Low-alloy high-strength hot-rolled steel strip suitable for extremely cold area and preparation method thereof

Abstract

The invention discloses a low-alloy high-strength hot-rolled steel strip suitable for the extremely cold area and a preparation method thereof. The low-alloy high-strength hot-rolled steel strip is prepared from the chemical compositions in percentage by weight: 0.06-0.10% of C, 0.6-0.7% of Si, 1.40-1.70% of Mn, 0.015-0.025% of Nb, 0.005-0.010% of Ti, 0.004-0.007% of Mg, less than or equal to 0.010% of P, less than or equal to 0.010% of S, less than or equal to 0.002% of Al, 0.002-0.005% of N, and the balance of Fe and unavoidable inclusions. The preparation method includes the following stepsof removal of S from molten iron through a KR method, removal of P and C through a duplex converter, an LF refining furnace, slab continuous casting, reheating of billets in a heating furnace, roughing and finish rolling, ultra-fast cooling, laminar cooling and coiling. According to the low-alloy high-strength hot-rolled steel strip suitable for the extremely cold area and the preparation methodthereof, the problem of the phenomenon of the uneven structure of rolled materials in the ultra-fast cooling process is solved.

Description

technical field [0001] The invention belongs to the technical field of strip steel production, and in particular relates to a low-alloy high-strength hot-rolled steel strip suitable for extremely cold regions and a production method thereof. Background technique [0002] The lowest temperature in extremely cold regions such as Siberia can reach below -60°C. Due to the large amount of oil, natural gas and other resources stored in this region, the international exploitation of this region is also increasing. Most of the mining equipment and its ancillary buildings are Made of steel, the corresponding steel used in this area also needs to have good mechanical properties at a low temperature of -60°C. [0003] Steel has a ductile-brittle transition temperature. Below this temperature, the fracture mode of steel changes from ductile fracture to brittle fracture, that is, low-temperature brittleness occurs. Steel with good toughness loses its proper toughness and becomes as britt...

AI Technical Summary

Problems solved by technology

However, in production practice, it was found that using this technology to control the free oxygen content in the range of 10-18ppm to feed magnesium-containing alloys produces a relatively small number of Mg-Ti series composite oxides, and the number of small inclusions is not enough. The content of acicular ferrite is small, and it is unreasonable to feed magnesium-containing alloys in the range of free oxygen content in the range of 10-18ppm

Images