650 MPa-grade low-alloy high-strength steel and production method thereof

Abstract

The invention relates to 650 MPa-grade low-alloy high-strength steel and a production method thereof. The low-alloy high-strength steel comprises the following chemical components of, in percentage bymass, 0.07-0.10% of C, 0.3-0.7% of Si, 1.5-1.6% of Mn, less than or equal to 0.03% of P, less than or equal to 0.015% of S, 0.025-0.05% of Als, less than or equal to 0.008% of N, 0.02-0.05% of Ti, 0.01-0.04% of Nb, and the balance Fe; the production process comprises the following steps of hot rolling process and continuous annealing process, in the hot rolling process, the hot rolling heating temperature ranges from 1200 DEG C to 1260 DEG C, the final rolling temperature ranges from 876 DEG C to 904 DEG C, the coiling temperature ranges from 613 DEG C to 650 DEG C, and obtaining the hot-rolled coiled plate with the microscopic structure as ferrite and pearlite. On the basis of low C, Ti element with relatively low cost is used for replacing Nb elements with relatively high cost, the hotrolling and cold rolling process parameters are improved, the stability of the low-alloy high-strength steel product is effectively controlled, the strength and the toughness of the product are improved, and meanwhile, the production cost is greatly reduced.

Description

technical field [0001] The invention relates to a 650MPa grade low-alloy high-strength steel and a production method thereof, belonging to the technical field of metallurgical plate production. Background technique [0002] With the continuous improvement of energy conservation and environmental protection awareness in modern society, automobile design is required to develop in the direction of low energy consumption and high safety. Automobile lightweight work is an effective means to achieve this goal; Under the circumstances, the higher the strength of the steel plate, the thinner the thickness of the required steel plate and the lighter the body. At present, 650MPa low-alloy high-strength steel has been widely used in automobile reinforcements and structural parts, which has a strong role in promoting automobile lightweight. [0003] At present, cold-rolled low-alloy high-strength steel is produced by continuous annealing process using Nb and Ti composite composition sy...

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Problems solved by technology

[0003] At present, cold-rolled low-alloy high-strength steel is produced by continuous annealing process using Nb and Ti composite composition system, but to make the strength reach more than 600MPa, it depends on adding a large amount of alloying elements Nb and Ti, and using Nb element to strengthen the crystal grains. The refining effect and the dispersion and precipitation of Ti elements are used to achieve a certain strength level, so the consumption of alloy elements is more, resulting in higher costs, which is not conducive to the reduction of the production cost of automobile sheets

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