In order to ensure good low-temperature impact toughness of LR AH32 Marine steel plate, strict II controlled rolling process is adopted for 355MPa class ship plate rolling.
The heating temperature of the billet is about 1140~1170℃, and the heating time is about 3.0~3.5h, so as to ensure the starting temperature of the rough rolling stage is about 1150℃. The amount of deformation completed in the recrystallization zone should make the thickness of the intermediate billet more than 5 times that of the finished LR AH32 Marine steel plate. The pass reduction is 15%~22%, and the rolling temperature in the recrystallization zone is above 960℃.
The intermediate billet shall be cooled by air or water. The rolling temperature in the non-recrystallized zone is below 900℃ and the deformation is above 60%. A total of 6 passes are rolled. After rolling 3 passes, the temperature is below 870℃, and then the last 3 passes are completed. The final rolling temperature is 840℃, and the actual temperature is 795~837℃. Air cooling is used after rolling.
