A microalloyed plate with high strength and toughness and good metallurgical quality in the core and its preparation method

Abstract

The invention discloses a micro-alloyed medium-thick plate with high strength and toughness and good metallurgical quality at the core and a preparation method thereof, belonging to the field of hot-rolled steel plate manufacturing. The microalloyed plate with high strength and toughness and good metallurgical quality in the core includes: 0.07‑0.17% of C, 0.05‑0.3% of Si, 0.8‑1.9% of Mn, 0.0005‑0.018% of P, and 0.0005‑05% of S 0.010%, Cr is 0.05‑0.25%, Nb is 0.005‑0.03%, Mo is 0.05‑0.3%, V is 0.09‑0.25%, N is 0.012‑0.025%, and the balance is Fe and unavoidable impurity elements; The metallographic structure of the core is acicular ferrite, granular bainite and pearlite. Its preparation method goes through molten iron pretreatment, smelting, LF refining, continuous casting, rough rolling, finish rolling, cooling, and through optimization of chemical composition, smelting, rolling, and cooling processes, the allowable hydrogen content in molten steel is increased to 4.5 ppm, no vacuum degassing process is required, which makes the steel plate have strong toughness and good core metallurgical quality.

Description

technical field [0001] The invention belongs to the field of hot-rolled steel plate manufacturing, and in particular relates to a micro-alloyed medium-thick plate with high strength and toughness and good metallurgical quality in the core and a manufacturing method thereof. The preparation method is a production process in which the permissible hydrogen content in molten steel is increased to 4.5ppm through the optimization of chemical composition design, smelting process, rolling and cooling process, and the steel plate has good strength, toughness and core metallurgical quality. Background technique [0002] Hydrogen atoms exist in high-strength steel, and when it reaches a certain concentration, it will damage the steel, form white spots in the steel or parts, or delay fracture, or cause a decrease in elongation and impact toughness, which are collectively called hydrogen embrittlement. . For high-strength and thicker medium-thick plate products, the hydrogen in the stee...

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Problems solved by technology

[0005] Aiming at the problem that existing medium-thick plate products have cracks in the center under the combined action of slab segregation and hydrogen in the steel, resulting in unqualified flaw detection, the present invention proposes a microalloying alloy with high strength and toughness and good metallurgical quality in the center. A medium-thick plate and a preparation method thereof, the preparation method is a new medium-thick plate preparation method suitable for Q460 and Q550 grades, the preparation method reduces the hydrogen embrittlement susceptibility of the core of the steel plate through the regulation of the chemical composition. Control the rolling and cooling process of the steel plate so that the hydrogen in the steel diffuses out of the steel plate in time; the allowable hydrogen content in molten steel can be increased to 4.5ppm, and the hydrogen content can be controlled only by conventional smelting process without vacuum The degassing process shortens the process flow, reduces energy consumption, reduces harmful gas emissions, and improves production efficiency. It is a green production technology

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