Arcelor France

Daniel Bouleau

Pascal Drillet

The invention relates to a process for manufacturing a corrosion-resistant cold-rolled sheet of iron-carbon-manganese austenitic steel, comprising the following steps: a sheet whose chemical composition comprises, the contents being expressed by weight: 0.35%&#x2266;C&#x2266;1.05%, 16%&#x2266;Mn&#x2266;24%, the balance of the composition consisting of iron and inevitable impurities resulting from its smelting, is provided; said sheet is cold-rolled; and a recrystallization annealing treatment is carried out on said sheet in a furnace containing a gas chosen from gases that are reducing with respect to iron, the parameters of said annealing being chosen in such a way that said sheet is covered on both its sides with an essentially amorphous (Fe,Mn)O oxide sublayer and with an external crystalline manganese oxide (MnO) layer, the total thickness of these two layers being equal to or greater than 0.5 microns.

Method for production of sheet of austenitic iron/carbon/manganese steel and sheets produced thus

The subject of the invention is a method for the hot-dip coating, in a liquid bath based on zinc containing aluminum, of a running strip of iron-carbon-manganese austenitic steel, in which said strip is subjected to a heat treatment in a furnace in which an atmosphere that is reducing with respect to iron prevails, in order to obtain a strip covered with a thin manganese oxide layer, and then the strip covered with the thin manganese oxide layer is made to run through said bath, the aluminum content in the bath being adjusted to a value at least equal to the content needed for the aluminum to completely reduce the manganese oxide layer, so as to form, on the surface of the strip, a coating comprising an iron-manganese-zinc alloy layer and a zinc surface layer.

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Metz, France

Daniel Bouleau