86results about How to "Improve precipitation strengthening effect" patented technology

The invention discloses a vanadium-chromium microalloying large-specification 500MPa ultra-fine grain corrosion-resisting anti-seismic steel bar and a preparation method thereof. The steel bar comprises, by weight percent, 0.21-0.25wt% of C, 0.45-0.55wt% of Si, 1.25-1.40wt% of Mn, 0.30-0.35wt% of Cr, 0.065-0.080wt% of V, not larger than 0.040wt% of S, not larger than 0.045wt% of P, not larger than0.0070wt% of O, 0.0165-0.0200wt% of N and the balance Fe and inevitable impurities. The preparation method of the steel bar comprises the procedures of molten steel smelting, deoxidization alloying,LF furnace refining, casting, steel blank heating and controlled rolling and controlled cooling. A certain amount of vanadium-containing pig iron is added into a tapping steel ladle to replace the expensive vanadium alloy, the V content of molten steel is increased, and the adding quantity of the vanadium alloy is reduced; in the deoxidization alloying process, a small quantity of silicon-nitrogenalloy is added, the nitrogen content in the molten steel is increased, and the proportion value of V / N in the steel is reduced, transferring of V from the solid solution state to a carbonitride precipitated phase in the rolling process is promoted, and the precipitation strength effect of the steel is obviously improved; and the preparation method is low in production cost and high in process applicability and controllability.

The invention discloses an ultra-fine grain high-strength and high-toughness 600MPa-grade anti-seismic steel bar and a preparation method thereof. The steel bar comprises, by weight, 0.23 wt%-0.27 wt%of C, 0.45 wt%-0.57 wt% of Si, 1.42 wt%-1.55 wt% of Mn, 0.20 wt%-0.25 wt% of Cr, 0.012 wt%-0.017 wt% of Nb, 0.095 wt%-0.110 wt% of V, less than or equal to 0.040 wt% of S, less than or equal to 0.043wt% of P, less than or equal to 0.0070 wt% of O, 0.0240 wt%-0.0265 wt% of N and the balance Fe and inevitable impurities. The preparation method of the steel bar comprises the procedures of molten steel smelting, deoxidation alloying, molten steel argon station refining, molten steel casting, billet heating and billet controlled rolling and controlled cooling. According to the steel bar and the preparation method, a small amount of silicon-nitrogen alloy is added in the steel-making deoxidation alloying process, the nitrogen content in molten steel is increased, the V / N and Nb / N ratio value in steel is reduced, transfer of V and Nb from a solid solution state to a carbonitride precipitated phase in the rolling process is promoted, a large number of fine dispersed V (C, N) and Nb (C, N) precipitated phases are formed and precipitated, and the phase change temperature is reduced, so that the precipitation strengthening effect of the steel is obviously improved; and according to the method, the production cost is reduced, the anti-seismic property is improved, and the market competitiveness of the product is improved.

The invention discloses a low-temperature-resistant and lamellar-tearing-resistant super-thick steel plate and a manufacturing method thereof. Steel is composed of chemical components of, by weight, 0.09-0.15% of C, 0.15-0.45% of Si, 1.05-1.45% of Mn, less than or equal to 0.003% of S, less than or equal to 0.010% of P, 0.06-0.08% of V, 0.015-0.040% of Als, 0.008-0.015% of N, 0.25-0.45% of Ni, oneor more elements of less than or equal to 0.15% of Cr, less than or equal to 0.15% of Cu and less than or equal to 0.04% of Ti, and the balance Fe and inevitable impurities. The production process ofthe steel plate comprises the steps of die casting, cogging rolling, finished product rolling, controlled cooling, normalizing treatment and slow cooling after furnace discharging. The produced thicksteel plate with the thickness being 180-250 mm has the good low temperature resistance and lamellar tearing resistance, and is suitable for welding structures.