High-strength thin-specification direct-plating steel based on thin slab casting and rolling process and making method thereof

Abstract

The invention provides high-strength thin-specification direct-plating steel based on a thin slab casting and rolling process and a making method thereof. The steel comprises the following chemical components in percentage by weight: C, 0.17-0.20%, Si, 0.09-0.25%, Mn, 0.90-1.40%, P, not more than 0.020%, S, not more than 0.010%, Als, 0.015-0.060%, and the balance of Fe and inevitable impurities. The process comprises the steps of molten iron desulfuration, bessemerize, argon blowing, LE furnace refining, continuous casting, descaling in a rotating way, soaking pit treatment, hydraulic jet descaling, seven-rack finish rolling, laminar cooling and reeling, wherein liquid core downward pressing is adopted in the step of continuous casting and the casting blank thickness is decreased to 50-55mm from 70-90mm; the discharging temperature of a soaking pit is 180-1200 DEG C to ensure that the temperature of blanks during the hydraulic jet descaling is between 1175-1190 DEG C and the temperature of a hydraulic jet descaling collecting pipe is 32-38 MPa; and the average cooling speed of laminar cooling after the seven-rack finish rolling is 30-60 DEG C / s.

Description

technical field [0001] The invention relates to a high-strength thin-gauge direct-plating steel based on thin-slab continuous casting and rolling technology and a manufacturing method thereof. The invention belongs to the technical field of hot-rolled steel for direct plating. Background technique [0002] Hot-rolled direct-galvanized steel refers to a hot-rolled plate that can be directly galvanized after pickling. Compared with the traditional cold-rolled galvanized substrate, due to the lack of two processes of cold rolling and annealing, hot-rolled direct There is a clear cost advantage in using steel. As early as the 1980s, developed countries such as the United States and Japan had begun large-scale production of hot-rolled direct-galvanized steel. For example, Japan’s Kawasaki Steel Chiba Works developed ordinary carbon steel and 400MPa grade steel in the late 1980s. Hot-rolled direct-galvanized steel. In addition, South Korea's Pohang Gwangyang Plant has also start...

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Problems solved by technology

[0011] The above-mentioned prior art has the following problems: 1) the mechanical properties are mainly improved by adding alloy elements, and the cost is relatively high; 2) hot-dip galvanizing can only be performed after cold rolling and annealing processes, the process is complicated and resource consumption is large; 3) few The technology of direct galvanizing without cold rolling after hot rolling is mentioned, such as literature [3], [7]. However, due to the use of conventional hot rolling technology, the thickness specifications of thick steel plates are generally greater than 2.0mm, and it is impossible to replace it with heat. cold

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