India’s steel industry has not only always been at the forefront of the country’s construction sector, but also other important industries such as shipbuilding, railway locomotive and heavy and light machinery. Today, manufacturing of steel and TMT steel bars is regarded as a major industry in its own right.
Before TMT Steel
TMT steel bars are a new generation of steel bars, ideally suited for concrete reinforcement. These bars are widely used in modern day construction work, where quality, safety and longevity are critical. Before the use of TMT bars, the industry relied on CTD bars – Cold Twisted Deformed bars and prior to that, M.S or Mild Steel bars were used for R.C.C (Reinforced Cement Concrete) construction work. As the need for infrastructure that matched global standards grew, so did the need for more robust and internationally acclaimed materials such as TMT Steel bars. As a result, TMT (Thermo Mechanically Treated) bars were introduced in India between 1980-1985.
TMT Steel today
The manufacturing process involves an advance heat treatment process where top quality raw materials such as coke, iron ore, dolomite and limestone are put inside a blast furnace where they are piled, recovered and mixed in the right proportions. These molten materials are treated with hot gases. And then, with the help of beneficiation process, the iron ore is raised to iron substance. The molten iron is then poured into a casting machine to be shaped into the desired shape. This is followed by rapid quenching of the red-hot bars coming out of rolling mill stand, using a series of water jets.
The rapid quenching induces intensive cooling of surface resulting a hardened surface at top of the bars, while core remains red hot. The rebars are then allowed to cool in ambient conditions. During this slow cooling process, the heat released from core tempers the hardened surface, while the core is turned into ferrite-pearlite aggregate composition. The TMT process, as a result, changes the material into a composite structure of ductile ferrite-pearlite composition, with a tough surface rim of tempered marten site, having an optimum combination of high strength, ductility, bendability and other desirable properties.
Ductility of TMT bars makes it ideal for making hooks, vibrating structures subjected to reversible stresses as in case of machine foundation and for high rise structures subjected to strong earthquake and wind forces. TMT bars of grade Fe415, Fe500 and Fe550 are now available in India.
The future of TMT Steel
Radha TMT 550 is a renowned brand name which uses revolutionary German Thermex technology to produce high-quality primary steel. Established in the steel trade in 1960, to supply the country’s growing need for quality steel, the company’s TMT Steel products get used in a wide range of construction projects from roads and dams, to high-rise buildings, and residential housing.
It is predicted that in the near future, steel bar producing companies like Radha TMT can produce higher grade TMT bars like Fe600 to Fe-650, which will possess even higher strength, ductility, bendability and other properties.