Strength, Ductility and TMT Part-I

Strength, Ductility and TMT Fe415 Rghtsteel

Reinforced steel bars, the supporting platforms in the construction of modern building structures. The current innovation in reinforcement steel is the TMT steel reinforced bars. Known for their unparalleled tensile strength and ductility factor, reinforced steel bars have literally dominated the construction sector in India and all over the world.

In this blog, we are going to see if strength or ductility really matters in a TMT steel bar for constructing a home. So, let’s dig in.

What is a TMT bar?

Thermo Mechanically Treated or TMT rebars is a type of reinforced steel bar which undergoes an additional process in its production cycle. This additional process consists of 3 stages which are Quenching, Self-Tempering and Annealing.

Strength of TMT

Simply put, tensile strength or ultimate tensile strength is the amount of stress (stretching) the steel reinforced bar can withstand without breaking. Alright, you read it right, breaking. Generally, the tensile strength typically has three definitions i.e Yield Tensile strength, Ultimate Tensile strength and Fracture Tensile strength. The yield tensile strength is the stress that the material can withstand before permanent deformation. Fracture or Breaking strength is the stress at which the material fails via fracture.

So how does strength really matters in steel bars?

As we know, the TMT reinforced steel bars are classified as different grades which are based on their Yield tensile strength. These grades are namely Fe 415, Fe 500, Fe 550 and Fe 600. These numbers denote the yield strength. The primary purpose of a reinforced steel bar is to provide the high tensile strength, which the concrete lacks in providing. Higher numbers mean higher tensile strength, the rebar exhibits without deformation.

Durable Ductility

Another important feature is the Ductility. It is termed as the ability of the metal which allows it to plastically deform under stress. Since it is a property of metal, there is no value that can be represented for ductility, however, it can be measured in terms of elongation percentage. In the TMT reinforced bars, ductility is formed as a result of the annealing process, in which the hot yet soft inner core cools under atmospheric temperature. This results in the formation of a ferrite-pearlite core which provides the ductility.

This blog doesn’t end here. There’s more to say about Ductility, which is explained in Part-II. Stay tuned.

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