The TMT in TMT Bars stand for Thermo-Mechanically Treated, it is a process of rapidly cooling down bars in the molten state. This cooling down process is either done spraying water at regular intervals. This regular interval will further define the characteristics of the bars. This interval of quenching of bars will give rise to different grades of TMT bars in fact. The goal here is to have a solid and hard outer surface with a pliable inner core. This outer shell is coated with a protective film, making them resistant to corrosion and rust, making them apt for constructing sensitive structures such as high rise residential buildings and bridges in humid areas. TMT bars and different Steel Grades.