Steel plate with thickness of smaller than 60mm and yield strength of 690MPa and preparation method of steel plate

Abstract

The invention belongs to the field of steel and iron and particularly relates to a steel plate with the thickness of smaller than 60mm and the yield strength of 690MPa. The steel plate contains the following chemical components in percentage by weight: 0.10-0.20% of C, 0.15-0.50% of Si, 1.00-1.60% of Mn, 0.10-0.60% of Cr, 0.015-0.050% of Als, 0.008-0.025% of Ti, 0.10-0.30% of Mo, 0.0008-0.0030% of B, less than or equal to 0.025% of P, less than or equal to 0.008% of S, less than or equal to 40ppm of N, less than or equal to 20ppm of O, less than or equal to 2ppm of H and the balance of Fe and unavoidable impurities. The steel plate provided by the invention has favorable mechanical properties, plasticity and toughness, has the yield strength of larger than or equal to 690MPa, and can be applied to manufacture of large engineering machines or steel structures such as hydraulic supports for coal mines, heavy engineering machines, ocean platforms and the like.

Description

technical field [0001] The invention belongs to the technical field of iron and steel. Specifically, the invention relates to a steel plate with a yield strength of 690 MPa and a preparation method thereof. Background technique [0002] With the vigorous development of the domestic steel structure industry, construction machinery, mining machinery and other industries, and in order to comply with the market demand trend of large-scale and high-strength construction machinery such as hoisting machinery, excavator cantilever beams, and hydraulic supports for mines, the yield strength of 690MPa The demand for high-grade high-strength steel plates is increasingly strong. Steel plates of this strength level are generally produced by off-line quenching + tempering (that is, quenching and tempering treatment) in domestic steel mills. This production process not only increases equipment investment, but also has many procedures, difficult production organization and scheduling, long ...

AI Technical Summary

Problems solved by technology

Although this patent provides a post-rolling online quenching production process based on the two-stage cooling method of air mist and water curtain, the disadvantage is that it only discloses the mechanical properties of steel plates with a thickness of 32 mm, and the composition system is complex and the alloy cost is high. The strength is too low to give full play to the effect of online quenching to rapidly increase the strength

The patent discloses that the steel plate produced by the direct quenching process not only has low strength, but also requires subsequent normalizing and tempering heat treatment processes, the production process is complex, and the alloy and process costs are high

[0007] After analyzing the existing technology, it is found that the yield strength of most of the steel plates in the published literature is not higher than 690MPa, or the yield strength reaches 690MPa, but the high content of precious metals or the complicated heat treatment process cause high production costs, or fail to realize industrial Production; at the same time, for the high-strength steel plate with a yield strength of 690MPa at the same time, no production process with only one off-line heat treatment has been found

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