MANUFACTURE OF COLD ROLLED STEEL PLATE WITH SUPERIOR WORKABILITY AND LESS DETERIORATION DUE TO AGING

摘要

PURPOSE:To obtain the titled cold rolled plate by heating steel contg. a specified amount of C and Mn and having a specified Al/N ratio to <=1,100 deg.C, thereafter the steel being hot rolled, cold rolled, annealed at the recrystallizing temp.- the Ac3 point, and cooled at a specified cooling rate or above in a temp. range of the Ar1 point and below while carrying out overageing at 300-200 deg.C. CONSTITUTION:Steel contg., by wt., <0.04% C and <0.4% Mn and having Al/ N>1 is heated to <=1,100 deg.C, hot rolled, cold rolled, and annealed at the recrystallizing temp.- the Ac3 point. The annealed plate is then cooled at >=20 deg.C/sec cooling rate in a temp. range of the Ar1 point and below. At this time, at 300-200 deg.C the plate is held for >=10min to carry out overageing.