History Of TMT Bars

TMT bars, or thermo-mechanically treated bars, are a type of reinforced steel bars or rods used in construction. If you try to trace back the origins of TMT bars, you would have to go as far as the 13th century BC, when steel was first processed. In this blog, you will get to know about the history of TMT bars and how they are used in India.

Invention

The history of TMT bars is that of continuous development. The modern steel industry began in 1856 when an English inventor blew air on top of molten iron to remove impurities. Since then, steel has been used to make various products and high-tech applications. Steel has powered major social, economic, and cultural changes and forms the backbone of the world’s economy today. 

TMT bars were first introduced in 1979. These bars came in grades Fe 415 and Fe 500. They blended well with Reinforced Cement Concrete (RCC), which was introduced in 1867. TMT  bars blended well with RCC, the most common material used for construction at present times. Concrete is strong in compression but weak in tension. Steel is strong in tension and provides tensile strength to concrete. Thermal expansion, i.e., change in volume due to temperature alterations, of steel and concrete is nearly the same. TMT bars bond well with concrete and have excellent bendability. They are the best materials to add strength to a concrete structure. 

Evolution

The steel manufacturing process was introduced in India in 1874. During the initial stages, mild steel bars were made. However, they were not adequate for construction use and needed advancement. As the process continued to develop, more steel bars were added with concrete, and eventually, TMT bars were manufactured. This caused the steel industry in India to flourish and created huge opportunities for economic development. India became famous for steel-making in the year 1907 when Jamshedji Tata established the TATA Iron & Steel companies. 

Over the next two decades, there was even more advancement in construction methods and technologies. The demand for higher reinforcement with higher yield strength arose. This contributed to the emergence of something that would be able to handle this strength. As a result, the thermomechanical treatment of steel was introduced. The manufacturing process of a TMT bar includes a series of controlled steps. First, the iron ore is purified and then poured into moulds. Then, the bars go through a unique process called quenching, where they are blasted with water. This gives the TMT bars their special feature of a hard exterior and soft ferrite pearlite core. In their initial days, the only grades of TMT bars available were Fe 415 and Fe 500. Since then, their demand has risen across the world and has aided in the construction of projects that support millions of people. 

Indian Standards

In India, mild steel bars were used until the introduction of ribbed bars in the 1960s. The first TMT bar to be used was of Fe415 grade in 1979. These bars are flexible and can be bent without any assistance from a tool. Then came Fe 500, which was significantly stronger and used in multistory buildings. 

The Bureau of Indian Standards (BIS) certifies thermomechanically treated (TMT) bars as per IS 1786:2008. The IS 1786 signifies the properties of TMT bars. However, IS 1852 defines the methods for testing steel bars for quality and mechanical properties.  The IS 7892 defines the requirements for the surface finish and dimensional tolerance of TMT bars. These standards cover the following grades: Fe415, Fe415D, Fe415S, Fe500, Fe500D, Fe500S, Fe550, Fe550D, Fe600. As one of the best steel bar manufacturers in West Bengal, Maan Shakti follows all the guidelines to create its products. 

The Bottom Line

TMT steel bars have become an essential part of the modern world. They are used in the most minimal projects to give them strength and increase their longevity. The quality and features of TMT bars are inseparable in construction, and they contribute toward the economic development of several countries. As the innovation and advancement in the steel industry continue, you can expect to see more developments in the industry and the construction of stronger and more durable buildings.