High-performance low-carbon bainite construction steel and producing method thereof

Abstract

The invention provides a high-performance low-carbon bainitic structural steel, the chemical composition of which is: C: 0.04% to 0.07%, Si: 0.20% to 0.50%, Mn: 1.50% to 1.80%, Nb: 0.03% to 0.06% %, Ti: 0.005% to 0.030%, Cr: 0.25% to 0.50%, Cu: 0.30% to 0.60%, Ni: 0.20% to 0.50%, Als: 0.010% to 0.070%, and the balance is Fe and unavoidable Impurities. The rolling process adopts TMCP+RPC process, the heating temperature before rolling is 1050-1220°C, two-stage controlled rolling is adopted, the rolling temperature in the recrystallization zone is controlled at ≥1000°C, and the rolling temperature in the non-recrystallization zone is controlled at 950°C~ (Ar3+0°C~100°C), the cumulative rolling deformation in the non-recrystallized area is greater than 50%, relax for 10-120s after rolling, and then accelerate cooling, the end cooling temperature is 380-530°C, and then air-cooled. The invention has low cost, does not need complex heat treatment, can obtain bainite structure without quenching and tempering, has high strength, high toughness, and good welding and weather resistance.

Description

technical field [0001] The invention belongs to the technical field of metal materials, and in particular relates to a low-alloy high-performance steel and a manufacturing method thereof. Background technique [0002] Reducing the initial construction costs and maintenance costs of steel bridges during their service has always been the focus of attention. With the development of bridge technology, bridges have higher and higher requirements for the strength, toughness, earthquake resistance and corrosion resistance of steel. Therefore, steel for modern bridges should have high performance, that is, excellent strength, toughness, good weldability, low yield ratio and good atmospheric corrosion resistance. In the past, the steel types with atmospheric corrosion resistance were mainly developed by the method of high P, Cu, supplemented with Cr, Ni and other alloying elements. The added P content is relatively high and the Mn content is relatively low. Their common shortcoming...

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This patented steel grade is produced by controlled rolling and controlled cooling proce

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