Benjamin Franklin once said, “There are three things extremely hard: steel, a diamond and to know one’s self.” Steel is made by going into a heated furnace and electric arc furnace. However, what is TMT? The full form of TMT is Thermo Mechanically Treated Bars. TMT is used for all types of construction purposes. It is important for us to know about the process and the manufacturing of TMT and steel, one of the finest metals of all times.
Steel production is a twenty- four hour and a three hundred and sixty -five days a year type of process. The production is dependent on a continuous supply of energy and raw materials.
The steel manufacturing process starts in the center of a wheel, with three main ingredients: iron ore, coke, and lime.
Steel is primarily made by using one of these two methods-
The blast furnace includes the usage of coke, iron ore, and limestone.
Coal is one of the major parts of the coke making process. The coal is first crushed and grounded into a powder and then put into an oven where it is heated in 1800-degree Fahrenheit in the absence of oxygen. This process involves the combination of oxygen with carbon in the iron, and that actually eliminates the carbon- dioxide that is present.
Now the molten steel is transferred spoon or a dipper, moved on to a continuous casting machine. The liquid steel flows onto the ladle and then into a casting spoon and then into cold water mold.
Solidification then starts in the mold
The second process is when the steel passes through EAF (Electric Arc Furnace) just to refine the steel. This process uses scrap steel and electricity to prepare and produce molten steel.
TMT bars production-
The best quality of TMT bars goes through a different sequence of procedures that regulates the flexibility and the strength of the bars. These bars go through basically three processes that are essential-
- Atmospheric cooling
- Self- tempering
The overall worth of these bars mainly relies on three major factors-
- Quality of unrefined material
- Quality system for quenching and tempering
- Quality rolling mill that gives the consistent and paper and proper form for all rebars
Raw Materials Used for TMT Manufacturing –
The raw materials that are used for these TMT bars are iron ore, dolomite, and coal. In this method, the raw materials are piled, mixed, recovered in the right percentage. The iron ore goes through the process of beneficiation just to raise the iron substance in it. During this point, the metals are brought together to contour an accumulation of pellets and sinter to enhance the effectiveness. The coal then changes to coke for upcoming purposes.
After all, this happens, limestone mixes with the existing are positioned to the furnace. During this process, the limestone molts a certain type of liquid due to its impurity.
Process of Thermos Mechanical Treatment –
After the bars are rolled in heat, it releases from the furnished mill and then enters into the water spray system that is called as, “Thermex system.” These TMT bars, especially the best quality ones, usually use Thermex technology that cools down the core of it rapidly.
It also ensures the ductility of the TMT rebars. The process of rapid cooling solidifies the external hub of the rebars to particular depth in each section, which in turn forms a quenched steel rim, whereas the core still remains hot. This cool technology is called as Quenching.
Once the rebars are done with the cooling process and the rebars are out of the thermex quench box, the core will still be hot compared to the bars’ surface. This allows the warmth to flow from the bottom, beginning the middle to the surface. Then, this enables the tempering of the outer martensite layer, which forms a particular layer called the “Tempered Martensite.
Atmospheric Cooling –
After the self- tempering is done, the next process begins. This procedure is called “atmospheric cooling.” This particular procedure is basically done on a cooling bed at normal temperature.
Natural healing is always the best, they say; well, the atmosphere is of utmost importance during this process. In this particular step, the austenitic core turns to a ferrite- pearlite formation or structure.
The concluding arrangement, therefore, consists of a stronger external coating with an elastic core. This step is the last one; however, it increases the strength, making it capable of being drawn out and unit on an increased side.
Thus, the manufacturing of steel and TMT bars do go through a lot of cooling and heating processes. This is why, the famous quote says, the finest steel goes through the hottest fire.