Technical field
[0001]
　The present invention relates to a Sn-plated steel sheet and the chemical conversion treated steel sheet and a method for their preparation.
　The present application, on February 6, 2015, claiming priority based on Japanese Patent Application No. 2015-22385 filed in Japan, the contents of which are incorporated here.
Background technique
[0002]
　The flat steel product, corrosion resistance, rust resistance, to ensure the characteristics of the paints adhesion, Sn in the steel sheet or steel sheet surface, the plated steel sheet surface to Zn or Ni or the like is plated, oxide Cr or metallic Cr and oxides Cr sometimes chromate treatment to form a chromate film comprising is applied. Chromate film, with respect to the steel sheet or plated steel sheet is formed by applying a cathodic electrolysis treatment (electrolytic Cr acid treatment) using laden process liquid hexavalent chromium in solution. However, in recent years, since hexavalent chromium is harmful environmental, there is a movement to replace chromate treated with other surface treatments.
[0003]
　As a kind of other surface treatment, surface treatment is known by the chemical conversion treatment agent containing Zr compound. For example, Patent Document 1 performs a chemical conversion treatment reaction by a chemical conversion treatment agent containing a Zr compound and F compound by the cathode electrolytic treatment, it is described that the formation of Zr-containing chemical conversion coating on the surface of the metal substrate. Further, Patent Document 2, Zr, and an inorganic surface treatment layer containing no phosphate ions with the main component O and F, the surface with the organic surface treatment layer mainly composed of organic components is formed processed metal material is described. In Patent Document 3, it is described that continuously against the strip with a processing solution containing a fluoride Zr ions and phosphate ions perform cathode electrolytic treatment to cover the chemical conversion coating on the strip there.
[0004]
　Also, a technique for crystal orientation of the Sn-plated to a specific surface are known. For example, Patent Document 4, for whisker measures, is preferentially oriented crystal orientation of the Sn-plated film on (220) plane. In Patent Document 4, the film stress after Sn plating film formation is -7.2 ~ 0 MPa. In Patent Document 5, which increases the roughness of the Sn plating film by crystal orientation of the Sn plating film on the copper foil (200) plane, reduce slippage between the Sn plated steel sheet and a roll during continuous plating . Further, Patent Document 5, since preferentially oriented crystal orientation of the Sn-plated film on (200) plane, it is disclosed that adhesion of Sn on the roll is reduced.
[0005]
　In Non-Patent Document 1, have been shown to have a corrosion resistance packed planes of Sn is excellent.
CITATION
Patent Literature
[0006]
Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-23422
Patent Document 2: Japanese Laid-Open Patent Publication No. 2006-9047
Patent Document 3: Japanese Laid-Open Patent Publication No. 2009-84623
Patent Document 4: Japanese Patent Laid-Open 2006-70340 Publication No.
Patent Document 5: Japanese Laid-open Patent Publication No. 2011-74458
Non-Patent Document
[0007]
Non-Patent Document 1: Shujiro Choya, Oyagi eighty-seven al, "crystal orientation and corrosion resistance of the plated tin", Iron and Steel, 1969, No. 2, P. 184-189
Summary of the Invention
Problems that the Invention is to Solve
[0008]
　In the case of forming the Zr-containing chemical conversion film on the Sn-plated steel sheet, as compared with the case of forming a chromate film on the Sn-plated steel sheet, there is a problem that the corrosion resistance is poor. For example, appearance oxide Sn is formed when transporting and long-term storage the chemical conversion treated steel sheet to form a Zr-containing chemical conversion coating on the Sn plated steel sheet is discolored yellow (hereinafter, yellowing and referred) has a problem that .
　Moreover, Sn-plated steel sheet may be used in a container and the contents of the beverage or food or the like. In such a case, when the contents are foods containing proteins (amino acids), and the reaction with S of Sn and in proteins (amino acids) of the Sn plated steel sheet, black SnS is formed (hereinafter , there is a problem that referred to) and sulfide blackening.
[0009]
　The present invention has been made in view of the above circumstances, and an object thereof is to provide a Sn-plated steel sheet and the chemical conversion treated steel sheet as well as their manufacturing method has excellent corrosion resistance.
Means for Solving the Problems
[0010]
　The present invention is to solve the above problems, adopts the following means in order to achieve the object.
(1) Chemical-treated steel sheet according to an embodiment of the present invention includes a steel plate, is provided as an upper layer of the steel sheet, and the Sn plating layer of matte finish consisting of beta-Sn, is provided as an upper layer of the Sn plated layer , and a chemical conversion coating layer, the Sn plating layer, in terms of metal amount of Sn 0.10 ~ 20.0 g / m 2 by weight of beta-Sn, (100) plane of the Sn plated layer crystal orientation index of the group is higher than the crystal orientation index of the other crystal orientation planes, the chemical conversion coating layer, to 0.50 ~ 50.0 mg / m terms of metal Zr content 2 Zr compound containing Zr of When, and a phosphoric acid compound.
[0011]
(2) In the chemical conversion treated steel sheet according to (1), when a crystal orientation index of (200) plane of the Sn plating layer was defined as X represented by the following formula (1), wherein X is 1.0 it may be greater than or equal to.
[0012]
[Number 1]

[0013]
(3) The method of producing chemical conversion treated steel sheet according to one embodiment of the present invention, on the steel sheet, a Sn plating layer current density contains beta-Sn by electroplating is 10 to 50% critical current density electrical Sn plating step of forming, by electrolytic treatment in the Sn-plated layer and the steel sheet to a chemical conversion treatment bath that has been formed, a chemical conversion treatment step of forming a chemical conversion coating layer on the Sn plating layer, the a.
[0014]
(4) In the manufacturing method of the chemical conversion treated steel sheet of the above (3), in the chemical conversion treatment step, the steel sheet which the Sn plated layer is formed, Zr ions 10 to 10000 ppm, of 10 to 10000 ppm F ions, 10 to includes a phosphate nitrate ions and 100 ~ 30000 ppm of 3000 ppm, in the chemical treatment bath temperature is ~ 90 ° C. 5, 1.0 ~ 100A / dm 2 electrolysis of current density and 0.2 to 100 seconds under the conditions of time, it may be electrolytic process.
[0015]
(5) Sn-plated steel sheet according to one embodiment of the present invention, the steel sheet and, provided as an upper layer of the steel sheet, and a plated layer of matte finish consisting of beta-Sn, the Sn plating layer weight metal Sn in terms 0.10 ~ 20.0 g / m to 2 by weight of beta-Sn, crystal orientation index of (100) planes of the Sn plating layer is higher than the crystal orientation index of the other crystal orientation planes.
[0016]
(6) the production method of the Sn-plated steel sheet according to one embodiment of the present invention, on the steel plate by electroplating current density is 10 to 50% critical current density, Sn plating layer containing beta-Sn having electrical Sn plating step of forming a.
Effect of the Invention
[0017]
　According to the above embodiment, it is possible to provide a Sn-plated steel sheet having excellent corrosion resistance and chemical conversion treatment steel sheet and a method for their preparation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018]
[FIG. 1A] is an explanatory view of the layer structure of the chemical conversion treated steel sheet according to the present embodiment shown schematically.
[FIG 1B] is an explanatory diagram of the layer structure of the chemical conversion treated steel sheet according to the present embodiment shown schematically.
It is a flow diagram illustrating an example of a manufacturing method of the chemical conversion treated steel sheet according to [2] The present embodiment.
DESCRIPTION OF THE INVENTION
[0019]
　Reference will now be described in detail preferred embodiments of the present invention. In the present embodiment, components having substantially the same function and structure are a repeated explanation thereof by referring to the figures.
[0020]
　[Chemically treated steel sheet 10]
　First, referring to FIGS. 1A and 1B, the chemical conversion treated steel sheet 10 according to the present embodiment will be described in detail. 1A and 1B are explanatory diagrams of the layer structure in the case where a chemical conversion treated steel sheet 10 according to this embodiment seen from the side schematically showing.
[0021]
　Chemical treated steel sheet 10 according to this embodiment, as shown in FIGS. 1A and 1B, it comprises a Sn-plated steel sheet 101, and the chemical conversion coating layer 107. Sn-plated steel sheet 101, the steel plate 103 serving as a base material, and a Sn plating layer 105 formed on the steel plate 103, a. Incidentally, Sn-plated layer 105 and the chemical conversion coating layer 107, as shown in Figure 1A, may be formed only on one surface of the steel sheet 103, as shown in FIG. 1B, one another of the steel sheet 103 it may be formed on two opposite surfaces.
[0022]
About steel 103]
　steel 103 is used as the base material of the chemical conversion treated steel sheet 10 according to this embodiment. About steel sheet 103 used in this embodiment is not particularly limited, it is possible to use generally known steel sheet 103 used as a container material. There is no particular limitation on the manufacturing method and the material of the known steel sheet 103 described above, the conventional billet manufacturing process, hot rolling, pickling, cold rolling, after annealing, the known steps of temper rolling or the like produced steel plate 103 can be used.
[0023]
[For Sn plating layer 105 '
　on the surface of the steel sheet 103, Sn-plated layer 105 is formed. Sn-plated layer 105 of the present embodiment is composed of a beta-Sn having a tetragonal crystal structure. The surface of the Sn-plated layer 105 according to this embodiment, a mat finish. The matte finish, JIS G3303: a finishing method of the surface, which is defined in 2008, processing to turn off the luster of the surface is applied. On the surface of the steel sheet 103 having a dull like surface in a state subjected to Sn plating, the surface of the Sn-plated layer 105 by not performing the melt溶錫treatment (reflow treatment) on the surface of matte finish is applied.
　Doing molten溶錫processing Sn plating layer 105, the surface roughness of the Sn-plated layer 105 is reduced. As a result, a Sn plated layer 105 is a glossy appearance, JIS G3303: 2008 is not preferable because the appearance that is defined is not obtained.
[0024]
　In the present embodiment, since the on the assumption that subjecting a matte finish on the surface of the Sn-plated layer 105, the reflow treatment after the formation of the Sn-plated layer 105 is not performed. Therefore, FeSn an alloy layer produced by the reflow treatment 2 phase and Ni 3 Sn 4 is phase, no principle in chemical conversion treatment steel sheet 10 of the present embodiment.
[0025]
　In the following, with reference to FIG. 1A, for example of the Sn-plated layer 105 of the present embodiment will be specifically described. Note that the "Sn plating" in the present embodiment, not only the plating using metal Sn, those inevitable impurities metallic Sn is mixed or, including those with added artificially trace elements in the metal Sn. In the present embodiment, as will be described later, it is formed by electroplating Sn plating the Sn-plated layer 105.
[0026]
　In the Sn-plated layer 105 of the present embodiment, the content of Sn is 0.10 ~ 20.0 g / m per side in terms of the metal Sn 2 and. Sn content, in terms of metal Sn 0.10 g / m 2 by weight, small thickness of the Sn-plated layer 105, can not be completely cover the steel plate 103 by Sn plating layer 105, a pin hole Occur. Sn is a metal nobler than Fe, for easily piercing corrosion occurs when the pin hole is exposed to be present in a corrosive environment, which is not preferable.
　On the other hand, the content of Sn is 20.0 g / m 2 in the case of more than, when was preferentially oriented to (100) planes of the Sn-plated layer 105 by a method to be described below, the crystal of (100) planes It is not preferable because the orientation index is saturated. The content of Sn is 20.0 g / m 2 in the case of exceeding, since the effect of corrosion resistance is saturated, economically undesirable. Further, the content of Sn is 20.0 g / m 2 in the case of exceeding, since the electrical quantity and the processing time in the electrical Sn plating treatment to form a Sn plating layer 105 is often required, it decreases productivity, preferably Absent.
[0027]
　Further, the Sn-plated layer 105 in the present embodiment, in the content of the metal in terms of Sn per side, preferably 1.0 g / m 2 - 15.0 g / m 2 , more preferably 2.5 to 10.0 g / m 2 or equal to. The reason is that less in terms of metal Sn content of (i) Sn, the influence of the orientation of the steel sheet 103 as the base material is increased, the orientation of the beta-Sn in Sn-plated layer 105 be possible to obtain the preferable effects by controlling becomes difficult, is not preferable because the, productivity is reduced high content of Sn (ii) Sn-plated layer 105.
[0028]
　Metal Sn content in the Sn-plated layer 105 is, for example, can be measured by fluorescent X-ray method. In this case, a metal Sn amount known Sn content samples, previously identified a calibration curve for the metal Sn content, to identify the relative metal Sn amount using the same calibration curve. Sn metal included in the Sn-plated layer 105 of the present invention is a beta-Sn.
[0029]
　Coverage to the steel sheet 103 of the Sn-plated layer 105 can be evaluated, for example, by the following method. coverage of beta-Sn (the exposure rate of iron) as a method for quantitatively evaluating include measurement of IEV (Iron Exposure Value). In IEV, the Sn plated steel sheet 101, and sodium chloride of 21g / L sodium carbonate, 17 g / L sodium bicarbonate and 0.3 g / L of, pH was 10, the temperature is 25 ° C. Test solution in the middle, Sn is then anodically polarized to a potential (1.2 V vs.SCE) passivating, to measure the current density after three minutes. The obtained value of the current density was IEV, as the value of the IEV is small, indicating that the coverage is good. In the present embodiment, IEV is 15 mA / dm 2 is preferably less.
[0030]
　Chemical treated steel sheet 10, when commercialized, it is desirable to have a good appearance. If the chemical conversion treated steel sheet 10 was used as a container for transportation or long-term storage, and the reaction Sn and oxygen chemical conversion treated steel sheet 10, oxidized Sn is formed, the appearance of the container there is a problem that yellowing.
　Moreover, the chemical conversion treated steel sheet 10 may be used in a container and the contents of the beverage or food or the like. Among such cases, when the contents are foods containing proteins (amino acids) may be reacted with S in Sn and protein chemical conversion treated steel sheet 10 (amino acids), black SnS is formed (hereinafter , there is a problem that referred to) and sulfide blackening. The present inventors have found that in order to prevent the above-mentioned yellowing and sulfide blackening, the Sn-plated layer 105 was found that the dense surface of the beta-Sn it is effective to preferentially oriented.
[0031]
　In the present embodiment, the crystal orientation of the Sn-plated layer 105, is preferentially oriented in the (100) planes. In other words, the Sn-plated layer 105 of the present embodiment, (100) crystal orientation index X of planes is higher than the crystalline orientation index X of other crystal orientation planes. beta-Sn is a tetragonal, closest-packed plane is (100) planes. (100) and a plane equivalent (100) Mengun is a (010), (200), (020). The chemical conversion treated steel sheet 10 of the present embodiment, (100) of the Sn-plated layer 105 by preferentially oriented planes, characteristic for yellowing (hereinafter, referred to as yellowing resistance) and characteristics for sulfide blackening (hereinafter, referred to as sulfidation blackening) corrosion resistance such as improved.
[0032]
　In the present embodiment, the crystal orientation index X of (100) planes in the Sn-plated layer 105 is higher than the other crystal orientation planes. In particular, the crystal orientation index X of (200) plane of the Sn-plated layer 105 is 1.0 or more, preferably 1.5 or more. When the crystal orientation index X of (200) plane of the Sn-plated layer 105 is 1.0 or less, even worse the corrosion resistance of the chemical conversion treated steel sheet 10. Note that the definition of the crystal orientation index X, described below.
　Further, in the present embodiment, the crystal orientation index X other than (100) planes in the Sn-plated layer 105 is less than 1.0. For example, the Sn-plated layer 105 is less than 1.0 crystal orientation index X of (211) plane. Preferably, the crystal orientation index X other than (100) planes in the Sn-plated layer 105 is less than 0.6. As described above, in the Sn-plated layer 105, a (100) crystal orientation index X of another crystal orientation plane other than planes be extremely low, it is preferentially oriented (100) planes.
[0033]

　crystal orientation index X described above was measured by X-ray diffractometer, it is calculated by using the following equation (2). Source of X-ray diffractometer is used CuKα ray was tube current 100 mA, a tube voltage 30 kV.
[0034]
[Number 2]

[0035]
　The present inventors have found that a ratio obtained by dividing (200) the peak intensity of X-ray diffraction of the plane I (200) to (101) is the peak intensity of X-ray diffraction of the plane I (101) there I (200) / I (101 ), was investigated the relationship between the crystal orientation index X obtained by the equation (2). As a result, the present inventors have found that even one than I (200) / I (101 ), the crystal orientation index X was found that not necessarily greater than 1. For example, while I (200) / I (101 ) is 2.0, there are cases crystal orientation index X is 0.668.
　Peak The cause of the results described above, the crystal orientation index X Whereas determined from relative peak intensity ratio of powder X-ray diffraction of the state not oriented crystals, obtained by X-ray diffraction intensity ratio is to not properly represent the orientation of the crystal. For the above reasons, in order to adequately represent the orientation of the crystals, the (2) crystal orientation index X obtained by the equation is considered appropriate.
[0036]
　In this embodiment, the Sn-plated layer 105 is formed on the upper layer of the steel sheet 103 including the alpha-Fe, the surface of the Sn-plated layer 105 side of the steel plate 103 is preferably preferentially oriented in a (100) plane . By Sn plated layer 105 side of the surface of the steel plate 103 are preferentially oriented in the (100) plane, the adhesion between the Sn-plated layer 105 that is preferentially oriented in the steel plate 103 (200) plane is enhanced.
[0037]
[Chemical conversion for film layer 107
　' on the Sn-plated layer 105, as shown in FIGS. 1A and 1B, the chemical conversion coating layer 107 is formed. Chemical conversion coating layer 107, in terms of 0.50 ~ 50.0 mg / m on the metal Zr amount per one side 2 is a coating layer comprising a Zr compound containing Zr, and a phosphoric acid compound.
[0038]
　Zr compound contained in the chemical conversion film layer 107 according to this embodiment has a function of improving corrosion resistance, adhesion and processability adhesion. Zr compounds according to the present embodiment, for example, in addition to the Zr oxide and phosphate Zr, hydroxide Zr, composed of a plurality of Zr compounds such as fluoride such as Zr. Zr contained in the chemical conversion film layer 107 in terms of metal Zr 0.50 mg / m 2 in the case of less than, coverage is insufficient, undesirably corrosion resistance decreases. Meanwhile, Zr contained in the chemical conversion film layer 107 is 50.0 mg / m 2 in the case of exceeding, in addition to requiring a long time to form a chemical conversion film layer 107 is not preferable because the adhesion unevenness.
[0039]
　Incidentally, in the chemical conversion coating layer 107 in the present embodiment, Zr compound, in terms of metal Zr content per one side, 5.0 ~ 25.0 mg / m 2 is preferably contained.
[0040]
　Moreover, the chemical conversion coating layer 107 described above, in addition to the Zr compounds described above, further comprising one or more phosphorus acid compound.
[0041]
　Phosphoric acid compound according to the present embodiment has a function of improving corrosion resistance, adhesion and processability adhesion. Examples of the phosphoric acid compound according to the present embodiment, the phosphate compound contained in the phosphate ions and the steel plate 103, Sn-plated layer 105 and the chemical conversion coating layer 107 is formed by the reaction Fe, phosphate Sn, phosphate Zr, and the like. Chemical conversion coating layer 107 may include one phosphoric acid compounds described above, may comprise two or more. Phosphoric acid compounds described above is excellent in corrosion resistance and adhesion, the amount of the phosphoric acid compound contained in the chemical conversion film layer 107 is more increased, the corrosion resistance and adhesion of the chemical conversion treated steel sheet 10 is improved.
　But not limited conversion amount of the phosphoric acid compound containing the treated film layer 107 is particularly, in terms of P content, 0.50 ~ 50.0 mg / m 2 is preferably. Chemical conversion coating layer 107 that contains a phosphate compound in an amount described above, it is possible to chemical conversion treatment film layer 107 has a suitable corrosion resistance, adhesion and processability adhesion.
[0042]
　Chemical conversion coating layer 107 of the present embodiment, by Sn plating layer 105 are preferentially oriented in the (100) planes, it has excellent corrosion resistance, adhesion and processability adhesion. The reason is that, in the Sn-plated layer 105 (100) plane beta-Sn preferentially oriented in groups uniformly activated by chemical conversion treatment solution components such as fluoride ions (surface cleaning effect), the Sn plating layer 105 affinity with the chemical conversion coating layer 107 is considered to be due to the fact that improved. That is believed to activate the intermediate layer between the chemical conversion coating layer 107 and the Sn plating layer 105 (not shown) is formed. Thus, activated intermediate layer (not shown), the Sn-plated layer 105 formed by the manufacturing method of the present invention is a specific layer, with the configuration elements having the effect of having a chemical conversion treated steel sheet 10 of the present invention It is estimated.
　Also has a (100) on the Sn-plated layer 105 which are preferentially oriented in planes, the chemical conversion coating layer 107 is be formed uniformly, chemical conversion treated steel sheet 10 is a suitable appearance. The reason for this is believed to be due to the compounds of the beta-Sn and the chemical conversion coating layer 107 in the Sn plating layer 105 are regularly arranged.
[0043]
　Zr amount and the amount of P contained in the chemical conversion coating layer 107 according to this embodiment, for example, can be measured by a quantitative analysis method such as X-ray fluorescence analysis. In this case, a sample is known samples and the amount of P is known Zr amount in advance to create a calibration curve of the calibration curve and P amount related Zr weight, relative amount of Zr and P using these calibration curves it is possible to identify the amount.
[0044]

　Next, a method for manufacturing the chemical conversion treated steel sheet 10 according to this embodiment. Figure 2 is a flow diagram illustrating an example of a method of manufacturing a chemical conversion treated steel sheet 10 according to this embodiment.
　In the method for producing chemical conversion treated steel sheet 10 according to this embodiment, first, remove oil and scale adhering to the surface of the steel sheet 103 as the base material (washing step) to. Next, to the surface of the steel sheet 103, and electroplated Sn to form an Sn plating layer 105 by the above method (electric Sn plating step). Thereafter, a chemical conversion film layer 107 by performing electrolytic treatment (chemical conversion treatment step). Then, applying the rust preventive oil to the chemical conversion film layer 107 surface (rust-preventive oil coating step). By such flow processing is performed, the chemical conversion treatment steel sheet 10 according to this embodiment is manufactured.
[0045]

　The cleaning step removes oil and scale adhering to the surface of the steel sheet 103 as the base material (step S101). Examples of the washing step, the alkali cleaning treatment to remove oil, dirt inorganic existing on the surface of the steel sheet, for example, rust, oxide film (scale), pickling treatment for removing smut like, used in these cleaning processes rinsing process for removing the cleaning liquid from the surface of the steel sheet, further draining process for removing the rinsing cleaning liquid adhered by rinsing process from the surface of the steel sheet and the like.
[0046]

　The electrical Sn plating process of the present embodiment, phenolsulfonic acid (Ferrostan) bath, with electrical Sn plating bath bath and methanesulfonic acid (Ronasutan), to produce the Sn-plated layer 105 (step S103).
　Phenolsulfonic acid bath to dissolve the sulfate Sn or Sn phenol sulfonic acid, a plating bath obtained by adding several kinds of additives. Methanesulfonic acid bath, a plating bath composed mainly of methane sulfonic acid and methane sulfonic acid first Sn. Can be used, but electric Sn plating bath of the above-described arrangement, the alkaline bath, is used sodium Sn acid is a tetravalent Sn as a source of Sn, the productivity is inferior, which is not preferable for practical use. Moreover, halogen-bath and fluoroborate compound bath is not preferable from the viewpoint of environmental burden.
[0047]
Sn　in electrical Sn plating bath 2+ ion concentration is preferably 10 ~ 100g / L. Sn 2+ when ion concentration is less than 10 g / L, the limiting current density is significantly reduced, it becomes difficult to electric Sn plating at a high current density. As a result, it is not preferable because the productivity is poor. On the other hand, Sn 2+ when ion concentration of 100 g / L greater, Sn 2+ ions becomes excessive, undesirable because the sludge containing SnO is produced in the electroplating Sn plating bath.
　Electrical Sn plating bath in addition to the aforementioned components may contain additives. Additives which may be included in the electrical Sn plating bath, ethoxylated α- naphthol sulfonic acids, ethoxylated α- naphthol, methoxybenzaldehyde, and the like. Electrical Sn plating bath by including these additives, precipitation of beta-Sn plating is suitably carried out.
[0048]
　The bath temperature of the electrical Sn plating bath, from the viewpoint of electrical conductivity, preferably at least 40 ° C., also preferably 60 ° C. or less from the viewpoint of preventing the plating bath is reduced by evaporation or the like.
[0049]
　Energization amount of time electricity Sn plating, in view of the Sn content and productivity of the Sn-plated layer 105, 170 ~ 37000C / m 2 is preferably.
[0050]
　When reflow process after the electrical Sn plating, gloss will occur on the surface of the Sn-plated layer 105 is not preferable because it can not be subjected to matte finish. Therefore, in this embodiment, the reflow process after the electrical Sn plating is not performed.
[0051]
describes a method for controlling the orientation of the beta-Sn plating Sn plating layer 105. In electrical Sn plating, but the reaction was carried to the electrode surface by diffusion, at a magnitude that the current density, reaction carried all consumed by the electrode reaction, reactant concentrations of the electrode surface is zero. The current density at this time that the limiting current density.
　Doing electrical Sn plating in the above current density limiting current density, there are cases where if precipitates powdery occurs or plating the plating surface is formed into dendritic undesirable. Further, when the electrical Sn plating in the above current density limiting current density is not preferable because the current efficiency decreases consumes current such as hydrogen generation. On the other hand, when the electric Sn plating, by lowering the current density, the productivity is lowered. For these reasons, industrial electrical Sn plating is typically carried out at a slightly lower current densities than the limiting current density.
[0052]
　The present inventors have found that by electrical Sn plating at a current density of a particular range for the limiting current density, with preferentially oriented beta-Sn (100) planes, Sn plating layer 105 is preferably steel 103 It was found that coating the. Further, the present inventors have found that by electrical Sn plating at a current density of a particular range for the limiting current density was found that chemical conversion treated steel sheet 10 has a suitable corrosion resistance.
[0053]
　In this embodiment, the current density the current efficiency of the electric Sn plating layer is 90% and the limiting current density. In the present embodiment, it is preferable to perform the electrical Sn plating at a current density of 10% to 50% with respect to the limiting current density. By performing electrical Sn plating at a current density of 10% to 50% critical current density, with Sn plating layer 105 is preferably coated steel sheet 103, beta-Sn preferentially oriented in the (100) planes .
　For example, the limiting current density of 30A / dm 2 when the electric Sn plating, current density, 3 ~ 15A / dm 2 is preferably carried out in. Current density is more preferably 25% to 40% relative to the limiting current density.
[0054]
　The current density of less than 50% of the limiting current density, beta-Sn preferentially oriented in a (100) planes of the beta-Sn (200) plane. If it exceeds 50% of the current density is a limit current density, since the (101) planes of the beta-Sn is preferentially oriented to a current density in the electric Sn plating 50% of the limiting current density is not preferable.
[0055]
　On the other hand, when the current density is less than 10% of the limiting current density, beta-Sn is (100) will be preferentially oriented in planes, because the nucleation frequency of plating becomes slow decrease crystal growth, sparse Sn plating to become. Sn is a noble potential than Fe does not have a sacrificial protection ability. Therefore, in the Sn-plated steel sheet 101, coverage of the steel sheet 103 by Sn plating layer 105 is insufficient (steel sheet 103 is exposed) to the case, rust occurs. Accordingly, since it is also important coverage of the steel sheet 103 by Sn plating layer 105, it is preferable that the current density in the electric Sn plating at least 10% of the limiting current density.
[0056]

　After electrophoresis Sn plating step, prior to subjecting the chemical conversion treatment step described below, it may be subjected to a pre-dip process on Sn-plated steel sheet 101. When performing the pre-dip step, before the chemical conversion treatment step, immersing 2-5 seconds Sn plated steel sheet 101 for example, 0.2 to 1.0% dilute nitric acid. In the example of other pre-dip step may be immersed for 1 to 5 seconds the Sn plated steel sheet 101 in the chemical conversion solution. The pre-dip step, components other than Sn which is contained in Sn plating bath has adhered are removed from the Sn-plated layer 105 surface, since the Sn plating layer 105 surface is activated, it performs a chemical conversion treatment step preferably it can.
[0057]

　In the present embodiment, the chemical conversion treatment step, to form a chemical conversion film layer 107 (step S105). In the chemical conversion treatment step of the present embodiment, a Zr ion concentration of the chemical treatment bath to 10 ~ 10000 ppm. By the Zr ions in the chemical treatment bath and 10 ~ 10000 ppm, the content of Zr compound in the chemical conversion coating layer 0.50 ~ 50.0 mg 107 / m 2 can be controlled to. Further, by the Zr ions in the chemical treatment bath and 10 ~ 10000 ppm, to improve affinity for the chemical conversion film layer 107 and the Sn-plated layer 105, preferably for improving the corrosion resistance of the chemical conversion coating layer 107.
[0058]
　When Zr ion concentration in the chemical treatment bath is less than 10ppm is insufficient to activate the beta-Sn, As a result, decreases the corrosion resistance of the chemical conversion treated steel sheet 10. On the other hand, when the Zr ion concentration in the chemical treatment bath exceeds 10000ppm, by beta-Sn of the Sn plating layer 105 surface is over-activated, resulting adhesion unevenness in Sn plating layer 105 surface, chemical treatment It is not preferable because the corrosion resistance of the steel sheet 10 is reduced. Zr ion concentration in the chemical treatment bath is preferably 100 ~ 10000 ppm.
[0059]
　In the chemical conversion treatment step of the present embodiment, the F ion concentration in the chemical treatment bath to 10 ~ 10000 ppm. By the F ion concentration in the chemical treatment bath and 10 ~ 10000 ppm, and the Zr ions and F ions to form a complex, Zr ions is stabilized. Further, by making the F ion concentration in the chemical treatment bath and 10 ~ 10000 ppm, affinity with improved wettability and Sn plating layer 105 and the chemical conversion coating layer 107 of the Sn-plated layer 105, the chemical conversion coating layer 107 preferable because the corrosion resistance of the can be improved.
　The cause of affinity is improved with the Sn-plated layer 105 and the chemical conversion coating layer 107, as in the case of Zr ions, the F ions in the chemical treatment bath by a 10 ~ 10000 ppm, the Sn-plated layer 105 of (100) beta-Sn preferentially oriented in planes are activated, considered binding of the chemical conversion coating layer 107 to the Sn-plated layer 105 is enhanced. That is believed to activate the intermediate layer between the chemical conversion coating layer 107 and the Sn plating layer 105 (not shown) is formed. This activated intermediate layer (not shown), the Sn-plated layer 105 formed by the manufacturing method of the present invention is a specific layer, assumed to be the components that achieve the effects possessed by the chemical conversion treated steel sheet 10 of the present invention It is.
[0060]
　If F ion concentration in the chemical treatment bath is less than 10ppm is a Zr ion and F ions do not form a complex, Zr ions is not preferable because it does not stabilize. Further, when the F ion concentration in the chemical treatment bath is less than 10ppm is insufficient to activate the beta-Sn, As a result, decreases the corrosion resistance of the chemical conversion treated steel sheet 10. On the other hand, when the F ion concentration in the chemical treatment bath exceeds 10000ppm, and Zr ions and F ions to form excessively complex, reactive Zr ions is low. As a result, Sn-plated layer 105 surface, i.e. the hydrolysis reaction is slow with respect to increase in pH at the cathode surface, it becomes remarkably responsiveness during electrolysis slowly, not practical since it takes a long electrolysis time. Further, when the F ion concentration in the chemical treatment bath exceeds 10000ppm, by requiring long electrolysis time as described above, there are cases where beta-Sn is excessively activated, resulting in deposition unevenness. F ion concentration in the chemical treatment bath is preferably 100 ~ 10000 ppm.
[0061]
　In the chemical conversion treatment step of the present embodiment, by a phosphoric acid ion concentration of the chemical treatment bath and 10 ~ 3000 ppm, the chemical conversion coating layer 107 to suitably containing phosphate compound is formed. In the case the phosphate ion concentration in the chemical treatment bath is less than 10 ppm, by chemical conversion treatment film layer 107 does not contain a phosphate compound is not preferred because the corrosion resistance is lowered. Furthermore, if the phosphoric acid ion concentration of the chemical treatment bath exceeds 3000 ppm, insoluble matter attributed to phosphate Zr (precipitate) is formed in the chemical treatment bath, because they may contaminate the chemical treatment bath , which is not preferable. Also, conversion if phosphate ion concentration in the treated bath exceeds 3000 ppm, for contributing phosphoric acid compound in corrosion resistance in the chemical conversion coating layer 107 is reduced, which is undesirable. Phosphoric acid ion concentration of the chemical treatment bath is preferably 100 ~ 3000 ppm.
[0062]
　In the chemical conversion treatment step of the present embodiment, by the nitrate ions in the chemical treatment bath and 100 ~ 30000 ppm, it is possible to maintain the electrical conductivity necessary for the electrolytic treatment can be suitably formed the chemical conversion coating layer 107 can. In the case of nitric acid ion concentration in the chemical treatment bath is less than 100 ppm, since the conductivity is lower than the level required for the electrolytic treatment is not preferable because the chemical conversion coating layer 107 is not formed. Also, if the nitrate ion concentration in the chemical treatment bath exceeds 30000 ppm, since the conductivity is increased excessively, the chemical conversion coating layer 107 with a minute current is formed. As a result, occurs locally grown like part of the chemical conversion coating layer 107, since the chemical conversion coating layer 107 is not uniformly formed, the corrosion resistance of the chemical conversion treated steel sheet 10 is reduced. Nitrate ion concentration in the chemical treatment bath is preferably 1000 ~ 30000 ppm.
[0063]
　In the chemical conversion treatment step of the present embodiment, by limiting the temperature of the chemical treatment bath to 5 ~ 90 ° C., and the Zr ions and F ions preferably form a complex. In the case the temperature of the chemical treatment bath is less than 5 ° C., insoluble matter attributed to phosphate Zr (precipitate) is easily formed. In the case where the temperature of the chemical treatment bath is higher than 90 ° C., without forming the Zr ions and F ions and are preferably complex is not preferable because the chemical conversion coating layer 107 is not suitably formed. Temperature of the chemical treatment bath is preferably from 10 ℃ ~ 70 ℃.
[0064]
　In the chemical conversion treatment step of the present embodiment, it is preferred that the pH of the chemical treatment bath is 2.0-6.0, more preferably pH 3.0 ~ 4.5. By pH of the chemical treatment bath is in the range described above, impurities are hardly generated, it is because it is possible to perform suitably chemical conversion treatment.
[0065]
　In the chemical conversion treatment step of the present embodiment, the energization time of the electrolytic treatment from 0.2 to 100 seconds. If the energizing time is less than 0.2 seconds is not preferable because the chemical deposition amount of treated film layer 107 is small, not suitable sulfurization blackening is obtained. If the energizing time is 100 seconds than the chemical conversion coating layer 107 is formed excessively, undesirably might chemical conversion coating layer 107 in the chemical treatment bath is peeled. Further, when the conduction time is 100 seconds greater it is not preferable because the productivity is lowered. Energizing time in the electrolytic treatment is preferably 1 to 50 seconds.
[0066]
　As described above, the crystal orientation of the Sn-plated layer 105 according to this embodiment is preferentially oriented in the (100) planes. The present inventors have found that preferentially oriented Sn plating layer 105 (100) planes, a chemical conversion treatment energizing time in the electrolytic process step can be shortened, and found that excellent productivity. That is, when the crystal orientation of the Sn-plated layer 105 is non-oriented, the energization time becomes long in the electrolytic process of the chemical conversion treatment step, is inferior in productivity, which is not preferable.
　As this cause, it by the crystal orientation of the Sn-plated layer 105 is preferentially oriented in the (100) planes, the surface of the Sn-plated layer 105 are uniformly activated, easy to form the chemical conversion coating layer 107 it is conceivable that. That is believed to activate the intermediate layer between the chemical conversion coating layer 107 and the Sn plating layer 105 (not shown) is formed. This activated intermediate layer (not shown), the Sn-plated layer 105 formed by the manufacturing method of the present invention is a specific layer, assumed to be the components that achieve the effects possessed by the chemical conversion treated steel sheet 10 of the present invention It is.
[0067]
　In the chemical conversion treatment step of the present embodiment, the current density 1.0 ~ 100A / dm 2 and.
　Current density 1.0A / dm 2 in the case of less than is not preferable because the chemical deposition amount of treated film layer 107 is small, not suitable corrosion resistance can be obtained. The current density is 1.0A / dm 2 in the case of less than the long electrolysis times undesirably lowers productivity required. Current density is 100A / dm 2 in the case of exceeding the locally becomes high current density, the chemical conversion coating layer 107 is not uniformly formed, is not preferable because the corrosion resistance of the chemical conversion treated steel sheet 10 is reduced. The current density is preferably 5.0 ~ 50A / dm 2 is.
　Incidentally, anodizing current density in the process may be constant, but the current density 1.0 ~ 100A / dm 2 may be varied in the range of. When changing the current density in the chemical conversion treatment step, since the surface in the near portion of the Sn plated layer 105 and the chemical conversion coating layer 107 are densely formed to improve the adhesion such as corrosion resistance and paint, current gradually it is preferable to increase the density.
[0068]
　In the chemical conversion treatment step of the present embodiment, the line speed preferably set to 50 ~ 800 m / min. The line speed stable supply to the cathode interface of Zr ions in the range described above, the chemical conversion coating layer 107 is preferably deposited.
[0069]

　After the chemical conversion coating layer 107 is formed by the chemical conversion treatment step, applying a rust preventive oil on the surface of the chemical conversion coating layer 107 (step S105). A specific example is the electrostatic oiling method.
[0070]
　The manufacturing method described above, by chemical conversion film layer 107 containing Zr compound is formed on the matte finish of the Sn-plated layer 105 oriented in a particular plane orientation, chemical conversion treated steel sheet 10 having suitable corrosion resistance may be produced that. In particular, chemical conversion treated steel sheet 10 according to this embodiment is suitable as a container for steel food sector and beverage cans art.
Example
[0071]
　Hereinafter, while showing Examples, the chemical conversion treated steel sheet and a manufacturing method thereof according to an embodiment of the present invention will be specifically described. Note that the embodiments described below is a mere example of the chemical conversion treated steel sheet and a manufacturing method thereof according to an embodiment of the present invention, chemical conversion treated steel sheet and a manufacturing method thereof according to an embodiment of the present invention is, in the following examples the present invention is not limited.
[0072]
(1) Formation of Sn plating layer
　annealing of 200 mm × 300 mm × 0.18 mm was subjected to temper rolling a low carbon steel (C: 0.05mass%, Si: 0.015mass%, Mn: 0.4mass%, P : 0.01mass%, S: using 0.004%). The low carbon steel sheet described above was immersed in a 5% aqueous solution of sodium hydroxide, temperature, and 1 kA / m of 90 ° C. 2 by performing cathodic electrolysis treatment under the conditions of a current density of performing alkali degreasing. After alkaline degreasing, then immersed low carbon steel plate in a 10% aqueous sulfuric acid solution, the temperature and 1 kA / m of 25 ° C. 2 by performing cathodic electrolysis treatment under the conditions of a current density of, were pickled. After pickling, the pump performs electrical Sn plating using a circulating cells composed of the electrode portion and the reservoir to form a Sn plating layer on the surface of a low carbon steel plate. The composition of the plating bath used for electric Sn plating shown in Table 1, shows the temperature of the plating bath of the examples, the limiting current density, current density, the current amount in Table 2.
　Flow rate of the plating bath in the circulation cell was controlled to 5 m / s in the pump flow rate. Temperature of the plating bath was measured by a thermostat provided in the reservoir. Current density was controlled using a DC power source. Coating weight was adjusted by energization amount which is the product obtained by multiplying the current density and electrolysis time. Incidentally, the counter electrode was used an insoluble anode plated with platinum titanium.
[0073]
[Table 1]

[0074]
[Table 2]

[0075]
(2) Measurement of metal Sn amount
　of Sn metal amount contained in the Sn plating layer was measured by a fluorescent X-ray method described previously. The results with electrical Sn plating condition, shown in Table 2.
[0076]
(3) Measurement of crystal orientation index
　subjected to X-ray diffraction using an X-ray diffractometer electric Sn plated steel sheet (which is not formed in the chemical conversion coating layer) was measured peak intensity of each orientation plane. X-ray diffraction, ray source using CuKα ray was performed under the conditions of a tube current 100mA and tube voltage 30 kV. Using the measured results crystal orientation index of (200) plane was calculated using the following equation (3).
[0077]
[Number 3]

[0078]
　When (200) crystal orientation index of plane is 1.0 or more, it determines that the Sn plating layer are oriented in the (200) plane. With electrical Sn plating condition, the results of the crystal orientation index shown in Table 2.
[0079]
(4) IEV measured
　were measured of the resulting Sn-plated steel sheet IEV (Iron Exposure Value). First, sodium carbonate the Sn plated steel sheet 21g / L, and sodium chloride of sodium bicarbonate and 0.3 g / L of 17 g / L, pH is 10, a test solution temperature of 25 ° C., Sn was shown anodically polarized to a potential (1.2 vs.SCE) to passivate. The current density after 3 minutes by anode polarization were measured, the current density obtained was IEV. IEV is 15 mA / dm 2 in the following cases, the coverage of beta-Sn is determined to be good. The measurement results of the IEV shown in Table 2.
[0080]
(5) Formation of chemical conversion coating layer
　of chemical conversion coating layer containing Zr compound and a phosphate compound on the surface of the above-mentioned Sn-plated steel sheet was formed under the conditions shown in Table 3 and Table 4.
[0081]
[table 3]

[0082]
[Table 4]

[0083]
(6) the amount of Zr and measurement of P content
　metallic Zr amount and the amount of P contained in the chemical conversion coating layer was measured by a fluorescent X-ray method described previously. The measured metal Zr content and P content shown in Table 4.
[0084]
(7) Evaluation of yellowing
　chemical conversion treated steel sheet described above was used as a test piece. The specimen 40 ° C., under 80% RH constant temperature and humidity environment established 1000 hours, measure the degree ΔE color change of the test piece before and after the test using a color difference meter (Konica Minolta, CM-2600d), calculated by was evaluated yellowing resistance. If ΔE is 2.0 or less, it was evaluated as yellowing resistance are preferred. Table 5 and Table 6, describing the evaluation results of yellowing.
　In Table 5 and Table 6, yellowing resistance evaluation result is "-" when it is shown to the yellowing proceeds unevenly, size variations be measured ΔE in the manner described above because too, it represents a case which could not be correctly evaluated.
[0085]
(8) sulfidation black evaluation of the modified
　volume ratio and a 0.1% aqueous sodium thiosulfate solution and 0.1N sulfuric acid 1: using 2 an aqueous solution prepared by mixing a sulfidation resistance blackening test solution. Cut out a chemical conversion treated steel sheet chemical conversion coating layer formed of the foregoing to 35mm, it was placed and fixed to the mouth of the heat-resistant bottle containing sulfidation blackening test solution. Thereafter, heat treatment was carried out for 60 minutes at 121 ° C.. To the area of sulfidation resistance blackening test solution touches the chemical conversion treated steel sheet (the area of the heat-resistant bottle mouth), to evaluate the sulfidation blackening at a rate of corroded area, a score of 1-5 points on the basis of the following criteria Wearing. In the case of three or more, since it is possible to practical use as containers for steel, it was passed three or more points. Table 5 and Table 6, describing the results of the sulfidation blackening evaluation.
[0086]

　　　5 points: less than 20% to 0% or more
　　　4 points: Less than 40% to more than 20%
　　　3 points: less than 60% to 40%
　　　2 points: less than 80% to 60%
　　　1 point: less than 100% to 80% or more
[0087]
[table 5]

[0088]
[Table 6]

[0089]
　From the above evaluation results, the chemical conversion treated steel sheet of the present embodiment was found to have excellent corrosion resistance.
[0090]
　Having described in detail preferred embodiments of the present invention with reference to the accompanying drawings, the present invention is not limited to such an example. It would be appreciated by those skilled in the relevant field of technology of the present invention, within the scope of the technical idea described in the claims, it is intended to cover various modifications, combinations, for even such modifications are intended to fall within the technical scope of the present invention.
Industrial Applicability
[0091]
　According to the above embodiment, it is possible to provide a Sn-plated steel sheet having excellent corrosion resistance and chemical conversion treatment steel sheet and a method for their preparation.
DESCRIPTION OF SYMBOLS
[0092]
　　10 chemically treated steel sheet
　101 Sn-plated steel sheet
　103 steel
　105 Sn-plated layer
　107 chemical conversion coating layer

claims
[Claim 1]
　And the steel sheet;
　provided as an upper layer of the steel sheet, and the Sn plating layer of matte finish consisting of beta-Sn;
　provided as an upper layer of the Sn plating layer, a chemical conversion coating layer;
comprises a,
　the Sn plating layer , in terms of metal amount of Sn 0.10 ~ 20.0 g / m 2 by weight of beta-Sn,
　crystal orientation index of said Sn plating layer (100) crystal orientation index of planes of other crystal orientation planes higher than,
　the chemical conversion coating layer, in terms of 0.50 ~ 50.0 mg / m on the metal Zr content 2 and Zr compound containing Zr of, and a phosphoric acid compound,
characterized in that, chemical conversion treatment steel plate.
[Claim 2]
　When the crystal orientation index of (200) plane of the Sn plating layer is defined as X represented by the following formula (1),
　wherein X is 1.0 or more
, characterized in that, according to claim 1 chemical conversion treatment steel plate.
[Number 1]

[Claim 3]
　On a steel plate, an electric Sn plating process and to form a Sn plating layer current density contains beta-Sn by electroplating is 10 to 50% critical current density;
　the steel sheet the Sn plated layer is formed by electrolysis treatment with chemical treatment bath, and chemical conversion treatment step of forming a chemical conversion coating layer on the Sn plated layer;
having
, characterized in that, the production method of the chemical conversion treated steel sheet.
[Claim 4]
　Wherein in the chemical conversion treatment step, the steel sheet which the Sn plated layer is formed, includes Zr ions 10 ~ 10000 ppm, F ions 10 ~ 10000 ppm, of 10 ~ 3000 ppm nitrate ions phosphate ions and 100 ~ 30000 ppm, temperature There at 5 ~ 90 ° C. at which the chemical treatment bath, 1.0 ~ 100A / dm 2 to electrolytic treatment under conditions of current density and 0.2 to 100 seconds of electrolytic treatment time
, characterized in that, claims method for producing a chemical conversion treated steel sheet according to 3.
[Claim 5]
　Steel plate and;
　provided as an upper layer of the steel sheet, beta-Sn plating layer of matte finish consisting of:
provided with,
　the Sn plated layer is converted into metal Sn amount 0.10 ~ 20.0 g / m 2 of containing beta-Sn,
　the crystal orientation index of (100) planes of the Sn-plated layer is higher than the crystal orientation index of the other crystal orientation planes,
and wherein the, Sn-plated steel sheet.
[Claim 6]
　On the steel sheet by electroplating current density is 10 to 50% critical current density has an electrical Sn plating step of forming a Sn-plated layer containing beta-Sn
, characterized in that, Sn-plated steel sheet the method of production.