PRODUCTION OF A QUENCHED AND TEMPERED ROLLED PRODUCT FOR THE REINFORCEMENT OF CONCRETE

Until recently, metallurgical plants in the nations of the CIS (Commonwealth of Independent States) ‐ including Russia and Ukraine ‐ produced weldable rolled products for the reinforcement of concrete by using hot-rolled killed low-alloy steels 35GS and 25G2S. These steels belong to strength class A400S (A-III) under GOST 5781 (mimimum yield point 400 MPa). The production of these steels consumed 28‐40 kg of ferroalloys per ton of steel, and the consumption coefficient realized in obtaining the rolled products from the ingots was 1.24‐1.30 kg/ton. The carbon content of steel 25G2S was limited to the standard 0.31%, while the carbon content of steel 35GS was 0.40%. Attempts were made to replace the hot-rolled killed low-alloy steel with hot-rolled semikilled steel 32G2Rps or quenched and tempered semikilled carbon steel St5ps, which also contains up to 0.40% C and correspond to strength class A400S (under GOST 10884, quenched and tempered steel St5ps corresponds to class At-IIIS). At such carbon contents, the reinforcement steel is characterized by poor cold shortness and limited weldability and fails to meet existing international standards. International standard YSO 9655/2, European standard EN 10080, and the national standards of different European nations specify a maximum carbon content of 0.24% for finished rolled products of the given designation. However, these norms stipulate only the carbon equivalent, not the methods used to make or cast the steel. In addition, the construction industry worldwide has instituted the widespread use of a new class of reinforcement steel, now using grade A500S instead of grade A400S. The export-oriented strategy being adopted for the growth of ferrous metallurgy in the CIS nations due to stagnation of the domestic construction industry makes it necessary to improve the quality of their rolled products and bring those products’ chemical composition and properties in line with world standards, to ensure that the products will be competitive in the world market. A reduction in production costs also improves their competitive standing. In 1993, a group of metallurgical researchers based at the West Siberian Metallurgical Combine organized the mass