| 摘要 |
PURPOSE:To obtain the titled cold rolled plate by annealing a steel plate contg. a specified amount of C, Mn and Al and having a specified B/N ratio at the recrystallizing temp.- the Ac3 point and cooling the annealed plate at a specified cooling rate or above in a temp. range of the Ar1 point or below while carrying out overageing at 300-200 deg.C for >=10min. CONSTITUTION:A steel plate contg., by wt., <0.04% C, <0.4% Mn and 0.01- 0.1% Al and having B/N >0,5 is annealed at the recrystallizing temp.- the Ac3 point and cooled at >=20 deg.C/sec cooling rate in a temp. range of the Ar1 point or below. At this time, at 300-200 deg.C the plate is held for >=10min to carry out overageing. |
