Patent ID: 7169244

Claim:
A process for manufacturing a steel strip with low aluminum content, comprising: hot-rolling a steel strip comprising between 0.050 and 0.080% by weight of carbon, between 0.25 and 0.40% by weight of manganese, less than 0.020% by weight of aluminum, and between 0.010 and 0.014% by weight of nitrogen, the remainder being iron and inevitable trace impurities, to form a strip; subjecting said strip to a first cold-rolling, to form a cold-rolled strip; annealing said cold-rolled strip, to form an annealed cold-rolled strip; and subjecting said annealed cold-rolled strip to a secondary cold-rolling; wherein said annealing is a continuous annealing comprising: raising the temperature of the strip to a temperature equal to or higher than the temperature of onset of pearlitic transformation Ac 1 , holding the strip above this temperature for a duration of longer than 10 seconds, and rapidly cooling the strip to a temperature below 350° C. at a cooling rate between 100° C. and 500° C. per second.