Thermo Mechanically Treated (TMT) bars are manufactured in different dimensions ranging from 8mm to 25mm.
We use in house manufactured MS Billets in our rolling mill rather then inferior alternative ingots which have impurities in them which somewhat effects the durability and other properties of the manufactured steel.
We use latest thermo mechanical treatment rather then the traditional cold twisting.
Thermo Mechanical Treatment is latest technology for manufacturing bars, it gives bars the combination of properties that will help to last decades.
Billets are reheated into oil or coal fired reheating furnace.
These reheated mild steel billets are passed through successive pair of grooved rollers “3 roughing, 4 intermediate, 2 finishing, 4 continuous” respectively.
When the red hot bar leaves the last rolling stand it has to go through the treatment process.
The treatment process has three successive stages
Quenching - When the red hot bar passes through the last set of rolls they go to the water cooling quenching box where series of water is sprayed on hot metal. This rapid cooling procedure cools the outer surface of the bar making it harder known as “Martensite”.
Self- Tempering-In this stage when the bar leaves the quenching machine. The surface of the bar in the quenching stage was cooled but the temperature of the core remains high. The heat from the core of the bar flows to the surface of the bar “Martensite” which is cooler heating up the quenched surface thus tempering the surface. The inner core of the bar is austenitic.
Atmospheric Cooling-When the bar makes its way to the cooling bed it is allowed atmospheric cooling. In this stage the unchanged core of the bar austenite is transformed to ferrite-pearlite. Ferrite – pearlite is ductile by nature.
These successive manufacturing stages give TMT bars the ultimate combination of strength and ductility with enhanced bending, welding,rust resisting ability which leads to easy application of TMT bars in different types of engineering works.