Effect of modification with disperse compositions on the mechanical properties of low-alloy structural steels

The study of the effect of modification pure metals with dispersed powders on the mechanical properties of low-alloy steels in cast and deformed state. Methodology. Dispersed powders of titanium and aluminum of granulometric size less than 200 nm were obtained at a high-frequency plant using plasma chemical synthesis from industrial waste. The object of the study was low-alloyed silicon – manganese steels 09G2 and 09G2S, used in building structures. Results. Pilot melting of low-alloy steels was carried out. Modification technology was developed, including the input method, temperature-time treatment in the melt. The composition and limits of the modifier consumption based on dispersed powders of titanium and aluminum were established. Castings were subjected to hot plastic deformation. Heavy plates were subjected to normalization. A comparative study of the steels in the original and modified state after casting, deformation and normalization was carried out. It was established that at the optimum modifier consumption of 0,2...0,3 % by weight of the melt, the modified steels had a higher complex of mechanical properties than the unmodified ones, both in the cast and in the deformed state. In forged bars, as a result of the modification, an increase in the ultimate strength by 10…21 %, a yield strength by 20...33 %, an elongation increase by 13...25 %, a relative narrowing by 29...31 %, and an impact strength by 26...67 % were achieved. Scientific novelty. A basic mechanism for improving the mechanical properties of modified Si−Mn steels: grain-boundary and dispersion hardening is proposed. Practical relevance. Technological instruction on the modification of steel melts with dispersed compositions in industrial production conditions was developed.