High-strength steel plate and manufacturing method thereof

Abstract

The invention discloses a high-strength steel plate and a manufacturing method thereof. The high-strength steel plate comprises the composition by the weight percentage: 0.165-0.185% of C, 0.02-0.08%of Si, 1.15-1.25% of Mn, no more than 0.015% of P, no more than 0.005% of S, 0.025-0.05% of Al, 0.1-0.3% of Mo, 0.001-0.005% of B, no more than 0.004% of N, 0.01-0.02% of Nb, 0.01-0.025% of Ti, 0.045-0.055% of V, and the balance Fe and inevitable impurity elements. The yield strength of the steel plate is no less than 1100 MPa, the tensile strength is no less than 1300 MPa, the elongation rate isno less than 10%, the straightness meets the requirement of no more than 3 mm / m, and the cold bending D meets the requirement of 6a and 90 degrees. The high-strength steel plate adopts simple and economical C-Mn composition design, and is supplemented by a small amount of Mo and Nb, V, Ti, B and other micro-alloying elements; through fine grain strengthening and phase transformation strengtheningof micro-alloys, high strength and high toughness of the steel type are realized; the content of precious alloy elements is low, and the production difficulty and the production cost are reduced.

Description

technical field [0001] The invention relates to the field of low-alloy steel manufacturing, in particular to a high-strength steel plate with a yield strength exceeding 1100 MPa and a manufacturing method thereof, especially a hot-rolled heat-treated high-strength steel plate for engineering machinery with a thickness of 2.5-6 mm. Background technique [0002] High-strength steel is widely used in construction machinery such as cranes, concrete pump trucks, dump trucks, etc. The strength of steel plates has also developed from the initial ordinary carbon steel to 960MPa-level low-alloy steel. With the increase of equipment tonnage, the strength of high-strength steel has gradually increased to the level of yield strength of 1100MPa or even 1300MPa, and higher requirements have been put forward for the unevenness, welding performance and formability of steel plates. [0003] High-strength steel plates can be obtained by controlled cooling and controlled rolling + off-line hea...

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Problems solved by technology

[0007] Chinese Patent Publication Nos. CN102747303A and CN102337480A disclose "a high-strength steel plate with a yield strength of 1100 MPa and its manufacturing method" and "ultra-high-strength steel plate with excellent environmental brittleness and fatigue resistance and its manufacturing method". It is a thick plate product, the former contains up to 2.0% Ni, and the cost is high; the latter has a Mn content of 2-6%, and contains more Si and Cr, which is not good for welding performance

[0008] Chinese Patent Publication No. CN104498834A discloses "a high-toughness ultra-high-strength steel composition and preparation process", which relates to a high-strength steel with a yield strength of 1600 MPa, but contains higher Cr, Ni, W, and is a forged part with higher toughness. Poor, not suitable for construction machinery field

Although C has the effect of phase transformation strengthening, too much C will inevitably lead to deterioration of welding performance, and more Si is also unfavorable to the surface, toughness and plasticity, and welding performance; and the addition of more precious alloys increases the cost on the one hand, and is also not possible To avoid deterioration of welding and forming performance, the difficulty of processing is greatly improved

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