Patent ID: 8449694

Claim:
A method for producing a surface-decarburised steel strip which is made of a heat-treatable steel containing at least 0.4% by weight of carbon, comprising the steps of: making of the steel strip from the heat-treatable steel, heating of the steel strip, when coiled into the open coil, to a decarburising annealing temperature which may be up to 20° C. below the A c1 temperature of the given heat-treatable steel and which does not exceed the A c3 temperature of the given heat-treatable steel, annealing of the steel strip, in the open coil, in a decarburising atmosphere for a decarburising annealing time of at least 90 minutes, the decarburising gas which forms the decarburising atmosphere flowing through the gaps which exist between the layers of the open coil, and accelerated cooling of the steel strip, wherein the accelerated cooling is carried out under a protective gas atmosphere, the depth of decarburisation, as measured from the given surface of the steel strip, thus being limited to a range which is in each case less than a quarter of the thickness of the steel strip.