern.
What are the Applications of Hot Rolled Steel?
Hot Rolled Steel is often used in welding and construction trades to prepare railroad tracks and I-beams. This type of steel is often used where precision in shape and finish is not a major issue. Depending on your steel supplier, they may have Hot Rolled Steel as an option.
Cold Rolled Steel
What is Cold Rolled Steel?
Cold Rolled Steel involves more processing than Hot Rolled Steel. Cold rolling is a process involving flat rolled coils and sheet products. As there is no melting taking place, it allows for more precise dimensions than Hot Rolled products.
There are only a few simple shapes that can be produced though cold rolling. However it is possible to produce other cold rolled shapes using a number of shaping operations.
This type of steel is common in automotive and construction parts. This is due to the product being used when the surface requires a higher quality finish.
What are the Applications of Cold Rolled Steel?
Cold Rolled Steel is in a variety of industries, particularly in the automotive and construction sector, where tolerance, superior surface finish, straightness and concentricity are major factors. Depending on your steel supplier, they may have Cold Rolled Steel as an option.
Cold Drawn Steel
What is Cold Drawn Steel?
The Cold Drawing process, like Cold Rolling, is conducted at room temperature. However, in this case, Hot Rolled Steel bars or coils are hammered to fit and then pulled through a die to reshape it thinner without losing volume.
Often this process requires more than one die to get the wire down to rught diameter. The Cold Drawing process allows more precision in terms of shape, measurement and corners. This is because Hot Rolled steel, by comparison, will change their shape during the cooling process. This allows Cold Drawn Steel to have an increased yield and tensile strength compared with other types of steel.
The surface finish of Cold Drawn products is of much higher quality than that of either Cold Rolled or Hot Rolled steel. The result is an aesthetically pleasing yet practical roll of steel. Depending on your steel supplier, they may have Cold Drawn Steel as an option.
What are the Applications of Cold Drawn Steel?
Cold Drawn Steel can be found in a variety of everyday consumer products.
These types of steel are used in car manufacturing, shafting and fabricated structural units. Cold Drawn Steel is used in a variety of products, including axles, spokes, fasteners, hand tools, cables, bolts and paper clips.
In summary, knowing the type of steel you are working with can make a big difference on the project you are working on. Choosing which steel is right for the job can help save time, money and any extra processing costs.
Armed with a proper understanding of the process behind your steel, it is easier to communicate with your steel supplier to get the right result for your project.