Steel Sheet Suitable for Enamelling and Method for Producing Such a Sheet

Abstract

The present invention is related to a rolled steel sheet suitable for enamelling, said sheet having a carbon profile, defined by a gradient in the C-level from a level Csurface at at least one surface of the sheet, to a level Cbulk in the bulk of the sheet, Cbulk being higher than Csurface, and with:Cbulk higher than 0 and lower than or equal to 0.08 wt %,Csurface between 0 and 0.015 wt %,Al between 0.012 wt % and 0.07 wt %,Mn between 0.12 wt % and 0.45 wt %,O lower than 0.01 wt %and optionally:Cu between 0.025 wt % and 0.1 wt %,S between 0.008 wt % and 0.04 wt %,Ca between 0.0005 wt % and 0.005 wt %,the balance being Fe and incidental impurities, and wherein the depth where the C-level reaches Cbulk+Csurface) / 2, is higher than 75 μm. The invention is equally related to a method for producing said steel sheet.

Description

FIELD OF THE INVENTION[0001]The present invention is related to a steel sheet suitable for enamelling, and to a method for the superficial decarburization of a steel sheet, as a preparation for enamelling the steel.STATE OF THE ART[0002]The carbon level of a steel sheet has an important influence on the results in terms of surface quality of an enamel layer applied on the surface of the sheet. A high carbon level at the steel surface may give rise to CO-gas bubble formation, which shows up as black spots and craters in the enamel surface. On the other hand, when a sufficiently high carbon level is present initially in the bulk, this carbon forms coarse cementite during hot rolling which cracks upon cold rolling. These cracks are capable of capturing hydrogen which enters the steel during the enamelling process. When hydrogen is insufficiently captured, pressure will rise at the steel / enamel surface which gives rise to the so-called ‘fish-scale’ deformation of the enamel.[0003]It is ...

AI Technical Summary

Benefits of technology

The invention relates to a method for making a material, where the material is heated to a high temperature and then cooled quickly. This process can lead to a more stable material. The method may also include steps to reduce the material's size and improve its appearance.

Problems solved by technology

On the other hand, when a sufficiently high carbon level is present initially in the bulk, this carbon forms coarse cementite during hot rolling which cracks upon cold rolling.

As the initial carbon level is quite low, fish-scale resistance due to cementite formation is not achieved.

However, this alloying involves extra costs and leads to some technical difficulties, e.g. involving casting with V. Furthermore, the prior art decarburized sheets have rather low formability as testified by the values of the Lankford coefficient (rm).

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