Hot-dip galvanized low-alloy high-strength steel with yield strength of 700Mpa and preparation method thereof

Abstract

The invention discloses hot-dip galvanized low-alloy high-strength steel with yield strength of 700Mpa and a preparation method of the hot-dip galvanized low-alloy high-strength steel. The hot-dip galvanized low-alloy high-strength steel comprises the following chemical components in percentage by weight: 0.07-0.12% of C; 0.2 to 0.5 percent of Si; mn: 1.1 to 1.5%; 0.02% to 0.06% of Nb; 0.06% to 0.12% of Ti; less than or equal to 0.020% of P; s is less than or equal to 0.012%; the content of Als is 0.02 to 0.06 percent; n is less than or equal to 0.006%, and the balance is Fe and inevitable impurities. The preparation method comprises the procedures of smelting, hot rolling, cold rolling and hot galvanizing. Through reasonable design of low-carbon, Nb and Ti microalloying components, hot rolling, cold rolling reduction rate and a hot dipping continuous annealing process are matched, a certain amount of temper mill extension is used, the precipitation strengthening effect of a steel plate is strengthened, and the hot-dip galvanized low-alloy high-strength steel which is uniform in structure, stable in mechanical performance, good in cold bending performance and high in corrosion resistance is obtained.

Description

technical field [0001] The invention belongs to the technical field of manufacturing hot-dip galvanized high-strength steel for automobiles, and particularly relates to a hot-dip galvanized low-alloy high-strength steel with a yield strength of 700 Mpa and a preparation method thereof. Background technique [0002] With the rapid development of the automobile industry, the pursuit of body safety, energy saving and emission reduction, and improvement of corrosion resistance has become an inevitable trend, and the use of high-strength steel in automobiles has increased rapidly. Galvanized low-alloy high-strength steel has high strength, good formability, weldability and corrosion resistance, and is mainly used in body structural parts and reinforcements. [0003] At present, most of the yield strength grades of research and application of galvanized low-alloy high-strength steel are below 500MPa, and no research has been done on galvanized low-alloy high-strength steel with a ...

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Problems solved by technology

[0003] At present, the yield strength level of the research and application of galvanized low-alloy high-strength steel is mostly below 500MPa, and there is no research on galvanized low-alloy high-strength steel with a yield strength of 700MPa. Steel can no longer meet the urgent needs of light weight and safety of the car body

[0004] The Chinese patent with the publication number CN111074165 discloses a hot-rolled pickled plate of 700MPa high-strength automobile steel and its production method. Tensile strength, because pickling products have not been treated with surface coating in the cold-rolled galvanizing process, it is difficult to control the dimensional accuracy of thick gauges, and there are poor surface quality, low corrosion resistance, and poor dimensional accuracy, which cannot meet the requirements of lightweight, high Corrosion Resistance Requirements

[0005] The Chinese patent with the publication number CN103014539 discloses a high-strength and high-toughness steel plate with a yield strength of 700 MPa and its manufacturing method. The invention belongs to hot-rolled medium-thick steel plates. The steel plate structure is tempered martensite and carbide, not low alloy Steel grades of high-strength steel series products, and medium-thick steel plate products are not used for forming body parts, which cannot meet the lightweight requirements of automobile bodies

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