EP1706514B1 - Stahlblech zur verwendung in behältern und herstellungsverfahren dafür - Google Patents

Stahlblech zur verwendung in behältern und herstellungsverfahren dafür Download PDF

Info

Publication number
EP1706514B1
EP1706514B1 EP05704017.2A EP05704017A EP1706514B1 EP 1706514 B1 EP1706514 B1 EP 1706514B1 EP 05704017 A EP05704017 A EP 05704017A EP 1706514 B1 EP1706514 B1 EP 1706514B1
Authority
EP
European Patent Office
Prior art keywords
steel sheet
equal
amount
present
nitriding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
EP05704017.2A
Other languages
English (en)
French (fr)
Other versions
EP1706514A1 (de
Inventor
Hidekuni c/o Nippon Steel Corporation MURAKAMI
Shigeru c/o Nippon Steel Corporation HIRANO
Akihiro c/o Nippon Steel Corporation ENOMOTO
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Nippon Steel and Sumitomo Metal Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Steel and Sumitomo Metal Corp filed Critical Nippon Steel and Sumitomo Metal Corp
Publication of EP1706514A1 publication Critical patent/EP1706514A1/de
Application granted granted Critical
Publication of EP1706514B1 publication Critical patent/EP1706514B1/de
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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 by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0257—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment with diffusion of elements, e.g. decarburising, nitriding
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • 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 by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties 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
    • 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 by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0436—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/02—Pretreatment of the material to be coated
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/24—Nitriding
    • C23C8/26—Nitriding of ferrous surfaces
    • 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 by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
    • C21D8/0457—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment with diffusion of elements, e.g. decarburising, nitriding
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals

Definitions

  • the present invention relates to a steel to be used in metal containers such as drink containers, and a manufacturing method therefor.
  • One of the objects of the present invention is to provide a steel sheet and a manufacturing method therefor in which it is possible to not only reform the surface state of the material by controlling the nitride configuration, but also to avoid the use of special treatments which could adversely affect productivity, and which solves the problems in using ultra-thin materials in the manufacture of containers, such as color tone of the container resulting from the surface state of the steel, surface coating adhesiveness and weldability.
  • JP-A 2001 107 189 and JP-A 2001 107 148 relate to methods for producing high strength and high ductility steel sheets for drink containers involving final nitriding.
  • the color tone, surface coating adhesiveness and weldability of the can are not greatly improved by simply constructing the surface hardness, but in the present invention, by limiting the constituent amounts, in particular, the amount of nitrogen, to be within a specific range, and further, by optimizing the nitriding conditions, it is possible to favorably control the surface layers of the material, in particular, the formation of nitrogen compounds on the uppermost layer. Furthermore, as it is possible to also modify the roughness etc. of the steel surface, as a result, it is also possible to improve the color tone, surface coating adhesiveness and weldability of the can which applies the ultra-thin material. According to certain exemplary embodiments of the present invention, such conditions can be provided, as well as the manufacturing method using these conditions.
  • a first aspect of the steel sheet according to the present invention is a steel sheet for use in a container, comprising: at least one portion having a sheet thickness of at most 0.400 mm, and including a material which contains at most: 0.0800% C, 0.600% N, 2.0% Si, 2.0% Mn, 0.10% P, 0. 05% S and 2.0% Al, optionally at least one constituent, and wherein an amount of the at least one constituent is at most: 0. 08% Ti, 0.08% Nb, 0. 015% B, 5.0% Ni, 2.0% Cu and 2.0% Cr, further optionally a sum of less than or equal to 0.
  • a first ratio of an area of nitrogen compounds on a surface of the at least one portion divided by a second ratio of an area of nitrogen compounds on a cross-sectional position at a depth of 1/4 of the thickness of the at least one portion is at least 1.5, and wherein a roughness of the surface of the at least one portion is at most 0.90 ⁇ m Ra, and wherein a number of peaks of the thickness in a region of the at least one portion with a length of 2.54 cm(1 inch) is at least 250 PPI.
  • a further embodiment of the present invention is a method for manufacturing a steel sheet for use in a container, the steel sheet having a sheet thickness of at most 0.400 mm, and including a material which contains at most 0.0800% C, 0.0300% N, 2.0% Si, 2.0% Mn, 0.10% P, 0.05% S and 2.0% Al, optionally at least one constituent, and wherein an amount of the at least one constituent is at most: 0.08% Ti, 0.08% Nb, 0.015% B, 5.0% Ni, 2.0% Cu and 2.0% Cr, further optionally a sum of less than or equal to 0.1 % of Sn, Sb, Mo, Ta, V, and W, and the balance being Fe and unavoidable impurities, the method comprising:
  • the first ratio divided by the second ratio is at least 6.
  • the sheet thickness is less than 0.300 mm.
  • the first ratio of the area of nitrogen compounds on the surface of the at least one portion is at least 1.0%.
  • the steel sheet according to the invention a density of a range of individual nitrogen compounds on the surface of the at least one portion which has a diameter of at least 0.1 ⁇ m is at least 0.001 units/ ⁇ m 2 .
  • An upper limit of the amount of C is preferable to avoid degradation of workability of the material, and should be less than or equal to 0.0800% C. It is preferable for this to be less than or equal to 0.0600%, and it is even more preferable for this to be less than or equal to 0.040% C.
  • the amount of N which has the similar properties as C
  • the amount of C contained therein and required from the viewpoint of ensuring strength it is possible for the amount of C contained therein and required from the viewpoint of ensuring strength to be low. It is possible to obtain the required strength with less than or equal to 0.0050% C, and can even be less than or equal to 0.0020%. If the amount is less than or equal to 0.0015%, there may be some overlap with the amount of nitriding, and it is still possible to manufacture ultra-soft materials which would fall outside of the standards using normal container materials. From the fact that increasing the r value will keep the press-forming properties of the material high, it is preferable to keep the amount of C prior to nitriding treatment as low as possible.
  • the amount of N in the final product may also be preferable to have an upper limit for the amount of N in the final product, and as, similar to C, it is necessary to avoid degradation of processability of the material, it is good to keep the amount of N to be less than or equal to 0.600%. It is preferable for the amount of N to be less than or equal to 0.200%, and it is even more preferable for the amount of N to be less than or equal to 0.150%. Even more preferable may be to set the amount ofN to be less than or equal to 0.100%. However, in order to obtain the efficacy of an exemplary embodiment of the present invention, a certain amount of N to form the appropriate amount of nitrogen compounds on the surface of the steel sheet is required.
  • this amount of N it may depend on the distribution of N in the thickness direction, but when using normal nitriding treatment, it is of course necessary to increase the amount of N in comparison to the amount prior to the nitriding treatment, and in particular, in the present invention, this has been increased to greater than or equal to 0.0002%. This may appear to be an extremely small increase in the amount of N, but from the view of the increase in the amount of N on the surface of the steel sheet, it is quite large.
  • the thickness corresponding to the surface constituents of the steel sheet is assumed to be 1/100, 0.20 mm sheet thickness, then the portion of 2 ⁇ m thickness will be determined to be the surface layer, and by increasing the amount of N by 0.0002% as an average sheet thickness, the amount of N increased in this surface layer will be 0.0100%. As this increase in the amount of N grows larger, the amount of nitrides on the surface which is required in the present invention will increase, and therefore, it is preferable for this to be greater than or equal to 0.0005%.
  • this is more preferable for this to be greater than or equal to 0.0010%; it is even more preferable for this to be greater than or equal to 0.0020%, and it is even more preferable for this to be greater than or equal to 0.0050%. Furthermore, a value of greater than or equal to 0.0100% is preferable to these lower values, and similarly, a value of greater than or equal to 0.0200% and 0.0400% is even more preferable. In particular, when the value is greater than or equal to 0.0100%, the amount of N on the surface of the steel sheet is very high, resulting in more than sufficient required nitrides, and the efficacy of the present invention will be stable.
  • the amount of N prior to nitriding treatment may also be preferable to have an upper limit for the amount of N prior to nitriding treatment, and as, similar to C, it is necessary to avoid degradation of the processing properties of the material, it is good to keep the amount of N to be less than or equal to 0.0300%. It may be preferable for the amount of N to be less than or equal to 0.0200%, and it is even more preferable for the amount of N to be less than or equal to 0.0150%. It may also be preferable for the amount of N to be less than or equal to 0.0100%, and even more preferable for the amount of N to be less than or equal to 0.0050%. Yet even more preferable may be to set the amount of N to be less than or equal to 0.0030%.
  • Si can be added in order to adjust the strength of the material, but if the amount of Si is too high, the processing and plating properties of the material may degrade. Therefore, it may be preferable to keep Si to be equal to or below 2.0%.
  • nitrides may be formed at the grain boundary N embedded within the steel during the nitriding treatment, and not only can these lead to brittle cracking, but they can also lead to a loss in the efficacy of the present invention, and therefore, there may be instances where the amount of Si needs to be kept to less than or equal to 1.5%, or even less than or equal to 1.0%.
  • the amount of Si is as low as possible, and by setting it to be less than or equal to 0.5%, 0.1% or even 0.07%, it is possible to increase the forming characteristics of the material as well as to control the formation of Si-nitrides.
  • Mn can be added in order to adjust the strength of the material, but as too much Mn can result in a degradation of workability of the material, it is proper to keep this amount to less than or equal to 2.0%. From the view that it ensures high forming characteristics in the material, it is preferable for the amount of Mn to be as low as possible, and by setting it to be less than or equal to 0.6%, or even 0.2%, it is possible to increase the forming characteristics of the material.
  • P can be added in order to adjust the strength of the material, but as too much P may result in not only a degradation of workability of the material but also in a reduction of the nitriding treatment of the steel sheet; it is preferable to keep this amount to less than or equal to 0.10%. From the view that it ensures high forming characteristics in the material, it is preferable for the amount of P to be as low as possible, and by setting it to be less than or equal to 0.05%, or even 0.01%, it is possible to increase the forming characteristics of the material.
  • S may degrade the hot ductility characteristics of the material as well as to provide an obstacle in casting or hot ductility the material, and therefore, it is preferable to keep the amount of S to be less than or equal to 0.05%. From the view that it ensures high forming characteristics in the material, it is preferable for the amount of S to be as low as possible, and by setting it to be less than or equal to 0.02%, or even 0.01%, it is possible to increase the forming characteristics of the material.
  • A1 may be an element added to deoxidize the material, but if the amount of A1 is high, casting the material may become difficult, and as damages such as flaws in the surface may increase, it is proper to keep the amount of A1 to be less than or equal to 2.0%. Furthermore, when the amount of A1 is high, at greater than or equal to 0.2%, a large amount of AlN can be formed within the steel as it bonds with the N embedded within the steel sheet through nitriding, resulting in a hardening of the nitride areas. However, as the formation of large AlN can result in embrittlement, care should be taken in the adjustment of the amount of Al.
  • the amount ofAl is as low as possible, and by setting it to be less than or equal to 0.2%, or even 0.1%, it is possible to increase the forming characteristics of the parts of the material where the level of being nitrified is low.
  • Ti can increase the recrystallization temperature of the steel sheet, and as it may also greatly degrade the annealing threading performance of the ultra-thin steel sheet which is the subject of the present invention; it is appropriate to keep the amount of Ti to be less than or equal to 0.080%. In particular, there may not be a need to add Ti in normal applications where a high r value is not required, and therefore, it is good to keep the amount of Ti to be less than or equal to 0.04% or even 0.01%. Furthermore, the Ti which is set within the steel sheet during nitriding treatment can form microscopic TiN within the steel as it bonds with the N embedded in the sheet through nitriding treatment, and it may have high efficacy in the hardening of the nitride area.
  • the amount of Ti is kept as low as possible, and by setting it to be less than or equal to 0.005% or even 0.003%, it is possible to control the unintentional hardening of the steel sheet.
  • the TiN formed on the steel sheet surface during nitriding treatment is very microscopic, and as the surface modification efficacy as intended by the present invention is small, it is possible to use these molecules to increase the surface modification efficacy. In this manner, it is possible to consciously add it such that it falls within the specific addition range of the present invention.
  • Nb shows the same effects as Ti.
  • Nb can increase the recrystallization temperature of the steel sheet (as well as significantly degrade the annealing threading performance of the ultra-thin steel sheet which is the subject of the present invention)
  • Nb there is no need to add Nb in normal applications where a high r value is not required, and therefore, it is good to keep the amount of Nb to be less than or equal to 0.04% or even 0.01%.
  • the Nb which is set within the steel sheet during nitriding treatment can form microscopic NbN within the steel as it bonds with the N embedded in the sheet through nitriding treatment, and it has strong efficacy in the hardening of the nitride area.
  • the amount of Nb is kept as low as possible, and by setting it to be less than or equal to 0.005% or even 0.003%, it is possible to control the unintentional hardening of the steel sheet
  • the NbN formed on the steel sheet surface during nitriding treatment can be very microscopic, and as the surface modification efficacy as intended by the present invention is small, it is possible to use these molecules to increase the surface modification efficacy. In this way, it is possible to consciously add it such that it falls within the specific addition range of the present invention.
  • B When B is added to a steel sheet which contains greater than or equal to 0.01 % of Ti and Nb, it can increase the recrystallization temperature of the steel sheet, and can greatly degrade the annealing threading performance of the ultra-thin steel sheet which is the scope of the present invention.
  • the amount of Ti and Nb in the sheet is low, there are few adverse effects of B, and as it actually can decrease the recrystallization temperature of the steel sheet, it is possible to perform recrystallization annealing at a lower temperature.
  • B As it also has the efficacy of increasing the annealing properties of the material, it is possible to add B proactively. If excessive B is added, breakages of the cast form during casting may become prominent.
  • B which is set within the steel prior to nitriding treatment can combine with the N embedded within the steel sheet during nitriding treatment to form microscopic BN, which is effective in hardening the nitride area.
  • the ratio between the amount of B and the amount of N contained prior to nitriding treatment is B/N>0.8. By making this ratio greater than or equal to 1.5, or to even greater than or equal to 2.5, hardening due to BN formation will become prominent. As there may be instances where the formation of BN may result in more hardening of the material than is required, care must be taken in the amount of B added.
  • the ratio of B contained and N contained prior to nitriding treatment is B/N ⁇ 0.8, or even more strictly, to set this ratio to be B/N ⁇ 0.1.
  • the BN formed on the steel sheet surface during nitriding treatment is very fine, and the surface modification efficacy as intended according to the exemplary embodiment of the present invention is small; lowerer it is possible to use these molecules to increase the surface modification efficacy. In this manner, it is possible to consciously add it such that it falls within the specific addition range according to the exemplary embodiment of the present invention.
  • the Cr which is set within the steel prior to nitriding treatment can combine with the N embedded within the steel sheet during nitriding treatment, with the effect of forming microscopic Cr-nitrides on the surface of the steel sheet, and utilizing these nitrides, it is possible to increase the efficacy of the present invention.
  • the annealing threading performance of the ultra-thin steel sheet which is within the scope of the present invention may be significantly degraded.
  • P, B, Sn and Sb can reduce the nitriding efficacy which is an important requirement in the present invention, and therefore it is necessary to pay attention to the upper limit of the amounts added in conjunction with the nitriding conditions.
  • Sheet thickness 1/4 depth illustrates the corresponding position within FIG. 1 .
  • the location corresponding to this "sheet thickness 1/4 depth” exists on both surfaces of the steel sheet, but in the present invention, it corresponds to either surface that is within the scope of the present invention.
  • An exemplary embodiment of the present invention may have this type of steel sheet with different surfaces on the top and bottom. This is due to the fact that it is possible to obtain an increase in efficacy in color tone, surface coating adhesiveness and weldability, which is the purpose of the present invention, even on only one side of the sheet.
  • the area ratio and the density relating to the nitride components in a specific position on the steel sheet surface or in the thickness direction of the steel sheet is regulated. It is possible to identify the existing precipitates through the diffraction pattern in an electron microscope or through an attached X-Ray analyzer. Of course, it is also possible to identify them in other methods such as chemical analysis. It is possible to quantify the diameter, the area ratio and the density, as shall be below, for example, an electron microscope for observation. In order to control the nitride size, the area ratio and the density, it is effective to appropriately control the temperature, the time and the cooling speed immediately prior to entering this temperature region to the range of 450 to 700°C to be explained later.
  • nitride size formed will be finer and the density will be greater as the speed is increased and the temperature lowered, and if the duration is increased, nitride size becomes larger and coarser.
  • the exemplary embodiments of the present invention do not concern only precipitates from nitrides, but also in complex precipitates along with oxides, carbides and sulfides.
  • complex precipitates when complex precipitates are formed, it may be difficult to specify the size of each compound, so excluding the instances where it is possible to clearly distinguish that a selected area is a nitride, it can be determined the complexes to be a nitride.
  • the observation method for the nitrides is not limited in particular, and it is equally acceptable to directly observe them using an EDX scanning electron microscope or some other surface observation device, or to observe them using extraction replicas obtained through a "SPEED" method.
  • extraction replicas it is usual to take certain care when creating the replicas such that the replicas are formed of only the information of the observed surface of the steel sheet. The reason is that, in the SPEED method, if the amount extracted through electrolysis is too large, the information in the thickness direction can overlap, and the number of precipitates observed may be larger than when directly observing the steel sheet. Therefore, the amount extracted through electrolysis should be kept to within 2 ⁇ m in terms of the steel sheet thickness.
  • N When performing analysis through EDX, when the main observed non-metallic elements are N, they can be treated as nitrides. Furthermore, as the size is small, even if the characteristic spectrum of the N is not distinguishable, Fe, Ti, Nb, B and Cr can be detected. Moreover, even if the distinguishable spectrums of O and S cannot be observed, precipitates which can be approximately determined to be nitrides from a comparison of the configuration of nitrides and other precipitates will be treated in the present invention as nitrides. Furthermore, it is acceptable to use an electron diffraction pattern in the quantization of the precipitates.
  • An identification of nitrides is not limited to methods using EDX or electron diffraction patterns, and it is acceptable to use other analytical devices.
  • the determination of the precipitate type, size and density can be performed in any method which is accepted as valid.
  • the precipitate there may be instances where it is difficult to differentiate between carbides and nitrides, but it is possible to exclude those items for which the type of precipitate cannot be validly determined using normal analytical devices from the present invention. In other words, those items which are exceedingly small, and where it is not possible to identify them using an EDX spectrum or some other normal type of analytical device, will be excluded from the nitrides which are the subject of the present invention.
  • the minimum size of precipitates may be provided which can be identified using analytical devices in common use to be approximately 0.02 ⁇ m.
  • analytical devices in common use to be approximately 0.02 ⁇ m.
  • the area ratio, etc. will likely increase.
  • the individual atomic arrangement is displayed, there may be difficulties in determining what of the ultra-fine atomic unit of the metal atom and the N is to be classified as a nitride, but considering the current state of analytical levels, it is possible to exclude items that are smaller than those having the above listed size.
  • nitrides may be seen for which the form has been elongated, but for those items where the shape is not isotropic, the average value between the long diameter and the short diameter will be taken as the diameter of that precipitates.
  • the steel sheet according to the exemplary embodiment of the present invention should preferably be ground in order to observe the cross-sectional position at 1/4 depth of the steel sheet.
  • the observed surface is preferably not the surface of the steel sheet, it is preferable to avoid any machining process. Therefore, it is preferable to select a particular type of method which may not require grinding.
  • it is preferable to limit the amount of sheet thickness reduced through the machining process to be less than 2 ⁇ m.
  • This exemplary embodiment of the present invention can control the configuration of nitrides on the surface of a steel sheet For example, by increasing the non-uniformity of the surface by blanketing the surface of the steel sheet with materials other than steel, it is possible to improve the characteristics relating to the desired surface state. Furthermore, the characteristics relating to the surface state may be dependent on the state of the nitrides formed on the surface, and the present invention makes it possible to control the configuration of the nitrides through the thermal history after nitriding treatment and through the cooling conditions. In this way, the uniqueness of the present invention lies in the state of the nitrides on the surface of the steel sheet.
  • the area ratio of the nitrides can be used as the method to regulate this, and the upper limit for this is greater than or equal to 1.0%. It is preferable to set this to be greater than or equal to 2.0%, or to 5.0%, 10%, 20%, or even more preferably, to set this to be greater than or equal to 40%. It is not a problem even if the entire surface of the steel sheet is covered in nitrides.
  • nitrides which are formed in a membrane shape may be easily broken, and in the transport of the sheet during the manufacturing process. Indeed, some will likely be broken. It is important to pay attention to when the film of nitrides on the surface is particularly thick, as this can become the origin for fractures of the sheet. There can be instances where it may be determined to be some type of surface defect. Therefore, it is important to avoid excessive concentrations of N on the surface.
  • this ratio be greater than or equal to 1.5; it may be more preferable for it to be greater than or equal to 3, 6, 10, 30, and for it to be even greater than or equal to 100. If this ratio is small, the efficacy of the present invention may be reduced, and it is not possible to obtain the desired steel sheet.
  • nitrides are used as a method of increasing the density of nitrides on the surface part in this way, it is also possible to regulate the ratio (nitrified area ratio on the surface position of the steel sheet after nitriding treatment) / (nitrified area ratio on the surface position of the steel sheet prior to nitriding treatment).
  • this ratio it is preferable that this ratio be greater than or equal to 1.5, it is more preferable for it to be greater than or equal to 3, 6, 10, 30, and for it to be even greater than or equal to 100. It goes without saying that, the greater this ratio is, the greater the basic efficacy of the present invention.
  • the configuration of the nitrides on the surface is one where relatively small nitrides are distributed uniformly rather than one where coarse items are distributed roughly:
  • the diameter of these particles be greater than or equal to 0.10 ⁇ m.
  • the density is limited in relation to the individual nitride area or the individual steel region on the surface of the steel sheet. According to an exemplary embodiment of the present invention, in the precipitate region and the steel region, it is possible to use the value for which the density is higher.
  • this density is preferable for this density to be greater than or equal to 0.001 units/ ⁇ m 2 . It is more preferable for it to be greater than or equal to 0.003 units/ ⁇ m 2 , even more preferable for it to be greater than or equal to 0.010 units/ ⁇ m 2 , as it is more preferable for it to be greater than or equal to 0.030 units/ ⁇ m 2 , 0.10 units/ ⁇ m 2 , 0.30 units/ ⁇ m 2 ,1.0 units/ ⁇ m 2 , and it is even more preferable for it to be greater than or equal to 3.0 units/ ⁇ m 2 .
  • FIGS. 2 and 3 illustrate diagrammatically the above area ratio and the density.
  • Ra should be less than or equal to 0.90 ⁇ m, and PPI should be greater than or equal to 250. If Ra is too high or if PPI is too low, the characteristics of color tone, surface coating adhesiveness and weldability as desired in the present invention degrades due to surface irregularities (concavo-convex like peaks). It is preferable for Ra to be less than or equal to 0.80 ⁇ m; it is more preferable for it to be less than or equal to 0.70 ⁇ m, or 0.60 ⁇ m, and it is even more preferable for it to be less than or equal to 0.50 ⁇ m.
  • PPI prefferably be greater than or equal to 300, it is more preferable for it to be greater than or equal to 350 or 400, and it is even more preferable for it to be greater than or equal to 450 or even 500.
  • irregularities concavo-convex like peaks
  • the lower limit for Ra is not particularly specified, but it can be controlled to the desired value according to the nitriding conditions and the temper rolling conditions. However, the lower limit of Ra is does not include 0, and in practice, it is greater than or equal to 0.02 ⁇ m.
  • the upper limit of PPI is not explicitly specified as well, and can be controlled to the desired value according to the nitriding conditions and the temper rolling conditions. Basically, in order to segregate the N such that the concentration of N in the vicinity of the surface can be high, Ra should be low and PPI should be high.
  • One method of segregating N on the surface is to perform nitriding treatment in a comparatively short period of time within an ammonia atmosphere.
  • the state of the surface may be affected by the grains diameter and steel constituents prior to that, as well as by the annealing temperature and the cold-rolling conditions, the reduction and pass number during temper rolling after nitriding treatment, the roll roughness and, if metal plating is performed, by the plating conditions. Therefore, it may be difficult to limit the state of the surface to a specific range, but the basic control is performed in the same manner as is conventionally performed, and it is possible to control this with no problems after a few trials.
  • the irregularity of the roller As the irregularities of the roller will gall through rolling, in order to set the irregularity of the surface of the steel sheet to a desirable range, it is not only necessary to perform regular exchanges of the roller or to machine the irregularities, production should be halted for these types of exercises, leading to an excessive burden in terms of productivity and labor cost.
  • the surface state of the steel sheet is hardly affected by the temper rolling method, and therefore, it is possible to perform processing of a large number without needing to manage the galling of the irregularities on the roller.
  • the reason why the roughness of the surface of the steel sheet is not greatly affected by the method of generating that roughness or by those conditions is thought to be the fact that the cause of the roughness is the steel sheet itself, in other words, it lies in the dispersion state of the nitrides on the surface of the steel.
  • the steel according to the exemplary embodiment of the present invention is covered to an extremely large extent by nitrides in comparison to conventional steel, and is in a state that is different from the conventional steel sheets which are formed from basically homogeneous Fe.
  • the surface of the steel sheet is covered in places by nitrides, it is natural to imagine that there will be different surface characteristics between the portions where the nitrides are exposed and the portions where the steel base material itself is exposed.
  • the nitrides which cover the surface differ greatly in terms of deformation characteristics from the steel, the deformations due to the bending process corresponding to the skin pass rolling or to the transport of the plate during the manufacture of the steel sheet are thought to differ in the micro-region between the nitride portion and the exposed steel sheet portion.
  • the effects of the machining conditions such as the skin pass rolling will be moderated in terms of the surface roughness, and so the surface roughness is strongly dependent on only the state of the nitrides on the surface of the metal sheet.
  • these nitrides will break microscopically due to even small deformations, and to it is possible to form a uniform surface roughness.
  • the coating material during the surface treatment can be unevenly distributed, dependent on the existence of nitrides on the surface of the steel sheet. Therefore, by either finely dispersing the nitrides or the exposed steel on the surface of the steel sheet during the manufacture of the steel sheet or by blanketing the entire surface of the steel sheet with finely broken nitrides, it is possible to finely disperse the coating material during surface treatment regardless of the surface treatment conditions. Then, the coating material which has been unevenly distributed in this way (in other words, micro-scale non-uniformities of the coating material) may increase the color tone, adhesiveness and weldability of the material.
  • the nitriding conditions are described below. From the viewpoint of productivity, it is preferable to perform the nitriding conditions in the present invention at the same time as the recrystallization annealing process after the cold-rolling, or after this process, in succession with the recrystallization annealing process, but it is not limited to this.
  • the method of annealing either the batch method or the continuous annealing method can be used.
  • the continuous annealing method from the view point of uniformity of the materials within the coil of the nitrified material and from the view point of the productivity during the nitriding treatment, it is likely advantageous to use the continuous annealing method.
  • the nitriding treatment in order to obtain the great efficacy in controlling the materials within the inner layer as prescribed by the exemplary embodiment of the present invention, from the point that it is disadvantageous to increase the duration of the nitriding treatment and of the following thermal history, it may be preferable to perform at least the nitriding treatment in a continuous annealing apparatus. If there is no particular reason, then it can be used in continuous annealing. There may be many merits in partially controlling the atmosphere within the furnace during the continuous annealing process and in performed recrystallization in the first half, with nitriding in the second half such as increasing the ease of controlling the nitride configuration, the productivity and the uniformity of the material.
  • the recrystallization can be significantly inhibited, and un-recrystallized structures may remain, leading to prominent degradation of the processing characteristics of the material, and therefore, sufficient care is required.
  • This boundary can be determined by the steel constituents, the nitriding conditions and the recrystallization conditions, but for one skilled in the prior art, it should be easy to determine the conditions where there can be no un-recrystallized structures remaining after the appropriate trials.
  • the plate temperature is within a range of 550 to 800°C.
  • the nitriding atmosphere is set to this temperature, and by passing the steel sheet through that atmosphere, it is possible to perform nitriding treatment in this range simultaneously.
  • the range should be within a range of 550 to 750°C. It is preferable for the range to be within a range of 600 to 700°C, and it is even more preferable for the range to be within a range of 630 to 680°C.
  • the ratio of nitriding gas in terms of the nitriding atmosphere, it is preferable for the ratio of nitriding gas to be greater than or equal to 10%. It is more preferable for it to be greater than or equal to 20%, and it is even more preferable for it to be greater than or equal to 40%. It is even better for it to be greater than or equal to 60%. As necessary, it is acceptable to set the amount of hydrogen gas to be less than or equal to 90%, less than or equal to 80%, 60% or even 20%. Furthermore, as necessary, it is possible to set the ammonia gas contained to be greater than or equal to 0.02%. It is possible to include various inactive gases such as oxygen gas, hydrogen gas, or carbon dioxide gas for the remainder.
  • ammonia gas shows high efficacy in increasing the nitriding efficiency, and as it is possible to obtain the specific nitriding amount in a short period of time, it is possible to inhibit the proliferation of N into the center of the steel sheet, and to obtain favorable effects in terms of the present invention. Less than or equal to 0.02% for this effect is sufficient, but it is preferable for this effect to be greater than or equal to 0.1 %, 0.2%, 1.0%, or even 5%. If the effect is greater than or equal to 10%, it is possible to obtain sufficient effects in less than 5 seconds of nitriding treatment.
  • the ratio of the main gas components other than ammonia gas, in particular, of nitrogen gas and hydrogen gas, (nitrogen gas) / (hydrogen gas) is greater than or equal to 1, and it is possible to obtain even more efficient nitriding if this ratio is greater than or equal to 2.
  • the annealing can be performed at conditions such as within an atmosphere of mainly nitrogen and hydrogen gas, where the material may not undergo nitriding, but for one experienced in the prior art, it should be possible to change the conditions under which nitriding will occur through modifications of the gas ratio, of the dew point, of the mixing of minute amount of gas regardless of the incorporation of the above ammonia gas after performing the appropriate trials.
  • the exemplary embodiment of the present invention has as its subject those items which have undergone nitriding treatment through a heat treatment including annealing, and which can be detected through current analytical methods.
  • the duration of time spent under the nitriding atmosphere is not particularly specified, but considering the temperature conditions of the exemplary embodiment of the present invention (greater than or equal to 550°C), and the thickness of the steel sheet, which is at most 0.400 mm, the upper limit for this duration is set to 360 seconds, since likely it would not be possible to obtain the hardness distribution or the N distribution as desired in the present invention if the duration were longer, as the N embedded within the surface of the steel sheet due to nitriding treatment would reach the center layers of the steel sheet through dispersion of the N within the steel during the holding period.
  • 1 second is required to obtain the hardness distribution and the nitrogen in the thickness direction of the steel sheet as well as the nitriding amount required in the present invention, even through improving the nitriding efficiency. It is preferable to take within a range of 2 to 120 seconds, it is more preferable to take within a range of 3 to 60 seconds or within a range of 4 to 30 seconds, and it is even better to take within a range of 5 to 15 seconds.
  • the duration to be a short period of time it may be important to increase the nitriding efficiency through such method as increasing the ammonia concentration.
  • the dispersion state of the nitrides on the surface of the steel sheet it is preferable to control the conditions during nitriding treatment as a method of controlling this dispersion effectively.
  • the gas nitride can be noted when using the most preferable ammonia gas.
  • the value which illustrates this equation should be less than or equal to 100, and it is preferable for it to be less than or equal to 50.
  • the sheet temperature at the beginning of the nitriding treatment is less than 550°C, the result of the above equation will be negative, but this case is also included within the present invention.
  • the denominator in the above equation is 0, no reasonable value can be obtained, but a value of 0 in the denominator means that no nitriding has occurred, and as the "nitriding initiation" part of the above equation will no longer apply, this case is automatically excluded.
  • the meaning of the above equation in other words, the technical meaning of this control, is as follows.
  • the dispersion state of the nitrides is dependent on the initial state of nitride formation, or to rephrase, it is greatly dependent on the state of nucleation of the nitrides, and therefore, the conditions at the initiation of nitriding affect the final dispersion state of the nitrides.
  • the nucleation of the nitrides is, in approximately the same manner as the precipitates within conventional steel, a phenomena wherein high density and fine nucleation occurs in a state where the deposited elements are supersaturated at low temperatures. In other words, while the supersaturated elements may try to form some kind of precipitate, if the temperature at that time is low, no dispersion may occur and the dispersion distance can grow small, resulting in a fine precipitate configuration.
  • the concentration of ammonia gas it is preferable for the concentration of ammonia gas to be high.
  • the temperature it too low insufficient nitriding can occur, and if the ammonia gas concentration is high, it may not be possible to sufficiently control the super-saturation state. It may be difficult to accurately describe the optimal conditions of this state in numeral equation, but basically, according to the above description, it can be represented in the kind of shape as in the control equation of the present invention.
  • the optimal state is where sufficient nitriding occurs, and in a temperature range where there is no excessive dispersion (for instance, when using ammonia nitriding, the temperature range is within a range of 550 to 700°C), and it is preferable to begin nitriding treatment at a relatively high gas concentration, and to perform nucleation of the nitrides at the surface of the steel sheet.
  • This does not contain any temporal factors, but by performing nucleation over a period of time at a low temperature which inhibits dispersion, it should be possible to perform fine nucleation dispersion.
  • the value of the above equation can be in the negative range, but inclusion in the present invention is as previously discussed.
  • the above exemplary control procedure is not limited to ammonia gas nitriding treatment, and therefore, the nitriding gas is not limited to ammonia. Furthermore, the nitriding treatment method is not limited to the gas nitride. In other words, the precipitate dispersion is controlled using well-known metallurgy of nucleation, and if one is experienced in conventional steel materials, it should be easy to establish favorable conditions according to the specific nitriding treatment method.
  • the procedure to obtain the steel sheet in the present invention is not limited to gas nitriding treatment, and it is also possible to perform this through liquid nitriding treatment, plasma nitriding treatment or ion injection.
  • the present invention requires the blanketing of at least a certain region of the surface with nitrides, and therefore, as long as it results in a concentration of N on the surface, it is possible to use any other applicable method.
  • the process is one wherein the N distribution in the thickness direction of the steel sheet is changed without increasing the total amount of N contained in the steel sheet and where N is concentrated on the surface only, modifications to the processing of the steel sheet can be minimized, which is optimal.
  • the level of color tone, surface coating adhesiveness and weldability resulting from the surface precipitates which is the characteristic of the present invention may be kept at levels equal to or greater that of conventional materials.
  • the second cold-rolling conditions can be determined according to the customer's needs within the range of prior art, and it is possible to employ the same second cold-rolling process in the present invention as is used in conventional steels. When no rectification of the form is required, it is possible to avoid the second cold-rolling process entirely.
  • rolling can be performed at a rolling reduction in the range of 0.5 to 2.5%, but the steel in the present invention can also undergo a similar rolling treatment. If the second cold-rolling reduction is high, the steel sheet itself will be sufficiently hardened. Therefore, as it can be possible to obtain a sufficiently can strength without controlling the material distribution in the thickness direction as provided for the exemplary embodiment of the present invention, the significance of increasing the second cold-rolling reduction greatly beyond the conventionally used range diminishes.
  • the reduction be on the scale of 70%. This limit can be determined after considering the can strength and ductility, but, for instance, when using a second cold-rolling reduction which is greater than 70%, there would be no loss in the increased efficacy of the control of the surface precipitates on the surface characteristics or weldability, which is the unique characteristic of the present invention.
  • a second cold-rolling operation is performed in order to manufacture a hard material, it goes without saying that it is preferable to have a high second cold-rolling reduction. It is appropriate for this second cold-rolling reduction to be greater than or equal to 6%, 10%, 20%, or 30%, and it is even more preferable for it to be greater than or equal to 40% to increase the hardness. If maintaining ductility is preferred, then it goes without saying that it is preferable to have a low rolling reduction in the second cold-rolling. It is good for this second cold-rolling reduction to be less than or equal to 50%, 40%, 30%, 20% or 10%, and it is even more preferable for it to be 5%, in order to secure the ductility of the steel sheet.
  • the timing of the second cold-rolling is appropriate for the timing of the second cold-rolling to be after the specific heat treatment in processes where the recrystallization annealing and the specific heat treatment are performed continuously.
  • the recrystallization annealing and the specific heat treatment are performed in separate processes, it is possible to perform the second cold-rolling prior to the specific heat treatment
  • the material may undergo localized softening due to the weld heat, and there have been problems where the process strain during formation of the flange may accumulate and degrade the formation characteristics of the material.
  • the steel in the present invention which contains a large amount of N on the surface part, as this softening due to weld heat can be controlled, it is possible to obtain merits even in terms of formation characteristics of the weld area.
  • the exemplary embodiment of the present invention is applicable to steel sheets of thickness less than or equal to 0.400 mm.
  • the reason for this is that, in steel sheets of thickness greater than this, it is difficult to have problems in color tone, surface coating adhesiveness and weldability of the formed material. It is preferable for the steel sheet in question to be less than 0.300 mm thick, and even more preferable for it to be less than or equal to 0.240 mm thick. In steel sheets of less than 0.190 mm of even 0.160 mm thickness, it is possible to obtain extremely prominent efficacy.
  • the effects of the exemplary embodiment of the present invention do not depend on the thermal history or manufacturing history after adjustment of the constituents or prior to annealing.
  • the slab when performing hot-rolling is not limited to manufacturing methods such as the ingot method or the continuous casting method, and as it does not depend on the thermal history leading up to the hot-rolling process, it is possible to obtain the efficacy of the present invention even in thin cast slabs where the rough rolling has been omitted, or in the CC-DR method which directly hot-rolls the material without reheating the cast slab through the slab reheating method. Furthermore, regardless of the hot-rolling conditions, it is possible to obtain the efficacy of the present invention even through dual stage rolling where the finish temperature is separated into a + ⁇ phase, or through continuous hot-rolling where rough bar is joined and rolled.
  • the surface layer with a high concentration of N will undergo rapid quenching and will harden, so it is also possible to improve the strength of the weld area. This affect will become even more prominent when elements which inhibit softening of the heat-affected part even in conventional materials, such as B or Nb, are added.
  • the steel sheet according to the exemplary embodiment of the present invention includes those which have undergone some sort of surface treatment.
  • these sheets can require color tone or welding after the surface treatment, and so the favorable state of the surface of the steel sheet which is required in these characteristics may not be lost due to the surface treatment in the steel sheet manufactured as described above.
  • there can be some change to the absolute values of Ra and PPI due to the surface treatment but it is possible to adequately detect the function which optimizes the surface state of the steel sheet generated through controlling the nitride configuration on the surface, in other words, the state where multiple short irregularities have been formed even on the steel sheet which have undergone surface treatment. Based on this effect, it is possible to provide extremely favorable color tone and weldability even in the steel sheet which have undergone surface treatment.
  • the surface state of the steel sheet prior to performing the surface treatment is important in terms of the adhesiveness of surface coatings such as metal plating, paint, or organic films (laminate).
  • surface coatings such as metal plating, paint, or organic films (laminate).
  • a commonly used method in surface treatment is metal plating, where tin, chrome (tin-free), nickel, zinc or aluminum is used. Not only can the adhesiveness of these coatings be improved, but the color tone and weldability after formation of the coating can also be improved.
  • the exemplary embodiments of the present invention may be used in all types of containers, whether they are 2-piece cans or 3-piece cans, and it is possible to use the present invention even when the above types of challenges are present in the application.
  • a steel sheet coating with Sn which is one of the most common types of steel sheet for use in containers, may be used, its color tone, surface coating adhesiveness and weldability can be evaluated.
  • the adhesiveness was measured through performing a T-type separation test on a test piece where a nylon adhesive was used to attach two layers of sheet on which a 25 mg/m 2 layer of an epoxy-phenol paint had been applied on both surfaces. The adhesive was heated in application, this test piece was wet with tap water, and the separation strength was measured. Of course, items where the separation strength was high were determined to have good adhesiveness, and were judged to be excellent
  • 10 ⁇ m may be painted on a transparent polyester resin which was then dried, and using a spectrophotometric colorimeter, the obtained value of L can be identified. If the value of L is high, this shows excellent color tone characteristics, and based on this value, the sample may be evaluated.
  • a seam weld can be performed as is used in conventional 3-piece cans, changing the weld current, and seeking the weldability current range from the surface damage in the weld area due to the arc current between the surface of the steel sheet and the polar ring during welding as well as the strength of the weld area through splash generation (dust generation) during welding and through the peel test (Hyne test), it is possible to determine the width of the range and the lower limit value.
  • a broader range results in higher stability in manufacturing, and when the lower limit is low, there is unlikely to be property changes or separation of the plating due to the increased temperature in the weld area.
  • the sample can be evaluated. The roughness was measured using a laser three-dimensional roughness meter.
  • the steel sheet after nitriding treatment did have some change in N concentration in the thickness direction, but it is possible to use the average value of thickness in the present invention.
  • the amount of N shown in Table 1 is the average amount of N in the thickness prior to nitriding treatment.
  • the sheet according to the conditions shown in Table 1 may be passed, and a nitriding performed. Nitriding-treatment was performed during or after the annealing, and the conditions were such where the recrystallization may be considered to have been complete prior to beginning nitriding.
  • the steel sheets can be manufactured using temper rolling.
  • the rolling reduction conditions, the final sheet thickness, the analysis results of the amount of nitriding and the results of the evaluation of the characteristics for each steel is shown in Table 2.
  • Table 2 By controlling the state in the thickness direction within the range prescribed in the present invention by using the manufacturing method of the present invention, it can be confirmed that it is possible to obtain favorable color tone, surface coating adhesiveness and weldability.
  • the steel sheet for use in containers and the manufacturing method therefor in the present invention it is possible to improve the color tone of the container, the surface coating adhesiveness and the weldability without needing to perform complex treatments after the nitriding treatment which could adversely affect productivity. In this way, it is possible to deterioration of the productivity of the manufacture of steel sheets for ultra-thin containers as well as to extraordinary efficacy in the manufacturing process.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Claims (6)

  1. Ein Stahlblech zur Verwendung in einem Behälter, umfassend: mindestens einen Teil mit einer Blechdicke von höchstens 0,400 mm und umfassend ein Material, das höchstens: 0,0800% C, 0,600% N, 2,0% Si, 2,0% Mn, 0,10% P, 0,05% S und 2,0% Al, gegebenenfalls mindestens einen Bestandteil, und wobei eine Menge des mindestens einen Bestandteils höchstens: 0,08% Ti, 0,08% Nb, 0,015% B, 5,0% Ni, 2,0% Cu und 2,0% Cr beträgt, ferner gegebenenfalls eine Summe von weniger oder gleich 0,1% Sn, Sb, Mo, Ta, V und W enthält und wobei der Rest aus Fe und unvermeidbaren Verunreinigungen besteht, wobei ein erstes Verhältnis einer Fläche von Stickstoffverbindungen auf einer Oberfläche des mindestens einen Teils geteilt durch ein zweites Verhältnis einer Fläche von Stickstoffverbindungen an einer Querschnittsposition bei einer Tiefe von 1/4 der Dicke des mindestens einen Teils mindestens 1,5 beträgt, und wobei eine Rauheit der Oberfläche des mindestens einen Teils höchstens 0,90 µm Ra beträgt und wobei eine Anzahl von Peaks der Dicke in einer Region des mindestens einen Teils mit einer Länge von 2,54 cm (1 Inch) mindestens 250 PPI beträgt.
  2. Ein Verfahren zur Herstellung eines Stahlblechs zur Verwendung in einem Behälter, wobei das Stahlblech eine Blechdicke von höchstens 0,400 mm aufweist und ein Material umfasst, das höchstens 0,0800% C, 0,0300% N, 2,0% Si, 2,0% Mn, 0,10% P, 0,05% S und 2,0% Al, gegebenenfalls mindestens einen Bestandteil, und wobei eine Menge des mindestens einen Bestandteils höchstens: 0.08% Ti, 0,08% Nb, 0,015% B, 5,0% Ni, 2,0% Cu und 2,0% Cr beträgt, ferner gegebenenfalls eine Summe von weniger oder gleich 0,1% Sn, Sb, Mo, Ta, V und W enthält und wobei der Rest aus Fe und unvermeidbaren Verunreinigungen besteht, wobei das Verfahren umfasst:
    a) Kaltwalzen des Stahlblechs;
    b) nach Schritt (a), Durchführen einer Nitrierbehandlung gleichzeitig mit oder nach einem Rekristallisationsglühverfahren;
    c) während Schritt (b) und wenn eine Blechtemperatur 550 bis 800°C beträgt, Halten der Blechtemperatur für länger als 0,1 Sekunden und weniger als 360 Sekunden in einer Umgebung, die mindestens 0,02% Ammoniakgas enthält; und
    d) Erhöhen der Menge an N um mindestens 0,0002% im Vergleich zur Menge vor der Nitrierbehandlung, derart dass ein erstes Verhältnis einer Fläche von Stickstoffverbindungen auf einer Oberflächenposition des Stahlblechs geteilt durch ein zweites Verhältnis einer Fläche von Stickstoffverbindungen an einer Querschnittssposition bei einer Tiefe von 1/4 einer Dicke des Stahlblechs mindestens 1,5 beträgt; und derart dass eine Menge an N innerhalb des Stahlblechs höchstens 0,600% beträgt, wobei das Verfahren ferner umfässt:
    e) während Schritt (b), Bereitstellen eines bestimmten Verhältnisses der Blechtemperatur (°C) - 550 zu einer Konzentration (%) eines Ammoniakgases zu Beginn der Nitrierungsbehandlung, derart dass es weniger als 150 beträgt.
  3. Das Stahlblech nach Anspruch 1, wobei das erste Verhältnis geteilt durch das zweite Verhältnis mindestens 6 beträgt.
  4. Das Stahlblech nach Anspruch 1 oder 3, wobei die Blechdicke weniger als 0,300 mm beträgt.
  5. Das Stahlblech nach einem der Ansprüche 1, 3 und 4, wobei das erste Verhältnis der Fläche von Stickstoffverbindungen auf der Oberfläche des mindestens einen Teils mindestens 1,0% beträgt.
  6. Das Stahlblech nach einem der Ansprüche 1, 3, 4 und 5, wobei eine Dichte eines Bereichs von einzelnen Stickstoffverbindungen auf der Oberfläche des mindestens einen Teils, welches einen Durchmesser von mindestens 0,1 µm aufweist, mindestens 0,001 Einheiten/µm2 beträgt.
EP05704017.2A 2004-01-19 2005-01-17 Stahlblech zur verwendung in behältern und herstellungsverfahren dafür Expired - Fee Related EP1706514B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2004011139 2004-01-19
PCT/JP2005/000796 WO2005068667A1 (en) 2004-01-19 2005-01-17 Steel sheet for use in containers and manufacturing method therefor

Publications (2)

Publication Number Publication Date
EP1706514A1 EP1706514A1 (de) 2006-10-04
EP1706514B1 true EP1706514B1 (de) 2015-03-11

Family

ID=34792320

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05704017.2A Expired - Fee Related EP1706514B1 (de) 2004-01-19 2005-01-17 Stahlblech zur verwendung in behältern und herstellungsverfahren dafür

Country Status (5)

Country Link
EP (1) EP1706514B1 (de)
JP (1) JP4299858B2 (de)
KR (1) KR100851691B1 (de)
CN (1) CN1910296B (de)
WO (1) WO2005068667A1 (de)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1806420A4 (de) * 2004-09-09 2008-04-23 Nippon Steel Corp Stahlblech für extrem dünnen behälter und zugehöriges herstellungsverfahren
JP4646858B2 (ja) * 2006-06-14 2011-03-09 株式会社神戸製鋼所 窒化処理用鋼板
US8518501B2 (en) 2010-03-10 2013-08-27 Restaurant Technology, Inc. Food holding device, method of making, and method of storing cooked food
KR101256516B1 (ko) * 2010-12-23 2013-04-22 주식회사 포스코 내꺽임성 및 내식성이 우수한 열연강판 제조방법 및 이에 의해 제조된 열연강판
DE102014112286A1 (de) * 2014-08-27 2016-03-03 Thyssenkrupp Ag Verfahren zur Herstellung eines aufgestickten Verpackungsstahls
CN106222551B (zh) * 2016-08-16 2018-05-01 武汉钢铁有限公司 一种表面无缺陷的渗氮铁制容器基板及生产方法
EP3875626B1 (de) * 2020-03-06 2024-07-17 ThyssenKrupp Rasselstein GmbH Verpackungsblecherzeugnis
DE102020106164A1 (de) * 2020-03-06 2021-09-09 Thyssenkrupp Rasselstein Gmbh Kaltgewalztes Stahlflachprodukt für Verpackungen

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3105380B2 (ja) * 1993-06-21 2000-10-30 新日本製鐵株式会社 耐デント性ならびに耐面ひずみ性に優れた深絞り用冷延鋼板の製造方法
JP3233770B2 (ja) * 1994-02-14 2001-11-26 新日本製鐵株式会社 耐デント性ならびに耐面ひずみ性に優れた深絞り用ｂｈ鋼板の製造方法
JP3448380B2 (ja) * 1994-12-27 2003-09-22 新日本製鐵株式会社 容器用鋼板の製造方法
JP3777049B2 (ja) * 1998-04-30 2006-05-24 新日本製鐵株式会社 耐デント性ならびに耐面ひずみ性に優れた深絞り用ｂｈ冷延鋼板の製造方法
JP4249860B2 (ja) * 1999-10-01 2009-04-08 新日本製鐵株式会社 容器用鋼板の製造方法
JP2001107189A (ja) * 1999-10-06 2001-04-17 Nippon Steel Corp コイル内の材質の均質性に優れる極薄鋼板およびその製造方法
JP3542946B2 (ja) * 2000-06-29 2004-07-14 新日本製鐵株式会社 加工性及びめっき密着性に優れた高強度鋼板及びその製造方法

Also Published As

Publication number Publication date
JP2007520628A (ja) 2007-07-26
JP4299858B2 (ja) 2009-07-22
CN1910296A (zh) 2007-02-07
EP1706514A1 (de) 2006-10-04
WO2005068667A1 (en) 2005-07-28
CN1910296B (zh) 2011-08-31
KR20060113984A (ko) 2006-11-03
KR100851691B1 (ko) 2008-08-11

Similar Documents

Publication Publication Date Title
EP1706514B1 (de) Stahlblech zur verwendung in behältern und herstellungsverfahren dafür
EP2003221B1 (de) Hartes extra dünnes stahlblech und verfahren zu seiner herstellung
EP2138599B1 (de) Hochfestes feuerverzinktes stahlblech und verfahren zu seiner herstellung
KR101624473B1 (ko) 고강도 용융 아연 도금 강판 및 그 제조 방법
EP2233597B1 (de) Hochfestes feuerverzinktes stahlblech mit hervorragender formbarkeit und herstellungsverfahren dafür
EP2128295B1 (de) Hochfestes feuerverzinktes stahlblech mit hervorragender formbarkeit und herstellungsverfahren dafür
EP2224033A1 (de) Verfahren zur herstellung von hochfestem feuerverzinktem stahlblech und hochfestes feuerverzinktes stahlblech
EP2479308B1 (de) Stahlblech für dosen mit hervorragender oberflächenaufrauungsbeständigkeit und herstellungsverfahren dafür
CN109072450A (zh) 模压淬火方法
WO2017022025A1 (ja) 高強度熱延鋼板
WO2020136988A1 (ja) 高強度溶融亜鉛めっき鋼板およびその製造方法
JP2008231448A (ja) 合金化溶融亜鉛めっき用鋼板及び合金化溶融亜鉛めっき鋼板
EP3578679A1 (de) Hochfestes warmgewalztes stahlblech aus zinkschmelze und herstellungsverfahren dafür
EP1709208B1 (de) Stahlplatte für behälter und zugehöriges herstellungsverfahren
JP4328124B2 (ja) 缶特性が著しく良好な極薄容器用鋼板およびその製造方法
EP4265751A1 (de) Heisspresselement, beschichtungselement, stahlblech zum heisspressen, verfahren zur herstellung eines heisspresselements und verfahren zur herstellung eines beschichtungselements
JP2006219717A (ja) 耐変形性、表面特性、溶接性が著しく良好な容器用鋼板及びその製造方法
WO2006027854A1 (ja) 極薄容器用の鋼板およびその製造方法
KR102370505B1 (ko) 내식성이 향상된 페라이트계 스테인리스강 및 이의 제조방법
JP4564289B2 (ja) 加工後表面被覆膜損傷の少ない高剛性缶用鋼板及びその製造方法
JP2004218061A (ja) 耐変形性が著しく良好な容器用鋼板およびその製造方法
KR20090007783A (ko) 극박 용기용 강판 및 그 제조 방법
WO2023162893A1 (ja) 鋼板、および鋼板の製造方法
WO2023132289A1 (ja) ホットスタンプ用鋼板およびホットスタンプ成形体
KR20070042576A (ko) 극박 용기용 강판 및 그 제조 방법

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20060803

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): BE DE ES FR GB

RBV Designated contracting states (corrected)

Designated state(s): BE DE ES FR GB

DAX Request for extension of the european patent (deleted)
RBV Designated contracting states (corrected)

Designated state(s): BE DE ES FR GB

17Q First examination report despatched

Effective date: 20100715

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: NIPPON STEEL & SUMITOMO METAL CORPORATION

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

INTG Intention to grant announced

Effective date: 20131203

GRAC Information related to communication of intention to grant a patent modified

Free format text: ORIGINAL CODE: EPIDOSCIGR1

INTG Intention to grant announced

Effective date: 20140423

GRAJ Information related to disapproval of communication of intention to grant by the applicant or resumption of examination proceedings by the epo deleted

Free format text: ORIGINAL CODE: EPIDOSDIGR1

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

INTG Intention to grant announced

Effective date: 20140709

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

INTG Intention to grant announced

Effective date: 20150108

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): BE DE ES FR GB

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 602005046033

Country of ref document: DE

Effective date: 20150416

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20150311

REG Reference to a national code

Ref country code: FR

Ref legal event code: PLFP

Year of fee payment: 12

REG Reference to a national code

Ref country code: DE

Ref legal event code: R097

Ref document number: 602005046033

Country of ref document: DE

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20151214

REG Reference to a national code

Ref country code: FR

Ref legal event code: PLFP

Year of fee payment: 13

REG Reference to a national code

Ref country code: FR

Ref legal event code: PLFP

Year of fee payment: 14

REG Reference to a national code

Ref country code: DE

Ref legal event code: R082

Ref document number: 602005046033

Country of ref document: DE

Representative=s name: VOSSIUS & PARTNER PATENTANWAELTE RECHTSANWAELT, DE

Ref country code: DE

Ref legal event code: R081

Ref document number: 602005046033

Country of ref document: DE

Owner name: NIPPON STEEL CORPORATION, JP

Free format text: FORMER OWNER: NIPPON STEEL & SUMITOMO METAL CORP., TOKYO, JP

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: BE

Payment date: 20191217

Year of fee payment: 16

Ref country code: FR

Payment date: 20191216

Year of fee payment: 16

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20200113

Year of fee payment: 16

Ref country code: DE

Payment date: 20200107

Year of fee payment: 16

REG Reference to a national code

Ref country code: DE

Ref legal event code: R119

Ref document number: 602005046033

Country of ref document: DE

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20210117

REG Reference to a national code

Ref country code: BE

Ref legal event code: MM

Effective date: 20210131

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20210131

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20210117

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20210803

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20210131