CIVIL

TMT 500W is a reinforcement bar possesses yield strength of 500 Mega pascals. Now what is  ‘W’, it means this bar is weldable. 

TMT full meaning is "Thermo Mechanically Treated".

This is a superior properties of new generation high strength steel. This technology, steel bars are  through a water cooling system where these are kept such a period for colling outer surface of bars, while the core remains hot. 

This creates atemperature gradient in bars. When the bars taken out of the cooling system, the heat flows from core to the outer surface causing further tempering of steel bars are helping them in attaining a higher yield strength.