JP5316938B2 - Pure nickel sheet and method for producing pure nickel sheet - Google Patents

Description

  The present invention relates to a pure nickel thin plate and a method for producing the pure nickel thin plate, for example, a pure nickel thin plate for a conductive component for producing a pure nickel thin plate used as a conductive component such as an internal wiring of a rechargeable secondary battery, and its It relates to a manufacturing method.

  Pure nickel thin plates have excellent corrosion resistance, so rechargeable secondary batteries (lithium ion batteries, lithium polymer batteries, nickel metal hydride batteries, etc.) that are power sources for portable electronic devices (cell phones, notebook computers, etc.) Are used as conductive parts for internal wiring.

  As a material for such a pure nickel thin plate, a material in which burr generation and deformation are suppressed at the time of press working is required. From such a demand point, for example, as disclosed in Patent Document 1, C: 0 in mass%. 0.03% or less, Si: 0.01% or less, Mn: 0.04% or less, the balance being substantially made of nickel, and a nickel material having a total amount of oxygen and nitrogen of 100 ppm or less is used.

By the way, this kind of pure nickel thin plate needs a certain degree of hardness in order to obtain the strength of a portable electronic device or the like.
On the other hand, pure nickel sheet is required to have a stable shape when molded as a component in order to reduce the size and weight of portable electronic devices, etc. Back is likely to occur, and shape stability in press molding is deteriorated. This is a phenomenon that occurs because the ratio YR (= YS / TS) of the yield strength (YS) to the tensile strength (TS) increases. In the case of the same tensile strength (TS), the shape stability is improved if YR decreases. Will be better.

  From this point of view, conventionally, as a manufacturing method of a pure nickel thin plate, first, a pure nickel plate is prepared by first melting a pure nickel and casting it with a mold to form a slab, and then hot rolling the slab to form a pure nickel plate. A hot rolling step to be formed, and a cold rolling step in which cold rolling and annealing (for example, about 800 to 1000 ° C.) of the hot-rolled pure nickel plate are repeatedly performed to thin the pure nickel plate, In order to adjust the hardness and thickness of the pure nickel rolled material after the final sinter, the temper rolling process is performed to form a pure nickel sheet by cold rolling (temper rolling) under light pressure (Patent Document 2).

Further, as a manufacturing method, from the viewpoint of improving solder wettability, impurities in the surface and the surface layer portion are obtained by heat-treating pure nickel at a predetermined temperature not higher than the recrystallization temperature of pure nickel after the temper rolling. There has also been proposed a method including a low-temperature treatment step for removing (Patent Document 3).
This low-temperature treatment step is performed at a temperature lower than the recrystallization temperature of nickel, that is, a sufficiently low temperature that does not change the mechanical properties, so that impurities can be removed without changing the hardness before and after the treatment. Can do.

JP 2003-89835 A Japanese Patent No. 3741311 JP 2005-82886 A

  However, according to the conventional method for producing pure nickel sheet, in order to produce pure nickel sheet with the same thickness and various hardness, prepare various thickness of intermediate material of pure nickel according to the hardness. Therefore, there is a problem that it takes time and cost in material management.

  In addition, the conventional method for producing a pure nickel thin plate has anisotropy in mechanical strength, restricts the press punching direction, impedes freedom of component design, and deteriorates the product yield. There is also a problem.

  Accordingly, in view of the above problems, the present invention is a production of a pure nickel sheet having an appropriate mechanical strength and excellent shape stability, and a pure nickel sheet having an appropriate hardness and excellent shape stability. It is an object of the present invention to provide a method for producing a pure nickel thin plate that can reduce labor and cost and has a good product yield.

In the present invention, the Vickers hardness HV0.3 is in the range of 100 to 200, and the tensile strength T.D. S. 0.2% proof stress Y. S. It is an object of the present invention to provide a pure nickel thin plate characterized in that the ratio R (= TS / YS) to the above satisfies the condition of the following formula (1).
R> 3.0-0.01 × HV0.3 (1)

According to such a pure nickel thin plate, the Vickers hardness HV0.3 is in the range of 100 to 200 and has an appropriate hardness. S. 0.2% proof stress Y. S. When the ratio R to the above satisfies the above formula (1), T.I. S. Y. S. Becomes relatively low, the spring back of press formation is suppressed, and the shape stability is improved.
The reason for this is not clear, but by performing heat treatment at 600 to 800 ° C. after cold rolling, recrystallization occurs partially, resulting in a structure in which recrystallized grains and non-recrystallized grains are mixed. In such a structure, an appropriate hardness is imparted by the non-recrystallized portion, and the recrystallized portion easily deforms during processing. S. Y. S. Is relatively low, and it is presumed that springback is suppressed.

In addition, Vickers hardness HV0.3 in this invention measures a load by 300g based on a Vickers hardness test-test method (JISZ2244).
Further, the tensile strength T.I. S. And 0.2% proof stress Y. S. Is measured according to a metal material tensile test method (JIS Z 2241) using a JIS 13B test piece according to a metal material tensile test piece (JIS Z 2201).

Further, the present invention provides a thickness adjusting step of adjusting the thickness of the pure nickel plate by cold rolling the pure nickel plate at a reduction rate of 30% or more, and the obtained pure nickel thin plate has a Vickers hardness of HV0.3. Is in the range of 100 to 200 and tensile strength T.sub. S. 0.2% proof stress Y. S. The pure nickel plate whose thickness was adjusted by the thickness adjusting step so that the ratio R (= TS / YS.) To the condition of the following formula (1) was satisfied was heat treated at 600 to 800 ° C. Then, a hardness adjustment step of reducing and adjusting the hardness of the pure nickel plate is performed to form a pure nickel thin plate, and a method for producing a pure nickel thin plate is provided.
R> 3.0-0.01 × HV0.3 (1)

According to such a method for producing a pure nickel sheet, it is possible to omit the temper rolling process, which was conventionally essential, by adjusting the hardness of the pure nickel sheet by heat treatment. And cost can be reduced.
Further, according to the method for producing a pure nickel thin plate, by adjusting the hardness in the hardness adjusting step after adjusting the thickness in the thickness adjusting step, it is not necessary to prepare pure nickel plates of various thicknesses. In both cases, it is possible to adjust the hardness to a desired level by heat treatment, and therefore labor and cost can be reduced in preparing a pure nickel plate.
Further, according to such a method for producing a pure nickel thin plate, by adjusting the hardness in the hardness adjusting step, a pure nickel thin plate that has an appropriate hardness and hardly generates a springback, that is, has an appropriate hardness. In addition, a pure nickel thin plate having excellent shape stability can be produced.
Moreover, the pure nickel thin plate manufactured by such a method of manufacturing a pure nickel thin plate has the same degree of hardness as the pure nickel thin plate, and has a springback as compared with the pure nickel thin plate manufactured by temper rolling. Not likely to occur. The reason for this is not clear, but heat treatment at 600 to 800 ° C. causes partial recrystallization in the pure nickel thin plate, and can have an appropriate hardness in the portion where recrystallization has not occurred. It is thought that springback is less likely to occur.
In addition, according to such a method for producing a pure nickel sheet, it is possible to suppress the occurrence of mechanical strength anisotropy in the produced pure nickel sheet by performing a heat treatment after the final cold rolling. Therefore, it is possible to manufacture a pure nickel thin plate having a good product yield.

In addition, the pure nickel used by this invention is a nickel material whose nickel content is 95 mass% or more.
Moreover, the value of the temperature of the heat treatment in the present invention means the highest temperature reached in the heat treatment.

  As described above, according to the present invention, it is possible to reduce labor and cost, and it is possible to produce a pure nickel thin plate having an appropriate hardness, excellent shape stability, and good product yield. The manufacturing method of the pure nickel thin plate which can be provided can be provided. Moreover, it is possible to provide a pure nickel sheet having an appropriate hardness and excellent shape stability.

  Hereinafter, an embodiment of the present invention will be described.

The pure nickel thin plate according to the present embodiment has a Vickers hardness HV0.3 in the range of 100 to 200.
When pure nickel is cold-rolled, the hardness is improved as compared with that before cold rolling, and the Vickers hardness HV0.3 can usually be improved to about 200. On the other hand, when pure nickel is completely annealed, the Vickers hardness HV0.3 decreases to about 80. In the present invention, after adjusting the hardness within this range, problems in processing such as spring back are prevented.
Therefore, as the hardness of the pure nickel thin plate according to the present embodiment, one having a Vickers hardness HV0.3 of 100 to 200 can be suitably employed.
About this hardness, it can adjust easily by heat-processing the pure nickel rolling material which is an intermediate material of the manufacturing process of a pure nickel thin plate at 600-800 degreeC in the hardness adjustment process mentioned later.

The pure nickel thin plate according to the present embodiment has a tensile strength T.D. S. 0.2% proof stress Y. S. R (= TS / YS) satisfies the condition of the following formula (1).
R> 3.0-0.01 × HV0.3 (1)
A pure nickel thin plate satisfying the above formula (1) is less likely to cause a springback than a conventional material.

Next, the manufacturing method of the pure nickel thin plate which concerns on this embodiment is demonstrated.
The method for producing a pure nickel thin plate according to the present embodiment is a method for producing the above pure nickel thin plate.

  The method for producing a pure nickel thin plate according to the present embodiment includes a thickness adjusting step of adjusting the thickness of the pure nickel plate by cold rolling the pure nickel plate at a reduction rate of 30% or more, and the thickness adjusting step. This is a method of forming a pure nickel thin plate by performing a hardness adjustment step of reducing and adjusting the hardness of the pure nickel plate by heat-treating the pure nickel plate having the adjusted thickness at 600 to 800 ° C.

As a pure nickel plate used in the thickness adjusting step, a nickel plate having a nickel content of 95% by mass or more is used.
The pure nickel plate is preferably one having a nickel content of 99% by mass or more, and specifically, an ordinary carbon nickel plate (alloy number: NW2200) (Ni) defined in JIS H4551. : 99 mass% or more, C: 0.15 mass% or less, Cu: 0.2 mass% or less, Fe: 0.4 mass% or less, Mn: 0.3 mass% or less, S: 0.010 mass% or less , Si: 0.3% by mass or less), low carbon nickel plate (alloy number: NW2201) (Ni: 99% by mass or more, C: 0.02% by mass or less, Cu: 0.2% by mass or less, Fe: 0.4 mass% or less, Mn: 0.3 mass% or less, S: 0.010 mass% or less, Si: 0.3 mass% or less) are used. When the nickel content is 99% by mass or more, the formed pure nickel thin plate has low electrical resistance and excellent corrosion resistance against the battery electrolyte solution. It is suitable as a lead part.
Examples of the thickness of the pure nickel plate include 0.04 to 2.5 mm, and more specifically 0.07 to 1.5 mm.

The rolling reduction in the thickness adjusting step is 30% or more. If the rolling reduction is less than 30%, the hardness of the pure nickel plate whose thickness has been adjusted is too small, and it may be difficult to adjust the hardness to a desired value in the hardness adjustment step performed after the pressure adjustment step. There is.
Further, the rolling reduction is preferably 50% or more, and more preferably 70% or more. When the rolling reduction is 50% or more, the range in which the hardness can be adjusted in the hardness adjusting step is widened. Therefore, it is possible to form pure nickel thin plates having various desired hardnesses from a single pure nickel plate whose thickness is adjusted. There is an advantage that productivity is improved.

  Examples of the thickness of the pure nickel plate adjusted in the thickness adjustment step include 0.03 to 0.25 mm, and more specifically 0.05 to 0.15 mm.

  Since the thickness of the pure nickel plate with the adjusted thickness can be the thickness of the pure nickel thin plate as it is, the thickness of the pure nickel thin plate is adjusted by adjusting the thickness of the pure nickel plate in the thickness adjustment process. can do.

The hardness adjustment step is a step of adjusting the pure nickel plate whose thickness has been adjusted by the thickness adjustment step by reducing the hardness of the pure nickel plate by heat treatment in a processing furnace at 600 to 800 ° C.
In the hardness adjusting step, a continuous annealing furnace is generally used in which processing is performed by continuously passing a pure nickel plate. Hereinafter, a continuous annealing furnace will be described as an example.

Specifically, in the hardness adjusting step, first, a mixed gas of hydrogen and nitrogen (for example, H ₂ : N ₂ = 1: 3 in terms of molar ratio) is introduced into the heating zone of the continuous annealing furnace. The inside of the tropics has a non-oxidizing atmosphere. By making the inside of the heating zone non-oxidizing atmosphere, it becomes difficult for an oxide film to form on the surface of the pure nickel plate. Therefore, a pure nickel thin plate with good surface quality without the descaling treatment to treat such an oxide film. Can be formed.

Next, the pure nickel plate produced in the thickness adjusting step is heated at 600 to 800 ° C. (holding temperature).
In the hardness adjustment step, the heat treatment holding time is 120 seconds or less. According to the present embodiment, a pure nickel thin plate that has an appropriate hardness and hardly generates a springback can be produced by this process. The holding time of the heat treatment is preferably 30 seconds or less, more preferably 0 seconds (the temperature starts to be lowered as soon as the target set temperature is reached).
In the present embodiment, the heat treatment holding time means the time for holding at the highest temperature reached.

The temperature increase rate of the heat treatment in the hardness adjusting step is not particularly limited as long as it can reach a predetermined heat treatment temperature because it does not affect the hardness of the pure nickel plate.
In the hardness adjusting step, the rate of temperature increase of the heat treatment is, for example, 10 to 80 ° C./second, more specifically 20 to 50 ° C./second.

  Thereafter, the pure nickel thin plate is cooled to 400 ° C. or lower, preferably 200 ° C. using nitrogen gas in a cooling zone.

  The pure nickel thin plate according to the present embodiment and the method for manufacturing the pure nickel thin plate according to the present embodiment have the above-described advantages due to the above-described configuration. However, the pure nickel thin plate according to the present invention and the book The manufacturing method of the pure nickel thin plate which concerns on invention is not limited to the said structure, A design change is possible suitably.

  For example, in the method for producing a pure nickel thin plate according to this embodiment, a mixed gas of hydrogen and nitrogen is used to make the inside of the heating zone non-oxidizing atmosphere in the hardness adjustment step. In the method for producing a pure nickel thin plate, an inert gas such as argon, a gas obtained by combining one kind or two or more kinds of hydrogen and nitrogen may be used.

Further, in the method for producing a pure nickel sheet according to the present embodiment, the inside of the heating zone is made non-oxidizing atmosphere in the hardness adjusting step. However, in the method for producing a pure nickel sheet according to the present invention, It may be omitted to make the atmosphere non-oxidizing. In that case, descaling is performed after the hardness adjustment step.
The descaling process is a process in which the surface of the pure nickel thin plate is washed with an acid such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, acetic acid after the hardness adjustment step.

  Next, the present invention will be described more specifically with reference to examples and comparative examples.

(Preparation of test piece)
A pure nickel plate (99.65 mass% nickel) having a thickness of 0.786 mm was cold-rolled to 0.125 mm (reduction ratio 84%), and the cold-rolled pure nickel was cut into 30 mm × 70 mm and a test piece Was made.

(Test Example 1)
This test piece was heat-treated in an infrared heat treatment furnace. In this heat treatment, first, the inside of the heating zone of this heat treatment furnace is vacuum degassed, and a mixed gas of hydrogen and nitrogen (in terms of molar ratio, H ₂ : N ₂ = 1: 3) is introduced inside the heating zone. Thus, the inside of the heating zone was made a non-oxidizing atmosphere. Next, the test piece is heated in this heat treatment furnace at a heating rate of 25 ° C./second and is held at 700 ° C. (holding temperature) for 1 second (holding time). Then, the test piece was cooled to 200 ° C., the inside of the heating zone was opened to the atmosphere, the test piece was taken out and cooled to room temperature, and a pure nickel thin plate of Test Example 1 was produced.
The temperature of the test piece was measured directly by welding a thermocouple to the center of the upper surface of the test piece.

(Test Examples 2 to 6)
Except for heating at holding times of 4 seconds, 7 seconds, 15 seconds, 20 seconds, and 30 seconds, pure nickel thin plates of Test Examples 2 to 6 prepared in the same manner as the pure nickel thin plate of Test Example 1 were obtained.

(Test Examples 7 to 12)
Each of the holding times of 1 second, 4 seconds, 7 seconds, 15 seconds, 20 seconds, and 30 seconds, except that the holding temperature was 720 ° C. Each pure nickel sheet was obtained.

The Vickers hardness HV0.3 of each of the pure nickel thin plates of Test Examples 1 to 12 was measured.
In addition, Vickers hardness HV0.3 was based on the Vickers hardness test-test method (JIS Z 2244), and measured the load at 300 g.

  FIG. 1 shows Vickers hardness HV0.3 with respect to holding time at each holding temperature (700 ° C., 720 ° C.).

  As shown in FIG. 1, the lower the heat treatment temperature, the longer the holding time until the same hardness is reached (lowered to the same hardness). By selecting an appropriate temperature and an appropriate time, Nickel can be obtained.

Further, for the purpose of investigating the influence of the heating rate, the Vickers hardness HV0.3 was measured for a pure nickel thin plate produced in the same manner as in Test Examples 1 to 12 except that the heating rate was 50 ° C./second. A result similar to the result shown in FIG. 1 was obtained.
Further, when the Vickers hardness HV0.3 was measured for the pure nickel thin plate produced in the same manner as in Test Examples 1 to 12 except that the rolling rate was 40 and 50%, the same result as the result shown in FIG. 1 was obtained. was gotten.

The pure nickel thin plate of an example was produced by adjusting the Vickers hardness HV0.3 of the obtained pure nickel thin plate to be in the range of 100 to 215 by the same production method as the pure nickel thin plate of the above test example. Tensile strength of this pure nickel sheet S. , And 0.2% yield strength Y. S. Was measured. The results are shown in FIG. 2 (indicated by “●” or “◯” in FIG. 2).
Further, as a conventional example, a pure nickel thin plate of a comparative example was prepared by adjusting the Vickers hardness HV0.3 of a pure nickel thin plate obtained by temper rolling after final annealing to be in the range of 80 to 180. Tensile strength of this pure nickel sheet S. , And 0.2% yield strength Y. S. Was measured. This result is also shown in FIG. 2 (indicated by “■” in FIG. 2).
The tensile strength T.I. S. And 0.2% proof stress Y. S. Was measured according to a metal material tensile test method (JIS Z 2241) using a JIS 13B test piece based on a metal material tensile test piece (JIS Z 2201).

  As shown in FIG. 2, the pure nickel thin plate of the example (indicated by “●”) has a higher R and excellent shape stability than the pure nickel thin plate of the conventional method (comparative example) having the same hardness. I understand that.

The relationship figure of holding time and Vickers hardness HV0.3 in each holding temperature (700 degreeC, 720 degreeC). Vickers hardness HV0.3 and tensile strength T. S. 0.2% proof stress Y. S. FIG.

Claims (2)

Vickers hardness HV0.3 is in the range of 100 to 200, and tensile strength T. S. 0.2% proof stress Y. S. A pure nickel thin plate characterized in that a ratio R (= TS / YS) to the condition of the following formula (1) is satisfied:
R> 3.0-0.01 × HV0.3 (1) A thickness adjusting step for adjusting the thickness of the pure nickel plate by cold rolling the pure nickel plate at a reduction rate of 30% or more, and a Vickers hardness HV0.3 of 100 to 200 for the obtained pure nickel thin plate And tensile strength in the tensile test. S. 0.2% proof stress Y. S. The pure nickel plate whose thickness was adjusted by the thickness adjusting step so that the ratio R (= TS / YS.) To the condition of the following formula (1) was satisfied was heat treated at 600 to 800 ° C. And a hardness adjusting step for reducing and adjusting the hardness of the pure nickel plate to form a pure nickel thin plate.
R> 3.0-0.01 × HV0.3 (1)

Images