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

Abstract

The invention belongs to the fields of steel and iron and particularly relates to a steel plate with the thickness of larger 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, 1.20-1.70% of Mn, 0.10-0.40% of Ni, 0.20-0.60% of Cr, 0.01-0.05% of Nb, 0.02-0.06% of V, 0.015-0.050% of Als, 0.008-0.025% of Ti, 0.15-0.45% 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 thickness greater than 60 mm and a yield strength of 690 MPa and a preparation method thereof. Background technique [0002] Economic construction and social development require a large amount of high-strength steel. With the vigorous development of domestic steel structure industry, construction machinery, mining machinery and other industries, at the same time, in order to adapt to the large-scale, With the trend of high-strength market demand, the demand for high-strength, high-quality steel for construction machinery is increasingly strong. At the same time, in order to meet the requirements of high-strength steel for reducing the sensitivity of welding cracks, major iron and steel enterprises have invested a lot of manpower and material resources in research and development. [0003] In the Chinese patent CN101812634A, a met...

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Problems solved by technology

Although this patent also provides a production method of 80kg grade steel plate with low welding crack sensitivity, the disadvantage is that it fails to make full use of the fine grain, phase transformation and dislocation strengthening mechanism of controlled rolling and controlled cooling in the rolling process. At the same time, the steel plate also needs to be quenched and tempered off-line, resulting in an increase in production costs

Although this patent provides a method for producing 80kg-class steel with low welding crack sensitivity without any heat treatment, 0.04-0.12% of precious metal V is added, resulting in high cost of the steel alloy

[0005] In Chinese patent CN100439545C, a method for manufacturing 800MPa grade high-toughness and low-yield ratio thick steel plate is disclosed. 0.30% to 0.70% of precious metal Ni is added to the composition design of the steel, resulting in high alloy cost, and the steel plate The yield strength can only be guaranteed to be greater than 540MPa

[0006] 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 the level of 80kg, but the high content of precious metals or complicated heat treatment process lead to high production costs

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