Double cold reduction strip for shadow mask and process for producing the same

Abstract

The present invention discloses a double cold reduction strip for shadow mask and a process for producing the same, comprising the following procedures: converter steelmaking.fwdarw.continuous billet casting.fwdarw.hot rolling.fwdarw.pickling and cold rolling.fwdarw.continuous annealing.fwdarw.double cold reduction.fwdarw.finishing and oiling. The weight percentages of essential elements of the shadow mask strip are: C: 0.001%, Mn: 0.100.40%, Al: 0.020.06%, Si: 0.025%, P: 0.015%, S: 0.01%, O: 0.004%, with remainders composed of Fe and inevitable impurities. Through the composition design for the elements in steel material according to the present invention, on the one hand, the weight percentage of carbon is controlled at a low level; on the other hand, the middle decarburization annealing process is omitted, the annealing temperature is declined, the production period is shortened and the production cost is reduced; through the optimization for rolling parameters and roller processing in the double cold reduction, procedures for degreasing and finishing are removed, and steels with excellent mechanical property and high surface quality are obtained.

Claims

1. A double cold rolled shadow mask strip steel, designed to consist of, in weight percentage, C: <0.001%, Mn: 0.10.40%, Al: 0.020.06%, Si: <0.025%, P: <0.015%, S: <0.01%, O: <0.004%, with remainders composed of Fe and inevitable impurities.

2. The double cold rolled shadow mask strip steel according to claim 1, characterized in that the weight percentage of Mn is 0.100.30%.

3. The double cold rolled shadow mask strip steel according to claim 1, characterized in that the average surface roughness R.sub.a thereof is 0.400.70 m, the maximum peak-to-valley distance R.sub.max is less than or equal to 6.0 m, the skewness R.sub.sk is more than or equal to 0, and the wave peak pitch S.sub.m is 50130 m.

4. A process for producing the double cold rolled shadow mask strip steel of claim 1, characterized in that, the process comprises following steps: 1) converter steelmaking, wherein ultralow-carbon-and-aluminum killed steel is adopted, the free oxygen F[O] in converter ladle is regulated to be 500700 ppm, the element S in molten iron is regulated to be less than or equal to 0.003% and the element P is regulated to be less than or equal to 0.035%, the converter ladle has a target temperature between 15401640 C., and the target free oxygen is 600 ppm, vacuum circulation degassing refine technology is utilized, and the decarburization time is 2025 min; 2) continuous billet casting; 3) hot rolling; 4) pickling and cold rolling; 5) continuous annealing; 6) double cold reduction; 7) finishing and oiling.

5. The process for producing the double cold rolled shadow mask strip steel according to claim 4, characterized in that, during the hot rolling, the temperature of heating furnace is set to be 11901250 C., the time that the billet is kept for therein is set to be 46 hours, the finish rolling temperature is set to be 900940 C. and the steel is coiled at a coiling temperature between 660700 C.

6. The process for producing the double cold rolled shadow mask strip steel according to claim 4, characterized in that, during the continuous billet casting, carbon-free stuffing sand is adopted in ladle, the process of complete argon blowing is utilized, and ultralow-carbon covering flux is adopted to prevent the increment of carbon in the middle ladle.

7. The process for producing the double cold rolled shadow mask strip steel according to claim 4, characterized in that, during the annealing, the target temperature in heating zone is set to be 580600 C., the target temperature in soaking zone is set to be 580600 C., and the target speed of continuous annealing unit is set to be 500650 m/min.

8. The process for producing the double cold rolled shadow mask strip steel according to claim 4, characterized in that, during the double cold reduction, a two-stand mill is adopted.

9. The process for producing the double cold rolled shadow mask strip steel according to claim 8, characterized in that, a rolling force of the first stand of the two-stand mill is set to be 4,0006,000 KN.

10. The process for producing the double cold rolled shadow mask strip steel according to claim 8, characterized in that, a rolling force of the second stand of the two-stand mill is set to be 2,0004,000 KN.

11. The process for producing the double cold rolled shadow mask strip steel according to claim 8, characterized in that, a tension force per unit at the entry of the two-stand mill is regulated to be 1316 kg/mm.sup.2, and a tension force per unit in the middle and at the exit thereof is regulated to be 1825 kg/mm.sup.2.

12. The process for producing the double cold rolled shadow mask strip steel according to claim 8, characterized in that a diameter of the work rollers of the two-stand mill is 410460 mm.

13. The process for producing the double cold rolled shadow mask strip steel according to claim 8, characterized in that a surface hardness of the work rollers of the two-stand mill is Hs 9397, and a surface hardness of the middle rollers is Hs 8185.

14. The process for producing the double cold rolled shadow mask strip steel according to claim 4, characterized in that, a deformation rate in double cold reduction is designed to be 3542%.

15. The process for producing the double cold rolled shadow mask strip steel according to claim 8, characterized in that, grinded work rollers are adopted as work rollers of the first stand of the two-stand mill, a surface roughness of which is 0.200.40 m.

16. The process for producing the double cold rolled shadow mask strip steel according to claim 8, characterized in that, electro-sparked work rollers are adopted as work rollers of the second stand of the two-stand mill, the surface roughness of which is 1.31.5 m, and the peak count per centimeter thereof is 130170.

17. The process for producing the double cold rolled shadow mask strip steel according to claim 4, characterized in that, a tension leveler is adopted for the finishing and oiling operation, and its elongation is set to be 0.401.0%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is the schematic diagram showing the surface roughness of electro-sparked work rollers of the second stand in double cold reduction.

(2) FIG. 2 is the schematic diagram showing the thickness accuracy of shadow mask strip produced according to Embodiment A of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(3) Depending on different process parameters in the present invention, 5 embodiments are shown to further describe the present invention and the related parameters to the process for producing the present invention.

(4) TABLE-US-00001 Embodiment A Composition C (%) Si (%) Mn (%) P (%) S (%) O (%) Al (%) Ti (%) Nb (%) Design (wt %) 0.0008 0.020 0.36 0.013 0.0076 0.003 0.042 / / Temperature Hot Rolling Parameters in Heating Furnace Temperature ( C.) Finish Rolling Temperature ( C.) Coiling Temperature ( C.) Hot Rolling 1198 915 683 Temperature Annealing in Cold Rolling Parameters in Target Temperature in Heating Zone Target Temperature in Soaking Rolling Speed Cold Rolling ( C.) Zone ( C.) (m/min) 596 582 610 Parameters for Diameter of Rolling Hardness Way of Roller Parameters for Double cold reduction Two Stand Mill Work Roller Force of Roller Processing Sets (mm) (KN) Surface (Hs) First 452 5274 95 Grinding Tension Force Deformation Stand per Unit (kg/mm.sup.3) Rate Entry Middle And Exit Second 436 3728 94 Electro-sparking 14 21 37 Stand Parameters for Surface Roughness of Work Rollers of Two Stand Mill in Double Cold Reduction Work Rollers The First Stand The Second Stand 0.32 1.33 Elongation of Elongation of Tension Leveler (%) Tension Leveler 0.65

(5) Finally, qualified products are obtained, with tensile strength of 510 MPa, yield strength of 464 MPa, elongation of 2.5%, surface roughness of 0.416 m, R.sub.max of 3.337 m, S.sub.m of 66.582 m, R.sub.sk of 0.201, HV of 160 and shape wave of less than 2 mm.

(6) The thickness accuracy of the shadow mask strip according to this embodiment is shown in FIG. 2.

(7) TABLE-US-00002 Embodiment B Composition C (%) Si (%) Mn (%) P (%) S (%) O (%) Al (%) Ti (%) Nb (%) Design (wt %) 0.0009 0.020 0.25 0.010 0.0082 0.002 0.051 / / Temperature Hot Rolling Parameters in Heating Furnace Temperature ( C.) Finish Rolling Temperature ( C.) Coiling Temperature ( C.) Hot Rolling 1221 924 679 Temperature Annealing in Cold Rolling Parameters in Target Temperature in Heating Zone Target Temperature in Soaking Rolling Speed Cold Rolling ( C.) Zone ( C.) (m/min) 592 588 594 Parameters for Diameter of Rolling Hardness Way of Roller Parameters for Double cold reduction Two Stand Mill Work Roller Force of Roller Processing Sets (mm) (KN) Surface (Hs) First 443 5683 94 Grinding Tension Force Deformation Stand per Unit (kg/mm.sup.3) Rate Entry Middle And (%) Exit Second 431 3842 95 Electro-sparking 14 20 38 Stand Parameters for Surface Roughness of Work Rollers of Two Stand Mill in Double Cold Reduction Work Rollers The First Stand The Second Stand 0.30 1.40 (PC 150) Elongation of Elongation of Tension Leveler (%) Tension Leveler 0.7

(8) Finally, qualified products are obtained, with tensile strength of 530 MPa, yield strength of 458 MPa, elongation of 2.2%, surface roughness of 0.404 m, R.sub.max of 3.432 m, S.sub.m of 61.392 m, R.sub.sk of 0.215, HV of 157 and shape wave of less than 2.5 mm.

(9) TABLE-US-00003 Embodiment C Composition C (%) Si (%) Mn (%) P (%) S (%) O (%) Al (%) Ti (%) Nb (%) Design (wt %) 0.0007 0.022 0.30 0.012 0.0092 0.001 0.048 / / Temperature Hot Rolling Parameters in Heating Furnace Temperature ( C.) Finish Rolling Temperature ( C.) Coiling Temperature ( C.) Hot Rolling 1235 937 682 Temperature Annealing in Cold Rolling Parameters in Target Temperature in Heating Zone Target Temperature in Soaking Rolling Speed Cold Rolling ( C.) Zone ( C.) (m/min) 592 588 594 Parameters for Diameter of Rolling Hardness Way of Roller Parameters for Double cold reduction Two Stand Mill Work Roller Force of Roller Processing Sets (mm) (KN) Surface (Hs) First 440 5543 94 Grinding Tension Force Deformation Stand per Unit (kg/mm.sup.3) Rate Entry Middle And (%) Exit Second 427 3759 95 Electro-sparking 14 20 38 Stand Parameters for Surface Roughness of Work Rollers of Two Stand Mill in Double Cold Reduction Work Rollers The First Stand The Second Stand 0.26 1.30 (PC 160) Elongation of Elongation of Tension Leveler (%) Tension Leveler 0.91

(10) Finally, qualified products are obtained, with tensile strength of 541 MPa, yield strength of 464 MPa, elongation of 2.6%, surface roughness of 0.442 m, R.sub.max of 3.425 m, S.sub.m of 61.279 m, R.sub.sk of 0.221, HV of 163 and shape wave of less than 2.6 mm.

(11) TABLE-US-00004 Embodiment D Composition C (%) Si (%) Mn (%) P (%) S (%) O (%) Al (%) Ti (%) Nb (%) Design (wt %) 0.0008 0.017 0.15 0.009 0.0085 0.002 0.034 / / Temperature Hot Rolling Parameters in Heating Furnace Temperature ( C.) Finish Rolling Temperature ( C.) Coiling Temperature ( C.) Hot Rolling 1241 925 671 Temperature Annealing in Cold Rolling Parameters in Target Temperature in Heating Zone Target Temperature in Soaking Rolling Speed Cold Rolling ( C.) Zone ( C.) (m/min) 596 591 565 Parameters for Diameter of Rolling Hardness Way of Roller Parameters for Double cold reduction Two Stand Mill Work Roller Force of Roller Processing Sets (mm) (KN) Surface (Hs) First 438 5831 95 Grinding Tension Force Deformation Stand per Unit (kg/mm.sup.3) Rate Entry Middle And (%) Exit Second 441 3952 96 Electro-sparking 15 22 38 Stand Parameters for Surface Roughness of Work Rollers of Two Stand Mill in Double Cold Reduction Work Rollers The First Stand The Second Stand 0.25 1.32 (PC 158) Elongation of Elongation of Tension Leveler (%) Tension Leveler 0.8

(12) Finally, qualified products are obtained, with tensile strength of 521 MPa, yield strength of 457 MPa, elongation of 2.5%, surface roughness of 0.439 m, R.sub.max of 4.276 m, S.sub.m of 71.374 m, R.sub.sk of 0.186, HV of 155 and shape wave of less than 1.6 mm.

(13) TABLE-US-00005 Embodiment E Composition C (%) Si (%) Mn (%) P (%) S (%) O (%) Al (%) Ti (%) Nb (%) Design (wt %) 0.0006 0.019 0.10 0.010 0.0081 0.003 0.025 / / Temperature Hot Rolling Parameters in Heating Furnace Temperature ( C.) Finish Rolling Temperature ( C.) Coiling Temperature ( C.) Hot Rolling 1221 918 688 Temperature Annealing in Cold Rolling Parameters in Target Temperature in Heating Zone Target Temperature in Soaking Rolling Speed Cold Rolling ( C.) Zone ( C.) (m/min) 589 583 580 Parameters for Diameter of Rolling Hardness Way of Roller Parameters for Double cold reduction Two Stand Mill Work Roller Force of Roller Processing Sets (mm) (KN) Surface (Hs) First 422 4843 94 Grinding Tension Force Deformation Stand per Unit (kg/mm.sup.3) Rate Entry Middle And (%) Exit Second 415 2716 96 Electro-sparking 14 21 34 Stand Parameters for Surface Roughness of Work Rollers of Two Stand Mill in Double Cold Reduction Work Rollers The First Stand The Second Stand 0.35 1.48 (PC 164) Elongation of Elongation of Tension Leveler (%) Tension Leveler 0.42

(14) Finally, qualified products are obtained, with tensile strength of 523 MPa, yield strength of 463 MPa, elongation of 2.5%, surface roughness of 0.446 m, R.sub.max of 4.193 m, S.sub.m of 73.193 m, R.sub.sk of 0.182, HV of 150 and shape wave of less than 1.6 mm.