JP3623620B2 - Etching property evaluation method for shadow mask material and shadow mask material that does not cause streak unevenness after etching - Google Patents

Description

【００１８】
各鋳塊を表２に示す製造条件下で分塊，ソーキングした。
ＩＭ材では、分塊圧延、或いは更にソーキングを施した。ＣＣ材では、そのままソーキングを施した。次いで、各スラブの表面を手入れし、熱間圧延により板厚６ｍｍの熱延鋼帯を製造した。更に、１０００℃の焼鈍及び冷間圧延を数回繰り返し、最終的に板厚０．１２ｍｍの冷延鋼帯を得た。
比重１．４５，温度６０℃の塩化第二鉄溶液を用い、各冷延鋼帯から切り出された試験片を板厚の５０％までハーフエッチングし、ハーフエッチング面におけるスジむらの発生状況を観察した。スジむらが全く観察されなかったものを最高レベルＡ，スジむらがほとんど観察されず、これ以上であれば高品位シャドウマスク用素材として使用可能なものをレベルＢ，比較的多数のスジむらが観察されたものをレベルＣ，明瞭なスジむらが多数現出したものを最低レベルＤとする４段階でスジむら発生状況を評価した。また、試験片の任意の箇所でハーフエッチングした面を触針式の表面粗さ計で測定し、算術平均粗さＲ_aを求めた。
各試験片について、算術平均粗さＲ_a （単位μｍ）及びスジむらレベルを表２に併せ示す。また、算術平均粗さＲ_aとスジむらレベルとの関係を図２に示す。
【００１９】

【００２０】
図２から、算術平均粗さＲ_aとスジむらレベルとの間に、強い相関関係があることが判る。すなわち、ハーフエッチング後の算術平均粗さＲ_aが０．６６μｍ以下であると、スジむらレベルがＢ以上となり、高品位が要求されるシャドウマスクに適した素材として使用できる。他方、算術平均粗さＲ_aが０．６６μｍを超えると、スジむらレベルがＣ又はＤになり、高品位シャドウマスク用素材としては不適当であった。
算術平均粗さＲ_aとスジむらレベルとの関係をＩＭ材についてみると、表２に示されているように、分塊圧延時に再加熱を施さない比較例７ではスジむらレベルがＤであった。これに対し、１回以上の再加熱を施した本発明例１，２では、算術平均粗さＲ_aが低減し、スジむらレベルがＢに改善されていた。これは、再加熱処理によってＮｉ偏析が解消され、その結果としてハーフエッチング後の算術平均粗さＲ_aも小さくなることを示唆している。しかし、１回の再加熱を施した比較例８のように均熱時間が不十分であると、十分な改善効果が発現せず、算術平均粗さＲ_aはあまり低減せず、結果としてハーフエッチング後にスジむらが発生した。
【００２１】
以上の結果及び他の製造結果から、分塊圧延時に十分な加熱時間で再加熱を２回以上施すことにより、算術平均粗さＲ_aが０．６６μｍ以下になり、スジむらの発生がほとんどないシャドウマスク用素材を得ることができた。なお、再加熱温度が高いほど、算術平均粗さＲ_aが低減した。
算術平均粗さＲ_aは、本発明例２と３との対比にみられるように、高温長時間の再加熱を２回施すことにより更に低減する。また、分塊圧延後のスラブを２４時間ソーキングした本発明例４にみられるように、算術平均粗さＲ_aが０．４０μｍと最も低い値を示した。算術平均粗さＲ_aの低い本発明例３，４は、何れもエッチング後にスジむらが全く観察されない最高レベルＡであった。
ＣＣ材についてみると、一般的にスラブをソーキングすることによりＮｉ偏析が解消されるといえる。しかし、比較例１０にみられるように均熱温度１１５０℃で２４時間ソーキングを施した場合、算術平均粗さＲ_aが０．６９μｍとなり、そのスジむらレベルはＣであった。他方、均熱温度を１２５０〜１３５０℃に設定した本発明例５，６では、算術平均粗さＲ_aが０．６６μｍ以下になり、スジむら発生のないシャドウマスク用素材を得ることができた。
【００２２】
以上のように、ＩＭ材及びＣＣ材の何れにおいても、シャドウマスク用素材のエッチング性をハーフエッチング後の素材表面における算術平均粗さＲ_aで評価できることが判った。また、ハーフエッチング後の素材表面における算術平均粗さＲ _a が０．６６μｍ以下となるように、分塊圧延条件，ソーキング条件等の製造条件を適正化するとき、本発明例１〜６にみられるように、スジむらレベルがＢ以上の高品位のシャドウマスク用素材が得られることが判った。
【００２３】
【発明の効果】
以上に説明したように、本発明によるとき、シャドウマスク用素材のエッチング性を迅速且つ的確に評価でき、エッチング穿孔後にスジむらが発生せず、高精細な画像品位が要求されるカラーテレビ，ディスプレイ用等のブラウン管に適したシャドウマスク用素材が提供される。
【図面の簡単な説明】
【図１】ハーフエッチングされたＦｅ−Ｎｉ系合金素材の表面で観察されるＮｉ欠乏域の分布状態
【図２】ハーフエッチングされたＦｅ−Ｎｉ系合金素材の算術平均粗さＲ_ａ とエッチング後の素材表面に発生するスジむらとの間に密接な関係をあることを示すグラフ[0001]
[Industrial application fields]
The present invention relates to a method for evaluating the etching property of a shadow mask material for judging the presence or absence of stripe unevenness when a large number of electron beam passage holes are formed by etching, and a shadow mask material that does not cause stripe unevenness after etching. About.
[0002]
[Prior art]
A shadow mask having a large number of electron beam passage holes is incorporated in a picture tube such as a cathode ray tube for a color television or a display of an OA device. The electron beam emitted from the electron gun passes through a specific passage hole, and forms a beam spot in each fluorescent portion according to each color tone.
As a material for a shadow mask, it is required to be excellent in etching property so that an accurate electron beam passage hole is formed, and conventionally, a low carbon Al killed steel has been used. However, the shadow mask is heated and thermally expanded by the collision of the electron beam. If the thermal expansion at this time is large, the position of the electron beam passage hole is displaced, and a doming phenomenon occurs in which the electron beam does not hit a predetermined phosphor screen.
[0003]
The doming phenomenon has become a big problem with high precision and high brightness of color televisions and displays. Since the doming phenomenon is suppressed by the use of a material having a low thermal expansion characteristic, an Fe—Ni-based alloy having a small thermal expansion coefficient has been used as a shadow mask material. However, since Fe-Ni alloys contain a large amount of Ni, the material price is higher than that of low-carbon Al-killed steel, as well as greater strength than low-carbon Al-killed steel, and press formability. Inferior to In addition, there are disadvantages such as low Young's modulus and lack of rigidity as a shadow mask, slow etching rate and poor etching perforation.
Therefore, various attempts have been proposed to modify the Fe—Ni alloy so as to satisfy the characteristics required as a shadow mask material. Above all, with regard to streak unevenness appearing in the shadow mask after etching, which is a major factor that degrades the quality of CRT, the component segregation of Ni and other alloy components is eliminated by casting method, hot working method, homogenizing heat treatment, etc. Therefore, it has been studied to suppress the occurrence of stripe unevenness.
[0004]
For example, in Japanese Patent Application Laid-Open No. 60-56053, the cause of streak unevenness is Ni component segregation, and it is assumed that streak unevenness occurs due to different etching properties between the segregated part and the base material part. This article introduces the regulation of the Ni component segregation rate and the suppression of streaking. Specifically, assuming that a segregation part in which Ni is concentrated in a string exists in the material, the volume ratio and length of the string segregated material are regulated, and the segregation ratio is regulated to 10% or less.
In Japanese Patent Laid-Open No. 60-128253, Ni segregation is eliminated by forging the ingot with a cross-section reduction rate of 40% or more with one heat or two heats or more. In JP-A-2-54743, the segregation of impurity elements such as C, Si, Mn, and Cr, and the residual columnar structure having a specific orientation that occurs during casting are the main causes of streak unevenness, and the equiaxed crystal ratio Is maintained at a temperature of 950 ° C. or 1100 ° C. or more for 1 hour or more to prevent streak unevenness.
Japanese Patent Application Laid-Open No. 1-252725 also introduces a method of reducing streak unevenness by homogenizing a slab or hot-rolled coil under specific conditions, assuming that the dominant cause of streak unevenness is component segregation. . Specifically, the ratio of the Ni concentration range in the thin plate product to the Ni concentration range in the slab is defined as the Ni segregation level, and if this value is 0.7 or less, streak unevenness is suppressed to the extent that there is no practical problem. It is going to be done.
[0005]
[Problems to be solved by the invention]
By eliminating the component segregation of Ni and other alloy components, the occurrence of stripe unevenness can be suppressed to some extent. However, recent demands for larger color televisions and larger displays and higher image brightness are severe. To meet these demands, electron beam passage holes with a smaller hole diameter than conventional ones are drilled at high density. There is a need for a shadow mask with a fine pitch between the holes. For this reason, the material produced by the conventionally proposed method cannot be said to have satisfactorily eliminated streak unevenness for use as a shadow mask that requires high quality.
In addition, various methods aimed at eliminating segregation not only lack clarity about the target degree of segregation, but also the amount of segregation remaining at the material stage, causing streak unevenness. It has not yet been clarified as to whether it is not suitable.
[0006]
For example, in the above-mentioned JP-A-60-56053, an X-ray microanalyzer is used to investigate component segregation in a material, the component concentration is measured from the X-ray intensity specific to the component, and the component concentration and average in the segregation region are measured. When the difference from the component concentration is divided by the average component concentration and expressed as a percentage, it is 10% or less, and the length of the segregated material is 30 mm or less. Further, in JP-A-1-252725, similarly, using an X-ray microanalyzer, a value obtained by dividing the Ni concentration fluctuation in the manufactured thin plate product by the concentration fluctuation at the stage of the slab is defined as the Ni segregation level. When the value is 0.7 or less, it is determined that there is no stripe unevenness.
[0007]
However, evaluating the degree of streak unevenness from the component segregation of the material is not an industrially applicable evaluation means. In other words, it is inefficient to use the X-ray microanalyzer to determine the streak unevenness that is expected to occur after etching in the process of manufacturing the shadow mask material at the material stage. It is not an accurate evaluation method.
The present invention has been devised to solve such problems, and it is closely related to the surface roughness and the occurrence of streak unevenness on the surface of the shadow mask material etched to 30 to 70% of the plate thickness. By carefully predicting the etching performance of the shadow mask material from the surface roughness, the quality of the shadow mask can be controlled with high accuracy and sufficient, and the surface roughness on the surface can be controlled. An object is to provide a high-quality shadow mask material that does not cause streaking after etching by strictly controlling.
[0008]
[Means for Solving the Problems]
In order to achieve the object, the etching property evaluation method of the present invention etches a Fe—Ni alloy material to 30 to 70% of the plate thickness, measures the surface roughness of the etched surface, and is defined in JIS B0601. the surface roughness arithmetic average roughness R _a is an index representing the those 0.66 [mu] m or less, and evaluating as a material for a shadow mask stripe unevenness does not occur after etching.
Further, the shadow mask material of the present invention is made of Ni: 30-50% by weight, Cr: 0.01-1.0% by weight, C: 0.015% by weight or less, Si: 0.2% by weight or less, Mn : Fe-Ni alloy having a composition of 0.5 wt% or less, Al: 0.02 wt% or less, B: 0.0040 wt% or less, and the surface of the material etched by 30 to 70% of the plate thickness arithmetic mean roughness R _a is an index of the surface roughness defined by JIS B0601 in is characterized in that at 0.66 [mu] m or less.
[0009]
[Action]
The stripe unevenness at the time of etching drilling is observed as a difference between light and dark lines or bands, and some of them reach a length of 300 mm. The present inventors investigated and studied the correspondence between the stripe unevenness generated in the shadow mask and the stripe unevenness generated on the surface by etching. As a result, it was not possible to grasp the correspondence with the stripe unevenness generated in the shadow mask only by etching the extreme surface layer of the material, but when etching to 30 to 70% of the plate thickness (hereinafter referred to as half-etching) The stripe unevenness similar to the stripe unevenness seen in the mask was generated. Then, the present inventors have found that the occurrence of streak unevenness at this time is closely related to the streak unevenness occurrence state of the shadow mask.
Therefore, quantitative mapping analysis was performed on the distribution state of Ni on the half-etched surface with an X-ray microanalyzer. As a result, as shown in FIG. 1, it was found that the Ni-deficient region 1 corresponding to the occurrence of streak unevenness was distributed in a streak pattern along the rolling direction 2. Compared with Fe, Ni has a smaller ionization tendency, and in the depletion region 1, a larger amount of Fe is present than in the normal portion. Therefore, in the Ni depletion region 1, a larger amount of metal elements are etched away from the surface of the material than in the normal portion. It is thought that it will elute. That is, in the depletion region 1, in the depletion region 1 where the etching rate is different from that of the surroundings, a difference in unevenness occurs on the etched surface, and it is assumed that the difference in unevenness on the surface is observed as optical unevenness.
[0010]
In addition, it was inferred that an index that can quantitatively evaluate the degree of streak unevenness can be obtained by accurately measuring the difference in unevenness. In fact, when a plurality of materials produced by various improvements for improving the stripe unevenness were investigated, it was found that there was a close correlation between the degree of the stripe unevenness and the difference in the unevenness.
From the above knowledge, the present inventors examined various manufacturing conditions such as ingot lump conditions and soaking conditions in order to obtain a material with small unevenness on the half-etched surface, and obtained product materials The difference in unevenness on the half-etched surface was measured with a surface roughness meter. As a result, we found that there is a strong correlation between the arithmetic average roughness R _a and streak unevenness level is an index representing the surface roughness defined by JIS B0601, the arithmetic mean roughness R _a is 0.66 It has been found that streak unevenness is reduced to the extent that it is hardly observed with the naked eye when it is less than μm .
[0011]
Hereinafter, components, contents and the like of the Fe—Ni alloy used in the present invention will be described.
Ni: 30 to 50% by weight
This is an important alloy component for keeping the thermal expansion coefficient of Fe-Ni alloys low. The Ni content is restricted to a range of 30 to 50% by weight in order to maintain a low coefficient of thermal expansion.
Cr: 0.01 to 1.0% by weight
It is an effective alloy component for increasing the etching rate of the Fe—Ni-based alloy, and the effect and effect of Cr addition become remarkable when the content is 0.01% by weight or more. However, if a large amount of Cr exceeding 1.0% by weight is contained, the thermal expansion coefficient of the Fe—Ni alloy increases.
C: 0.015% by weight or less It is a harmful element that forms carbides in the material and impairs etching properties. In the present invention, the upper limit of the C content is set to 0.015% by weight in order to prevent harmful effects caused by carbides.
[0012]
Si: 0.2% by weight or less Si is an element added as a deoxidizer, and has a tendency to increase the thermal expansion coefficient and deteriorate the etching property and blackening film property. Therefore, in the present invention, the condition for the Si content is set to 0.2% by weight.
Mn: 0.5 wt% or less Although it is an effective element as a deoxidizer, it exhibits an effect of increasing the thermal expansion coefficient.
Therefore, in the present invention, the upper limit of the Mn content is set to 0.5% by weight.
Al: 0.02% by weight or less Hard inclusions that cause generation of surface defects and the like are formed, which adversely affects surface quality. Therefore, in the present invention, the upper limit of the Al content is 0.02% by weight.
Set to.
[0013]
B: 0.0040% by weight or less An effective alloying component that increases the etching rate. However, if B exceeding 0.0040 wt% is contained, annealing unevenness is likely to occur after soft annealing, and the formation unevenness of the blackened film is promoted.
In the Fe—Ni-based alloy targeted by the present invention, other inevitable impurities include S, P, O, and N. The amount of these inevitable components contained in the alloy is 0.010% by weight or less. If the content is such a level, the performance as a shadow mask material is not adversely affected.
[0014]
Arithmetic average roughness (R _a ) on the half-etched surface: 0.66 μm or less The larger the arithmetic average roughness R _a, which is an index representing the surface roughness specified in JIS B0601, the more the etched shadow mask material Strong unevenness is observed on the surface. The smaller the arithmetic average roughness Ra, the smaller the difference in unevenness on the surface after half-etching. As a result, optical unevenness is less likely to be observed, and streaks are uneven on the surface of the etched shadow mask material. It is suppressed. According to the investigations and researches of the present inventors, in order to obtain a material that can be used as a high-quality shadow mask with almost no stripe unevenness observed by the naked eye by half-etching, the arithmetic average roughness R on the half-etched surface _a, it was found that may be at 0.66 μm or less.
[0015]
The arithmetic average roughness _Ra is measured by using a contact needle type surface roughness meter, for example, by the following procedure. Using a ferric chloride solution having a specific gravity of 1.45 and a temperature of 60 ° C., the Fe—Ni alloy material is half-etched with a spray-type etching apparatus. Next, the length of 4 mm perpendicular to the rolling direction is measured using a diamond stylus having a radius of curvature of 2 μm at the tip and an opening angle of 45 degrees for the corroded surface of the material at an arbitrary location. Rolling direction to move 20μm increments Repeat this measurement, an average value in the range of 4mm angle as the arithmetic mean roughness R _a.
In addition, in order to obtain an Fe—Ni alloy material having an arithmetic average roughness _Ra of 0.66 μm or less on the half-etched surface, it is subjected to block rolling while repeating reheating, and annealing and cold rolling after hot rolling. A method of repeating (Japanese Patent Application No. 8-46616), a method of performing intermediate annealing at 850 to 1200 ° C. during the cold rolling (Japanese Patent Laid-Open No. 8-260103), and the like are employed.
[0016]
【Example】
An Fe—Ni alloy having the composition shown in Table 1 was melted and a 9-ton ingot was cast using a mold to obtain an IM material. Further, a 10-ton slab was cast by continuous casting to obtain a CC material.
[0017]

[0018]
Each ingot was shredded and soaked under the production conditions shown in Table 2.
The IM material was subjected to partial rolling or further soaking. CC material was soaked as it was. Subsequently, the surface of each slab was cared for and a hot-rolled steel strip having a thickness of 6 mm was manufactured by hot rolling. Furthermore, annealing at 1000 ° C. and cold rolling were repeated several times to finally obtain a cold-rolled steel strip having a thickness of 0.12 mm.
Using a ferric chloride solution with a specific gravity of 1.45 and a temperature of 60 ° C., half-etch the specimen cut from each cold-rolled steel strip to 50% of the plate thickness, and observe the occurrence of streak unevenness on the half-etched surface did. The highest level A where no stripe unevenness was observed, almost no stripe unevenness was observed, and if it was more than this level B, which was usable as a high-quality shadow mask material, a relatively large number of stripe unevenness was observed. The level of streak unevenness was evaluated in four stages, with level C as the result and minimum level D as the number of clear streak appearing. Further, the half-etched surface of an arbitrary portion of the test piece was measured with a stylus type surface roughness meter, and the arithmetic average roughness _Ra was obtained.
Table 2 shows the arithmetic average roughness _Ra (unit: μm) and the stripe unevenness level for each test piece. FIG. 2 shows the relationship between the arithmetic average roughness _Ra and the stripe unevenness level.
[0019]

[0020]
FIG. 2 shows that there is a strong correlation between the arithmetic average roughness _Ra and the stripe unevenness level. That is, when the arithmetic mean roughness R _a after the half etching is 0.66 [mu] m or less, stripe unevenness level becomes more B, can be used as a material suitable for the shadow mask high quality is required. On the other hand, if the arithmetic mean roughness R _a of more than 0.66 [mu] m, stripe unevenness level becomes C or D, it was unsuitable as a material for high-definition shadow mask.
When the relationship between the arithmetic average roughness _Ra and the stripe unevenness level is seen for the IM material, as shown in Table 2, the uneven stripe level is D in Comparative Example 7 in which reheating is not performed during the ingot rolling. It was. On the other hand, in Examples 1 and 2 of the present invention in which reheating was performed one or more times, the arithmetic average roughness _Ra was reduced and the stripe unevenness level was improved to B. This is because Ni segregation is eliminated by reheating treatment, suggesting that the resulting also small arithmetic mean roughness R _a after the half etching. However, if the soaking time is insufficient as in Comparative Example 8 in which reheating is performed once, the sufficient improvement effect is not exhibited, and the arithmetic average roughness _Ra is not reduced so much. Stripe unevenness occurred after etching.
[0021]
From the above results and other manufacturing results, the arithmetic average roughness _Ra becomes 0.66 μm or less when reheating is performed twice or more with sufficient heating time at the time of ingot rolling, and streak unevenness is hardly generated. No shadow mask material could be obtained. In addition, arithmetic mean roughness _Ra reduced, so that reheating temperature was high.
The arithmetic average roughness _Ra is further reduced by performing reheating at a high temperature for a long time twice, as seen in the comparison with Examples 2 and 3 of the present invention. Further, as seen in Example 4 of the present invention in which the slab after the bulk rolling was soaked for 24 hours, the arithmetic average roughness _Ra was the lowest value of 0.40 μm . Lower invention example of an arithmetic mean roughness R _a 3, 4 are each was the highest level A that stripe unevenness after etching is not observed at all.
Regarding CC materials, it can be said that Ni segregation is generally eliminated by soaking slabs. However, as shown in Comparative Example 10, when soaking was performed at a soaking temperature of 1150 ° C. for 24 hours, the arithmetic average roughness _Ra was 0.69 μm , and the stripe unevenness level was C. On the other hand, in Examples 5 and 6 of the present invention in which the soaking temperature is set to 1250 to 1350 ° C., the arithmetic average roughness _Ra is 0.66 μm or less, and a shadow mask material that does not cause stripe unevenness can be obtained. It was.
[0022]
As described above, in any of IM material and CC material it was also found to be evaluated by an arithmetic mean roughness R _a of etchable material for a shadow mask in the material surface after half etching. Further, as the arithmetic mean roughness R _a in the material surface after half etching becomes 0.66 [mu] m or less, slabbing condition, when optimizing the manufacturing conditions such as soaking conditions, the present invention Examples 1-6 As can be seen, it was found that a high-quality shadow mask material having a stripe unevenness level of B or higher can be obtained.
[0023]
【The invention's effect】
As described above, according to the present invention, the color mask and the display which can evaluate the etching property of the shadow mask material quickly and accurately, do not cause streak irregularity after etching drilling, and require high-definition image quality. A material for a shadow mask suitable for a cathode ray tube is provided.
[Brief description of the drawings]
[1] distribution [2] of Ni depletion region observed by the half etched Fe-Ni based alloy material surface arithmetic mean roughness of the half etched Fe-Ni based alloy material R _a and after etching Showing that there is a close relationship with streaks on the surface of the material

Claims (2)

Etching the Fe-Ni based alloy materials to 30% to 70% of the sheet thickness, the surface roughness of the etched surface was measured, the arithmetic mean roughness R _a is an index representing the surface roughness defined by JIS B0601 is 0 A method for evaluating the etching property of a shadow mask material, wherein a material having a thickness of .66 μm or less is evaluated as a shadow mask material in which stripe unevenness does not occur after etching. Ni: 30-50% by weight, Cr: 0.01-1.0% by weight, C: 0.015% by weight or less, Si: 0.2% by weight or less, Mn: 0.5% by weight or less, Al: 0 0.02 wt% or less, B: Fe-Ni alloy having a composition of 0.0040 wt% or less, and the surface roughness specified in JIS B0601 on the surface of the material etched 30 to 70% of the plate thickness material for a shadow mask stripe unevenness after etching is not generated arithmetic mean roughness R _a is an index is equal to or is 0.66 [mu] m or less.

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