Cold-rolled hot-dip galvanized steel and manufacturing method thereof

Abstract

The invention discloses cold-rolled hot-dip galvanized steel. The cold-rolled hot-dip galvanized steel comprises the following chemical elements of, in percentage ration by mass, 0.06%-0.14% of C, 1.3%-2.4% of Mn, 0.1%-1.0% of Si, and the balance Fe and inevitable impurities; and the microstructure of the cold-rolled hot-dip galvanized steel is ferrite + martensite + bainite + retained austenite.In addition, the invention further discloses a manufacturing method of the above cold-rolled hot-dip galvanized steel. The manufacturing method comprises the steps that (1) smelting and casting are carried out; (2) hot rolling is carried out; (3) acid pickling is carried out; (4) cold rolling is carried out; (5) hot galvanizing recrystallization annealing is carried out, specifically, a cold-rolled sheet is heated to the soaking temperature T1 for thermal insulation for a period of time; and then the soaked steel plate is cooled to the intermediate temperature T2 at the first cooling speed andthen cooled to T3 at the second cooling speed, thermal insulation is carried out for a period of time, then the temperature is increased to the zinc pool temperature T4 for thermal insulation for a period of time, wherein the cooling speed is less than the second cooling speed, T2 is larger than or equal to 640 DEG C and less than or equal to T1, and T3 is larger than Ms and less than or equal toT4; and (6) cooling is carried out to the room temperature.

Description

technical field [0001] The invention relates to a steel grade and a manufacturing method thereof, in particular to a hot-dip galvanized steel and a manufacturing method thereof. Background technique [0002] In addition to good manufacturability, good mechanical properties and corrosion resistance, hot-dip galvanized dual-phase steel has been widely used in body structural parts and reinforcements. In recent years, with the design of the body structure becoming more and more complex, the traditional hot-dip galvanized dual-phase steel has a large difference in strength between the two phases of martensite and ferrite, which makes it difficult to ensure the performance of hole expansion and flanging, and cannot meet the needs of some The design requirements of the body structure. Therefore, it is particularly important to develop steels with high formability without increasing the cost and difficulty of manufacturability. [0003] For example: the publication number is CN10...

AI Technical Summary

Problems solved by technology

In the technical solution disclosed in this patent document, although the hot-dip galvanized dual-phase steel has good flanging performance, the cold rolling reduction is relatively large, and the dew point range of the annealing furnace is too small, which increases the difficulty of production

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