How is steel made?
From Raw Material to Fabricated Steel Structures
It seems very straightforward to think about; ore is sourced, processed, and then you find it in a construction site, as the skeleton to an incredible future structure, or in your microwave. But what does the process from raw material to finished product actually entail? Read on for an overview of what the world’s second most mass-produced and completely recyclable commodity looks like.
It starts with sourcing the raw material; iron ore – where 98% of mined iron ore is used to make steel. Iron is the second most abundant metal in Earth’s crust, and the fourth most abundant element in Earth’s crust overall. Other materials, such as lime from limestone and coke from coal, are combined with the iron to be put into a blast furnace and to be then melted down into molten iron. As there are many impurities in this mixture, such as high quantities of carbon, they must be removed to make sure the metal isn’t brittle. This is known as smelting.
The next step is referred to as primary steelmaking, in which the molten iron is infused with scrap steel. Using basic oxygen steelmaking, oxygen is blown through the molten mixture to lower the carbon content of the alloy that changes it to steel. During this process, other impurities such as phosphorus and silicon are also removed. A similar result can be achieved with another form of primary steelmaking, which is through use of an electric arc furnace, though the former is the most commonly used method.
After this, the secondary steel making step of the process encompasses the creation of multiple grades of steel, where some more elements may be removed, different combinations of various elements added, and other processes such as stirring, removing gasses, de-oxidising, vacuum degassing, chemistry modification, de-sulphurisation and homogenisation occurs. These stages allow for various types of steel to be created for varying end-use properties, such as corrosion resistance, durability, higher strength, flexibility, ductility, and heat and electrical conductivity.
HIsarna Ironmaking Process
There is another emerging method called the HIsarna ironmaking process, in which iron ore is processed into liquid iron. This process is much more energy efficient and has a lower carbon footprint because it does not require the manufacture of iron ore pellets or production of coke, which are required for a blast furnace process. A demonstrated 50% of CO2 emission reduction is possible with this process.
Casting into Moulds
After the desired grade is achieved, the final molten steel is cast into moulds that are prepared for the cooling process. Here, steel becomes hard and is drawn out while still hot. Rollers pull this steel out where it is then cut into preferred lengths. They can be used for beams, billets or slabs which are then sent somewhere else for the primary forging and secondary forming processes.
Forging steel involves hot rolling to remove defects in shape and to create seamless tubes, as well as long and flat products. Then to form, final techniques are applied such as coating, joining, drilling, thermal treating and machining. Here is where a variety of final products can result from the previous processes, such as tubes, sheets, bars, beams and flat plates.
The entirety of the steelmaking process involves technique, high amounts of energy, extreme pressures and temperatures that only the most experienced can understand. Here at Hard Bakka, we have an advanced knowledge of the steelmaking process which allows for us to distinguish the best steel that is suited to each need, whether it be structural, architectural or for parts. With our tight traceability procedures (ITPs) and monitoring manufacturing data records (MDRs) in compliance with AS/ANZ ISO 3834 part2, ISO IMS integrate management systems (9001, 14001, 45001) as well as AS/ANZ 5131 CC2; you can be sure you are getting the best of the best in the supply of fabricated steel structures.
To learn more, American Iron and Steel Institute has published a great interactive diagram illustrating the production process.
Australia’s history with steelmaking is fascinating, dating back all the way to 1840 when iron ore deposits were found in South Australia. Follow this link to read our post on the history of Australian steel manufacturing.
American Iron and Steel Institute (2021) Steel Production, viewed 9 June 2021, <https://www.steel.org/steel-technology/steel-production/>.