Effect of vanadium, niobium, and silicon on the properties of low-pearlite steel
- 46 Downloads
Small additions of vanadium and niobium either separately or together substantially increase the strength of low-pearlite hot-rolled steel, which is accompanied by an increase of σ0.2/σb and lower ductility.
The greatest increase in strength results from additions of about 0.04% Nb and V. With larger amounts of these elements the strength increases at a smaller rate. The highest strength is attained with around 0.04% V and 0.03% Nb.
Separate additions of 0.04%V and Nb showed that the effectiveness of Nb in raising the strength of the steel is approximately double that of vanadium, and with 0.11–0.13% Nb the effectiveness is 40–50% higher than that of vanadium.
Raising the carbon content from 0.05 to 0.20% in the steel with 0.04% V and 0.03% Nb increases the ultimate strength from 50 to 74 kg/mm2 and the yield strength from 40 to 54.5 kg/mm2; σ0.2/σb decreases from 0.80 to 0.72. Within these limits, carbon shifts the ductile-brittle temperature (T50) of the hot-rolled steel from −50 to +20° and reduces the work of crack propagation ap (with completely ductile fracture) from 10 to 2 kg-m/cm2.
Raising the silicon content from 0.02 to 0.44% leads to a substantial increase of the ultimate strength from 41 to 50 kg/mm2, the yield strength from 28 to 36 kg/mm2, and the toughness from 4 to 8 kg-m/cm2 at −40°.
The effects of vanadium and niobium on the strength are evidently due to the formation of nitrides (carbonitrides) of these elements with residual nitrogen.
KeywordsSilicon Vanadium Ductility Nitrides Yield Strength
Unable to display preview. Download preview PDF.
- 1.W. Duckworth et al., J. Iron Steel Inst.,203 (1965).Google Scholar
- 2.K. Irvine et al., J. Iron Steel Inst.,205 (1967).Google Scholar
- 3.I. Irani et al., Strong Tough Structural Steels, London (1967).Google Scholar
- 4.A. P. Gulyaev, Toughness and Brittleness of Structural Steels [in Russian], Mashinostroenie, Moscow (1969).Google Scholar
- 5.A. Meier, F. Shmidt, and Kh. Shtrasburger, Chernye Metally, No. 22 (1969).Google Scholar