Steel sheet mfr. - by hot and cold rolling, cooling, bainitic heat treatment annealing and quenching

摘要

At the exit from the hot rolling mill, the steel sheet is subjected to a first rapid cooling, to 500-600 deg.C so as to form an at least partially bainitic structure, and after the cold rolling operation the sheet is annealed by heating rapidly to 700-730 deg.C, held at this temp. then quenched in an aq. medium at its boiling point. - The process is used to prepare a steel sheet with a hardness at least equal to T6 in the ASTM "Tempers" classification corresponding to hardnesses above 68 Rockwell HR30T.(0/0)