Procedure for heat treatment of a strip of cold rolled steel, suitable for forming, and thus obtained steel strip.

摘要

Procedure for heat treatment of a steel strip cold rolled with low carbon content, in order to confer a biphasic structure, or "dual phase", comprising grains of martensite dispersed in a ferrite matrix, comprising, by weight of 0.06 to 0.2% carbon, 0.6 to 2% manganese and less than 0.5% silicon, preferably 0.1 to 0.4% silicon, said strip having a thickness between 0.3 and 2 mm, said method comprising: - heating to a temperature higher than the annealing temperature A3 and stabilizing at said annealing temperature for a period less than one minute; - cooling at a rate above 50 ° C / s to an intermediate temperature in the intercritical region between the transformation points A1 and A3, and stabilizing at said intermediate temperature for a period of 5 to 15 seconds; and - tempered to a temperature below the critical temperature Ms of martensite transformation temperature so that, during the annealing process of the steel strip, it is immersed in a galvanizing bath maintained at a temperature between 460 and 500 ° C.