Have you ever wondered why TMT bars are gaining so much popularity among construction engineers? How are TMT bars different from ordinary steel bars? The difference between TMT steel bars and ordinary steel bars lies in the manufacturing process. TMT steel bars undergo three stages of production processes to become distinct ones. This article discusses the manufacturing processes of TMT bars followed by top TMT bars manufacturers. It identifies in detail various stages of production processes which are the key reason for its superiority. 

The Transition from Raw Materials to Molten Iron

Iron ore, coal, dolomite, and limestone are used in making TMT steel bars. These materials act as impurities to the iron. The sole aim of the process at this stage is to make the iron free from impurities and prepare billets. This is done in three substages. 

• Stage One: The iron ore, coal, dolomite, and limestones are accumulated, stacked, reclaimed, and blended in set proportion. The mixture will be heated in the furnace to get the real iron.
• Stage Two: The sole aim of this stage is to make the iron ore ready for use in preparing TMT steel bars. That is why it is heated to get rid of minerals, identifiable impurities, and other gangue materials. Fine iron ores are agglomerated to develop sinter and pellets. These products will be added with the beneficiated iron ore to reduce waste and ensure better use of the product. Through the process of heating, the iron ore is converted into coke in this stage. In the later stage, the coke will be converted into steel.
• Stage Three: The top TMT bar manufacturers separate the iron ore from basic impurities with the influence of high heat and limestone. In this stage, the iron ore, sinter, pellets, and coke are charged into the furnace. A hot air blast at the bottom of the furnace set the temperature for melting at 1800 degree centigrade. The high heat melts the iron ore and puts it at the bottom of the furnace. The limestone separates the iron ore from impurities and combines with molten rock and sinter to develop molten slag. The molten slag rests above the molten iron. Through the associated tap hole of the furnace, the molten slag and molten iron are separated from the heated finance. This way, the iron is extracted from its ore. 

Conversion Of Molten Iron to Billets

In this stage, the molten iron is influenced further under heat to eliminate all the unnecessary alloys and impurities to produce steel billets. The process is operated in three stages. These are as discussed below.

• Stage One: The molten iron is transferred from the blast furnace to the basic oxygen furnace. In the basic oxygen furnace, the molten iron is heated and oxidized. In this process, oxygen reacts with the carbon present in the iron. The oxygen is released as carbon-di-oxide. It further purifies the iron to produce steel.
• Stage Two: The malleable steel is transferred to the ladle heating furnace. In this furnace, the steel undergoes the process of dephosphorization and desulfurization. It also removes oxygen present in the steel by making steel purer. The inter gasses leave the steel at high temperature. The steel also becomes free from different alloys and impurities present in the molten steel. 
• Stage Three: In this stage, the steel is produced in the continuous casting process. The process produces steel in billets of 130 mm2 and more. These steel billets are purified steel which is free from alloys and other impurities.

Process Thermo Mechanical Treatment to Produce Final TMT Steel Bars

In this process, the best TMT bar company makes a distinction in producing high-quality steel from other ordinary steel-producing companies. This process also follows three key stages such as quenching, self-tempering, and atmospheric cooling. These three stages are discussed below.

• Stage One (Quenching): The steel billets are heated at 1200 to 1250 degrees centigrades. Under the influence of this high heat, the billets are produced with the final shape and size of the reinforced bar before passing it to the rolling mill stand. After this, the bars are produced in a controlled heat treatment where it is rapidly cooled down to 450-degree centigrade from the highly heated state at 900-degree centigrade. This process hardens the outer layer of the bar while keeping the inner layer softer.
• Stage Two (Self-Tempering): In this stage, the TMT bars are allowed to undergo self-tempering. The inner cross-section of the bar remains highly heated while the outer layer gradually cools down. This gradient of heat transfer from the inner core to the outer layer develops tempered martensite in the outer layer. It forms intermediate rings of martensite and bainite in the outer layer. The core develops a typical crystalline cubicle structure as an austenitic form. 
• Stage Three (Atmospheric Cooling): The top TMT bar manufacturers perform this stage at the end of the manufacturing of TMT steel bars. In this stage, the TMT bars are kept in a special cooling bed and allowed to cool at room temperature. As the inner core releases temperature, it gradually transforms into a ductile ferrite-pearlite structure. Thus, the resultant TMT bars develop a tempered martensite outer layer and ductile ferrite-pearlite inner layer. 

Top TMT bars manufacturers follow these key processes for producing TMT bars. Manufacturers make conditional changes in temperatures, purifications, cooling, and other processes, which make some TMT steel bars different from others. However, the key focus remains in the complete manufacturing process to reduce waste, errors, and malfunctioning so that the resultant TMT bars are of superior quality.