Process for producing components having regions of differing ductility

Abstract

The invention relates to a process for producing sheet steel components having regions of differing ductility, in which either a sheet metal plate composed of a hardenable steel alloy is used to produce a component by deep-drawing and the deep-drawn component is then at least partially austenitized by a heat treatment and subsequently quench hardened in a die or the plate is at least partially austenitized by a heat treatment and shaped in the hot state, and is quench hardened during or after this, with the sheet metal plate having a zinc-based cathodic corrosion protection coating, characterized in that in regions of a desired higher ductility of the component, at least one additional sheet is attached to the plate, situated so that during the heat treatment, the plate is heated to a lesser degree there than in the remaining region.

Description

FIELD OF THE INVENTION[0001]The invention relates to a process for producing sheet steel components.BACKGROUND OF THE INVENTION[0002]In automotive construction, the use of sheet metal products—preferably composed of sheet steel—that vary in thickness and material quality is on the rise. This makes it possible to reduce the weight of vehicle body components while adapting the material used to their functions. Body components of this kind include, for example, A, B, and C pillars, bumpers and their cross members, roof frames, side impact members, exterior body parts, etc.[0003]In this connection, the prior art uses so-called tailored blanks. These are plates that are welded together out of a plurality of sheet metal pieces with the same or different sheet thicknesses and material qualities. The use of so-called patchwork blanks is also known. These are plates of varying thicknesses and material qualities that are placed parallel to one another.[0004]In the latter process, the sheets a...

AI Technical Summary

Benefits of technology

[0019]2. Providing enough austenitizing time for complete through-hardening of a plate with a galvanized starting material of 22MnB5 connected to a plate component B composed of a respectively galvanized soft deep-drawing steel, a micro-alloyed steel, a carbon-manganese steel, or a dual-phase steel while producing a sufficient cathodic corrosion protection during the press hardening.

[0021]4. Providing enough austenitizing time for complete through-hardening of plates A and B while producing a sufficient cathodic corrosion protection.

Problems solved by technology

Patchwork blanks have the disadvantage that the spot-welded connections are subjected to high stresses during shaping and can sometimes even fracture.

In addition, the gap that is present between the sheet metal layers can lead to corrosion problems; controlling these requires an expensive sealing treatment.

Furthermore, the transition between the individual thickness regions is relatively abrupt in both tailored blanks and patchwork blanks.

This can result in undesirable stress peaks in the immediate transition region.

Although a significant weight reduction is achieved with tailored and patchwork blanks, the corrosion protection is relatively expensive.

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