390MPa-grade low-cost hot rolling structural steel plate and manufacture method thereof

Abstract

The invention provides a 390MPa-grade low-cost hot rolling structural steel plate and a manufacture method of the 390MPa-grade low-cost hot rolling structural steel plate. The 390MPa-grade low-cost hot rolling structural steel plate is prepared from the following components in percentage by weight: 0.15 to 0.20% of C, 0.05 to 0.20% of Si, 0.1 to 0.5% of Mn, 0.0005 to 0.004% of B, not greater than 0.0060% of N, 0.02 to 0.05% of Al, 0.015 to 0.025% of Ti, 0.0025 to 0.0060% of Ca, 0.12 to 0.2% of Ca / Al, and the balance of Fe. The manufacture method comprises steps as follows: melting by a converter; refining outside the converter; continuously casting; and rolling; Al is added to remove oxygen during refining, and Ti is added for fixing nitrogen, so that O is not greater than 0.002%, and N is not greater than 0.006%; boron is added for alloying before ending the refining, and an Si-Ca line is fed; a temperature in hot-charging of a continuous casting blank is more than 840 DEG C; a slab blank is processed by heating to reach the temperature of 1100 to 1180 DEG C, maintaining the temperature for 2 to 3 hours, roughly rolling at the temperature of 1020 to 1100 DEG C, wherein an intermediate blank / finished product is in thickness of 5; refining at the temperature of 950 to 1000 DEG C, wherein accumulation deformation is more than 50%; finally rolling at the temperature of 850 to 900 DEG C, cooling to reach the temperature of 500 to 600 DEG C at 6 to 20 DEG C per second after rolling, and coiling, and then cooling by air. The manufacture method is simple in technology and low in cost; and the product is high in toughness and plasticity and high in welding performance.

Description

technical field [0001] The invention belongs to the technical field of iron and steel production, and in particular relates to a 390MPa grade hot-rolled structural steel plate with a thickness specification of 2-12mm and a manufacturing method thereof. Background technique [0002] Structural steel is generally divided into low-strength grade ordinary carbon structural steel and high-strength grade low-alloy structural steel. Generally, ordinary C-Mn steel is used to manufacture low-strength hot-rolled structural steel plates, but for high-strength structural steel plates with a yield strength exceeding 300 MPa, it is usually necessary to add alloy elements such as Nb, V, and Ti to the chemical composition to ensure its strength and toughness. For example, the Chinese patent CN101280390A mainly refines the crystal grains by adding microalloying elements such as Nb, V, Ti, etc., and improves the strength and toughness. The high-strength structural steel produced by this meth...

AI Technical Summary

Problems solved by technology

However, the load on the rolling mill is required to be large, which will damage the on-board equipment and reduce the service life of the roll and the rolling mill.

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