Coating/baking curable type cold rolled steel sheet with excellent strain aging resistance and method for producing the same

A steel slab comprising the composition of not larger than 1.0% of Si, not larger than 3.0% of Mn, from 0.01 to 0.2% of Al and from 0.001 to 0.2% of Ti while controlling its C, P, S, and N contents; the value A=(AIQUENCH-AI)/AIQUENCH is greater than 0.4; ALQUENCH is greater than 30; and the ratio of average intergranular angle M (degree) and the average crystal grain size G ( m) is greater than 0.8. Said composition may further contains from 0.001 to 0.2% of Nb and/or from 0.001 to 0.0080% of B in term of % by weight. The steel slab may adjust Si, Mn, S, Al, N to suitable values and contains from 0.05% to 0.02% of C, less than 0.05% of P, from 0.025% to 0.19% of Nb in term of % by weight and satisfy the equation of 0.7x(C/12) ≤ Nb/93 ≤ 1.2x(C/12) (In this case c refers to c content (weight %), Nb refers to Nb content (weight %). The slab is heated and finish the rolling at a temperature ranging from 960 DEG C to 650 DEG C and coiled the resulted sheet steel at a temperature ranging from 750 DEG C to 400 DEG C, and thereafter the resulted sheet steel is cold-rolled to a reduction falling between 50 and 95%, and then annealed for recrystallization at a temperature falling between 750 and 920 DEG C. The steel slab may further contains B, Ti. According to this invention, a coating/baking curable type steel sheet with excellent strain aging resistance may be obtained.