TMT Rebar

FE500D

Introduction

Tata Tiscon 500D, a product from TATA STEEL, is the new generation high strength ribbed reinforcement bar. It is different from ordinary bars in its method of manufacturing and consequently, in its combination of properties.

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Chemical Properties Unit IS:1786 Fe 500 IS:1786 Fe 500D TATA Tiscon 500D
Carbon % 0.300max 0.250 max 0.250 max
Carbon equivalent (C + Mn/6) % 0.420max 0.420 max 0.400 max
Sulphur % 0.055max 0.040 max 0.035 max
Phosphorus % 0.055max 0.040 max 0.035 max
S and P % 0.105max 0.075 max 0.070 max

TATA TISCON 500D's unique method of manufacturing creates a combination of strength and ductility that far exceeds the minimum limit specified in the standard IS:1786. In the case of the yield strength for TATA TISCON 500D, though the standard specifies a minimum of 500 N/mm2, and designers use this value for design, the typical values are as high as 540 N/mm2. For the same product, the typical value of ductility as measured by elongation is 18% minimum as against the standard value of 16% minimum, Undoubtedly, the superior values of strength and ductility are a guarantee of higher levels of safety for ages. UTS/YS ratio and percentage elongation are important properties in a rebar that reflect the ability to handle the pressure of earthquakes, Higher these values, the better.

Mechanical Properties Unit IS:1786 Fe 500 IS:1786 Fe 500D TATA Tiscon 500D*
Yield Stress (YS) N/mm2 500 min 500 min 540 min
Ultimate Tensile Strength (UTS) N/mm2 545 min 565 min 600 min
UTS/YS Ratio 1.08 min 1.10 min 1.12 min
Elongation % 12 min 16 min 18 min

*As obtained in 90% of the heats

CRSD

Introduction

The durability of concrete structures depends on how well the concrete can withstand chemical and physical aberrations and protect its embedded reinforcement against corrosion. Environmental exposure, especially to air salinity, impurities in ground water and presence of acid particles in the air are common factors that cause corrosion. The CRSD (Corrosion Resistance Steel with Fe500D properties) rebar from Tata TISCON is an answer to this problem and has been a major innovation breakthrough to help builders and architects.

Tata TISCON CRSD rebars come with a special protective chemistry that creates a shield against corrosion. This protects the life of RCC structures like buildings, bridges, dams and industrial works.

Tata TISCON CRS - Mechanical Properties
IS:1786 Fe500D Tata TISCON CRSD *
Yield Stress, YS (min, N/mm2) 500 500
% Elongation 16 16
Ultimate Tensile Strength, UTS (min, N/mm2) 565 580

*Typical values for 90% of batches

CRS D - Process Technology

The innovative technology used in making Tata TISCON CRSD rebars involves diminishing the Phosphorus (P) content in steel by selecting corrosion resistant elements. Produced using Thermo Mechanical Treatment (TMT) route Tata TISOCN CRSD rebars are compliant with the chemical composition of Fe500D grade. Corrosion resistant qualities in the resulting microstructure are increased due to:

  • Elimination of residual torsional stresses
  • A thin oxide film developing on the steel surface that helps plug holes in the oxide layer
  • Presence of self-tempered lathe martensitic layer on surface that prevents corrosion attack
  • Consistent spreading of corrosion resistant elements from core to surface
Chemical composition of Tata TISCON CRS (in %)
Carbon (max) Sulphur (max) Phosphorus (max) Copper (min)
0.25 0.04 0.04 0.40

Advantages of Tata TISCON CRSD

  • Greater Corrosion resistance makes it more long-lasting
  • High yield strength together with better ductility and bendability
  • More convenience in material handling and transportation
  • No extra operations required during fabrication
  • Easy to weld
  • Can be bend and rebend using very small mandrel

FE600

Introduction

There has been a rising demand in recent years for TMT rebars with higher strength and better ductility for use in different types of applications. The latest IS 1786: 2008 has addressed these requirements and incorporated changes that were necessary in order to meet latest technological developments in manufacturing steel bars and steel wire.

Following are some of the important modifications incorporated in the fourth revision:

  • Fe 600 - a new strength grade has been introduced.
  • For elongation, two categories for each grade have been introduced (except for Fe 600).
  • 'Percentage total elongation at maximum force' has been introduced as a new parameter.
  • Nominal sizes have been rationalized.
Chemical Composition of Fe 600 bars
Constituent Percent, Maximum
Carbon 0.30
Sulphur 0.040
Phosphorus 0.040
Sulphur and Phosphorus 0.075

For any grade, including Fe 600, it is not imperative to add micro alloying elements. In case of strengthening elements like Nb, V, B, Ti being used individually or in combination, the total contents shall not exceed 0.30 percent.

Mechanical Properties
SL No. Property Fe 600
1 0.2 percent proof stress/yield stress, Min., N/sq. Mm 600
2 Elongation, percent, Min., on gauge length 5.65xSq root of A, where A is the cross sectional area of the test piece. 10
3 Tensile Strength, Min. 6 percent more than the actual 0.2 percent proof stress/yield stress but not less than 660.0 N/sq. mm