The effect of the tempering temperature on the structure and mechanical properties of thermomechanically strengthened rebar rolled products

The article considers the influence of the tempering temperature on the structure and mechanical properties of low-carbon reinforcing steels of grades St3 and St5. It is established that steel of the St3 brand in bars $\varnothing$ 14 mm is effectively processed by the VTMO method, being strengthened to the level of the 3rd class. The mechanical properties recorded directly after the VTMO are steadily preserved after the release by electric heating to tempera-tures of 350$\ldots$370$^\circ$C. It was found that after tempering at a temperature of 500$\ldots$ 550$^\circ$C, the hardening in St5 steel remains at the level of the 6th strength class only if the heating is carried out according to the speed mode (28$^\circ$ C/sec). It is shown that the substructure created during VTMO is de-stroyed during accelerated tempering to a lesser (to a lesser) extent than after furnace tempering. All this determines a higher level of steel hardening as a result of VTMO and high-speed tempering.