These are the following grades of TMT bars for which we got BIS approvals.
Thermo Mechanically Treated steel or TMT bars as are more popularly known, is the 'new generation' steel, that has high strengths not obtained in any other process of steel-making. TMT steel is manufactured by heating initially at 1200^0c, which is then austenitzied (the technical term used for the procedd of converting ferrite materials in iron to austenites), is then taken through a process called quenching that allows rapid cooling and conversion to maternsite, the high strength structure of steel.
During the Thermo Mechanical Treatment, the steel bars are made to pass through a specially designed water-cooling system. The bars are cooled in water for a specific period of time such that the surface is colder than the inner core which remains hot. This makes the heat flow from the inner core to outer surface, causing tempering. This additional tempering of steel bars helps to impart a higher strength to the steel thus treated.