Method for controlling corner cracks of boron micro-alloy steel continuous-casting billet

Abstract

The invention discloses a method for controlling corner cracks of a boron micro-alloy steel continuous-casting billet. The method comprises the following steps: a refining step: after adjusting components and temperature, feeding an aluminum wire to steel liquid, wherein in the treated steel liquid: S is less than or equal to 0.01 percent, Mn / S is more than or equal to 40, N is less than or equal to 0.0055 percent, Als is equal to 0.015 to 0.035 percent; after feeding the aluminum wire, slightly blowing argon for four minutes, adding ferrotitanium into the steel liquid, wherein the content of Ti in the steel liquid is 0.015 to 0.025 percent, then feeding ferro-boron into the steel three minutes later, carrying out the calcium treatment for the steel liquid; a continuous casting step: the width of the casting billet is 1600mm to 2100mm, the thickness of the casting billet is 180mm to 250mm, controlling the pulling speed at 0.9 to 1.4 m / min when pouring the steel liquid; oscillating a crystallizer in a non-sinusoidal manner when the steel liquid is poured, the waveform deflection rate of the non-sinusoidal oscillation curve is 10 percent, and the negative slip time tn is 0.137 to 0.145s; stabilizing the water amount on a wide surface and a narrow surface of the crystallizerat 4100 to 4500L / min and 410 to 450L / min; adding protection residue into the crystallizer, wherein the alkalinity of the protection residue is 1.2+ / -0.1, a melting point is 1140+ / -20DEG C, and the viscosity at 1300 DEG C is 0.15+ / -0.05Pa.s; controlling the secondary cooling water amount at 0.5 to 0.55 L / kg during the continuous casting process.

Description

technical field [0001] The invention belongs to the field of metallurgy, and in particular provides a method for controlling cracks at corners of boron microalloyed steel continuous casting slabs. Background technique [0002] Micro-alloying technology is to add a very small amount of micro-alloying elements to steel, using the strengthening effect of these micro-alloying elements, supplemented by high-purity smelting technology, non-defect continuous casting billet production technology, and controlled cooling and rolling methods. Under the condition of adding as little or no precious alloying elements (mainly Cr, Ni, Mo) as possible, the steel can obtain high strength, high toughness, high weldability and good formability in the hot rolled state. [0003] Adding a small amount of boron to steel can double the hardenability of the steel, and without affecting the plasticity and toughness, it can greatly increase the strength of the steel and obtain excellent mechanical prop...

AI Technical Summary

Problems solved by technology

At present, at home and abroad, most of the cracks at the corners of the slabs that exist in boron-containing medium carbon steels are eliminated by grinding the edges of the slabs. This method not only reduces the pass rate of the slabs, but also affects the smooth flow of production.

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