800mpa grade hot-rolled trip steel based on csp process and its manufacturing method

Abstract

The invention discloses 800MPa-stage hot rolled TRIP steel based on a CSP process. The 800MPa-stage hot rolled TRIP steel is prepared from the following chemical elements according to weight percent: 0.165 to 0.20% of carbon, 1.40 to 1.60% of silicon, 1.45 to 1.60% of manganese, 0.06 to 0.08% of phosphorus, less than or equal to 0.005% of sulfur, 0.015 to 0.060% of acid soluble aluminum and the balance of iron and inevitable impurities. A manufacturing method of the steel comprises the steps of smelting in a converter, refining, performing continuous casting on a sheet billet, soaking the continuous casting billet, descaling with high-pressure water, performing controlled rolling, performing controlled cooling and reeling. Economic C-Si-Mn-P composition design is adopted, and metallographic structures adopt 50 to 65% of ferrite, 20 to 40% of bainite and 7 to 15% of retained austenite; the yield strength is 500 to 550 MPa, the tensile strength is 800 to 880 MPa, the elongation A80 is 27 to 31%, and the steel has good strength and plasticity matching.

Description

technical field [0001] The invention belongs to the technical field of hot-rolled iron and steel strip production, and in particular relates to an 800MPa hot-rolled TRIP steel based on a CSP process and a manufacturing method. Background technique [0002] With the improvement of people's requirements for the environment, energy, safety, etc., automobiles are developing in the direction of lightweight, high strength, and low cost. The adoption of AHSS (Advanced high-strength steels) is what the automobile and steel industry needs to respond to this trend. The main measures taken together. In AHSS, TRIP steel (transformation-induced plasticity steel) has attracted much attention because of its high matching of strength and elongation, and good comprehensive performance. TRIP steel is mainly used to make car baffles, car door guards, bumpers, chassis components, wheel rims and door impact beams. In Japan, TRIP steel plates have been used to make about 80 parts on the chassis...

AI Technical Summary

Problems solved by technology

[0009] The thin slab continuous casting and rolling short-process production line generally adopts a compact rolling mill arrangement, and the output roller table between the rolling mill and the coiler is usually short (70-90m), and the thickness specification of the "heat instead of cold" automotive steel is relatively thin , the rolling speed is fast, which will lead to insufficient intermediate air cooling time to form a sufficient proportion (≥50%) of polygonal ferrite, which in turn will lead to insufficient carbon in the remaining austenite, and the amount of ferrite in the final structure formed And the amount of residual austenite is insufficient, and a certain amount of martensite is formed, which deteriorates the microstructure and properties of TRIP steel

In addition, the thin slab continuous casting and rolling process has unique metallurgical laws, and there are certain restrictions on the content of C, Mn, and Al in the composition design. Bottleneck problem of hot-rolled TRIP steel produced in process line

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