Steel sheet suitable for enamelling and method for producing such a sheet

Abstract

A rolled steel sheet suitable for enameling, having a carbon profile, defined by a gradient in the C-level from a level C surface at at least one surface of the sheet, to a level C bulk in the bulk of the sheet, C bulk being higher than C surface , and with C bulk higher than 0 and lower than 0.08 wt %, C surface between 0 and 0.015 wt %, Al between 0.012 wt % and 0.07 wt %, Mn between 0.12 wt % and 0.45 wt % and O lower than 0.01 wt % and wherein the depth where the C-level reaches (C bulk +C surface )/ 2 , is higher than 75 μm.

What is claimed is: 
     
         1 . A rolled steel sheet suitable for enameling, said sheet having a carbon profile, defined by a gradient in the C-level from a level C surface  at at least one surface of the sheet, to a level C bulk  in the bulk of the sheet, C bulk  being higher than C surface , and comprising:
 C bulk  higher than 0 and lower than or equal to 0.08 wt %,   C surface  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,   wherein a particular depth where the C-level reaches a midpoint C-level of (C bulk +C surface )/2 is higher than 75 micron, the midpoint C-level being a fixed value greater than 0 that is a single point on the gradient.   
     
     
         2 . Steel sheet according to  claim 1 , having an r m  value between 1.8 and 2.1. 
     
     
         3 . Steel sheet according to  claim 1 , wherein C surface  is between 0.005 wt % and 0.015 wt %. 
     
     
         4 . Steel sheet according to  claim 1 , wherein C surface  is between 0 and 0.005 wt %. 
     
     
         5 . Steel sheet according to  claim 1 , wherein C bulk  is between 0.02 wt % and 0.08 wt %. 
     
     
         6 . Steel sheet according to  claim 5 , wherein C bulk  is between 0.025 wt % and 0.08 wt %. 
     
     
         7 . Steel sheet according to  claim 5 , wherein C bulk  is between 0.025 wt % and 0.06 wt %. 
     
     
         8 . Steel sheet according to  claim 1 , wherein the Al-level is between 0.02 wt % and 0.06 wt %. 
     
     
         9 . Steel sheet according to  claim 1 , wherein said depth is between 130 μm and 200 μm. 
     
     
         10 . Enameled steel sheet consisting of a steel sheet according to  claim 1 , provided with an enamel layer. 
     
     
         11 . Steel product produced from a sheet according to  claim 1 . 
     
     
         12 . Enameled steel product consisting of a product according to  claim 11 , provided with an enamel layer.