KR20080038145A - Once-cold-rolled steel strip for shadow mask and its manufacture process - Google Patents

Abstract

Once-cold-rolled steel strip for shadow mask and its manufacture process. The process includes: smelting, casing, hot-rolling with a rolling finish temperature of 880~900, coiling at 510~610 ; pickling and cold-rolling; trimming to remove defects on edge such as cracks and burrs; continuous annealing, in which the steel temperature in heating stage and soaking stage is 675~695 and soaking time is 20~35s; dry-flattening using levelling machine with double frames and 6 rollers. The once-cold-rolled steel strip for shadow mask manufactured from the composition, process and process parameters of the present invention is excellent in properties, with significantly reduced or even disappearing longitudinal streaking on surface. The steel strip is good in shape, high in production efficiency, low in manufacture cost, and the quality of which could better meet the requirements of steel strip for shadow mask of CRT.

Description

Once-cold-rolled steel strip for shadow mask and its manufacture process}

The present invention relates to a shadow mask strip steel for use in color CRT and a manufacturing method, and more particularly, to the characteristics and quality control of a once cold rolled shadow mask strip steel, in particular the length on the surface according to the rolling direction Directional stripe and plate-shaped control technology.

Chinese patent ZL01113107.1 provides strip steel produced by a kind of one-step cold rolling continuous annealing method and overcomes the shortcomings of international patent (W096 / 13618).

From a chemical point of view, if the carbon content is too high, the performance of the final strip steel for shadow masks is relatively poor and the addition of a small amount of Nb may improve the anti-ageing resistance, but at the same time cannot fix all the carbon in the steel The magnetic property is reduced and the production cost increases.

In terms of the production process, simply added Nb steels are easily cracked in the playing slab during continuous casting and are very sensitive to hot rolling process parameters. In particular, in order to increase the recrystallization temperature of the final shadowmask screen finished product, the user must significantly increase the annealing temperature, thus increasing energy consumption. Also, due to the increased temperature, the shadow mask screen will be curled after annealing, the plate shape deteriorates, and the bonding defects will also increase according to the high temperature annealing.

The production process disclosed in Chinese patent ZL01113107.1 is simple and the production efficiency is significantly improved. The patent provides IF steel by adding a small amount of strong carbide forming elements Ti or Ti and Nb to ultra low carbon steel (pure steel) or ultra low carbon steel (ultra low-carbon steel). Therefore, the carbon in the steel is mainly in the form of carbides, and the content of solid carbon in the steel is drastically reduced to improve anti-aging and to secure drawing properties, in particular, molding uniformity. Reasonable design of chemicals and control and optimization of production process parameters ensure that the material and magnetic performance of shadowmask strip steel can meet the requirements of use.

Advantages of the shadow mask strip steel produced by the above invention are excellent material performance and post-processability, the production process is simple and the production cost is lower than the conventional two-stage cold rolled shadow mask strip steel, but there are obvious drawbacks to the invention. .

First of all, the chemical component range of the invention is not ideal. In practice, some elements, such as C, Mn, Ti, Al, and Nb, must be strictly limited. Otherwise, there will be significant fluctuations in both material and fairness, affecting your use. However, some elements, such as O and S, are too tightly limited and production costs will increase significantly. Next, in the production process of the invention, the limitation on the central process technology parameters of the shadow mask material performance, such as heating temperature, finish rolling temperature, continuous annealing temperature and time of the hot rolled slab, or winding temperature and temper rolling elongation (temper- Some process technical parameters, such as rolling elongation percentages, are unreasonable. Particularly in the process of temper rolling, which has a significant influence on the surface quality and plate shape, such as the crown of the temper-rolling, surface roughness, temper rolling tension, rolling force and bend rolling force. Did not optimize and strict limits. However, the shadow mask strip steel produced by the general temper rolling process variable is extremely easy to have longitudinal cracks on the surface and shows severe waves at the edges. They not only have a dramatic effect on the appearance, but also affect the normal use of the user.

The present invention aims to provide a one-time cold-rolled shadow mask strip steel and a method for manufacturing the same, and the surface appearance and performance of the produced shadow mask strip steel may satisfy the needs of users. Significantly improve the material performance and post-processability of the strip steel for one cold rolled shadow mask, improve production efficiency and operational stability of the continuous strip, reduce the production cost and at the same time to the surface of strip steel for one cold rolled shadow mask. It is intended to provide a control technique for the problem that longitudinal stripe and edge wave easily occur.

The present invention for achieving the above object uses the following technology. The compositional composition of the strip steel for one-step cold rolled shadow mask is in weight percent, C ≤ 0.002, preferably C ≤ 0.0017, Ti: 0.035-0.05, Mn: 0.10-0.25, preferably 0.15- 0.25, Al: 0.03-0.06, Cr: 0.002-0.03, Si ≦ 0.03; N? 0.003, P? 0.012, S? 0.01, O? 0.004, and impurities contained inevitably with the remaining Fe.

The method for producing a single process cold rolled strip steel for a shadow mask according to the present invention includes the following processes:

a. Smelting, casting, hot-rolling: the hot rolling finish temperature is 880-900 ° C., the coiling temperature is 510-610 ° C .;

b. Pickling and cold-rolling;

c. Cutting of edge defects such as cuts, cracks, burs, etc. as preparation lines;

d. Continuous annealing: the temperature for heating and soaking in the continuous annealing is limited to the range of 675 ~ 695 ° C., the soaking time is 20 ~ 35s;

e. crude rolling; Temper rolling is carried out with a double rolling mill having six working rolls. The roll diameter of the work roll is 410 ~ 460mm, the crown of the work roll is 0.12 ~ 0.24mm, the rolling force of the first compactor is 9,000 ~ 12,000KN and the second compactor rolling force is 6,000 ~ 8,000KN.

In addition, the surface hardness of the work roll is Hs 93 ~ 97 and the surface hardness of the intermediate roll is Hs 81 ~ 85.

The work roll surface is subjected to a frost treatment, such as an electrical spark discharge frost, and preferably further chromium plating.

The surface of the work roll was subjected to chrome plating after spark frosting, and the average surface roughness (Ra) range was 0.80 to 1.20 µm, and the number of peaks (pc) of unit length (cm) was 130 to 170.

The band rolling force of the double compactor is all 300 ~ 500KN.

The per unit tension at the inlet of the dual tempered rolling press is limited to 11 ~ 13kg / mm ² and the unit tension of the middle and the outlet is limited to 35 ~ 48kg / mm ² .

The temper rolling elongation is 1.3 ~ 2.0%.

The production process parameters of the production method is a hot rolling slab described in Chinese patent ZL01113107.1, the heating temperature is 1200-1250 ℃, the cold rolling deformation is 87-93%, and the optimization of other hot rolling process parameters Same as: hot rolling finish temperature is 880-900 ° C, hot rolling winding temperature is 510-610 ° C. In addition, trimming and cutting process of the preparation line is added before continuous annealing for the operational stability of the continuous strip. Subsequent continuous annealing and temper rolling process parameters are also strictly limited and the main process variables are as follows: Annealing temperature and time are 675-695 ° C. and 20-35 s, respectively, and the crown and roll diameter of the temper rolling work roll are 0.12-, respectively. 0.24mm and 410-460mm. The values of surface roughness Ra and PC of the temper rolls are 0.80-1.20 μm and 130-170 pieces / cm, respectively.

The present invention has the following changes in comparison with Chinese patent ZL01113107.1 in terms of chemical composition. The first narrowed the range of C, Ti, Mn and Al to strictly limit the major elements and make the strip steel performance for shadow masks more stable. Secondly, the cost of production was drastically reduced by not adding expensive Nb elements. Thirdly, the scope of O and S has been extended to reduce the cost of the smelting process.

The present invention has the following changes compared to the control Chinese patent ZL01113107.1 at the process angle. First, the hot rolling finish temperature and the winding temperature are low, and the range is reduced, which is advantageous for the quality control of the hot rolled slab, which improves the pickling speed, the surface quality of the finished product, and greatly reduces the production cost. Secondly, the continuous annealing temperature was constantly lowered, the temperature range was reduced, and the cracking time was shortened to increase production speed. Therefore, continuous annealing temperature and cracking time are reduced, which not only reduces the production cost but also improves production efficiency and product quality. Thirdly, the trimming process of the preparation line is added to effectively eliminate the edge defects (e.g., ice patterns, protrusions, etc.) of the strip steel, thereby improving the safety of the continuous strip and the operating efficiency of the continuous strip. Improved safety of continuous strips of thin materials. Fourth is the most important, and the present invention provides process parameters for a series of temper rolling processes. It provides detailed variables such as temper rolling method, temper rolling work roll roll diameter, work roll crown, temper roll roll surface frost and post treatment method and surface hardness, surface roughness, temper rolling elongation, rolling force, tension and band rolling force. The quality of the strip steel surface and the quality of the plate shape were significantly improved.

Strip mask strip steel produced by the chemical composition and production process parameters provided by the present invention has good material performance and surface quality, the longitudinal cracking of the surface is significantly reduced or eliminated and the plate shape is excellent. Using the chemical composition and production process parameters of the present invention, a double size band shadow mask, which is a strip steel for a shadow mask having a width of 490 mm, can also be produced. The production process according to the Chinese patent ZL01113107.1 is comparable to produce single-band, low production efficiency and relatively low yield of finished products. By the process of this patent, it is possible to produce a double size band (ie 490mm × 2), the production efficiency is twice that of the original, and the finished product yield is improved from about 70% to 90% or more.

The control and principle of the present invention are as follows.

Relatively low hot-roll finishing temperatures and winding temperatures reduce the scale layer of the strip steel surface. This strictly limits the surface quality from the upstream process, thus reducing the defects that can occur during the hot rolling stage and also more precisely reducing the temperature range, which is advantageous for stable control of strip steel quality.

The present invention added the cutting and cutting process of the preparation line. In the case of the shadow mask strip steel in the rough rolling production process, edge defects (for example, protrusions and small cracks) of the strip steel are easily rolled into the rough rolled strip steel under conditions of high tension. According to the present invention, the semi-finished products of the strip steel for shadow masks are cut and cut first with CPL (coil preparation line) before CAPL (continuous annealing line) and temper rolling to completely remove cracks and protrusions generated in the whole process, In rolling, it is possible to prevent the breakage of the strip that occurs under conditions of high tension, so that the shadow mask strip steel more effectively improves the quality of the strip steel surface under the conditions of relatively high tension and rolling force and eliminates longitudinal cracking.

After trimming and cutting the shadow mast strip steel into the preparation line, the shadow mask strip steel is subjected to continuous annealing. The material is subjected to annealing and restoring the hardened strip steel after cold rolling. Thereby improving the plate-like and tissue structure of the strip steel and partially removing work hardening. Since the strip steel material performance is very sensitive to the annealing temperature because the high temperature restoration annealing is performed at a temperature close to the recrystallization temperature of the material, the temperature and the immersion time of the heating and dipping step are important variables in the continuous annealing process. As is actually demonstrated, the higher the two temperatures are advantageous for the control of longitudinal cracking, but too high a temperature may cause recrystallization nuclei to form locally in the strip steel, causing local recrystallization or even grain growth to etch and additionally. It is disadvantageous to control the microstructure of the strip steel for shadow mask after the second annealing and to control the quality and properties of the products of the strip steel. Through experiments, the inventors of the present invention suggest that the strip steel for shadow mask according to the invention limits the plate (strip) temperature during heating and dipping to 675-695 ° C. and the dipping time to 20-35 s during continuous annealing. I found it necessary. The annealing temperature and time should be suitable for each other, and the lower the annealing temperature and the shorter the time, the less material will serve the purpose of improving the strip shape and the material by high temperature recovery. On the contrary, the higher the annealing temperature and the longer the plate, the better the plate shape. However, local recrystallization of the strip steel easily occurs, worsening the material imbalance and etching property of the shadow mask strip steel.

After the continuous annealing treatment, the strip steel for the shadow mask undergoes a very major temper rolling process and the main action of the temper rolling is as follows:

1. After high temperature restoring and annealing, increase the strength and hardness of the strip steel for shadow mask.

2.Improve strip shape and get good strip steel flatness

3. Make suitable surface morphology including Ra, Rmax, Sm and Rsk on the surface of strip steel.

4. Remove various surface defects of shadow mask strip steel.

Based on the above action of the temper rolling equipment, the correlation variables of the temper rolling equipment must be strictly limited. Temper Rolling Mode, Temper Rolling Elongation, Crown of Temper Rolling Roll, Roll Diameter of Surface Roll, Surface Roughness, Surface Treatment Condition, Surface Hardness and Temper Rolling Force of Temper Rolling Roll, Tension of Each Stage, Double Temper Including the band rolling forces of two temper rolling mills, in particular the intercongruence of the latter three technical parameters determines the situation of the shadow, strip morphology, material performance and surface defect removal of shadowmask strip steel products. . After several industrial tests, the following process rolling parameters were obtained.

Strip steel can produce various surface defects, especially roll marks, rolling traces, scratches, etc., in each step before temper rolling. However, it is possible to eliminate or reduce the defects on the surface of the strip steel after constant compression deformation in the dual tempered rolling press, and limit the elongation to the range of 1.3 ~ 20.% to improve the quality of the strip steel surface and to control the surface shape. . In general, the hard rolling elongation of hard materials is much lower than 1.3%. According to the experiment, to improve the tempered rolling elongation, rolling force, unit tension and band rolling force must be greatly increased, but excessive tempered rolling elongation easily causes production instability, strip steel plate becomes poor and use of tempered rolling roll Life is also shortened. On the other hand, if the elongation is too small, the surface roughness of the work roll is difficult to replicate on the surface of the strip steel, making it difficult to reach the surface roughness of the strip steel, and it is difficult to reduce and eliminate surface defects generated in the previous process.

The crown of the work roll of the dual temper rolled compactor of strip steel for shadow mask is 0.12-0.24 mm. The crown is generally larger than the crown of a rough rolling work roll that presses ordinary steel. According to the experiment, when the crown of the shadow mask strip steel of the present invention is too large and exceeds 0.24 mm, an intermediate wave is easily generated. If the crown is too low and less than 0.12 mm, a wave is easily generated at the edge and the plate-shaped control is disadvantageous. .

The roll diameter of the work roll of the double rolled compactor is 410-460 mm. If the roll diameter is too large, the actual rolling force will increase, and the driving motor output of the tempered rolling equipment should also be increased, otherwise the elongation will not reach 1.3%. If the roll diameter is too small, the actual rolling force is so small that it is difficult to control the shape and surface quality of the strip steel surface, and it is difficult to duplicate the surface of the strip steel according to the demand of roughness of the work roll, and at the same time, it is difficult to remove the surface defects.

Through repeated experiments and user verification, the average surface roughness (Ra) of the double rolled compactor press roll is 0.80-1.20μm, and the number of peaks (cm) per unit length (cm) is 130-170. The roll Ra and PC values directly affect the Ra, Rmax, Rsk and Sm values of the strip steel products for shadow masks, therefore the work roll Ra and PC values should be adequate and if the surface roughness is too large the etching of the shadow mask screen plate It affects the periphery of the hole, and if too small, the strip steel for the shadow mask affects the vacuum degree when forming the vacuum state before exposure.

It is preferable that the surface of the work roll of the dual temper rolling press machine is subjected to the chrome plating treatment after the electric discharge spark frost treatment. After chrome plating, the working rolls have a significantly longer service life and are advantageous for improving and stabilizing the surface roughness and the indicators of each section.

The surface hardness of the work roll of the dual rough rolling press is Hs 93-97, and the middle roll surface hardness is Hs 81-85. If the hardness of the roll surface is too high or the surface hardness range is small, eg work rolls Hs 95-97, the service life of the roll is reduced and requires an increase in the amount of plated chromium, leading to an increase in production costs. If the hardness of the roll surface is too low, roll marks are easily formed on the surface of the strip steel.

Tensile force per unit at the inlet of the dual tempered rolling press is limited to 11-13 kg / mm ² and the unit tension at the middle and outlet is 35-48 kg / mm ² . Too large a tension causes breakage of the strip easily, unstable production and too little tension lead to poor strip steel plate and surface quality.

The rolling force of the first press is 9,000-12,000KN and the rolling force of the second press is 6,000-8,000KN. If the rolling force is too large, an edge wave is easily generated in the strip steel and the mechanical energy consumption is increased. If the rolling force is too small, the roughness of the roll surface is difficult to replicate to the strip steel surface, so that the tension is not increased to reach the required temper elongation. This must increase the risk of strip breaking.

The band rolling force is 300-500KN in the dual tempered rolling press. If the band rolling force is too small, the edge wave is easily generated, especially when the wide strip steel presses for shadow masks are produced more easily, so the band rolling force of the first press and the second press is 300-500KN. Should be limited to If the band rolling force is too large, the facility's capacity will not be able to follow.

The shadow steel strip steel obtained through the above limitations on the related process variables of the temper rolling has not only all the advantages of the Chinese patent ZL01113107.1, but also the production efficiency is improved and the production cost is lowered. At the same time, surface defects were effectively removed and the plate shape was good, especially surface longitudinal cracking was almost eliminated.

Hereinafter, the content of the present invention will be described in more detail with reference to examples according to different process variables of the present invention.

The process procedure of each example was: The playing slab was wound up after hot rolling, finishing rolling and laminar flow cooling with heating to hot rolling cogging temperature before hot rolling. After cooling at room temperature for 2-3 days, it passes through CDCM facility line (pickling and cold continuous rolling), additionally through cutting and cutting process through preparation line, and then through CAPL facility line (continuous annealing and temper rolling). Finally, internal defects and surface quality inspections were carried out to produce strip steel products for shadow masks through cutting, cutting, coiling and finishing.

Refer to Table 1 for chemical composition, refer to Table 2 for major process technology variables, and Table 3 for quality performance.

Chemical Composition (wt%) of Examples and Controls Example Number C Ti Mn Al Cr Si N P S O (%) Remainder One 0.0008 0.035 0.22 0.030 0.011 0.012 0.002 0.008 0.008 0.0038 Fe 2 0.001 0.042 0.25 0.039 0.015 0.014 0.003 0.006 0.006 0.0028 Fe 3 0.0013 0.050 0.24 0.042 0.014 0.014 0.003 0.006 0.006 0.0028 Fe 4 0.0015 0.037 0.20 0.041 0.015 0.017 0.0012 0.006 0.007 0.0025 Fe 5 0.0014 0.040 0.10 0.060 0.021 0.019 0.0021 0.005 0.007 0.0040 Fe 6 0.0017 0.036 0.24 0.045 0.015 0.023 0.002 0.009 0.009 0.0038 Fe 7 0.002 0.039 0.15 0.051 0.030 0.010 0.0011 0.001 0.010 0.0027 Fe 8 0.0019 0.048 0.25 0.036 0.002 0.030 0.0021 0.012 0.005 0.0015 Fe Comparative Example 1 0.0013 0.039 0.15 0.039 0.018 0.014 0.0025 0.007 0.0076 0.0014 Fe Comparative Example 2 0.0012 0.023 0.16 0.033 0.018 0.013 0.0019 0.007 0.004 0.0013 Fe Comparative Example 3 0.0005 0.007 0.20 0.031 0.010 0.013 0.0018 0.008 0.008 0.0013 Fe

Main Process Technology Variables of Examples and Controls (1)

Main Process Technology Variables of Examples and Controls (2)

 Quality results of Examples and Controls Indicators Finished product material performance Surface longitudinal crack Plate Wave Height (mm) Surface Roughness Ra （μm） Crackle demand Satisfaction of use requirements Surface longitudinal cracks are not clear Wave height 0.40-0.70 none Example 1 Great Basic phase removal Edge Wave 1.3 0.43 none 2 Great Complete removal Edge Wave 1.0 0.50 none 3 Great Complete removal Medium Wave 1.0 0.58 none 4 Great Basic phase removal Edge Wave 1.0 0.42 none 5 Great Complete removal Edge Wave 1.0 0.45 none 6 Great Complete removal Edge Wave 1.5 0.55 none 7 Good Basic phase removal Edge Wave 2.0 0.47 none 8 Good Complete removal Medium Wave 2.0 0.60 none Comparative Example 1 Great * Sharp surface longitudinal cracks 2.5 0.50 *has exist 2 Great * Sharp surface longitudinal cracks 3.0 0.40 *has exist 3 Great * Sharp surface longitudinal cracks 3.0 0.59 *has exist

Note: * is a fail term.

Strip steel for shadow mask obtained by using the production process and the parameters of the present invention is that the longitudinal cracking of the surface is significantly reduced or eliminated and can meet the requirements of surface roughness, the quality is very stable and the production efficiency is significantly improved. According to the contrasting production process of Chinese patent ZL01113107.1, some of the process variables are not strictly limited, so the plate shape of the strip mask strip steel produced is not good, and there are defects such as longitudinal cracks and cracks on the surface, and the surface roughness value is also unstable. Do.

Claims (10)

In weight percent, C≤0.002%, Ti: 0.035-0.05%, Mn: 0.10-0.25%, Al: 0.03-0.06%, Cr: 0.002-0.03%, Si≤0.03%, N≤0.003%, P≤ 0.012%, S≤0.01%, O≤0.004%, and strip steel for a one-time cold rolled shadow mask, comprising Fe and inevitable impurities as residual components. The method of claim 1, The content of C is ≤0.0017%, the content of Mn is strip steel for one cold rolled shadow mask, characterized in that 0.15 ~ 0.25%. (a) smelting, casting, hot rolling; Wherein the hot rolling finish temperature is 880 ~ 900 ℃, winding temperature is 510 ~ 610 ℃, (b) pickling and cold rolling; (c) cutting and cutting using the preparation line; Eliminates edge defects such as frings and bumps; (d) continuous annealing; The temperature of the strip of heating and dipping in the continuous annealing is limited to the range of 675 ~ 695 ℃ and the dipping time is 20 ~ 35s, and (e) crude rolling; The temper rolling uses a dual tempered rolling press having six work rolls, the roll diameter of the work roll is 410 ~ 460mm, the crown of the work roll is 0.12 ~ 0.24mm, the rolling force of the first press is 9,000 ~ 12,000 KN and the rolling force of the second compactor is 6,000 ~ 8,000 KN, characterized in that the process for producing a strip steel for cold rolled shadow mask, characterized in that it comprises a process. The method of claim 3, The surface hardness of the work roll is Hs 93 ~ 97 and the surface hardness of the intermediate roll Hs 81 ~ 85, characterized in that the manufacturing method of strip steel for cold rolled shadow masks. The method of claim 3, Frosting the surface of the work roll, optionally further chromium plating process characterized in that the method for producing a strip steel for cold rolled shadow mask. The method according to claim 3 or 5, After the frosting of the surface of the work roll, and optionally additional chromium plating treatment, the average surface roughness range of the work roll is 0.80 to 1.20 μm and the number of peaks of unit length (cm) is 130 to 170. Method for manufacturing a strip steel for one time cold rolling shadow mask. The method of claim 3, The band rolling force of the dual temper rolled pressing machine are all 300 ~ 500 KN, characterized in that the manufacturing method of strip steel for cold rolled shadow mask once. The method of claim 3, The unit tension at the inlet of the dual temper rolled compactor is 11 ~ 13kg / mm ² and the unit tension of the middle and the outlet is 35 ~ 48kg / mm ^{2 The} method of manufacturing a strip steel for cold rolled shadow mask for one time. The method of claim 3, The tempered rolling elongation is a method of manufacturing a strip steel for cold rolled shadow mask, characterized in that 1.3 to 2.0%. 7. The method for manufacturing a strip steel for cold rolled shadow mask according to claim 5 or 6, wherein the frost treatment is an electric spark discharge frost treatment.