RATHI Steel Bars draw their strength from the computer controlled in-line process of hardening and tempering during hot rolling (TMT). After leaving the last rolling stand at the precise temperature, the hot rolled bar passes through a set of specially designed cooling pipes. The outer layer gets cooled, while the core is still hot. The surface of the bar gets self-tempered by the heat from the core. The combination of a tempered martensite surface and ferrite + fine pearlite core provides considerably higher strength and ductility to the finished material, making it ideally suited for building strong structures.