Process for producing high-strength hot-dip galvanized steel sheet with excellent material-quality stability, processability, and deposit appearance

A technology of hot-dip galvanized steel sheet and manufacturing method, which is applied in the direction of chemical instruments and methods, manufacturing tools, metal material coating technology, etc., which can solve problems such as increased deviation, decreased mass production efficiency, and poor shape, and achieves high ductility , The effect of high utilization value and high hole expansion
CN103597102AActive Publication Date: 2014-02-19JFE STEEL CORP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
JFE STEEL CORP
Publication Date
2014-02-19

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Abstract

Provided is a process for producing a high-strength hot-dip galvanized steel sheet which has a tensile strength TS of 540 MPa or higher and which is excellent in terms of material-quality stability, processability, and deposit appearance. A steel sheet that contains, in terms of mass%, 0.04-0.13% C, 0.7-2.3% Si, 0.8-2.0% Mn, up to 0.1% P, up to 0.01% S, up to 0.1% Al, and up to 0.008% N is subjected to a first heating step in which the steel sheet is heated to 400-750 DEG C in an atmosphere having an O2 concentration of 0.1-20 vol.% and an H2O concentration of 1-50 vol.% and then heated to 600-850 DEG C in an atmosphere having an O2 concentration of 0.01-0.1 vol.%, excluding 0.1 vol.%, and an H2O concentration of 1-20 vol.%. The steel sheet is subsequently subjected to a second heating step in which the steel sheet is held at 750-900 DEG C for 15-600 seconds in an atmosphere having an H2 concentration of 1-50 vol.% and a dew point of 0 DEG C or lower, cooled to a temperature in the range of 450-550 DEG C, and then held at this temperature for 10-200 seconds. Thereafter, the steel sheet is subjected to hot-dip galvanization.
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Description

technical field

[0001] The present invention relates to a method for manufacturing a high-strength galvanized steel sheet suitable for use as parts in the automotive, electric and other industrial fields, having excellent material stability and workability, as well as excellent coating appearance. Background technique

[0002] In recent years, improving the fuel efficiency of automobiles has become an important issue from the viewpoint of protecting the global environment. Along with this, the study of reducing the weight of the body itself has been active by increasing the strength of the body material to achieve thinning.

[0003] However, the reduction in ductility, that is, the reduction in formability due to the increase in strength of the steel sheet. Therefore, development of a material having both high strength and high processability is desired.

[0004] In addition, when high-strength steel sheets are formed into complex shapes such as automobile parts, cracks or...

Claims

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