TMT - Micro Process

Red hot steel bars coming out of Finishing Mill is passed through TMT Plant which by its special water quenching process turns its periphery into a tempered martensite (hard) zone while keeping its inner surface ferrite pearlite (soft).

To understand this, a sliced piece of a TMT Bar can be compared with half cut coconut, the outer skull of which is very hard while inner is very soft. The hard outer periphery of a TMT bar makes it more strong, more corrosion resistant and more fire resistant. The soft inner surface gives it ductility, i.e. more bendability, more elongation for easy workability, better fatigue resistance and a safe structure in hazards like Fire, Earthquake etc.

TMT - Test

The two layers in a TMT Bar can be seen with naked eyes by a simple test. Slice a piece of TMT Bar, grind its face with a sand paper, immerse it in a solution of Nitral (Nitric Acid 2% + Alchohol 98%) for a few seconds. Allow it to dry. Two circles (as shown in the picture) will be seen on the face of TMT Bar. Outer circle is of Tempered Martensite (hard) and inner circle is of Ferrite Pearlite (soft).