Research of technological parameters of hot variety rolling in the production of corrosion-resistant and fire-resistant reinforcement rolling

Abstract

The purpose of the work is to adapt the computer mathematical model of the process of continuous grade rolling developed in the Department of Pressure Metal Processing (VOMT) of the Institute of Chemical Engineering of the National Academy of Sciences of the Russian Academy of Sciences for the study and prediction of the mechanical properties of corrosion-resistant and fire-resistant reinforcing bars. Recently, stainless steel grades have been used as a material for such production of rebar. Such rental is usually used in the construction of responsible structures for special purposes of similar objects. Unfortunately, reinforcing bars from stainless steel grades are not produced in Ukraine. Therefore, it is relevant to determine the parameters of the technology of hot grade rolling and subsequent heat treatment from rolling heating in the production of corrosion-resistant and fire-resistant reinforced rolled steel from stainless steel grades. Analytical studies were carried out with the help of a mathematical model for predicting mechanical properties developed at the Institute of Chemical Engineering of the National Academy of Sciences of Ukraine, adapted to the conditions of fine-grade state 250-1 of ArcelorMittal Kryvyi Rih PJSC. It has been established that in the production of thermally strengthened reinforcing bars of a periodic profile with a diameter of 12 mm (rolling start temperature 1150 °С and rolling speed 12.5 m/s), the current technology does not allow to obtain a finished rolled product above class A500 according to the norms of DSTU 3760:2019. This is due to high values of the temperature at the end of rolling Tk.pr.=1095-1109 °С. All investigated stainless steel grades have calculated values of the temperature at the end of rolling by 22-32 °C higher than for low-alloy steel grades. The analysis of research results showed that with a decrease in the initial rolling temperature and subsequent thermal strengthening of rebar No. 12 made of stainless steel grades, for example, according to the strengthening mode for class A600, it is possible to obtain a ready-made corrosion- and fire-resistant rebar with a conditional yield strength above 600 N/mm2. At the same time, the calculated values of plastic characteristics are on average 2 times higher than the normalized values of these properties of DSTU 3760:2019.