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Abstract

The invention relates to a method of producing a cold-rolled band of dual-phase steel with a ferritic/martensitic structure. The inventive method consists in hot rolling a slab having a chemical composition which comprises, by weight, 0.01%.ltoreq.C.ltoreq.0.1%., 0.05%.ltoreq.Mn.ltoreq.1%, 0.01%.ltoreq.Cr.ltoreq.1%, 0.01%.ltoreq.Si.ltoreq.0.5%, 0.001%.ltoreq.P.ltoreq.0.2%, 0.01%.ltoreq.Al.ltoreq.0.1%, N.ltoreq.0.01%, the remainder being iron and impurities resulting from the preparation thereof. The method also comprises the following subsequent steps consisting in: hot winding the band obtained at a temperature of between 550 and 850.degree. C.; cold rolling the band with a reduction ratio of between 60 and 90%; annealing the band continuously in the intercritical region; cooling said band to ambient temperature, in one or more steps, the rate of cooling between 600.degree. C. and ambient temperature being between 100.degree. C./s and 1500.degree. C/s; and, optionally, tempering same at a temperature of less than 300.degree. C. The aforementioned annealing and cooling operations are performed such that the end band comprises between 1 and 15% martensite. The invention also relates to the steel band thus formed.

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First Claim