The history of steel and TMT bars is the story of development. From the first time steel got invented in the 13th century BC to its high-tech usage in modern times, steel has become a robust backbone for social, cultural and economic changes. It contributes majorly to the world’s economy today.
Steel is a proven match to bond firmly with Reinforced Cement Concrete (RCC), invented in 1867. No other material has as much reliability, strength and flexibility as RCC, which has now become to most commonly used construction material. Historians and archaeologists sayIndia started manufacturing metals as early as 1600 BCE. But talking about the industrial production of steel is concerned, TMT materials manufacturers in India began with the indigenous Bengal Iron Works or the BIW (Barakar Iron Works), which was set up in Kulti, near Asansol in West Bengal, in 1874. However, the defining moment in the history of steel manufacturing was inaugurated by the Tata Iron and Steel Company or TISCO in Sakchi, Jamshedpur in Bihar by Jamshedji Tata in 1907, who has the credits of laying the foundation of heavy industries in India.
EVOLUTION
In the initial days of steel manufacturing, concrete was reinforced by mild steel. By the end of World War 2, deformed high-strength rebars started coming in trend globally. Cold twisted and hot-rolled deformed rebars started coming in use widely. The yield stress of complexconvoluted, deformed bars (CTD) was 415 MPa compared to the 250 MPa of MS rebars. Though the chemical compositions of CTD and MS bars were nearly the same, the physical strength of CTD bars was roughly 60% more than MS steel bars.
With the advancement of construction technologies and methods over the next two decades, TMT materials manufacturers in India witnessed the rising demand for stronger reinforcement with higher yield strength. The thermos mechanical treatment of reinforced steel was one key innovation back then. The manufacturing consists of heating the rebars to about 900 degrees Celsius and then rapidly quenching them to about 450 degrees Celsius to produce a softer ferrite-pearlite core and a harder martensite periphery. First introduced in 1979, these TMT bars were available in grades Fe 415 and Fe 500. Since then, the demand for TMT bars has risen globally due to their pleasing combination of ductility, high strength, bendability and other desirable properties. If construction requires 1000 tons of reinforcement with MS bars, the same can be fulfilled with 400 tons of TMT bars.
INDIAN STANDARDS
In India, rods and the classic plain mild steel bars were used during the construction till the mid-1960s, when CTD bars were introduced. Due to a more straightforward manufacturing process and significant savings in building rebar consumption, MS bars were replaced by CTD by 1975. TMT bars were introduced in India from 1980 to 1985. Today, most of the steel companies in India focus on manufacturing Fe 500 or Fe 550 TMT bars.
CONCLUSION
Due to their benefits, TMT bars are the most preferred and acclaimed construction material globally and in India, contributing to the development and economic growth.
