Process for producing deep-drawing cold rolled steel strip by continuous annealing

A process for consistently producing a deep-drawing cold rolled steel strip by continuous annealing, said process comprising the successive steps of:

• (1) hot rolling a steel containing:
• not more than 0.06% C,
• 0. 12 to 0.40% Mn,
• 0.005 to 0.05% acid soluble Al,
• not more than 0.0040% N,
• 0.0005% to 0.0019% B
• wherein the ratio of B to N is in the range of from 0.56 to 0.90
• balance iron and unavoidable impurities;
• (2) coiling the hot rolled steel strip from step (1) at a temperature not greater than 680.degree. C.,
• thereby precipitating BN by reaction between the boron and nitrogen thereby preventing precipitation of boron carbides;
• (3) cold rolling the coiled roll of step (2);
• and thereafter
• (4) continuously annealing the cold rolled strip of step (3)
• thereby developing large crystal grains in the steel, providing a high r value not lower than 1.9, a substantial elongation value and a low yield point value to the resulting cold rolled steep strip.