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RAJURI 500 CRS
 
 Corrosion :
 
Corrosion is one of the major problems which result in destructing the life of any concrete structure reinforced with steel. In this sense corrosion is a deadly enemy to reinforced structures.

Coastal Breezes, Seawater, Saline Subsoil, Gaseous emissions in industrial regions are some of the main reasons that accelerates corrosion. In recent days only, there are numerous examples of such structures that have been destroyed due to corrosion living less than half of its expected life.

Solution


Cement slurry coated rebars, Galvanized rebars, and Epoxy coated rebars etc. have been developed to fight corrosion. But it is observed that many of these products failed to serve the purpose and ultimately end up with leading to accelerate corrosion. The only practical solution is to develop corrosion resistant steel though controlling its composition so as to impart it corrosion resistant properties intrinsically. Such Bars not only reduce the rate of corrosion but will also prove
to be a cost effective solution to prevent corrosion. The result will be ‘Cost Effective Corrosion Resistant Steel with improved lifespan’.

 RAJURI 500 CRS Bars :
 
RAJURI 500 CRS Bars are produced using a judicious selection of corrosion resistant elements (Cu, P & Cr). Billets from Continuous Casting Process (Concast) are used as raw material. These Billets are maintained chemically so as to have proper combination of various corrosion resistant elements. Copper plugs pores in rust. Phosphorus acts as inhibitor as P2O5. The oxide layer formed is dense and with very little pores/ cracks and thus cuts down ingress of O2, SO2, and Chloride etc. through oxide metal interface. Further, reducing chromium content in steel has improved the pitting resistance.
 
 Advantages of Continuous Cast Billets :
 
  • No impurities are present
  • Homogeneous distribution of various corrosion resistance elements due to purging process
  • No surface defects such as blowholes, piping, black holes, flaws etc.
  • Maintained and consistent properties throughout the length.
Then these CRS Billets are passed on to go through Rolling by ‘Quenching and Self Tempering Process (TMT)’ provided by Thermex, Germany. The microstructure resulting from QST process leads to high corrosion resistance as compare to conventional Cold Twisted Deformed (CTD) Bars and Ordinary TMT Bars due to following reasons:
  • No Torsional Stresses
  • Tempered Martensite Case known to inhibit Corrosion attack.
 
 
 Advantages of Continuous Cast Billets :
 
Chemical Properties
 
Elements % (Max) Composition
Carbon (C) 0.15 Max
Sulphur (S) 0.05 Max
Phosphorus (P) 0.09 – 0.12
Silicon (Si) 0.2 - 0.4
Copper (Cu) Upto 0.5
Chromium (Cr) Upto 0.5
Carbon Equivalent (CE) 0.54
Corrosion Resisting Elements (CRE)
(CRE = Cu + Cr + P)
0.5 Min
 
Mechanical Properties
 
Properties IS 1786 : 1985
(Fe 415)
IS 1786 : 1985
(Fe 500)
RAJURI 500 CRS (Fe 415) RAJURI 500 CRS
(Fe 500)
Yield Strength, Min. (N/mm2) 415 500 450 530
Ultimate Tensile Strength, Min. (N/mm2) 485 545 560 650
Elongation % 14.5 12.0 18-25 18-22
 
 
Bend Properties

Rajuri 500 Bars have excellent bend properties due to the unique ductility (elongation values) obtained when using the German HSE Thermex Technology.

 
Weldability

Rajuri 500 Bars with carbon content less than 0.25% can be used for butt and other weld joints without reduction in strength at the weld joints.  No pre-heating or post heating is necessary in case of manual arc welding.

 
Fire Resistance

Unlike Torsteel and CTD bars, RAJURI 500 bars have high thermal stability.  They are the preferred choice when elevated temperatures of 400-600C may be encountered (Chimneys, Fires).

 
Earthquake Resistance

RAJURI 500 Bars have high fatique resistance to Dynamic / Seismic Loads due to its higher ductility quality.  This makes Rajuri 500 bars most suitable for use in earthquake prone areas.

 
Formability

Due to very high elongation values and consistent properties through out the length of bar, RAJURI 500 Bars have excellent workablility and bendability.

 
Strain Ageing

Due to unique and scientific manufacturing process and chemical composition, RAJURI 500 Bars show no tendency of embrittlement either during welding or cold deformation of welded joints.

 
Cost Effective

RAJURI 500 Bars required 15-20% less usage then CTD bars for it work with cost 5% more than CTD bars.  This results in overall saving of 10-15%.

 
 
 RAJURI 500 CRS : Advantages :
  • Longer life due to superior pitting corrosion resistance.
  • More strength along with greater safety.
  • No extra precaution while handling and transporting the material.
  • No extra precaution during welding
  • Suitable for applications in Seismic Zones
  • Cost Effective
 
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