Manufacturing & Infrastructure

TMT Process

ATLAS TMT bars are the new generation and high strength ribbed reinforcement bars having superior mechanical properties in strength, weldability, ductility, and bendability, meeting International quality standards. ATLAS TMT bars are produced in state-of-the-art manufacturing plants under close supervision of our experienced frontline engineers and metallurgists. ATLAS TMT bars have a uniform and concentrated hardened periphery, with a softer core that has the desired tensile strength coupled with high elongation, specially required in seismic zones.

Under thermo mechanical treatment (TMT), our steel bars are passed through a specially designed water-cooling system where they are kept till the outer surface of the bars becomes colder while the core remains hot. This creates a temperature gradient in the bars. When the bars are taken out of the cooling system, the heat flows from the core to the outer surface, further tempering of the bars, which helps them attain higher yield strength. The resulting heat-treated structure imparts superior strength and toughness to the bars. The microstructure of the core is a very fine-grained ferrite and pearlite.

At ATLAS TMT, the production of high quality TMT bars depends on three major factors

  • Quality raw material, which is ensured through an extensive vendor selection process
  • Advanced & technically designed automated manufacturing mill
  • Well-designed quenching and tempering technology

ATLAS TMT  bars are 'hot rolled' from steel billets/ingots and then subjected to a PLC controlled on-line thermo mechanical treatment in three successive stages


Quenching is generally done by cooling at a sufficiently high rate to avoid undesirable internal microstructure as well as to ensure uniform mechanical properties, minimize residual stresses, and avoid warpage. The experienced Quality Assurance & Control department at ATLAS ensures that a uniform quench rate is maintained along with required agitation near the surfaces of the parts, thus avoiding residual stress and warpage of the parts, and ensuring highest quality ATLAS TMT bars in the industry.


Tempering is done to toughen the metal by transforming brittle martensite into tempered martensite. As the bar leaves the quenching box and is subjected to air-cooling, the core remaining hot compared to the outer surface allows heat to flow to the surface, causing tempering of the outer martensitic layer into a structure called Tempered Martensite. At ATLAS, we ensure precise control of time and temperature during the tempering process, which results in our ATLAS TMT bars with well balanced mechanical properties.

Atmospheric Cooling

This takes place on the cooling bed where austenitic core is transformed into a ductile ferrite-pearlite core.

The final structure consists of an optimum combination of a strong outer layer (tempered martensite) with ductile core (ferrite-pearlite), giving ATLAS TMT bars a unique combination of higher strength and ductility

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