THIN STEEL SHEET WITH SUPERIOR STATE OF SURFACE, FORMABILITY AND WORKABILITY, AND METHOD OF PRODUCING THE SAME Russian patent published in 2008 - IPC C21D8/04 C22C38/14 C21D9/48 

FIELD: manufacture of thin sheet from low-carbon steel.

SUBSTANCE: method involves producing thin sheet from low-carbon steel having superior surface characteristics, formability and workability, containing, wt%: 0.0003≤C≤0.003, Si≤0.01, Mn≤0.1, P≤0.02, S≤0.01, 0.0005≤N≤0.0025, 0.01≤ acid-soluble Ti≤0.7, acid-soluble Al≤0.003, 0.002≤La+Ce+Nd≤0.02, iron the balance and unavoidable admixtures. Steel sheet contains at least cerium oxysulfide, lanthanum oxysulfide and neodymium oxysulfide. Method involves heating steel blank; providing hot rolling of blank and winding rolled blank to thereby produce hot-rolled steel strip; providing cold rolling of said strip at reduction extent of 70% or more, followed by continuous recrystallization annealing at temperature of 600-900 C. During continuous annealing process, inclusions are finely dispersed in steel sheet to thereby promote growth of recrystallized grains with radius r equal to or than 2.0 and total percentage of elongation equal to or more than 50%.

EFFECT: increased efficiency in preventing coalescence and growth of inclusions in steel, surface defects and cracks in the process of stamping.

9 cl, 2 tbl, 1 ex