STEP BY STEP PROCESS:-
Thermomechanical processing is also known as Thermo Mechanical Treatment (TMT). It is a metallurgical process that integrates work hardening and heat treatment into a single process. The description of process is as follows:-
The steel used to produce PRACHAND TMT is of superior quality billets and has a desired composition.
During this process mixture of sponge iron, pig iron & other allied raw material are fed into the furnace and chemicals are added to the molted metal to refine the same and achieve the desired chemical composition of quality steel Billets. The chemical tests are done during the proess and after the process so as to ensure the quality and purity of steel Billets.
Reheating and rolling:-
The steel Billets are then heated in reheating furnace at the temperature of 1200 ° C. The heated steel Billets are then rolled through a series of mill stands which progressively reduce the Billets to the final size and shape of TMT bars at the final mill stand.
As soon as the bars leaves the final mill stand,it is rapidly and vigorously cooled from 1000 degree to the optimal temperature . It is done in a completely automated quenching box,where the product undergoes a uniform surface hardening treatment to form a hardcore martensitic layer, which provides the steel its strength along with adhesive layering.
The bar leaves the quenching box with the temperature gradient through its cross section,the temperature core being higher than that of the surface. This allows the heat to flow from core to the surface ,resulting in tempering of surface ,giving a structure called Tempered Martensite,which is strong and tough .The core is still austenitic at this stage.
The fifth stage takes place while the rebars lies on the cooling bed where the bar is subjected to the normal air-cooling reduced to ambient temperature. The austenitic core is then transformed to a ductile ferrite-peartile core. Thus, the final structure consists of a combination of strong outer layer of tempered martensite and a ductile core of ferrite-pearlite.
Fulled with excellence fatigue & uniform properties, bonded strength and resistance to heat upto 600°C TMT bars certainly provide good ductility, optimum yield strength and bendability, better tendency for ageing and resistance to earthquakes and are less prone to corrosion as compared to CTD bars.