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Mechanical Property

Steel GradeStandardFrog MarkYield Strength (MPa)TS/YS RatioElongation% (G.L = 5D)EMF%
RSM // Dia // B500DWR5001.3xYS(min)1.25138

Chemical Property

Steel GradeStandardFrog MarkC% (Max)Mn% (Max)Si% (Max)S% (Max)P% (Max)CEV% (Max)
RSM // Dia // B500DWR0.321.800.550.0400.0400.61

TMT Process

RAHIM STEEL is using the world prominent latest STS technology to develop Thermo Mechanically Treated (TMT) rebars. The deformed bars are produced in state-of-the-art plants under the close supervision of high-caliber metallurgists and engineers. RSM B420DWR rebars are hot rolled from steel billets and subjected to PLC controlled on line thermo mechanical treatment in three successive stages.

Quenching: The hot rolled bar leaving the final mill stand is rapidly quenched by high pressure water in special venturi tubes. This hardens the surface of the bar to a depth optimized for each section through formation of magnetic rim, while the core remains hot and austenitic.

Self Tempering: As the bar leaves the quenching venturi tube the core remains hot compared to the surface, allowing heat to flow from the core to the surface which causes tempering of the outer martensitic layer into a structure called Tempered Martensite. The core still remains austenitic at this stage.

Atmospheric Cooling: This takes place on the cooling bed, where the austenitic core is transformed into a ductile ferrite-pearlite structure. Thus the final structure consists of an optimum combination of strong outer layer (tempered martensite) with a ductile core (ferrite-pearlite).This gives RSM rebars a unique combination of high strength and ductility.


It has excellent bend ability and great resistance on seismic loading thats why it could be used in RCC constructions of Hign Rise Building, Skyscraper stucture, Long Span Bridge, Flyover, Power Plant, Underground Tunnel and Railway etc.

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From the modest beginning in 1958, Rahim Group has today grown into one of the leading steel manufacturers of Bangladesh.