JPH0456107B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an Fe-Ni low thermal expansion alloy that has excellent press formability and etching property. The present invention relates to an Fe--Ni low thermal expansion alloy that has excellent press formability and etching properties and can be suitably used for low-temperature equipment manufactured by molding. (Conventional technology) Fe-Ni alloy containing 30 to 45% Ni is
Because its coefficient of thermal expansion is extremely small in the temperature range of 300°C, it is used as a material for various electron tubes, and its use is expanding in particular as a functional material for shadow masks, mask frames, mask holders, etc. Conventionally, color picture tube shadow masks have had problems with thermal expansion due to temperature rise. The electron beam that passes through the aperture of the shadow mask emits light on the fluorescent surface, but the electron beam that does not pass through the aperture is irradiated onto the shadow mask and heated, so the shadow mask thermally expands and the electron beam is determined. A so-called doming phenomenon occurs in which the light does not hit the fluorescent surface, but in order to eliminate this doming phenomenon, the use of an amber alloy with low thermal expansion is being considered. However, since the amber alloy has a yield strength 0.2% higher than that of conventional mild steel, it is difficult to perform high-precision processing such as shadow masks, which has hindered its practical use. In order to improve the above-mentioned high-precision machinability, lowering the yield strength has begun to be considered, and as a method,
No. 59-27434, JP-A No. 59-27435, JP-A No. 60-
The method described in No. 21331 is known. According to the above-mentioned Japanese Patent Application Laid-Open No. 59-27434, an invar material is etched into a mask, vacuum annealed, and coarsened to reduce the yield strength.
% or less, it is disclosed that it is more effective. Furthermore, JP-A-60-21331 discloses that by limiting the cold rolling reduction to 50 to 80%, the in-plane anisotropy can be reduced. (Problem to be solved by the invention) However, even though such a method has been used to reduce the yield strength, the value is not necessarily sufficient. There is a major problem in that if the particles are coarsened by heat treatment in order to increase their strength, the mask will become rough when pressed, making it impossible to put it to practical use. Also, JP-A-60-
According to the method described in No. 21331, even if the in-plane anisotropy is reduced, it is impossible to extremely reduce the spring back during pressing, and there is a drawback that it cannot be put to practical use. (Means for Solving the Problems) The object of the present invention is to provide an alloy that eliminates and improves the drawbacks or problems of the conventional Fe-Ni-based low thermal expansion alloys, and has improved press formability and etching properties. The above object can be achieved by providing an Fe-Ni-based low thermal expansion alloy that has excellent properties. That is, the present invention has C0.009% or less,
Si0.2% or less, Mn0.5% or less, Ni30-45%, Cr1.5
~6%, B0.001~0.02%, and the balance is Fe, which has excellent press formability and etching properties.
-Ni-based low thermal expansion alloy (hereinafter referred to as "first invention")
The above first invention alloy further contains 4% or less of Co as a second invention alloy, and the first invention alloy further contains 0.005 to 0.4% Ta as a third invention alloy. . Next, the present invention will be explained in detail. Since conventional alloys for shadow masks must be etched, they are required to have good etching properties, and for this purpose, the alloys have to have a fine grain structure. On the other hand, since alloys for shadow masks are required to have low yield strength, they must be heat treated to coarsen the crystals before pressing. However, since the alloy of the present invention originally has a fine-grained crystal structure, it not only has good etching properties but also has low yield strength, making it an extremely excellent alloy for shadow masks and a relatively small coefficient of thermal expansion. The present inventors attempted to reduce the yield strength by adding a predetermined amount of Cr to the conventional so-called 36Ni amber alloy, and also added B to the rolled surface, which is the crystal plane with the fastest etching rate among various crystal planes.
The present invention was completed based on the new finding that the 00 crystal planes tend to aggregate and have excellent etching properties. That is, in the case of the alloy of the present invention, the present inventors have newly found that Cr causes a drastic decrease in yield strength, and B comes to aggregate in 100 crystal planes parallel to the rolling surface during recrystallization. Next, experimental data and experimental results regarding the alloy of the present invention will be explained. Figure 1 shows C0.005%, Si0.05%, Mn0.4%,
An alloy containing 36.0% Ni and the balance consisting of Fe (hereinafter referred to as
When Cr is added to 30Ni base alloy)
It is a diagram showing the influence of Cr amount on 0.2% proof stress,
It can be seen that the 0.2% yield strength decreases significantly as Cr increases. This 0.2% reduction in proof stress reduces the amount of spring back during press processing, making it easier to perform high precision processing. Figure 2 shows B for the degree of aggregation of 100 crystal planes on the rolled surface for the same alloy as shown in Figure 1 above.
It is a figure showing the effect of quantity. The vertical axis is the aggregation degree,
311,110,100,111 by X-ray diffraction
FIG. 3 is a diagram showing the ratio of the peak intensity of 100 planes to the total peak intensity of the planes. It can be seen from the figure that as B increases, 100 planes with a high etching rate gather on the rolled surface. From Figures 1 and 2, it was found that the addition of Cr lowered the yield strength by 0.2% and improved the pressability, and the addition of B caused the 100 planes to gather on the rolled surface, improving the etching properties. Next, the reason for limiting the composition of the alloy in the present invention will be explained. C: C is an element that increases the coefficient of thermal expansion and also increases the yield strength by 0.2%, and it is desirable that the content be as small as possible, and C should be 0.009% or less. Si:Si increases the coefficient of thermal expansion like C, and
It is an element that increases yield strength by 0.2%, and it is desirable to have as little amount as possible. Furthermore, since the segregation of Si causes uneven etching during mask etching, it is desirable to have a small amount in order to prevent segregation, and the content of Si must be 0.2% or less. Mn: Like C and Si, Mn is an element that increases the coefficient of thermal expansion and increases the yield strength by 0.2%, and is preferably as small as possible. Also, the segregation of Mn is
As in the case of Si, it is desirable that the amount of Mn is small because it causes uneven etching during mask etching, and Mn needs to be 0.5% or less. Ni: Ni is a basic component element that controls the coefficient of thermal expansion, and at low temperatures below 100℃, Ni36%
In the vicinity, and on the higher temperature side, the coefficient of thermal expansion is the smallest at around 42% Ni. If it is less than 30%, martensite will be formed and the coefficient of thermal expansion will increase, while if it exceeds 45%, the coefficient of thermal expansion will increase again, so Ni needs to be in the range of 30 to 45%. Cr: Cr is an element that significantly lowers the 0.2% proof stress, improves press formability, and increases the coefficient of thermal expansion. But less than 1.5% is 0.2%
Cr is 1.5 because the reduction in yield strength is not sufficient and, on the other hand, if it exceeds 6%, the coefficient of thermal expansion becomes too large and, for example, when used as a shadow mask material, the electron beam will not hit the fluorescent surface. It is necessary to make it ~6%. B: As the amount of B increases in materials with the same degree of cold working and the same annealing temperature,
For example, when performing etching such as a shadow mask, the 100 crystal planes with the fastest etching rate gather on the plate surface, so holes can be opened quickly in the same etchant, making it an element that greatly contributes to improving productivity. It is. However, B is 0.001
If it is less than 0.01%, the above effect will be poor, while if it exceeds less than 0.01%, the amount of solid solution of B will increase, and as with C.
Increases proof stress by 0.2% and inhibits press formability. Therefore, B needs to be within the range of 0.001% to less than 0.01%. Ta: Ta is an element that combines with C and N to form carbides and nitrides, contributing to refinement of crystal grain size. On the other hand, B also combines with C and N in steel to form carbides and nitrides, but Ta has a stronger affinity with C and N than B. Therefore, adding Ta to fix C and N as carbides and nitrides increases the effective amount of B, and it is an element that contributes to improving the action of B, which is extremely effective. It is valid. The amount of Ta added is
If it is less than 0.005%, the above contribution effect cannot be obtained sufficiently, while if it is more than 0.4%, it will combine with C and N and have a strong affinity with O, so oxides of these elements will be generated in the surface layer. 0.005 to 0.005 because it makes it easier and inhibits the decline in yield strength by 0.2%.
Must be within 0.4%. Co: Co is an element that contributes to improving amber properties, and as the Co content increases, the lower limit of Ni content that exhibits amber properties expands, but when Co exceeds 4%, the yield strength increases by 0.2% Co content must be kept at 4% or less since it inhibits pressability. Next, a method for manufacturing the alloy of the present invention will be explained. After melting various raw materials for manufacturing the alloy of the present invention in an electric furnace in the atmosphere, the AOD method (argon-oxygen blowing decarburization method) is performed.
Or, after refining by the VOD method (vacuum-oxygen blown decarburization method), agglomerates are formed in the air or in a vacuum. The final product is then subjected to hot rolling, cold rolling, annealing, and pickling processes. Note that the annealing is performed in air and/or
Or apply in a non-oxidizing atmosphere. Next, the present invention will be explained with reference to examples. Examples The table below shows the alloy of the present invention containing Cr and B as essential elements and the conventional Fe-Ni alloy that does not contain B.
0.2% Shows the degree of aggregation of 100 crystal planes that are effective for yield strength, hardness, coefficient of thermal expansion, and etching properties. All the sample materials in the table are 0.20mm thick material.
After being heat treated for 1 minute at ℃, it was subjected to various tests. 0.2% proof stress is JIS No. 13B test piece after processing.
Hardness tests were conducted in accordance with G4303 and JIS Z2244. The thermal expansion test measured the average thermal expansion from room temperature to 100°C. In addition, the aggregation degree was determined by scanning from 45° to 20° using a Mo target, 311, 110,
The peak heights of planes 100 and 111 were each measured, and the ratio of the height of plane 100 to the total height was determined.

[Table] As can be seen from this table, the alloy of the present invention with the addition of Cr and B has a yield strength of 0.2% compared to the comparative alloy.
It can be seen that the hardness is low and the 100 aggregation degree is high. Comparative alloy No. 12 (36Ni-3Cr-balance Fe) is an alloy having the same composition range as described in JP-A-59-59861. According to the same publication, the addition of Cr improves strength and
It is reported that adding 3% Cr to 36% Ni steel significantly increases the hardness. However, as is clear from Comparative Alloy No. 12, the present inventors have newly discovered that, to the contrary, Cr contributes to a decrease in 0.2% yield strength and hardness. Furthermore, we have newly found that the 100 aggregation degree can be increased by adding B to this Cr-added alloy. (Effects of the invention) Compared to conventional alloys, the coefficient of thermal expansion of the alloy of the present invention does not become so large that it becomes a problem.
For materials with a high degree of aggregation of 00 crystal planes, the etching speed can be increased during the production of a shadow mask, and the shape of the mask holes can also be finished neatly by etching. In addition, such a 0.2% reduction in yield strength and hardness reduces spring back during press processing of the shadow mask manufactured by etching, increases conformability to the mold, and provides a good press shape.

[Brief explanation of the drawing]

Figure 1 shows 0.2 when Cr is added to a 36% Ni alloy.
Diagram showing the effect on % proof stress, Figure 2 is 36%Ni
FIG. 3 is a diagram showing the effect on 100 agglomeration degree when B is added to a -3% Cr alloy.

Claims (1)

[Claims] 1 C0.009% or less, Si 0.2% or less, Mn 0.5% or less,
An Fe-Ni low thermal expansion alloy containing 30 to 45% Ni, 1.5 to 6% Cr, 0.001 to less than 0.01% B, and the balance being Fe, which has excellent press formability and etching properties. 2 C0.009% or less, Si0.2% or less, Mn0.5% or less,
Ni30~45%, Co4% or less, Cr1.5~6%, B0.001
An Fe-Ni-based low thermal expansion alloy containing less than ~0.01% Fe, with the remainder being Fe, which has excellent press formability and etching properties. 3 C0.009% or less, Si0.2% or less, Mn0.5% or less,
Fe containing 30-45% Ni, 1.5-6% Cr, 0.001-less than 0.01% B, and 0.005-0.4% Ta, with the balance being Fe, which has excellent press formability and etching properties.
-Ni-based low thermal expansion alloy.