Method for improving dent-resistance of a steel plate

Abstract

The present invention relates to a method for enhancing a dent-resistant property of an outer panel of a vehicle. Pre-straining is performed to a steel plate by applying a certain reduction rate during a skin pass mill process performed for enhancing a density of a steel plate and adjusting a shape of the same, so that it becomes possible to enhance yield strength of a steel plate and to obtain an excellent forming property. The present invention is basically directed to fabricating an outer panel material such as a roof, a door, a hood, etc. of an excellent vehicle material having an excellent forming property and dent-resistant property. Therefore, it is possible to decrease a thickness of a vehicle material based on an enhanced strength of an outer panel of a vehicle. The present invention may contribute to a government environment regulation counter measurement and a combustion ratio of engine.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority of Korean Application No. 10-2003-0049099, filed on Jul. 18, 2003, the disclosure of which is incorporated fully herein by reference. FIELD OF THE INVENTION [0002] The present invention relates to a method for improving dent-resistance of a steel plate by prestraining the steel plate through a skin pass mill process where a certain reduction rate is provided. BACKGROUND OF THE INVENTION [0003] In general, an outer panel of a vehicle requires improved processability for fabricating a certain part into a desired shape after a press forming process. the outer panel may also require an improved dent-resistant property. An outer panel of a vehicle body is generally made of a cold-rolled steel plate having a high elongation rate and a large plastic deformation rate. A high yield strength as well as excellent processability for fabricating an outer panel such as a door, a hood, a panel, etc. may be desirable. B...

AI Technical Summary

Benefits of technology

[0008] Embodiments of the present invention relate to a method for improving the dent-resistance of a steel plate. It may be possible to enhance yield strength of a steel plate and obtain an excellent forming property in such a manner that a steel plate is pre-strained by providing a certain reduction rate during a skin pass mill process performed for a density and shape modification of the steel plate.

[0009] In one embodiment of the present invention, an outer panel comprising steel material such as a roof, a door, a hood, etc., having an excellent processability and a dent-resistant property is fabricated using the method of the present invention. Increasing strength of an outer panel of a vehicle may allow for decreasing the thickness of the material.

[0010] In another embodiment of the present invention, yield strength of a steel plate may be enhanced based on an increase in the degree of work-hardening by pre-straining the steel plate in a state of one axis tensile prior to a press process.

Problems solved by technology

However, when yield strength of a steel plate is too high, a process defect may occur during a forming process before the steel plate is formed.

It may therefore become challenging to fabricate a certain part in a desired shape.

Nevertheless, in the above methods, a surface defect called as a stretcher strain may occur on a surface of a steel plate, and reduce the ability to accurately control the amount of components.

Moreover, the processability by the products is not uniform.

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