C - Chemistry – Metallurgy – 21 – D
Patent
C - Chemistry, Metallurgy
21
D
C21D 8/02 (2006.01) C21D 1/18 (2006.01)
Patent
CA 2514736
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 % </= C </= 0.1 %, 0.05 % </= Mn </= 1 %, 0.01 % </= Cr </= 1 %, 0.01 % </= Si </= 0.5 %, 0.001 % </= P </= 0.2 %, 0.01 % </= Al </= 0.1 %, N </= 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 DEG 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 DEG C and ambient temperature being between 100 DEG C/s and 1500 DEG C/s; and, optionally, tempering same at a temperature of less than 300 DEG 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.
L'invention concerne un procédé de fabrication d'une bande d'acier dualphase à structure ferrito-martensitique, laminée à froid dans lequel on lamine à chaud une brame dont la composition chimique comprend, en poids 0,010% <= C <= 0,100% 0,050% <= Mn <= 1,0% 0,010% <= Cr <= 1,0% 0,010% <= Si <= 0,50% 0,001% <= P <= 0,20% 0,010% <= AI <= 0,10% N <= 0,010% le reste étant du fer et des impuretés résultant de l'élaboration, ledit procédé comprenant ensuite les étapes consistant à - bobiner la bande à chaud obtenue à une température comprise entre 550 et 850°C, puis - à laminer à froid la bande avec un taux de réduction compris entre 60 et 90%, puis - à recuire la bande de façon continue dans le domaine intercritique, et - à la refroidir jusqu'à la température ambiante, en une ou plusieurs étapes, la vitesse de refroidissement entre 600°C et la température ambiante étant comprise entre 100°C/s et 1500°C/s, - et éventuellement à lui faire subir un revenu à une température inférieure à 300°C, les opérations de recuit et de refroidissement étant menées de telle sorte que la bande comprenne finalement de 1 à 15% de martensite, et la bande d'acier ainsi formée.
Norton Rose Or S.e.n.c.r.l. S.r.l./llp
Usinor
LandOfFree
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