We all knew the concrete is strong in compression and weak against tensile force. The steel reinforcement has been used to enhance the concrete tensile strength.

Reinforced Cement Concrete

The steel is smoothly merged with the concrete and turned as a homogeneous element reinforced cement concrete.

What Fe (number) means on reinforcement drawings?

You may have seen this in reinforcement drawing, the rod details are mentioned as Fe415 steel, and somewhere it is said as Fe500 steel. 

Fe denotes the symbol of iron (chemical element) and the number nearby that represents the tensile stress of that steel.

So if it is mentioned as Fe415, then we know that the iron has 415 N/Sq mm of tensile strength.

Difference Between Fe 415 And Fe 500 Steel

The main difference between Fe415 and Fe500 steel is the minimum tensile strength and ductility. 

different ribbed Steel Rods

Fe500 steel has great strength and ductility compared to Fe415.

The minimum yield stress of Fe 500 = 500 N/Sqmm; The minimum yield stress of Fe 415 = 415 N/Sq mm 

The Fe 415 steel will bend when the tensile load applied beyond 415 N/sq mm; similarly, the Fe 500 steel will bend when the tensile load applied beyond 500 N/sqmm.

Like cement is graded based on its compressive strength, the TMT steel also classified based on its tensile strength, as mentioned below.

Grade Fe 415 Fe 415D Fe 500 Fe 500D Fe 550 Fe 550D Fe 600
Minimum Tensile Stress 415 N/Sqmm 415 N/Sqmm 500 N/Sqmm 500 N/Sqmm 550 N/Sqmm 550 N/Sqmm 600 N/Sqmm
Ultimate tensile Strength 485 N/Sqmm 500 N/Sqmm 545 N/Sqmm 565 N/Sqmm 585 N/Sqmm 600 N/Sqmm 660 N/Sqmm
Elongation Percentage 14.50% 18.00% 12.00% 16.00% 10.00% 14.50% 10.00%

The physical properties are mostly the same for all grades of steel, but the chemical properties of steel will vary based on the grade.

Constituent Fe 415 Fe 415D Fe 500 Fe 500D Fe 550 Fe 550D Fe 600
Carbon 0.3 0.25 0.3 0.25 0.3 0.25 0.3
Sulphur 0.06 0.045 0.055 0.04 0.055 0.04 0.04
Phosphorous 0.06 0.045 0.055 0.04 0.05 0.04 0.04
Sulphur and Phosphorous 0.11 0.085 0.105 0.075 0.1 0.075 0.075

D mentioned in the Fe500 D denotes the high ductility of steel. It means that Fe500 steel consists of lower percentages of sulphur and phosphorus value. High sulphur content means a low melting point of steel where the steel melts under extremely high temperatures. Becomes exceptionally harmful to the structure.

different size steel rods

The provision of high strength steel reinforcement depends on the structure location and load occurrence.

Mostly Fe415 is used for small and medium-scale buildings. High strength and high ductility steel such as Fe500D, Fe 600 used for unique structures like high rise buildings, bridges, or seismic zone structure. 

Happy Learning 🙂


Satheesh is a Civil Engineer who has more than 9+ Years of experience in residential construction. He is the author, editor of Civil Planets

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