PROCESS FOR MANUFACTURING MICROALLOYED THERMO-MECHANICALLY TREATED REBAR WITH IMPROVED SUB-ZERO IMPACT TOUGHNESS.

摘要

A process for manufacturing high strength microalloyed TMT rebar with improved sub-zero impact toughness is provided by suitably selecting the levels of microalloying elements in the steel. The process comprises providing steel billet having a composition of 0.05 to 0.1 wt% carbon, 0.3 to 0.5 wt% manganese, 0.05 to 0.2 wt% silicon, upto 0.035 wt% sulfur and atleast 0.008 wt% of microalloying elements comprising niobium and phosphorus wherein the level of phosphorus is in the range of 0.08 to 0.1% when niobium is not present or upto 0.04 wt% when niobium is present in the range of 0.005 to 0.015 wt%, the balance being iron, heating said steel billet at a temperature between 1200 to 1250 degree C, rolling heated billet to rebar, short intensive cooling the rolled rebar and further cooling in atmosphere. The rebars of the present invention have wide applications in the construction sector such as general concrete reinforcement in buildings, bridges and various other concrete structures and especially high rise buildings.