JPH02170922A - Manufacture of fe-ni alloy sheet for shadow mask - Google Patents

Abstract

PURPOSE:To manufacture an Fe-Ni alloy sheet for shadow mask for color cathode-ray tube having superior characteristics by subjecting a continuously cast slab of Fe-Ni alloy with a specific composition to heat treatment, hot rolling, cold rolling, and then recrystallization annealing under respectively specified conditions. CONSTITUTION:A continuously cast slab of Fe-Ni alloy having a composition consisting of, by weight, 30-50% Ni, 0.01-1.00% Si, 0.10-2.00% Mn, <0.05% Al, <0.02% O, and the balance Fe is subjected to soaking treatment at 1200-1350 deg.C for >=1hr and to surface conditioning. Subsequently, heating is applied to the above slab up to 1100-1200 deg.C in an N2-gas atmosphere of <=0.1vol.% O2 concentration to carry out hot rolling, and, after the surface of the hot rolled plate is ground to undergo the removal of surface flaws, etc., formed at the time of hot rolling, the above plate is cold-rolled and the cold rolled sheet is subjected to recrystallization annealing in a nonoxidizing atmosphere, or further, this sheet is subjected, if necessary, to double skin pass rolling and to stress relief annealing in a nonoxidizing atmosphere at 550-750 deg.C for 1-300sec. By this method, the Fe-Ni alloy sheet for shadow mask free from the occurrence of striped irregularity at the time of piercing by etching can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is an Fe-Ni alloy plate for a shadow mask used in a color cathode ray tube, in particular, suppresses streak unevenness that occurs during etching in the shadow mask manufacturing process, and Shadow mask re- with improved workability and yield
The present invention relates to a method for manufacturing Ni plywood.

[Conventional technology]

Low carbon steel is used in -i as a material for color cathode ray tube shadow masks. A color cathode ray tube is the faceplate part (panel) of a glass bulb that forms a vacuum tube.
A fluorescent film that emits the three primary colors of red, green, and blue is coated on the top, and the neck on the opposite side is equipped with an electron gun that fires an electron beam to stimulate the fluorescent film to emit light. The shadow mask is installed near the phosphor screen between the phosphor screen and the electron gun, and allows the three electron beams corresponding to the three primary colors emitted from the electron gun to pass through an object called a sloft, each corresponding to a different one. It performs a color selection function that applies only to the phosphors that are used. Therefore, it is necessary that the sloft on the shadow mask and the phosphor have an accurate positional relationship.

However, when a color cathode ray tube is used continuously, about 80% of the energy of the electron beam is consumed as thermal energy on the shadow mask, so the temperature of the shadow mask locally rises to about 90 degrees Celsius, causing the electrons to expand due to thermal expansion. The beam and phosphor will no longer be able to match, and the image will become unclear.

For this reason, efforts have been made to compensate for the thermal expansion of the shadow mask by modifying the structure of the color cathode ray tube, but this is not sufficient.

Therefore, in recent years, a low thermal expansion Fe--Ni alloy plate containing 30 to 50% Ni, which has an extremely small thermal expansion coefficient compared to low carbon steel, has been used as a material for shadow masks.

However, when such a Fe--Ni alloy plate is etched in the process of manufacturing a shadow mask, a defect called stripe-like pattern, that is, a stripe-like pattern along the rolling direction, may occur.

Therefore, there is a strong need for a method of manufacturing a Fe-Ni alloy plate for shadow masks used in color cathode ray tubes, especially a Pe-Ni alloy plate for shadow masks that suppresses the uneven streaks that occur during etching in the manufacturing process of shadow masks.
It is requested.

It is said that component segregation is the most dominant cause of uneven streaks, and as a method to reduce component segregation in Fe-Ni alloy sheets, soaking heat treatment is performed on hot-rolled sheets to reduce Ni.
JP-A-60-56053 discloses a method for improving etching perforation by reducing the segregation of .However, there are problems in terms of yield and workability.

[Problem to be solved by the invention]

When Fe-Ni alloys are heated in the atmosphere at high temperatures and for long periods of time, subscales such as grain boundary oxidation and internal oxidation occur significantly just below the surface scale, so soaking heat treatment on hot-rolled sheets is not recommended to avoid surface defects caused by subscales. occurs frequently, significantly deteriorating yield and workability. On the other hand, if the heat treatment temperature is lowered or the heat treatment time is shortened from the viewpoint of subscale suppression, Ni diffusion will be insufficient and streaks will occur due to component segregation.The present invention is used in color cathode ray tubes. Fe-Ni alloy plates for shadow masks, especially suppressing uneven streaks that occur during etching in the shadow mask manufacturing process,
The present invention also aims to improve the workability of surface grinding for removing subscale surface defects and the yield of thin sheet products, and to provide a method for stably assembling FeNi alloy sheets for shadow masks on an industrial scale.

[Failure to solve the problem]

The present invention was achieved as a result of various studies on manufacturing processes and conditions for this purpose, and the gist thereof is as follows.

(1) In weight%, Ni: 30-50%, Si
: 0.01~1.00%, Mn: 0.1
0 to 2.00%, 8l: 0.05% or less.

o: o, 1200 ~
After soaking heat treatment at 1350℃ for 1 hour or more, the surface is treated, then heated to 1100-1200''C in an atmosphere with an oxygen concentration of 0.1νo1% or less, hot rolled, surface ground and cold rolled. A method for producing a Fe-Ni alloy plate for a shadow mask, which comprises rolling and recrystallization annealing.

(2) In weight%, Ni: 30-50%, Si
: 0.01~1.00%, Mn: 0.10~2
．． 00%, N: 0.05%, At: 0.05% or less O
: Continuous casting slab of Fe-Ni alloy consisting of 0.02% or less, balance Fe and inevitable impurities, 1200~
After performing soaking heat treatment at 1350″C for more than 1 hour, surface care was performed, and then oxygen concentration 0, I vo1
% or less, heated to 1100-1200°C, hot rolled, surface ground and cold rolled, recrystallized annealed,
A method for producing a Fe--Ni plywood board for a shadow mask, which comprises performing dull skin bath rolling and then performing strain relief annealing at 550 to 750°C for 1 to 300 seconds in a non-oxidizing atmosphere.

[For production]

The reasons for the limitations of the present invention will be explained in detail below.

If the content of Ni is less than 30%, the thermal expansion coefficient becomes extremely high and the image clarity of the color cathode ray tube deteriorates. On the other hand, even if the content exceeds 50%, the coefficient of thermal expansion increases. Therefore, the Ni component range was set to 30 to 50%.

Si is added for the purpose of deoxidizing, but if it is less than 0.01%, the deoxidizing effect will be small, but if it is more than 1.00%, the formation of coarse silicate inclusions will be significant, and this will cause etching. It inhibits perforation and causes poor perforation. Therefore, the Si component range was set to 0.01 to 1.00%.

Mn is added for the purpose of deoxidizing and improving hot workability, but if it is less than 0.10% it has no effect, and if it is contained more than 2.00%, the strength of the alloy increases and press formability deteriorates. do. Therefore, the component range of Mn is 0.10 to 2.00.
%.

Eight! When the content exceeds 0.05%, the formation of alumina-based cluster inclusions is significant, which impedes etching performance and causes poor drilling. Therefore, eight! The component range was set to 0905% or less.

When the content of 0 exceeds 0.02%, oxide-based inclusions are formed significantly, which inhibits etching performance and causes poor drilling. Therefore, the component range of 0 is 0.
0.02% or less.

When the soaking heat treatment temperature of the slab is lower than 1200℃, the effect of reducing the segregation of components such as Ni is small, and the generation of uneven streaks cannot be suppressed during etching. Even if the oxygen concentration is reduced, the occurrence of subscales will hardly be improved. Therefore, the soaking heat treatment temperature range is 12
The temperature was 00 to 1350°C.

If the soaking heat treatment time is shorter than 1 hour, the N
The effect of reducing the segregation of components such as i is small, and the occurrence of uneven streaks cannot be suppressed during etching. Therefore, the soaking heat treatment time was set to 1 hour or more.

Furthermore, a preferable range is 5 hours or more.

The atmosphere for the soaking heat treatment should have a low oxygen concentration, preferably 0.10% or less, in order to reduce the maintenance load for removing surface flaws due to subscales such as grain boundary oxidation and internal oxidation. Heating furnaces that can control oxygen concentration include direct current heating furnaces and electric heating furnaces. Furthermore, in order to block oxygen, which is the cause of subscale generation, the slab surface may be covered with a thin plate or coated with an antioxidant, but this method is inferior in workability and subscale suppression effect compared to atmosphere control.

Since the slab has surface defects caused during continuous casting, the surface is usually treated by grinding with a grinder or the like, but in the present invention, this is done after soaking heat treatment. Even if subscale is generated on the slab due to the soaking agent treatment, the generation is slight in the slab soaked under the conditions of the present invention, so that it can be removed with a light load by surface care.

The oxygen concentration in the heating atmosphere before hot rolling is 0.1 Ovo
1. %, subscales such as grain boundary oxidation and internal oxidation will significantly occur on the surface of the slab soak heat-treated material (hereinafter referred to as soaking material), and surface flaws and grain boundary oxidation due to the subscales will occur after hot rolling. Frequent ear cracking occurs,
This increases the load of surface grinding in the subsequent process and significantly reduces the yield of hot rolled sheets. Therefore, the oxygen concentration in the heating atmosphere before hot rolling was set to 0.10 vol.% or less.

If the heating temperature before hot rolling is lower than 1100°C, the temperature of the rolled material will drop significantly by the time hot rolling is completed, resulting in cracking due to deterioration of hot workability and the inability to roll due to increased deformation resistance. . Furthermore, if rolling is carried out at a temperature exceeding 1200° C., grain boundary oxidation occurs even if the oxygen concentration in the heating atmosphere is reduced, and edge cracking occurs after hot rolling. Therefore, the Kn range of the heating temperature before hot rolling was set to 1100-1200°C.

When annealing a hot-rolled strip or plate (hereinafter referred to as hot-rolled plate), if the hot rolling is completed at a temperature of 900°C or higher, recrystallization due to processing in hot rolling is promoted, and the hot-rolled plate is Since the structure is a recrystallized structure, it may be omitted.

Since the surface of the hot-rolled sheet has surface flaws such as roll flaws and abrasion flaws that occur during the hot rolling process, the surface is ground to remove these flaws, and then cold rolling is performed. As surface grinding, heald grinding, grinding with a grindstone roll, grinding with a brush roll, etc. can be performed. In the case of belt grinding, it is preferable to descale the hot-rolled plate and perform mild cold rolling to flatten the surface, but in the case of grinding with a grindstone roll and grinding with a brush roll, hot rolling It is sufficient to carry out the process with the scale adhered to the hot rolled sheet or after annealing the hot rolled sheet. In the case where the hot rolling was carried out under the conditions of the present invention, the occurrence of subscale is suppressed, and even if it occurs, it is mild, so that it can be removed by normal grinding for removing flaws.

Cold rolling may be performed without intermediate annealing up to the product thickness, or intermediate annealing may be performed at an intermediate thickness depending on the capacity of the rolling mill or the degree of work hardening of the material. It is preferable that the surface finish of the product plate is dull from the viewpoint of adhesion during resist film formation in shadow mask production.
Preferably, the final bath of cold rolling is carried out on dull rolls.

Recrystallization annealing is performed in a non-oxidizing atmosphere after cold rolling, and by forming a recrystallized grained m weave through this treatment, uniform etching perforations can be performed when producing a shadow mask.

The method according to claim (1) of the present invention includes the steps up to recrystallization annealing described above.

In the method according to claim (2) of the present invention, dull skin pass rolling and strain relief annealing are further performed. When cold rolling is performed under high pressure, even if the final pass is rolled with dull rolls, the plate may be work hardened and a dull finish may not be obtained. In that case, after recrystallization annealing, skin bath rolling using dull rolls is performed to obtain a dull finish. In this case, residual stress is generated near the dull surface, and the residual stress is released during etching to cause warping, so it is necessary to perform strain relief annealing.

The strain relief annealing temperature has a small effect if it is lower than 550℃, and if it exceeds 750℃, if local strain is introduced by skin bath rolling, the strained area will recrystallize and the unstrained area will become grainy. As the particles grow, the structure of the product board becomes mixed grains, which inhibits etching perforation. Therefore, the strain relief annealing temperature range was set at 550 to 750°C.

When the strain relief annealing time is shorter than 1 second, the effect is small, and when it exceeds 300 seconds, the effect is saturated and there is no advantage in terms of productivity or cost. Therefore, the strain relief annealing time was set to 1 to 300 seconds.

The strain relief annealing is performed in a non-oxidizing atmosphere to prevent surface scale and subscale formation.

Thus, if Fe-Ni alloy sheets are manufactured by the method of the present invention as described above, the occurrence of surface flaws due to subscale and edge cracks due to grain boundary oxidation in hot-rolled sheets will be reduced and prevented, and surface grinding will be easier. Workability is greatly improved, yield drop in hot-rolled sheets is greatly reduced, inclusions and component segregation such as N+ are significantly reduced, and the occurrence of uneven streaks during etching is suppressed, reducing the occurrence of uneven etching due to poor etching. Yield loss is significantly reduced.

〔Example〕

A Pe-Ni alloy was melted in an electric furnace, refined in an AOD furnace, and then cast by a continuous casting method. The chemical composition of the slab is shown in Table 1. These slabs were manufactured into thin plate products with a thickness of 0.20 mm by the manufacturing process shown in FIG. In FIG. 1, (a) and (b) show the process of the present invention, and (C) shows the comparative process. The soaking heat treatment in the process of the present invention and the heating before hot rolling are performed in a direct current heating furnace in which the oxygen concentration in the atmosphere is controlled using NZ gas.

We investigated the work time for surface grinding of hot rolled sheets in these processes, the yield of thin sheet products, and evaluation of uneven streaks during etching.

Table 2 shows the surface grinding work time, the yield of thin plate products, and the evaluation of streak irregularities in the process of the present invention and the comparative process. From the same table, the process of the present invention greatly improves surface grinding work compared to the comparative process, and the RF! It can be seen that the amount of smearing is significantly reduced, and the occurrence of uneven streaks is also significantly suppressed.

The stripe irregularity rank in Table 2 is 43% FeC for thin plate products.
Judgments were made by visually observing the uneven streaks after etching with the ZZ solution. A: No streaks, E: Severe streaks: B-D: Ranked between A and E. The B rank and C rank have uneven streaks to the extent that there is no problem in practical use.

〔Effect of the invention〕

As is clear from the above, if Fe-Ni alloy plates for shadow masks are manufactured by the method of the present invention, the workability and yield during the manufacture of alloy plates will be greatly improved, and etching perforations will be required when manufacturing shadow masks. In some cases, etching defects caused by uneven streaks are eliminated, and yield loss during etching is also significantly reduced.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment, and (a) shows claim (1).
), (b) is a diagram showing the present invention process according to claim (2), and (C) is a diagram showing a comparative process.

Claims (2)

[Claims] (1) In weight%, Ni: 30-50%, Si: 0.0
1-1.00%, Mn: 0.10-2.00%, N: 0
．． A continuously cast slab of Fe-Ni alloy consisting of 0.05% or less, O: 0.02% or less, and the balance Fe and unavoidable impurities was subjected to soaking heat treatment at 1200 to 1350°C for 1 hour or more, and then surface-treated. , then the oxygen concentration is 0
．． Fe-N for a shadow mask characterized by heating to 1100 to 1200°C in an atmosphere of 1 vol% or less, hot rolling, surface grinding and cold rolling, and recrystallization annealing.
i Method for manufacturing alloy plate. (2) In weight%, Ni: 30-50%, Si: 0.0
1-1.00%, Mn: 0.10-2.00%, Al:
A continuously cast slab of Fe-Ni alloy consisting of 0.05% or less, O: 0.02% or less, and the balance Fe and unavoidable impurities is subjected to soaking heat treatment at 1200 to 1350°C for 1 hour or more, and then surface care is performed. and then heated at 1100 to 1200°C in an atmosphere with an oxygen concentration of 0.1 vol% or less.
heated to , hot rolled, surface ground and cold rolled, recrystallized annealed, Dullskin pass rolled, and then strain relief annealed at 550 to 750°C for 1 to 300 seconds in a non-oxidizing atmosphere. Fe-N for shadow masks characterized by
i Method for manufacturing alloy plate.