Method of manufacturing toles in steel a structure has two phases having a resistance to traction high, a ratio of elasticity of low value and a high

摘要

P process for the production of sheet steel with a structure with two phases having a high tensile strength, a ratio of elasticity of low value and a high ductility. / p & & p & the process according to the invention makes it possible to obtain a sheet of steel having a structure with two phases having a high tensile strength, a ratio of elasticity that is low and high conductilité which is mainly constituted by a ferrite phase and a conversion phase produced by rapid cooling and which has excellent ability to be formed with a tensile strength of 40 kg / mm 2 or more * *. The method comprises the cooling of the sheet metal continuously annealed in the following conditions: 1°C. / second = r1 = 30°C. / second in which r1 represents a mean rate of cooling between the temperature of the continuous annealing to an intermediate temperature / p & & p & t °C. the cooling process; 4°C. / second = r2 = 100°C. / second, where r2 represents an average speed of cooling between t °C. and a temperature which is not greater than 200°C; r1 & r2, and 420°C. = & t = 700°C. / p & & p & application to the manufacture of sheet steel. / p