Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/12—Electroplating: Baths therefor from solutions of nickel or cobalt
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/48—After-treatment of electroplated surfaces
  • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
  • B21B37/16—Control of thickness, width, diameter or other transverse dimensions
  • B21B37/165—Control of thickness, width, diameter or other transverse dimensions responsive mainly to the measured thickness of the product
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/013—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium
  • B32B15/015—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium the said other metal being copper or nickel or an alloy thereof
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/26—Methods of annealing
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0236—Cold rolling
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/48—After-treatment of electroplated surfaces
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/34—Pretreatment of metallic surfaces to be electroplated
  • C25D5/36—Pretreatment of metallic surfaces to be electroplated of iron or steel

Definitions

• the present invention relates to a method for manufacturing a rolled surface-treated steel sheet and a rolled surface-treated steel sheet.
• nickel-plated steel foil has been known as a material for members constituting batteries and components constituting electronic-related equipment.
• a diffusion alloy layer containing nickel and iron is formed on the steel plate, and the texture of the diffusion alloy layer is further controlled.
• a method has been adopted in which a nickel-plated steel sheet is subjected to cold rolling at a high reduction rate to obtain a nickel-plated steel foil.
• Patent Document 1 discloses that a steel plate with nickel plating is annealed to cause Ni in the plating and Fe in the steel plate to interdiffuse, and then cold rolled at a cumulative reduction rate of 70% or more to reduce the thickness to 100 ⁇ m or less.
• the present disclosure discloses a method for producing steel foil in which a specific texture is formed on the surface layer.
• Steel foil obtained not only by the above manufacturing method but also by conventional manufacturing methods has the following problems.
• the plating layer portion cracks due to elongation, exposing the base iron, and causing highly corrosive, for example alkaline, There was a concern that it would elute into the electrolyte.
• the foil is passed between sheet rolls multiple times on the production line, and there has been a need for a steel foil that can prevent damage to the foil surface during this process.
• the present invention has been made in view of solving the above problems, and it is possible to suppress the occurrence of cracks even when elongated while maintaining the hardness of the surface, and to suppress the occurrence of cracks in the drawing roll. It is an object of the present invention to provide a method for manufacturing a rolled surface-treated steel sheet that improves the threadability when the steel sheet is passed between rollers and rolling rolls.
• the method for manufacturing a rolled surface-treated steel sheet in this embodiment includes (1) an iron-nickel alloy layer forming step of forming an iron-nickel alloy layer on a steel sheet serving as a base material; After the step, there is a rolling step of rolling the steel plate having the iron-nickel alloy layer at a reduction rate of 5 to 25%.
• the iron-nickel alloy layer forming step includes a nickel plating step of forming a nickel plating layer on the steel plate serving as the base material, and a heat treatment on the nickel-plated material obtained in the nickel plating step.
• the method preferably includes a heat treatment step of applying and diffusing the iron-nickel alloy layer to form the iron-nickel alloy layer.
• the rolled surface-treated steel sheet in this embodiment includes (3) a base material made of steel, and an iron-nickel alloy layer provided on the base material,
• the layer contains Fe 1 Ni 1 , has an orientation index of 0.7 or more in X-ray diffraction of the (200) plane of Fe 1 Ni 1 , and has an orientation index of 0.7 or more in the X-ray diffraction of the (220) plane of Fe 1 Ni 1 . It is characterized by an orientation index of 0.7 or more and less than 2.5.
• the average crystal grain size of nickel obtained by EBSD measurement on the surface of the iron-nickel alloy layer is 0.4 ⁇ m to 1.1 ⁇ m.
• the difference (absolute value ) between the orientation index in X-ray diffraction of the (200) plane of Fe 1 Ni 1 and the orientation index in X-ray diffraction of the (220) plane ) is preferably 1.0 or less.
• the orientation index of the (111) plane of the Fe 1 Ni 1 in X-ray diffraction is 0.3 to 2.0.
• the present invention it is possible to provide a method for manufacturing a rolled surface-treated steel sheet, which suppresses the occurrence of cracks even in a state where elongation is applied while maintaining hardness, and improves threadability.
• FIG. 1 is a flowchart showing a method for manufacturing a rolled surface-treated steel sheet according to the present embodiment.
• FIG. 2 is a schematic diagram showing a method for measuring hydrogen permeation current density of a rolled surface-treated steel sheet according to the present embodiment.
• FIG. 2 is a schematic diagram showing a method for measuring hydrogen permeation current density of a rolled surface-treated steel sheet according to the present embodiment.
• FIG. 2 is a schematic diagram showing a method for measuring hydrogen permeation current density of a rolled surface-treated steel sheet according to the present embodiment.
• FIG. 1 is a schematic diagram showing a cross section of a rolled surface-treated steel sheet of the present embodiment.
• FIG. 2 is a schematic diagram showing how to determine the thickness of an iron-nickel alloy layer included in the rolled surface-treated steel sheet of the present embodiment. It is a schematic diagram which shows the cross section of the rolled surface-treated steel plate in the modification of this embodiment.
• the method for manufacturing a rolled surface-treated steel sheet of the present embodiment includes an iron-nickel alloy layer forming step of forming an iron-nickel alloy layer on a steel sheet (original sheet) serving as a base material, and After the layer forming step, the method includes a rolling step of rolling the steel plate having the iron-nickel alloy layer at a reduction rate of 5 to 25%.
• the original plate herein refers to a portion of steel that will become a base material on which an iron-nickel alloy layer will be formed in the iron-nickel alloy layer forming step described later.
• the original plate is preferably made of low carbon steel or extremely low carbon steel.
• a low carbon hot rolled steel plate (hot coil) of about 2.0 mm to 3.0 mm is descaled by a known pickling method.
• rolling is performed using a known cold rolling method at a reduction rate of 60% or more to obtain a cold rolled steel plate with a thickness of about 0.16 mm to 1.2 mm, and then subjected to known continuous annealing to remove work hardening and soften it. I do.
• intermediate rolling makes it possible to obtain an original sheet with a desired thickness. Note that the preliminary steps for obtaining the original plate are not limited to those described above.
• the thickness of the original plate is not particularly limited and is in the range of 0.03 mm to 0.8 mm.
• the thickness is preferably 30 ⁇ m to 190 ⁇ m.
• an iron-nickel alloy layer is formed on the original plate (iron-nickel alloy layer forming step), and then the steel plate having the iron-nickel alloy layer is rolled down.
• rolling step By rolling at a rate of 5 to 25% (rolling step), it is possible to manufacture the rolled surface-treated steel sheet of this embodiment.
• ⁇ Iron-nickel alloy layer formation process As the iron-nickel alloy layer forming process of this embodiment, a nickel plating layer is formed on a steel plate as a base material (nickel plating process), and then the nickel plating material obtained in the nickel plating process is heat treated and diffused. A method of forming an iron-nickel alloy layer (heat treatment step) can be mentioned.
• Nickel plating bath (Watt bath) and plating conditions]
• ⁇ Bath composition Nickel sulfate hexahydrate: 200-300g/L Nickel chloride hexahydrate: 20-60g/L Boric acid: 10-50g/L Bath temperature: 40-70°C pH: 3.0-5.0
• Stirring Air stirring or jet stirring Current density: 5 to 30 A/dm 2
• a known nickel sulfamate bath or citric acid bath may be used.
• additives such as known brighteners may be added to the plating bath to produce bright nickel plating or semi-bright nickel plating, but in order to avoid hardening of the nickel film, matte nickel plating that does not contain sulfur-containing brighteners is possible. Nickel plating or semi-bright nickel plating is preferred.
• the amount of nickel deposited in the nickel plating layer or iron-nickel alloy plating layer formed on the steel sheet is determined from the viewpoint of cost and electrolyte resistance of the rolled surface-treated steel sheet obtained.
• the amount per side is preferably 0.89 g/m 2 to 28.1 g/m 2 , more preferably 0.93 g/m 2 to 26.7 g/m 2 .
• Heat treatment process Regarding the heat treatment process in this embodiment, heat is applied to the nickel layer formed on the original plate to cause the iron of the original plate and nickel of the nickel layer to interdiffuse, and to form an iron-nickel alloy layer by thermal diffusion.
• the heat treatment step of this embodiment may be continuous annealing or batch annealing (box annealing).
• Continuous annealing is preferably carried out at a temperature and time of 650° C. to 950° C. and a soaking time of 15 seconds to 150 seconds. If the temperature is lower than this or the time is shorter than this, there is a possibility that a sufficient iron-nickel alloy layer 30 cannot be obtained, which is not preferable. On the other hand, heat treatment at a higher temperature or for a longer time than the above-mentioned range is not preferable because the mechanical properties of the base material, such as steel foil, will change significantly, resulting in a significant decrease in strength, or from a cost perspective.
• An example of temperature and time for batch annealing is 450°C to 690°C with a soaking time of 1.5 to 20 hours, and a total time of heating, soaking, and cooling times. It is preferable to carry out the treatment within the range of 4 hours to 80 hours. If the temperature is lower than this or the time is shorter than this, there is a possibility that a sufficient iron-nickel alloy layer 30 cannot be obtained, which is not preferable. On the other hand, if the heat treatment is performed at a higher temperature or for a longer time than the above-mentioned range, the mechanical properties of the base material, such as steel foil, may change significantly, resulting in a significant decrease in strength, or from a cost perspective. Undesirable.
• the rolling process in this embodiment is a process of cold rolling the steel plate on which the iron-nickel alloy layer has been formed after passing through the iron-nickel alloy layer forming process. This rolling process is performed to obtain the desired thickness of the rolled surface-treated steel sheet, to control the metal crystals contained in the iron-nickel alloy layer to a favorable state, and to improve the cracking resistance of the resulting rolled surface-treated steel sheet.
• the purpose is to improve sexuality, etc.
• the rolling reduction rate in the rolling process of this embodiment is characterized by being 5 to 25%.
• the orientation of both the (200) plane and the (220) plane can be properly adjusted to the crystal grains of the iron-nickel alloy (Fe 1 Ni 1 ) contained in the iron-nickel alloy layer. It is thought that a mixed state can be created.
• the orientation index in X-ray diffraction (XRD) is changed to the orientation index in X-ray diffraction of the (200) plane of Fe 1 Ni 1 (hereinafter also referred to as the orientation index of the (200) plane).
• the orientation index in X-ray diffraction of the (220) plane of Fe 1 Ni 1 (hereinafter also referred to as the orientation index of the (220) plane) is 0.7 or more and less than 2.5. It is preferable. Furthermore, the difference (absolute value) between the orientation index in X-ray diffraction of the (200) plane of Fe 1 Ni 1 and the orientation index in X-ray diffraction of the (220) plane of Fe 1 Ni 1 may be 1.0 or less. preferable.
• the rolling process of this implementation process improves the cracking resistance while maintaining the appropriate surface hardness of the obtained rolled surface-treated steel sheet by controlling the crystalline state of the iron-nickel alloy as described above. is considered possible.
• the upper limit of the rolling reduction in the rolling process is 25%.
• the average crystal grain size of nickel is set to 0.4 ⁇ m to 1.1 ⁇ m according to electron beam backscatter diffraction (EBSD) measurement data by the rolling process of the present embodiment.
• EBSD electron beam backscatter diffraction
• the average crystal grain size measured by electron beam backscatter diffraction (EBSD) can be obtained using a known measuring device and measuring program.
• the average crystal grain size can be obtained by obtaining and analyzing information on a diffraction pattern called a Kikuchi pattern under the following conditions.
• the average crystal grain of nickel based on the EBSD measurement data in the present invention
• the diameter is the average crystal grain size of nickel crystals, iron-nickel alloy crystals, or nickel crystals and iron-nickel alloy crystals.
• the crystal orientation of the nickel alloy is moderately adjusted to both the (200) plane and the (220) plane.
• the average crystal grain size of nickel can be controlled in the range of 0.4 ⁇ m to 1.1 ⁇ m based on the EBSD measurement data as described above by making the nickel exist in the nickel and applying processing strain. It is considered that by setting the average grain size within this range, it is possible to suppress an increase in the coefficient of friction on the surface of the resulting rolled surface-treated steel sheet. Furthermore, it is considered possible to set the hardness of the outermost surface of the resulting rolled surface-treated steel sheet and the intermediate layer between the base material and the outermost surface within an appropriate range.
• the number of rolling rolls that act in the rolling process of this embodiment may be one set or multiple sets.
• a rolling mill is usually constructed by combining a plurality of upper and lower rolls that directly act to thin the sheet, that is, rolling rolls, and rolls for threading the sheet. During rolling, a single set of rolling rolls may act, or a plurality of rolling rolls may act.
• the number of rolling rolls that act in the rolling process may be one set or multiple sets, or, for example, three sets of rolling rolls may be passed through twice for a total of six sets of rolling rolls. good. Generally, as the number of passes through the rolling rolls increases, problems due to work hardening tend to occur during rolling.
• the number of rolling rolls acting on the rolling is 6 or less, more preferably 3 or less, and the number may be 2 or 1.
• one set of rolling rolls herein refers to the upper and lower rolls that directly touch the plate and whose thickness changes before and after the rolls.
• the above-mentioned rolling reduction ratio refers to the rolling reduction ratio obtained from the thickness of the plate before and after the rolling process. In other words, when the sheet is passed through three sets of rolling rolls twice, the rolling reduction is determined from the thickness before the first passing and the thickness after the second passing.
• the rolling reduction ratio is more preferably 10 to 20% from the viewpoint of improving the cracking resistance and threadability of the rolled surface-treated steel foil.
• the rolling reduction rate by the first set of rolling rolls is not particularly limited.
• a rolled surface-treated steel sheet After the rolling process, a rolled surface-treated steel sheet can be obtained.
• the amount of nickel deposited on the obtained rolled surface-treated steel sheet is preferably 0.89 g/m 2 to 26.7 g/m 2 per side.
• the rolled surface-treated steel sheet 1 of this embodiment includes a base material 20 made of steel, and an iron-nickel alloy layer 30 provided on the base material 20.
• the base material 20 constituting the rolled surface-treated steel sheet 1 of this embodiment is preferably an iron-based steel sheet containing less than 1.0% by weight of Cr and other additional metal elements.
• low carbon steel represented by low carbon aluminum killed steel (carbon content 0.01 to 0.15% by weight), ultra-low carbon steel with carbon content less than 0.01% by weight, or ultra-low carbon steel A non-aging ultra-low carbon steel made by adding Ti, Nb, etc. to the steel is preferably used.
• the thickness of the base material 20 constituting the rolled surface-treated steel sheet 1 of this embodiment is preferably in the range of 0.03 mm to 0.8 mm, and more preferably in the range of 0.03 mm to 0.15 mm.
• the thickness of the base material 20 is suitably measured by cross-sectional observation using an optical microscope or a scanning electron microscope (SEM).
• the iron-nickel alloy layer 30 included in the rolled surface-treated steel sheet 1 of the present embodiment is an alloy layer containing iron (Fe) and nickel (Ni), and is an alloy consisting of iron and nickel ("iron-nickel alloy", " This is a metal layer containing a Fe--Ni alloy (also referred to as "Fe--Ni alloy”).
• the state of the alloy consisting of iron and nickel may be any of a solid solution, eutectoid/eutectic, and compound (intermetallic compound), or they may coexist.
• the iron-nickel alloy layer 30 included in the rolled surface-treated steel sheet 1 of this embodiment may contain other metal elements or unavoidable impurities as long as the problems of the present invention can be solved.
• the iron-nickel alloy layer 30 may contain metal elements such as cobalt (Co) and molybdenum (Mo), and additive elements such as boron (B).
• the proportion of metal elements other than iron (Fe) and nickel (Ni) in the iron-nickel alloy layer 30 is preferably 10% by weight or less, more preferably 5% by weight or less, and still more preferably 1% by weight or less. preferable. Since the iron-nickel alloy layer 30 may be a binary alloy consisting essentially only of iron and nickel, the lower limit of the content ratio of other metal elements excluding unavoidable impurities is 0%.
• the type and amount of other metal elements contained can be measured by known means such as an X-ray fluorescence (XRF) measurement device or GDS (glow discharge emission surface analysis).
• XRF X-ray fluorescence
• GDS low discharge emission surface analysis
• the above-mentioned iron-nickel alloy layer 30 contains Fe 1 Ni 1 , and the orientation index in X-ray diffraction of the (200) plane of Fe 1 Ni 1 is 0.7.
• the orientation index in X-ray diffraction of the (220) plane of Fe 1 Ni 1 is 0.7 or more and less than 2.5.
• the difference (absolute value) between the orientation index in the X-ray diffraction of the (200) plane of Fe 1 Ni 1 and the orientation index in the X-ray diffraction of the (220) plane of Fe 1 Ni 1 is 1.0 or less. preferable.
• the above orientation index can be achieved by applying rolling to the iron-nickel alloy layer 30. It is considered that the above-mentioned orientation index makes it possible to improve the cracking resistance and threadability while maintaining the appropriate hardness of the surface of the rolled surface-treated steel sheet 1. Furthermore, by providing a random orientation in which (200) planes and (220) planes are appropriately mixed, it is possible to lengthen the passage (route) of hydrogen between crystals, and it is thought that excellent hydrogen barrier properties are achieved. From the viewpoint of maintaining appropriate hardness, cracking resistance, and improving sheet passability, the orientation index of the (220) plane is preferably 0.7 or more and less than 2.0, more preferably 0.7 or more and less than 1. It is less than 9.
• the upper limit value of the (200) plane is preferably 2.0 or less, more preferably 1.7 or less. Further, from the viewpoint of obtaining more stable sheet threadability, it is more preferable that the difference (absolute value) between the orientation index of the (200) plane and the orientation index of the (220) plane is 0.8 or less, and 0. More preferably, it is .7 or less. Since the orientation index of the (200) plane and the orientation index of the (220) plane may have the same value, the lower limit value of the difference between them is 0.
• Crystal orientation index of X-ray diffraction of ( 200 ) plane of Fe 1 Ni 1 Ico_Fe 1 Ni 1 (200), and crystal orientation index of X-ray diffraction of (220) plane of Fe 1 Ni 1 Ico_Fe 1 Ni 1 (220) was defined and calculated using the following formula.
• the subscript "co” means crystal orientation.
• Ico_Fe 1 Ni 1 (200) [I_Fe 1 Ni 1 (200)/[I_Fe 1 Ni 1 (111)+I_Fe 1 Ni 1 (200)+I_Fe 1 Ni 1 (220)+I_Fe 1 Ni 1 (311)+I_Fe 1 Ni 1 (222)]] / [I S _Fe 1 Ni 1 (200) / [I S _Fe 1 Ni 1 (111) + I S _Fe 1 Ni 1 (200) + I S _Fe 1 Ni 1 (220) + I S _Fe 1 Ni 1 (311) + I S _Fe 1 Ni 1 (222)]]]
• Ico_Fe 1 Ni 1 (220) [I_Fe 1 Ni 1 (220)/[I_Fe 1 Ni 1 (111)+I_Fe 1 Ni 1 (200)+I_Fe 1 Ni 1 (220)+I_Fe 1 Ni 1 (311)+I_Fe 1 Ni 1 (222)]] / [I S _Fe 1 Ni 1 (220) / [I S _Fe 1 Ni 1 (111) + I S _Fe 1 Ni 1 (200) + I S _Fe 1 Ni 1 (220) + I S _Fe 1 Ni 1 (311) + I S _Fe 1 Ni 1 (222)]]]
• the diffraction intensity of each crystal plane of Fe 1 Ni 1 measured by X-ray diffraction is expressed as follows.
• Diffraction intensity of crystal plane I_Fe 1 Ni 1 (220): Fe 1 Ni 1 (220) measured by X-ray diffraction
• the diffraction intensity here refers to the diffraction intensity measured within the range of each diffraction angle (2 ⁇ ) ⁇ 0.11° described in JCPDS (Joint Committee on Powder Diffraction Standards, PDF card number: 01-071-8322). This is the maximum value of intensity (cps). Specifically, the (111) plane is 43.83° ⁇ 0.11°, the (200) plane is 51.05° ⁇ 0.11°, the (220) plane is 75.10 ⁇ 0.11, and the (311 ) plane is 91.23 ⁇ 0.11, and (222) plane is the maximum value in the range of 96.56 ⁇ 0.11.
• the iron-nickel alloy in the iron-nickel alloy layer 30 of the rolled surface-treated steel sheet 1 in this embodiment is Fe 1 Ni 1 (111) calculated in the same manner as above. It is preferable that the plane orientation index is 0.3 to 2.0. Although the details are unknown, it is thought that characteristics can be further improved by having a crystal orientation that is not biased towards the (111) plane in addition to the (200) plane and the (220) plane. More preferably, the orientation index of the Fe 1 Ni 1 (111) plane is 0.3 to 1.3. Further, it is preferable that the orientation index of the Fe 1 Ni 1 (111) plane is 0.3 to 1.0, or that the orientation index of the (111) plane is smaller than that of the (200) plane and the (220) plane.
• the inventors conducted measurements and evaluations, and found that in order to suppress the occurrence of voltage drop (self-discharge) as described above, the rolled surface-treated steel sheet of this embodiment is electrically It was concluded that the hydrogen permeation current density obtained from the chemically measured oxidation current value is preferably 10 ⁇ A/cm 2 or less.
• the measurement conditions for the hydrogen permeation current density in this embodiment are as follows: The temperature of the electrolytic solution is 45°C, and a current of 2.25 A is applied on the hydrogen intrusion side to a measurement area (28.26 cm 2 ) with a measurement diameter of 60 mm. , no current is applied to the hydrogen detection side. The reason why the current value on the hydrogen generation side was set to 2.25 A is to generate a sufficient amount of hydrogen necessary to permeate and move through the rolled surface-treated steel sheet.
• the hydrogen entry side is also referred to as the hydrogen generation side, and is the side on which the hydrogen storage alloy of the bipolar electrode structure is arranged.
• the hydrogen detection side is the opposite side to the hydrogen entry side, and is the positive electrode side of the bipolar electrode structure.
• Each measurement cell was filled with an electrolyte (alkaline aqueous solution containing 6 mol/L of KOH as a main component and having a total concentration of KOH, NaOH, and LiOH of 7 Mol/L), and the counter electrodes (CE1 and CE2) were immersed therein. ing. Platinum (Pt) is used for the counter electrode. Further, the temperature of the electrolytic solution is 45°C. Further, as shown in FIG. 2(b), the measured diameter of the rolled surface-treated steel sheet is ⁇ 60 mm (measured area 28.26 cm 2 ).
• a rectifier For current control on the hydrogen intrusion side, a rectifier is used as shown in FIG. 2(a).
• the rectifier for example, "Compact DC Stabilized Power Supply PMX18-5A” manufactured by Kikusui Electronics Co., Ltd. can be used.
• the current measurement on the hydrogen detection side uses an ammeter as shown in FIG. 2(a).
• the ammeter for example, "Digital Multimeter DT4282” manufactured by Hioki Electric Co., Ltd. can be used. Note that the sample of the rolled surface-treated steel sheet to be evaluated and the connection of each device can be performed as shown in FIG. 2(a).
• the hydrogen permeation current on the hydrogen detection side is measured using the apparatus shown in FIG. It was concluded that a rolled surface-treated steel sheet with a density of 10 ⁇ A/cm 2 or less is suitable for bipolar electrodes from the viewpoint of hydrogen barrier properties. From the viewpoint of further suppressing the voltage drop, it is more preferably 2.5 ⁇ A/cm 2 or less, further preferably 2.0 ⁇ A/cm 2 or less, particularly preferably less than 1.0 ⁇ A/cm 2 .
• the average crystal grain size of nickel according to electron beam backscatter diffraction (EBSD) measurement data is set to 0.4 ⁇ m to 1.1 ⁇ m. is preferred.
• the above average grain size can be achieved by applying rolling to the iron-nickel alloy layer 30.
• the average crystal grain size measured by electron beam backscatter diffraction (EBSD) can be obtained using a known measuring device and measuring program as described above. It is considered that by controlling the average grain size, it is possible to suppress an increase in the coefficient of friction on the surface of the rolled surface-treated steel sheet 1. Further, it is considered possible to set the hardness of the outermost surface of the rolled surface-treated steel sheet 1 and the intermediate layer between the base material and the outermost surface within an appropriate range.
• the surface hardness of the rolled surface-treated steel sheet 1 in this embodiment is 0 to 2.2 ⁇ m from the surface when measured using a micro Vickers hardness tester at a load of 10 g from the viewpoint of cracking resistance and scratch resistance.
• the hardness at depth is 120-230. More preferably 126-230, still more preferably 136-230.
• the hardness at a depth of 2.2 to 4.4 ⁇ m from the surface is preferably 110 to 200, more preferably 120 to 200, when measured under a load of 50 g.
• the friction coefficient in four rounds in a ball-on-disc friction test is 0.4 or less.
• the lower limit of the friction coefficient it is usually 0.05 or more.
• the sum of the friction coefficients at 0.5 lap pitch from 0 to 5 laps (hereinafter referred to as the friction coefficient up to 5 laps) (also referred to as the sum of coefficients) is preferably less than 4.0, more preferably less than 3.5, and still more preferably 3.1 or less. Note that there is no particular lower limit for the total sum of the friction coefficients up to five rounds, but it is usually 0.3 or more.
• the ball-on-disc friction test was conducted in accordance with JIS R 1613:2010 using a chrome steel ball (SUJ2) with a ball diameter of 6 mm as a contact, under the conditions of a rotation radius of 10 mm, a load of 1.0 N, and a motor speed of 10 rpm. , after conducting the test at a rotational speed of 10, the friction coefficient for four revolutions and the sum of the friction coefficients for up to five revolutions can be determined.
• SUJ2 chrome steel ball
• the thickness of the iron-nickel alloy layer 30 included in the rolled surface-treated steel sheet 1 of this embodiment is preferably 0.4 ⁇ m or more, more preferably 0.5 ⁇ m or more, and even more preferably 0.6 ⁇ m or more. .
• the thickness of the iron-nickel alloy layer 30 included in the rolled surface-treated steel sheet 1 of this embodiment is preferably 0.4 ⁇ m or more, more preferably 0.5 ⁇ m or more, and even more preferably 0.6 ⁇ m or more. .
• the thickness of the iron-nickel alloy layer 30 is preferably 3.5 ⁇ m or less, more preferably 3.0 ⁇ m or less.
• the thickness of the iron-nickel alloy layer 30 is calculated by analyzing the cross section of the rolled surface-treated steel sheet 1 using SEM-EDX (energy dispersive X-ray spectroscopy). Quantitative analysis of nickel and iron at depths up to 10 ⁇ m can be performed. If the thickness of the iron-nickel alloy layer exceeds 10 ⁇ m, quantitative analysis is performed to the required depth.
• SEM-EDX energy dispersive X-ray spectroscopy
• FIG. 4 An example of a method for obtaining the thickness of the iron-nickel alloy layer 30 from a graph obtained by SEM-EDX is shown.
• the horizontal axis represents the depth direction distance ( ⁇ m) from the surface layer side
• the vertical axis represents the X-ray intensity of Ni and Fe.
• the graph of FIG. 4 shows that the shallower portion in the thickness direction has a high nickel content and a low iron content.
• the iron content increases as the thickness increases.
• the distance between 2/10 of the respective maximum values of nickel and iron is defined as the iron-nickel alloy layer 30, and its thickness can be read from the graph. is possible.
• the reason why the thickness of the iron-nickel alloy layer 30 is defined as the distance between 2/10 of the maximum values of nickel and iron in this embodiment is as follows.
• the thickness of the iron-nickel alloy layer 30 is a predetermined thickness or more, but when the thickness of the iron-nickel alloy layer 30 is measured by SEM-EDX, it is difficult to measure the thickness of the iron-nickel alloy layer 30 using a sample that has not been heat-treated. It was found that even in samples where there is no iron diffusion, the iron strength at the position where the nickel strength peaks is detected at a value of about 10% to 20% of the nickel strength. Further, after the nickel strength attenuated, that is, in the measurement of the base material 20 portion, the nickel strength continued to be detected at a value of about 3 to 8% of the maximum nickel strength.
• the nickel strength at this time was also about 2% of the iron strength, and it did not fall below 1% even if measurements were continued over 2 ⁇ m after attenuation. In other words, it was found that nickel strength and iron strength are influenced by each other in a trace amount range in measurements by SEM-EDX. Therefore, in this specification, the thickness of the alloy layer that is more reliably formed into an alloy is defined as a range in which a strength of 2/10 or more of each maximum strength is detected.
• the iron-nickel alloy layer 30 is provided on one side of the base material 20 in FIG. 1, it is not limited to this, and it is preferable that it is provided on both sides of the base material 20, although not shown. Further, when iron-nickel alloy layers 30 are provided on both sides, the thickness of one iron-nickel alloy layer 30 may be the same as that of the other iron-nickel alloy layer 30, or may be different.
• the method for forming the iron-nickel alloy layer 30 is preferably plating or a method using plating and heat treatment, and examples of the plating include methods such as electrolytic plating, electroless plating, hot-dip plating, and dry plating. Among these, the method using electrolytic plating is particularly preferred from the viewpoint of cost, film thickness control, etc.
• a nickel plating layer is formed on at least one side of the base material 20 by a method such as electrolytic plating, and then iron (Fe) in the base material 20 and nickel (Ni) in the nickel plating layer are diffused by heat diffusion treatment or the like.
• examples include a method of forming an alloy by plating the metal, and a method of forming an alloy layer by iron-nickel alloy plating.
• nickel plating is applied, and iron and nickel are alloyed by interdiffusion through heat treatment.
• a nickel alloy layer is formed.
• the amount of nickel deposited in the iron-nickel alloy layer 30 is preferably 0.89 g/m 2 to 26.7 g/m 2 .
• the amount of nickel deposited on the iron-nickel alloy layer 30 can be measured by X-ray fluorescence analysis (XRF) or the like.
• the method described in International Publication No. WO2020/017655 and International Publication No. WO2021/020338 can be appropriately adopted. That is, it can be determined by measuring the total nickel amount of the rolled surface-treated steel sheet 1 using X-ray fluorescence analysis (XRF) or the like.
• XRF X-ray fluorescence analysis
• the overall thickness of the rolled surface-treated steel sheet 1 in this embodiment will be explained. Note that the "thickness of the rolled surface-treated steel sheet 1" in this embodiment may be measured by cross-sectional observation using a scanning electron microscope (SEM) or by using a micrometer.
• SEM scanning electron microscope
• the overall thickness of the rolled surface-treated steel sheet 1 in this embodiment is preferably in the range of 0.03 mm to 0.8 mm.
• it is more preferably 0.03 mm to 0.3 mm, and when used as a foil requiring better cracking resistance and threadability, 0.03 mm to 0.3 mm. 0.15 mm is more preferably used.
• the thickness range is exceeded, if the plate thickness is large, the surface load (such as elongation) against deformation during sheet passing becomes larger, which is not preferable, as the surface deformation increases.
• the thickness is less than the lower limit of the above thickness range, there is a high possibility that tears, tears, wrinkles, etc. will occur during handling, and when used as battery materials, there will be a risk of damage caused by battery charging and discharging. In some cases, it may be difficult to have sufficient strength.
• this embodiment may be a rolled surface-treated steel sheet 2 in which a metal layer 40 is formed on an iron-nickel alloy layer 30.
• the metal layer 40 may be a nickel layer or a layer made of a metal other than nickel, such as a layer made of zinc, tin, or chromium. Zinc or tin may be an alloy layer based on these.
• the layer consisting of chromium also includes a chromate layer.
• the iron-nickel alloy layer 30 of this embodiment follows the elongation of the base material and has the property of being difficult to break.
• the thickness of the metal layer 40 is preferably 0.05 to 3.0 ⁇ m.
• the thickness of the upper nickel layer is 0.05 mm from the viewpoint that the crystal structure inherits the crystal structure of the lower iron-nickel alloy layer 30 and good cracking resistance can be achieved. It is preferably 0.8 ⁇ m to 0.8 ⁇ m, more preferably 0.1 to 0.8 ⁇ m, and even more preferably 0.15 to 0.7 ⁇ m.
• the upper nickel layer can be formed by nickel plating on the steel sheet after rolling the iron-nickel alloy layer.
• the crystal orientation and the average crystal grain size of nickel are measured in the formed state when the metal layer 40 is a nickel layer or a layer made of chromium. That is, the iron-nickel alloy layer 30 in the rolled surface-treated steel sheet 2 contains Fe 1 Ni 1 , and the orientation index in X-ray diffraction of the (200) plane of Fe 1 Ni 1 is 0.7 or more, and Fe 1 Ni It is characterized in that the orientation index in X-ray diffraction of the (220) plane of No. 1 is 0.7 or more and less than 2.5.
• the difference (absolute value) between the orientation index in X-ray diffraction of the (200) plane of Fe 1 Ni 1 and the orientation index in X-ray diffraction of the (220) plane of Fe 1 Ni 1 is 1.0 or less. is preferred. Further, it is more preferable that the orientation index in X-ray diffraction of the (111) plane of Fe 1 Ni 1 is 0.3 to 2.0.
• the metal layer 40 is a layer consisting of zinc or tin, it is preferable to measure after melting only the metal layer 40.
• the average crystal grain size of nickel on the surface of the metal layer 40 is 0.00000000000000 according to electron beam backscatter diffraction (EBSD) measurement data. It is preferably 4 ⁇ m to 1.1 ⁇ m.
• the average crystal grain size of nickel in the present disclosure is the average crystal grain size of nickel crystals, iron-nickel alloy crystals, or nickel crystals and iron-nickel alloy crystals.
• the iron-nickel alloy layer 30 may be partially exposed on the surface of the rolled surface-treated steel sheet 2 depending on the thickness and unevenness of the metal layer 40, but the nickel on the surface of the rolled surface-treated steel sheet 2 may
• the value of the average crystal grain size is a value that reflects the grain sizes of both the iron-nickel alloy layer 30 and the metal layer 40.
• the metal layer 40 is a layer consisting of zinc or tin, it is preferable to measure after melting only the metal layer 40.
• the surface thereof is an iron-nickel alloy layer 30, and the proportion of iron at least on the outermost surface is preferably 0 to 65% or less.
• the proportion of iron on the surface of the rolled surface-treated steel foil can be measured by GDS (glow discharge luminescent surface analysis).
• the surface of the rolled surface-treated steel sheet 2 in the above modification has a metal layer 40 (for example, a nickel layer). Even in the modified example where the metal layer 40 is a nickel layer, it is preferable that the proportion of iron at least on the outermost surface is 0 to 65% or less.
• the above-mentioned proportion of iron can be measured by GDS.
• Example ⁇ The present invention will be described in more detail below with reference to Examples. First, the measurement method in Examples will be described.
• the Vickers hardness of the surface layer of the rolled surface-treated steel sheet was measured and evaluated using a hardness meter. It was measured using a micro Vickers hardness tester (HM-103 manufactured by Mitutoyo) according to JIS Z 2244 (Vickers hardness test - test method). Two types of indenters were used: one with a load of 10 g and one with a load of 50 g. As a result of measurement under a load of 10 g, hardness could be obtained at a depth of 0 to 2.2 ⁇ m in all Examples and Comparative Examples. Further, as a result of measurement under a load of 50 g, hardness was obtained at a depth of 2.2 ⁇ m to 4.4 ⁇ m in all Examples and Comparative Examples.
• the count number of K ⁇ of Ni to the count number of K ⁇ of Fe was calculated as a ratio. This ratio is defined as the K ⁇ count ratio.
• the portion where the K ⁇ count ratio was less than 3.0 was defined as a portion other than the Fe-rich portion, and the portion where the K ⁇ count ratio was maximum was defined as the most Fe-rich portion. Then, the ratio (count number ratio) between the K ⁇ count ratio of the parts other than the Fe-rich part and the K ⁇ count ratio of the most Fe-rich part was calculated, and the degree of exposure of the iron component was evaluated.
• the count ratio in Table 2 is calculated by the following formula.
• K ⁇ count ratio K ⁇ count number of Fe at the measurement point / K ⁇ count number of Ni at the measurement point
• Count ratio K ⁇ count ratio of the most Fe-rich area / K ⁇ count ratio of areas other than the Fe-rich area
• the count ratio exceeds 100, it is determined that the iron in the base material is exposed, if it is 20 or more and 100 or less, it is determined that the iron in the base material or iron-nickel alloy layer is exposed, and if it is 5 or more. If it is less than 20, it is determined that at least iron components are exposed, and if it is less than 5, it can be determined that iron exposure is sufficiently suppressed.
• the coefficient of friction For the coefficient of friction, the value provided by the software of the testing machine was used. Then, the threadability was evaluated by comparing the friction coefficient at four turns, where there is a clear difference in the friction coefficient, and the sum of the friction coefficients at a pitch of 0.5 turns from 0 to 5 turns.
• the lower coefficient of friction reduces damage to molds and rolls during processing and continuous coating, leading to improved material quality, and less damage to equipment (molds, rolls), extending the life of the equipment. In view of this, it was rated as having high threadability.
• the measured diameter of the rolled surface-treated steel sheet was ⁇ 60 mm (measured area 28.26 cm 2 ).
• a rectifier manufactured by Kikusui Electronics Co., Ltd., compact DC stabilized power supply PMX18-5A
• an ammeter manufactured by Hioki Electric Co., Ltd., digital multimeter
• a meter DT4282 was used.
• the specific measurement conditions are to apply 2.25 A to the sample for 30 minutes on the hydrogen generation side to generate hydrogen on the sample surface, and to measure the change in oxidation current that occurs when hydrogen atoms pass through on the hydrogen detection side. Measured every second. Note that no current was applied to the hydrogen detection side.
• it is immersed in an electrolytic solution for 20 minutes or more, and the current value of the ammeter on the hydrogen detection side becomes stable at 10 ⁇ A or less. It was confirmed.
• Hydrogen permeation current density I ( ⁇ A/cm 2 ) was calculated from the change in oxidation current on the hydrogen detection side obtained by the above method.
• X-ray diffraction (XRD) measurement was performed for the purpose of evaluating the state of the alloy consisting of iron and nickel contained in the rolled surface-treated steel sheet.
• X-ray diffraction measuring device Rigaku's SmartLab
• the sample was cut into 20 mm x 20 mm.
• the specific measurement conditions for X-ray diffraction were as follows.
• Crystal orientation index of X-ray diffraction of (200) plane of Fe 1 Ni 1 crystal orientation index of X-ray diffraction of (220) plane of Fe 1 Ni 1
• crystal orientation index of X-ray diffraction of (111) plane of Fe 1 Ni 1 The crystal orientation index was calculated for each, and the difference between the crystal orientation index for the (200) plane and the (220) plane was determined. The results are listed in Table 5.
• ⁇ Device configuration> ⁇ X-ray source: CuK ⁇ ⁇ Goniometer radius: 300nm ⁇ Optical system: Concentration method (incidence side slit system) ⁇ Solar slit: 5° ⁇ Longitudinal limit slit: 5mm ⁇ Divergence slit: 2/3° (Receiving side slit system) ⁇ Scattering slit: 2/3° ⁇ Solar slit: 5° ⁇ Light receiving slit: 0.3mm ⁇ Monochromatic method: Counter monochromator method ⁇ Detector: Scintillation counter ⁇ Measurement parameters> ⁇ Target: Cu ⁇ Tube voltage - tube current: 45kVKv 200mA ⁇ Scanning axis: 2 ⁇ / ⁇ (concentration method) ⁇ Scanning mode: Continuous ⁇ Measurement range: 2 ⁇ 40 ⁇ 100° ⁇ Scanning speed: 10°/min ⁇ Step: 0.02°
• the nickel grain size was determined by performing crystal orientation analysis by EBSD (electron back scattering diffraction) measurement using a scanning electron microscope (SEM). Specifically, the average crystal grain size was obtained by obtaining and analyzing information on a diffraction pattern called a Kikuchi pattern under the following conditions. Specifically, the value calculated as Average Number (Diameter) was obtained as the average crystal grain size.
• the crystal grain size is the average crystal grain size of nickel crystals, iron-nickel alloy crystals, or nickel crystals and iron-nickel alloy crystals. Table 6 shows the average grain size obtained.
• Example 1 a cold rolled foil (thickness: 55 ⁇ m) of low carbon aluminum killed steel having the chemical composition shown below was prepared as a base material.
• C 0.04% by weight
• Mn 0.32% by weight
• Si 0.01% by weight
• P 0.012% by weight
• S 0.014% by weight
• balance Fe and inevitable impurities.
• the prepared base material was electrolytically degreased and pickled by sulfuric acid immersion, and then nickel plating was performed on both sides of the steel foil under the following conditions to form a 0.5 ⁇ m thick nickel plating layer on both sides. Formed.
• the conditions for nickel plating were as follows. (Nickel plating conditions) Bath composition: Nickel sulfate hexahydrate: 250g/L Nickel chloride hexahydrate: 45g/L Boric acid: 30g/L Bath temperature: 60°C pH: 4.0-5.0 Stirring: Air stirring or jet stirring Current density: 10A/dm 2
• the steel foil having the nickel plating layer formed above was heat treated by box annealing at a soaking temperature of 560° C. for a soaking time of 6 hours in a reducing atmosphere (heat treatment step). Through this heat treatment, a nickel-plated surface-treated steel sheet having iron-nickel alloy layers on both sides was obtained. Next, this nickel-plated surface-treated steel sheet was rolled (rolling step). The rolling conditions were cold rolling with a rolling reduction of 11%. The rolling reduction ratio was calculated based on the assumption that the thickness of the nickel-plated steel sheet before rolling (the thickness of the base material and the thickness of the nickel-plated layer on both sides) was set to 50 ⁇ m by rolling.
• Example 2 The same procedure as in Example 1 was carried out, except that the thickness of the nickel plating layer on both sides was 1.0 ⁇ m, and the reduction rate in the rolling process was 12%.
• Example 3 The same procedure as in Example 1 was conducted except that the soaking temperature in the heat treatment step was 590°C.
• Example 4 Example 2 except that the thickness of the nickel plating layer on both sides was 1.0 ⁇ m, the soaking temperature in the heat treatment process was 590°C, and the rolling reduction rate in the rolling process was 12%. I did the same thing.
• Example 5> The same procedure as in Example 3 was carried out, except that the thickness of the base material was 60 ⁇ m, the soaking temperature in the heat treatment step was 590° C., and the reduction rate in the rolling step was 18%.
• Example 6 Example 5 except that the thickness of the nickel plating layer on both sides was 0.4 ⁇ m, the soaking temperature in the heat treatment process was 560°C, and the rolling reduction rate in the rolling process was 18%. I did the same thing.
• Example 7 The same procedure as in Example 6 was carried out except that the thickness of the nickel plating layer on both sides was 0.2 ⁇ m.
• Example 8> The same procedure as in Example 6 was performed except that the thickness of the nickel plating layer on both sides was 0.18 ⁇ m.
• Example 9 The same procedure as in Example 5 was carried out except that the thickness of the nickel plating layer on both sides was 0.2 ⁇ m.
• Example 10> The same procedure as in Example 6 was carried out except that the thickness of the nickel plating layer on both sides was 0.1 ⁇ m.
• Example 11> After the rolling process, a strike nickel plating process and a second nickel plating process were further performed to form a nickel layer on the iron-nickel alloy layer. Other than that, the same procedure as in Example 8 was carried out. The second nickel plating treatment was performed under the same plating conditions as when the base material was subjected to nickel plating treatment. The thickness of the nickel layer on the iron-nickel alloy layer after the second nickel plating treatment was 0.5 ⁇ m. Each evaluation was performed using a rolled surface-treated steel sheet after the nickel layer was formed.
• ⁇ Comparative example 1> The thickness of the base material was 50 ⁇ m, the thickness of the nickel plating layer on both sides was 0.35 ⁇ m, and no heat treatment or rolling was performed.
• ⁇ Comparative example 2> The thickness of the base material was 200 ⁇ m, and the thickness of the nickel plating layer on both sides was 0.4 ⁇ m on one side and 1.0 ⁇ m on the other side. Further, in the heat treatment step, the heat treatment temperature was 800° C., the heat treatment time was 1 minute, and continuous annealing was performed without rolling. Other than that, the same procedure as in Example 1 was carried out.
• ⁇ Comparative example 3> The thickness of the base material was 200 ⁇ m, and the thickness of the nickel plating layer on both sides was 3.0 ⁇ m on one side and 1.0 ⁇ m on the other side. Further, in the heat treatment step, the heat treatment temperature was 800° C., the heat treatment time was 1 minute, and continuous annealing was performed without rolling. Other than that, the same procedure as in Example 1 was carried out.
• ⁇ Comparative example 4> The thickness of the base material was 200 ⁇ m, and the thickness of the nickel plating layer on both sides was 5.0 ⁇ m. Further, the heat treatment temperature in the heat treatment step was 670° C. , and continuous heat treatment was performed for 40 seconds. The rolling reduction rate in the rolling process was 65-75%, which was the initial rolling reduction rate after the nickel plating process. Other than that, the same procedure as in Example 1 was carried out.
• Table 1 shows the thickness of the base material and the conditions of each step. In addition, each measurement value and evaluation result are shown in Table 2 and thereafter.
• the rolled surface-treated steel sheet of this embodiment could be evaluated as follows.
• Comparative Example 4 which was rolled at a high reduction rate, broke before applying 3% tension, and the iron was exposed even at 1% elongation.
• the rolled surface-treated steel sheets of Examples can be evaluated as having good properties in that iron exposure is difficult to occur and it is difficult to crack even when a 3% tension is applied.
• Comparative Example 5 which was subjected to rolling at a high reduction rate and then heat treatment again and rolling again, had a hardness comparable to that of Comparative Example 1, and 3. % iron exposure after tension was also improved, while the rolled surface-treated steel sheets of the examples can be evaluated to have even better properties in terms of crackability.
• the results of comparing Examples and Comparative Examples showed that the rolled surface-treated steel sheets of Examples had a significantly lower coefficient of friction than the nickel-plated steel sheets of Comparative Examples. Specifically, it was shown that the friction coefficient for 4 laps was excellent at 0.4 or less, and the total sum from 0 to 5 laps was also significantly lower than that of the comparative example. As a result, it is possible to obtain a good surface with few scratches due to wear, and it is possible to suppress scratches due to wear during roll passing. In particular, it has excellent scratch resistance during passing through a squeeze roll, when passing through a progressive roll, and during coating when applying another layer such as an active material to the upper layer.
• the rolled surface treated steel sheet of the example has Fe 1 Ni 1 crystal grains in the iron-nickel alloy layer in a state where both (200) and (220) are moderately mixed. It is thought that by oriented in this manner, it is possible to create a layer that is difficult to break while maintaining appropriate hardness. It is also considered to have excellent hydrogen barrier properties and to be able to suppress an increase in the coefficient of friction. On the other hand, since Comparative Examples 4 and 5 underwent a rolling process at a high rolling reduction ratio, the (220) orientation was dominant.
• the rolled surface treated steel sheet of the Examples was found to have the following properties: It was confirmed that the Ni-based fcc crystal grain size was larger than that of Comparative Example 1, which was a nickel-plated plate. Based on the examples of the present invention, it is considered that it is possible to suppress an increase in the coefficient of friction by setting the average crystal grain size to 0.4 ⁇ m or more.
• Comparative Example 3 which was heat treated after nickel plating, and Examples 1 to 11, it was confirmed that in Comparative Example 3, the crystal grains became coarse due to the heat treatment, and the average crystal grain size became larger. Furthermore, since Comparative Example 3 has a large average crystal grain size and is soft, it is sheared and deformed by shear stress during friction, so it can be understood that the coefficient of friction becomes high. On the other hand, in the examples, it is considered that it is possible to suppress an increase in the coefficient of friction by setting the average crystal grain size to 0.4 ⁇ m to 1.1 ⁇ m. Furthermore, it is considered possible to set the hardness of the outermost surface of the rolled surface-treated steel sheet and the intermediate layer between the base material and the outermost surface within an appropriate range.
• Comparative Example 5 which was rolled at a high reduction rate after forming an iron-nickel alloy layer, and Examples 1 to 11, it was found that in Comparative Example 5, the crystal grains were coarsened due to rolling at a high reduction rate and heat treatment. , I confirmed that it was getting bigger.
• the rolled surface-treated steel sheet of the present invention can be applied to various types of battery current collectors, battery members such as battery containers and terminals, electronic related equipment, and the like.

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