What are the Different Grades of TMT Steel Bars Used in Construction

TMT bars also known as “Thermo Mechanically Treated bars” are predominantly used in the construction industry since 1979. A unique technique used in the manufacturing process of these steel rods for construction results in TMT bars with a tough outer core and a soft inner core which ultimately leads to superior strength, high yield stress & elongation, corrosion resistance, earthquake resistance and more. TMT steel bars come in various grades based on the quality of raw materials, grade of steel used and the composition of elements such as Carbon, Sulphur, Phosphorous & Slag.

Grade are assigned to steel rods used in construction based on 3 important factors, namely –

• Chemical composition
• Mechanical properties
• Manufacturing process

Now, let’s look at the different grades of TMT bars available across India are:

• Fe 500:

TMT steel rods for construction of this grade possess higher yield strength, corrosion resistance in comparison with Fe 415 and are extremely bendable. Therefore Fe 500 grade steel rods are used in RCC constructions such as bridges, underground structures, multi – storey commercial building & more.

• Fe 500D:

Fe 500D is the grade of TMT steel bars with iron and a “D,” which stands for ductility or elongation property of the TMT steel bars. using Fe 500D TMT rebar can save 1.70 kg. per metric ton when compared to 500 or lower grade TMT bars. Fe 500D has a higher percentage of elongation than any other grade of TMT bar

• Fe 550:

The chemical & mechanical properties of Fe 550 TMT steel bars are similar to that of Fe 500 however they are a class apart in terms of strength, yield strength, elongation and shock withstanding capacity. Therefore, they are an ideal choice for constructions that are slightly larger in scale and a bit difficult for Fe 500 grade TMT steel bars to handle.

• Fe 550D:

550D or Fe 550D is a grade of Thermo-Mechanically Treated (TMT) steel bars, as defined by IS:1786. Use of 550D TMT steel bars is more prevalent in earthquake prone areas because D grade steel is highly resistant to seismic activity. The lower carbon, Sulphur and phosphorus in Fe550D TMT steel bars helps in preserving the steel and resisting earthquake shocks.

• Fe 600:

Fe 600 grade TMT bars are exceptionally tough and possess strength like no other grade TMT steel bars. Therefore, they are generally used for heavy industrial construction projects as they require extraordinary strength and resistance.

The numbers here indicate the level of stress under which each of them would deform, i.e., TMT bars that can withstand the highest level of stress are superior in strength and rigid.