| 摘要 |
PURPOSE:To produce a titled steel plate of quality more than equal to that of conventional products in simpler stages by heating a low carbon hot rolled steel plate contg. Cr, Ni, Mo, Al, N to temps. higher than its recrystallization temp., and cooling the same at specific average rates then subjecting the strip to controlled cooling and cold rolling to product thickness. CONSTITUTION:The hot rolled steel strip contg., by wt%, <=0.10 C, 15-20 Cr, <=0.6 Ni, <=2.5 Mo, <=0.4 Al, <=0.025 Ni, and if necessary, contg. >=1 kind of <=1.0% Cu, <=0.5% Ti, <=0.5% Nb, <=0.5% V, <=0.006% B and consisting of the balance substantially Fe is subjected to the following heat treatments: After said steel strip is heated to a temp. region of the recrystallization temp. - the recrystallization temp. +100 deg.C, it is cooled at <=10 deg.C/sec average rate down to a 700-900 deg.C temp. region. Thereafter, it is cooled under controlling at the average rate in accordance with the content of Al or the contents of Al+Ti+ Nb+V down to <=200 deg.C. Such steel strip is cold rolled down to product thickness. |
