The billets are heated in a computer controlled reheating
furnace and rolled through a sequence of rolling mill
stands which produces TMT bars of uniform diameter and
length. Next, the bars are subject to heat treatment
in three stages:
The First Stage of “Quenching” begins when the hot
rolled bar leaves the final mill stand and is rapidly
quenched by special water spray system. This converts
the surface layer of the bar to the hardened structure
called ‘Martensite' while the core remains austenitic.
The Second Stage of “Self Tempering” begins when the
bar leaves the quenching box with a temperature gradient
through its cross section, with the temperature of the
core being higher than that of the surface. In this
stage hear flows from the core to the surface called
‘Tempered Martensite'. The core is still austenitic.
The Third Stage of “Atmosphere Cooling” is on the cooling
bed, where the austenitic core is transformed to a ductile
ferrite core.
Thus, the grain structure consists of a combination
of tough outer layer of tempered martensite and a ductile
core ferrite – pearlite. This is what gives Vijayaa
– TMT its unique package of properties – an excellent
combination of strength and ductility.
We offer grades Fe 415, 500, 550 ranging from 8mm to
32 mm conforming to ISI and Tempcore standards.
Every TMT bar that we produce passes through a series
of rigorous tests and checks, to verify its structural
integrity and metallurgical properties. The result:
We not only meet ISI standards – we exceed them. |
