High-silicon steel sheet and cryogenic pack rolling technology for preparing same

[0028] Example 1

[0029] A vacuum induction furnace is used to cast high silicon steel ingots. The chemical composition of the ingot is as follows: Si 6.91%, Al 0.4%, Y 0.008%, Zr 0.05%, C 0.007%, Mn 0.008%, P 0.005%, S 0.004% , N0.002%, O 0.002%, the balance Fe.

[0030] At a temperature of 1200°C, the temperature is kept for 140 minutes and then free-forged with air to form a 40mm thick square billet. The heating temperature during the hot rolling of the cast slab is 1150℃, and the holding time is 100min. After the holding time, the non-lubricated hot rolling is carried out on a two-roll reversible experimental hot rolling mill and hot-rolled to 3.5mm through 12 passes. The opening temperature is 1150℃, and the final rolling The temperature is 900°C, then air-cooled to room temperature. The hot-rolled sheet was pickled with a 5% concentration hydrochloric acid solution, the pickling temperature was 50℃, and the pickling time was 10 min to remove the surface oxide scale.

[0031] The pickled plate was heated to 550°C in a heating furnace, and after holding for 10 minutes, it was quickly taken out on an asynchronous rolling mill for constant-temperature warm rolling at a temperature of 550°C and warm rolled to 0.7 mm through 18 passes. The upper and lower surfaces of the warm-rolled plate are turned over every two passes. After each pass, the rolled piece is quickly returned to the heating furnace, and the temperature of the rolled piece is kept at 550°C for 1 to 3 minutes. The whole warm rolling process adopts asynchronous warm rolling, the different speed ratio is 1.15, the work roll diameter is the same, the lower roll is a slow roll, the roll speed is always kept constant, the upper roll is a fast roll, and the upper roll speed is adjusted according to the different speed ratio. The reduction ratio of the first and last two passes is 4%, the different speed ratio is 1.15, the lower roll speed is 0.2m/s, the upper roll speed is 0.23m/s, and the rolling force is 100kN. The pass reduction rate of the remaining intermediate passes is 10%, the different speed ratio is 1.25, the lower roll speed is 0.4 m/s, the upper roll speed is 0.5 m/s, and the rolling force is 150 kN. The intermediate annealing temperature is 980°C, and after holding for 30 minutes, it is water cooled to room temperature. Use 5% hydrochloric acid solution to pickle the intermediate annealing board, pickling temperature is 50℃, pickling time is 5min, to remove the surface oxide scale.

[0032] A four-roll cold rolling mill is used for deep cold stack rolling. First, five annealed sheets of the same thickness are stacked together to form a multi-layer slab with a thickness of 3.5mm. Before the sheets are stacked, the anti-sticking lubricant nozzle is used to spray the anti-sticking lubricant on the upper and lower surfaces of the thin plates to facilitate the separation of adjacent thin plates after the rolling. Before cryogenic rolling, the rolls were turned on and rotated with zero load, and the upper and lower work rolls of the rolling mill were cooled by the nitrogen cooling spray gun of the rolling mill. The surface temperature of the rolls was -120℃. Before each pass of rolling, the rolled plate needs to be cooled in a cryogenic box filled with liquid nitrogen for 3 to 5 minutes to achieve a multi-layer slab temperature of -120℃. After the rolled plate is cooled in liquid nitrogen, it is quickly taken out Perform cryogenic rolling. In the first two passes, the multi-layer slab is fed into the cold rolling mill along its length for deep cold rolling, and then the multi-layer slab is rotated by 90° every two passes for cross rolling. The reduction rate of the first and last passes is 3%, the rolling mill roll speed is 0.04m/s, the rolling force is 80kN, the other intermediate passes have a reduction rate of 5%, and the rolling mill roll speed is 0.08m/s. The force is 120kN. After each pass of rolling, the rolled piece is put back into the liquid nitrogen tank for heat preservation, and the above operations are repeated until each sheet reaches 0.15 mm.

[0033] A three-stage heating and continuous annealing process is adopted, first heating to 500℃ at a rate of 3℃/s, holding for 3min, then heating at a rate of 4℃/s to 800℃, holding for 3min, and finally at 5℃/s The rate is heated to 1050°C, the temperature is kept for 5 minutes, nitrogen is introduced to prevent oxidation, and then air-cooled to room temperature.

[0034] Example 2

[0035] A vacuum induction furnace is used to cast high silicon steel ingots. The chemical composition of the ingot is as follows: Si 6.95%, Al 0.55%, Y 0.015%, Zr 0.065%, C 0.007%, Mn 0.008%, P 0.005%, S 0.004% , N0.002%, O 0.002%, the balance Fe. At a temperature of 1230°C, hold for 90 minutes and then use air to free forge into a 35mm thick square billet. The heating temperature during the hot rolling of the cast slab is 1180℃, the holding time is 90min, and then the non-lubricated hot rolling is carried out on the two-high reversible experimental hot rolling mill and 11 passes are hot rolled to 3.0mm, the opening temperature is 1130℃, and the final rolling temperature At 880°C, then air-cooled to room temperature. The hot-rolled sheet was pickled with a 6% hydrochloric acid solution, the pickling temperature was 60°C, and the pickling time was 15 minutes to remove the surface oxide scale.

[0036] The pickled plate was heated to 580°C in a heating furnace, and after holding for 7 minutes, it was quickly taken out on an asynchronous rolling mill for constant-temperature warm rolling at a temperature of 580°C, followed by 16 passes of warm rolling to 0.6mm. The upper and lower surfaces of the warm-rolled plate are turned over every two passes. After each pass, the rolled piece is quickly returned to the heating furnace, and the temperature of the rolled piece is kept at 570°C for 1 to 3 minutes. The whole warm rolling process adopts asynchronous warm rolling, the work rolls have the same diameter, the lower roll is a slow roll, and the roll speed is always constant, and the upper roll is a fast roll. The upper roll speed is adjusted according to the different speed ratio. The reduction ratio of the first and last two passes is 5%, the different speed ratio is 1.2, the lower roll speed is 0.15m/s, the upper roll speed is 0.18m/s, and the rolling force is 120 kN. The pass reduction ratio of the remaining intermediate passes is 11%, the different speed ratio is 1.3, the lower roll speed is 0.35m/s, the upper roll speed is 0.455m/s, and the rolling force is 170kN. The intermediate annealing temperature is 1020°C, and after holding for 25 minutes, it is water cooled to room temperature. The intermediate annealing board was pickled with a 7% concentration of hydrochloric acid solution, the pickling temperature was 60°C, and the pickling time was 8 minutes to remove the surface oxide scale.

[0037] A four-roll cold rolling mill is used for deep cold stack rolling. First, 5 annealed sheets of the same thickness are stacked together to form a multilayer slab with a thickness of 3mm. Before the sheets are stacked, the anti-sticking lubricant nozzle is used to spray the anti-sticking lubricant on the upper and lower surfaces of the thin plates to facilitate the separation of adjacent thin plates after the rolling. Before cryogenic rolling, the rolls are turned on and rotated with zero load, and the upper and lower work rolls of the rolling mill are cooled by the nitrogen cooling spray gun of the rolling mill to achieve a roll surface temperature of -160°C. Before each pass of rolling, the rolled plate needs to be cooled in a cryogenic box filled with liquid nitrogen for 3 to 5 minutes to achieve a multi-layer slab temperature of -160℃. After the rolled plate is cooled in liquid nitrogen, it is quickly taken out Perform cryogenic rolling. In the first two passes, the multi-layer slab is fed into the cold rolling mill along the length for deep cold rolling, and then the multi-layer slab is rotated by 90° every two passes for cross rolling. The reduction rate of the first and last passes is 4%, the rolling mill roll speed is 0.05m/s, the rolling force is 90kN, the other intermediate passes have a reduction rate of 7%, and the rolling mill roll speed is 0.09m/s. The force is 140kN. After each pass of rolling, the rolled piece is put back into the liquid nitrogen tank for heat preservation, and the above operations are repeated until each sheet reaches 0.12 mm.

[0038] A three-stage heating and continuous annealing process is adopted. Firstly, it is heated to 550°C at a rate of 3°C/s and the holding time is 2.5min, and then heated to 850°C at a rate of 4°C/s, and the holding time is 2.5min. Heat to 1100°C at a rate of 5°C/s, heat the sheet for 4 minutes, pour in nitrogen to prevent oxidation, and then air-cool to room temperature.

[0039] Example 3

[0040] A vacuum induction furnace is used to cast high silicon steel ingots. The chemical composition of the ingot is as follows: Si 6.98%, Al 0.7%, Y 0.02%, Zr 0.08%, C 0.008%, Mn 0.007%, P 0.005%, S 0.004% , N0.002%, O 0.002%, the balance Fe. At a temperature of 1250°C, hold for 80 minutes and then use air to free forge into a 30mm thick square billet. The heating temperature during the hot rolling of the cast slab is 1200℃, the holding time is 80min, and then the non-lubricated hot rolling is carried out on the two-high reversible experimental hot rolling mill and hot rolled to 2.5mm through 12 passes. The opening temperature is 1100℃ and the final rolling temperature At 870°C, then air-cooled to room temperature. The hot-rolled sheet was pickled with 8% hydrochloric acid solution, the pickling temperature was 70°C, and the pickling time was 20 minutes to remove the surface oxide scale.

[0041] The pickled plate was heated to 620°C in a heating furnace, and after holding for 5 minutes, it was quickly taken out on an asynchronous rolling mill for constant temperature rolling at a temperature of 620°C, and it was warm rolled to 0.5mm through 15 passes. The upper and lower surfaces of the warm-rolled plate are turned over every two passes. After each pass, the rolled piece is quickly returned to the heating furnace, and the temperature of the rolled piece is kept at 620°C for 1 to 3 minutes. The whole warm rolling process adopts asynchronous warm rolling, the work rolls have the same diameter, the lower roll is a slow roll, and the roll speed is always constant, and the upper roll is a fast roll. The upper roll speed is adjusted according to the different speed ratio. The reduction rate of the first and last two passes is 6%, the different speed ratio is 1.2, the lower roll speed is 0.1m/s, the upper roll speed is 0.12m/s, and the rolling force is 130kN. The pass reduction rate of the remaining intermediate passes is 12%, the different speed ratio is 1.3, the lower roll speed is 0.3m/s, the upper roll speed is 0.39m/s, and the rolling force is 180kN. The intermediate annealing temperature is 1050°C, and the temperature is kept for 20 minutes and then water cooled to room temperature. The intermediate annealing board was pickled with 8% hydrochloric acid solution, the pickling temperature was 70°C, and the pickling time was 10 minutes to remove the surface oxide scale.

[0042] A four-roll cold rolling mill is used for deep cold stack rolling. First, six annealed sheets of the same thickness are stacked together to form a multilayer slab with a thickness of 3mm. Before the thin plates are stacked, the anti-adhesive lubricant nozzle is used to spray the anti-adhesive lubricant on the upper and lower surfaces of the thin plates to facilitate the separation of adjacent thin plates after the rolling. Before cryogenic rolling, the rolls are turned on and rotated with zero load, and the upper and lower work rolls of the rolling mill are cooled by the nitrogen cooling spray gun of the rolling mill to achieve a surface temperature of -180°C. Before each pass of rolling, the rolled plate needs to be cooled in a cryogenic box filled with liquid nitrogen for 3 to 5 minutes to achieve a multi-layer slab temperature of -180℃. After the rolled plate is cooled in liquid nitrogen, it is quickly taken out Perform cryogenic rolling. In the first two passes, the multi-layer slab is fed into the cold rolling mill along the length for deep cold rolling, and then the multi-layer slab is rotated by 90° every two passes for cross rolling. The reduction rate of the first and last passes is 4%, the rolling mill roll speed is 0.06m/s, the rolling force is 100kN, the reduction rate of the remaining intermediate passes is 8%, the rolling mill roll speed is 0.1m/s, and the rolling The force is 150kN. After each pass of rolling, the rolled piece is put back into the liquid nitrogen tank for heat preservation, and the above operations are repeated until each sheet reaches 0.1mm.

[0043] A three-stage step-by-step heating and continuous annealing process is adopted, first heating to 600°C at a rate of 3°C/s, holding time for 2min, then heating at a rate of 4°C/s to 900°C, holding time for 2min, and finally at 5°C It is heated to 1150°C at a rate of 1/s, the holding time of the thin plate is 3 minutes, nitrogen is introduced to prevent oxidation, and then air-cooled to room temperature.

[0044] Comparative Example 3 Conventional cold rolled sheet

[0045] A vacuum induction furnace is used to cast high silicon steel ingots. The chemical composition of the ingot is as follows: Si 6.98%, Al 0.7%, Y 0.02%, Zr 0.08%, C 0.008%, Mn 0.007%, P 0.005%, S 0.004% , N0.002%, O 0.002%, the balance Fe. At a temperature of 1250°C, hold for 80 minutes and then use air to free forge into a 30mm thick square billet. The heating temperature during the hot rolling of the cast slab is 1200℃, the holding time is 80min, and then the non-lubricated hot rolling is carried out on the two-high reversible experimental hot rolling mill and hot rolled to 2.5mm through 12 passes. The opening temperature is 1100℃ and the final rolling temperature At 870°C, then air-cooled to room temperature. The hot-rolled sheet was pickled with 8% hydrochloric acid solution, the pickling temperature was 70°C, and the pickling time was 20 minutes to remove the surface oxide scale.

[0046] The pickled plate was heated to 620°C in a heating furnace, and after holding for 5 minutes, it was quickly taken out on an asynchronous rolling mill for constant temperature rolling at a temperature of 620°C, and it was warm rolled to 0.5mm through 15 passes. The upper and lower surfaces of the warm-rolled plate are turned over every two passes. After each pass, the rolled piece is quickly returned to the heating furnace and kept for 1 to 3 minutes. The whole warm rolling process adopts asynchronous warm rolling, the work rolls have the same diameter, the lower roll is a slow roll, and the roll speed is always kept constant, and the upper roll is a fast roll. The upper roll speed is adjusted according to the different speed ratio. The reduction ratio of the first and last two passes is 6%, the different speed ratio is 1.2, the lower roll speed is 0.1m/s, the upper roll speed is 0.12m/s, and the rolling force is 130kN. The pass reduction ratio of the remaining intermediate passes is 12%, the different speed ratio is 1.3, the lower roll speed is 0.3m/s, the upper roll speed is 0.39m/s, and the rolling force is 180kN. The intermediate annealing temperature is 1050°C, and the temperature is kept for 20 minutes and then water cooled to room temperature. The intermediate annealing board was pickled with 8% hydrochloric acid solution, the pickling temperature was 70°C, and the pickling time was 10 minutes to remove the surface oxide scale.

[0047] A four-high cold rolling mill is used for cold rolling. The reduction rate of the first and last passes is 4%, the rolling speed of the rolling mill is 0.06m/s, the rolling force is 100kN, and the reduction rate of the remaining intermediate passes is 8%. The roll speed is 0.1m/s, the rolling force is 150kN, and the cold rolled sheet is 0.1mm. A three-stage step-by-step heating and continuous annealing process is adopted, first heating to 600°C at a rate of 3°C/s, holding time for 2min, then heating at a rate of 4°C/s to 900°C, holding time for 2min, and finally at 5°C It is heated to 1150°C at a rate of 1/s, the holding time of the thin plate is 3min, nitrogen is introduced to prevent oxidation, and then air-cooled to room temperature.