Many commercial businesses that sell steel products often have their own on-site steel processing, but what exactly is it and more importantly how does it work?
The melting and casting process
Firstly to make stainless steel you need raw material, namely iron ore, silicon, chromium, nickel etc. these raw materials are melted together in a super-hot furnace (often approaching 2000 degrees) usually for around 8-12 hours. Once the metal has sufficiently melted the molten liquid is cast into various incarnations such as rectangular shapes (blooms), square, or round shapes (normally 3.8cms thick otherwise known as billets), and even rods, tubes or slabs.
The forming process
Even though the metal is melted and cast, it isn’t stainless steel yet. It now has to go through a forming process. First of all it gets hot rolled. This means the casts are heated once more and then pushed through huge rollers. Billets and blooms for example are formed into wire and bar respectively, while the slabs are formed into plates, sheets, and strips. The rollers themselves can be adjusted depending upon the thickness required.
The annealing process
Once the steel has been formed it has to go through the annealing process. This is done to eradicate any internal stresses found in the newly formed metal. During this process the metal gets heated up again but is also cooled under tightly controlled conditions. The reason for this is that any slight variant in the temperature can result in a weakened piece of metal. In addition the rates of heating and cooling can produce different grades of metal. For instance, lower annealing temperatures produce a high strength metal but a lower resilience to fracture. Alternatively higher heating and faster cooling promote a lower strength metal which has a better resilience to fracturing.
When the annealing process occurs it causes scale or surface build-up to form on the newly-manufactured steel. Obviously it needs to be removed. This can be achieved using several processes including pickling (using an acid bath) or electro-cleaning where an electric current is applied.
The cutting process
The cleaned metal is then cut to various lengths and sizes using large cutting machines. Metal can be cut using circular shearing, guillotining, sawing, punching and nibbling (this is a process where a series of overlapping holes are punched out and is ideal for irregular shaped metals).
The finishing process
Finally once the metal has been cast, formed, heated, cooled, de-scaled and cut it enters the last part of the process which is finishing. Depending upon the use of the metal it needs to be finished accordingly. For example, metals used for sanitary purposes would usually require a smooth, glass-like surface to make it easier to clean. The same goes for metals used for their glossy aesthetic appearances. In some circumstances abrasive finishes are required to help with the lubrication process particularly factory machinery.
As you can see it’s quite a process from start to finish and one that requires a lot of skill to get right. Fortunately at Metro Steel we’ve been in the industry for many years and know exactly what it takes to produce high grade steel that’s fit for purpose. Why not contact us today on 07 3204 1000 to see just what we can do for you.