Low-carbon manganese steels with vanadium carbonitrides

Conclusions

• 1. Vanadium carbonitride phase in low-carbon steel improves the strength characteristics. The increase in strength due to vanadium carbonitrides depends on the structure in which the carbontride particles precipitate and, consequently, on their dispersity. With precipitation of vanadium carbonitrides in ferrite, i.e., in the upper range of transformation temperatures, the yield strength is 8–10 kg/mm² higher than for the same steel without carbonitride phase. With precipitation of vanadium carbonitrides in bainite the yield strength increases 20–25 kg/mm².

• 2. We recommend low-carbon, low-alloy, high-manganese steel 03G4AF (up to 0.05% C, 0.25–0.50% Si, 3.9–4.5% Mn, 0.07–0.15% V, 0.015–0.022% N, up to 0.015% S, up to 0.015% P, 0.02–0.05% Al), which has good weldability and the following mechanical properties: σ_b=70kg/mm², δ=20%, ψ=60%,a _n−60=5 kg-m/cm², T₅₀=−10°C in the tempered condition after hot rolling; σ_b=70kg/mm² δ=25%, ψ=55%,a _n−60=8 kg-m/cm², T₅₀=−30°C in the improved condition.