A production method of ultra-high-strength steel plate with large thickness, high toughness and yield strength of 1100mpa

Abstract

The present invention relates to a production method of ultra-high-strength steel plate with large thickness, high toughness and yield strength of 1100MPa: the process flow is: converter or electric furnace steelmaking->LF refining->VD or RH vacuum degassing->Ca treatment->continuous casting- >Slab slow cooling diffusion treatment->heating->rolling->steel slow cooling diffusion treatment->quenching->tempering. The invention adopts the residual temperature of the cast slab and the steel plate to carry out slow cooling and diffusion treatment. The starting temperature of the slow cooling diffusion of the slab is controlled at 600-700°C, the diffusion time is ≥48 hours, and the diffusion termination temperature is ≤300°C; the steel plate diffusion starting temperature is ≥300°C, and the diffusion time is ≥24 hours. The two slow cooling and diffusion processes greatly reduce the harmful gas content in the finished steel plate, homogenize the distribution of different chemical elements, reduce the generation of internal stress in the steel plate, and lay a solid foundation for improving the ultra-low temperature impact toughness and uniformity of thickness direction properties of the steel plate. good foundation.

Description

technical field [0001] The invention relates to, in particular, a large-thickness, high-toughness, yield strength 1100MPa grade ultra-high-strength steel plate and a production method thereof. Background technique [0002] High-strength steel plates with a yield strength of 1100MPa and above are mainly used in key stress-bearing parts of construction machinery such as booms, pull plates, rotating tables, and frames of construction cranes. They have high requirements for steel plate strength, toughness, welding, cutting, etc., and the current consumption is mainly 20mm and below thin gauge steel plate. In recent years, with the increasing number of large-scale and super-large mines, nuclear power, hydropower, wind power and other engineering projects around the world, the further large-scale construction machinery and equipment have gradually developed. Demand is also growing. [0003] As the thickness increases, the following problems are bound to be brought: (1) Due to th...

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Problems solved by technology

[0003] As the thickness increases, the following problems are bound to be brought: (1) Due to the limitation of the quenching capacity of the quenching machine, the mechanical properties of the steel plate surface and the core are quite different; the problem of uneven performance along the thickness direction is difficult to solve; (2) It is difficult to guarantee the low-temperature impact toughness of large-thickness steel plates; especially for engineering applications in extremely cold regions, how to ensure the ultra-low temperature impact toughness of large-thickness steel plates in an environment of -60°C is a difficult problem

[0004] Chinese patent CN106191673B introduces a quenched ultra-high-strength steel plate with a yield strength of 1100MPa. The steel plate C: 0.15-0.20%; Mn: 1.00-1.40%. Performance; the thickness is thinner than 20mm; and there is no research on the impact toughness at -60°C ultra-low temperature;

[0008] To sum up, the current existing technologies involving ultra-high-strength steel plates with a yield strength of 1100MPa mainly solve the manufacturing problems of thin plates with a thickness of ≤40mm; and only study the low-temperature impact toughness in the environment of -40°C; There is no clear method for the core properties of large thickness steel plates and the ultra-low temperature impact toughness in the extremely cold environment of -60 °C

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