ON DETERMINATION OF RATIONAL TEMPERATURES OF SELF-TEMPERING OF BAR REINFORCEMENT FROM HIGH-CARBON STEELS DURING THERMAL HARDENING

Abstract

The effect of self-tempering temperatures during thermal hardening and separate heating on the change in the mechanical properties of rebar made of steels C56D, C70D, C80D and C82D (EN 16120-2:2017) was studied. In general, reinforcing bars before and after heating complies with the requirements of the DSTU 3760:2019 standard, which apply to steel of strength classes A800 and A1000. Rational self-tempering temperature intervals have been established for guaranteed production of reinforcing bars of strength classes A800 and A1000 with the prevention of cracking. With an increase in the carbon content, it is necessary to increase the self-tempering temperature of rolled products, which accordingly reduces the level of steel hardening. In the production of rebar, strict control over the temperature-time conditions of water cooling and the actual values of self-tempering temperatures should be observed due to the fact that high-carbon steels are very sensitive to cracking when using intensive water cooling modes.