JP2021055143A - Galvanized steel plate with surface treatment and manufacturing method of the same - Google Patents

Abstract

To provide a galvanized steel plate with a surface treatment excellent in a galling resistance, a lubricity, a peeling resistance of a phosphate, and a processability, the surface treatment being performed in a time shorter than that of a phosphate treatment.SOLUTION: A galvanized steel plate with a surface treatment has a steel plate, a galvanized layer, a phosphate film which is arranged contacting a surface of the galvanized layer and contains a phosphate crystal, and a lubricant film arranged contacting the phosphate film. A thickness of the galvanized layer (M) is 0.05 μm or more and 1.5 μm or less, a coating weight of the phosphate crystal is 0.5 g/m2 or more and 3.5 g/m2 or less, a ratio (H/M) of the coating weight (H) of the phosphate crystal to a layer thickness (M) of the galvanized layer is 0.90 or more, and a coating weight of the lubricant film to a volume of the phosphate crystal is 35 volume % or more and 500 volume % or less.SELECTED DRAWING: Figure 2

Description

The present invention relates to a surface-treated galvanized steel sheet and a method for producing the same.

When processing such as pressing and forging is applied to a steel sheet, the steel sheet and gold are used to improve the lubricity between the steel sheet and the die and to suppress wear (galling) of the steel sheet such as seizure. Lubricating oil may be impregnated between the mold and the steel sheet, or the surface of the steel sheet may be lubricated in advance. In particular, when the processing conditions are severe, unlike the impregnation with lubricating oil, the oil film is less likely to break and the adhesion between the steel sheet and the steel sheet is high. Therefore, phosphate crystals and metals are formed on the surface of the steel sheet before processing. A lubrication treatment layer containing soap may be formed (bonding treatment).

It is known that the galvanizing resistance of a steel sheet can be improved by forming phosphate crystals on the surface of the galvanized layer.

Patent Document 1 describes the processability of a steel sheet by adjusting the adhesion amount and surface roughness of the galvanized layer and the adhesion amount of the phosphate film to reduce the peeling amount of the zinc phosphate film. It is stated that it can increase. Specifically, in Patent Document 1, the amount of adhesion of zinc plating is set to 2.0 to 29.6 g / m ² , the surface roughness (Ra) of the zinc plating layer is set to 0.5 to 1.6 μm, and phosphorus is set. It is described that the processability of the steel sheet can be improved by setting the adhesion amount (M) of the acid salt film to 0.5 to 3.5 g / m ^{2 and further setting the M / Ra to 1.2 or more.}

Further, in Patent Document 2, an ^{electrogalvanized layer having a plating amount of 4 g / m 2} or less is formed on the annealed steel sheet, and further treated with phosphoric acid (for example, the amount of phosphoric acid adhered is 2.1 g / m ^2). , 2.2 g / m ^2, etc.) or a method for producing a cold-rolled steel sheet to be chromated.

Japanese Unexamined Patent Publication No. 2001-214281 Japanese Unexamined Patent Publication No. 2000-087257

According to the study by the present inventors, when the bonde treatment is applied to the steel sheet, it is necessary to take a sufficient time for the phosphate treatment in order to sufficiently adhere the phosphate crystals to the surface of the steel sheet. Therefore, it is difficult to increase the production speed of the bonded steel sheet.

Furthermore, according to the study by the present inventors, the phosphate crystals precipitated directly on the surface of the steel sheet as in the bonde treatment are destroyed by contact and friction with the mold during processing, and are destroyed from the surface of the steel sheet. Easy to peel off. Therefore, when performing multi-stage press working on a steel sheet, most of the phosphate crystals are peeled off in the first-stage processing, and the steel sheet is partially exposed during the second and subsequent stages of processing, resulting in poor lubricity. It may decrease.

Patent Document 1 describes that the amount of peeling of the zinc phosphate film can be reduced by adjusting the amount of adhesion and surface roughness of the zinc plating layer and the amount of adhesion of the phosphate film to form the phosphate film. ing. However, according to the studies by the present inventors, it cannot be said that the method described in Patent Document 1 can sufficiently suppress the peeling of the zinc phosphate film.

Further, in Patent Document 2, ^{by limiting the plating amount to 4 g / m 2} or less, it is possible to suppress a decrease in the processing speed of the entire continuous annealing line of the cold-rolled steel sheet due to the rate-determining formation of the electrogalvanized layer. It is described as. However, it cannot be said that the zinc-based plated steel sheet produced by the method described in Patent Document 2 can sufficiently suppress the peeling of the zinc phosphate film.

The present invention is based on the above problems, and surface treatment can be performed in a short time as compared with bonde treatment, galvanizing resistance and lubricity are high, phosphate is hard to peel off, and workability is good. An object of the present invention is to provide a surface-treated galvanized steel sheet and a method for producing the galvanized steel sheet.

The present invention includes a steel sheet, a zinc-based plating layer arranged on at least one surface of the steel sheet, and a phosphate film containing a phosphate crystal arranged in contact with the surface of the zinc-based plating layer. The present invention relates to a surface-treated zinc-based plated steel sheet having a lubricating film arranged in contact with the phosphate film. Thickness (M) of the zinc-based plating layer is 0.05μm or more 1.5μm or less, the adhesion amount of the phosphate crystals (H) is 0.5 g / ^{m 2} or more 3.5 g / ^{m 2} The ratio (H / M) of the adhesion amount (H) of the phosphate crystals to the layer thickness (M) of the zinc-based plating layer is 0.90 or more, and the adhesion amount of the lubricating film is 0.90 or more. , 35% by volume or more and 500% by volume or less with respect to the volume of the phosphate crystal.

Further, the present invention comprises a step of preparing a zinc-based plated steel sheet having a zinc-based plating layer having a layer thickness (M) of 0.11 μm or more and 1.6 μm or less, and a step of contacting the surface of the zinc-based plating layer. The amount of phosphate crystals adhered (H) is 0.5 g / m ² or more and 3.5 g / m ² or less, and the amount of the phosphate crystals adhered to the layer thickness (M) of the zinc-based plating layer. The step of forming a phosphate film in which the ratio (H / M) of (H) is 0.90 or more, and 35 with respect to the volume of the phosphate crystal in contact with the surface of the phosphate film. The present invention relates to a method for producing a surface-treated zinc-based plated steel sheet, which comprises a step of forming a lubricating film having a volume of% or more and 500% by volume or less.

According to the present invention, surface treatment can be performed in a shorter time as compared with bonde treatment, galvanizing resistance and lubricity are high, phosphate is hard to peel off, and surface-treated zinc has good workability. A system-plated steel sheet and a method for producing the zinc-based plated steel sheet are provided.

FIG. 1A is a cross-sectional view schematically showing a state in the vicinity of the surface of a steel sheet in which phosphate crystals are directly precipitated on the surface before press working, and FIG. 1B is a cross-sectional view showing the state of the vicinity of the surface of the steel sheet during press working. FIG. 1C is a cross-sectional view schematically showing the state of the vicinity of the surface of the steel sheet after press working. FIG. 2A is a cross-sectional view schematically showing a state in the vicinity of the surface of the surface-treated zinc-based plated steel sheet according to the embodiment of the present invention before press working, and FIG. 2B is a cross-sectional view of the steel sheet being pressed. FIG. 2C is a cross-sectional view schematically showing a state near the surface, and FIG. 2C is a cross-sectional view schematically showing a state near the surface of the steel sheet after press working. FIG. 3A schematically shows a state in the vicinity of the surface of a zinc-based plated steel sheet in which a phosphate crystal and a lubricating film are formed on the surface of the zinc-based plating layer by increasing the thickness of the zinc-based plating layer before press working. 3B is a cross-sectional view schematically showing the state of the vicinity of the surface of the steel sheet during press working, and FIG. 3C is a schematic view of the vicinity of the surface of the steel sheet after press working. It is sectional drawing which shows. FIG. 4A is a cross-sectional view schematically showing the state of the zinc-based plated steel sheet having a larger amount of the lubricating film adhered to the vicinity of the surface of the steel sheet before press working, and FIG. 4B is a cross-sectional view showing the state of the steel sheet during press working. FIG. 4C is a cross-sectional view schematically showing the state of the vicinity of the surface of the die, and FIG. 4C is a cross-sectional view schematically showing the state of the mold after press working. FIG. 5 is a workflow showing a method for manufacturing the galvanized steel sheet according to the embodiment of the present invention.

1. 1. Surface-treated galvanized steel sheet The surface-treated galvanized steel sheet according to the present embodiment is composed of at least a galvanized steel sheet and a galvanized steel sheet arranged on at least one surface of the steel sheet and the galvanized steel sheet. It has a plurality of phosphate crystals arranged in layers in contact with the surface, and a lubricating film arranged in contact with the plurality of phosphate crystals. In the surface-treated galvanized steel sheet according to the present embodiment, the layer thickness (M) of the zinc-based plated layer is 0.05 μm or more and 1.5 μm or less, and the adhesion amount (H) of the phosphate crystals is Is 0.5 g / m ² or more and 3.5 g / m ² or less, and the ratio (H / M) of the adhesion amount (H) of the phosphate crystals to the layer thickness (M) of the zinc-based plating layer is , 0.90 or more, and the amount of adhesion of the lubricating film is 35% by volume or more and 500% by volume or less with respect to the volume of the phosphate crystals.

Since the surface-treated galvanized steel sheet is in contact with the surface of the plating layer to precipitate phosphate crystals, it is shorter than the bonde treatment in which phosphate crystals are directly precipitated on the surface of the steel sheet. Phosphate crystals on the steel sheet can be arranged (precipitated) in time. It is considered that this is because zinc, which is the main component of the zinc-based plating layer, has higher reactivity to the phosphate treatment liquid than iron constituting the steel sheet.

Further, in the above-mentioned galvanized steel sheet, the amount of phosphate crystals adhered to the layer thickness (M) of the zinc-based plated layer, the amount of phosphate crystals adhered (H), and the layer thickness (M) of the zinc-based plated layer. By setting the ratio (H / M) of (H) to the above range, peeling of phosphate crystals is unlikely to occur during processing. It is considered that this is because the zinc-based plating layer, which is relatively soft, deforms during processing to absorb stress, while maintaining the contact state between the phosphate crystal and the mold.

Further, in the surface-treated galvanized steel sheet, the amount of the lubricating film adhered is set within the above range, so that the phosphate crystals are less likely to peel off during processing and seizure is less likely to occur. It is considered that this is because the lubricating film acts as a binder for phosphate crystals during processing, and the lubricating film suppresses contact between the zinc-based plating layer and the mold.

FIG. 1 is a cross-sectional view schematically showing the state of a steel sheet in which phosphate crystals are directly precipitated on the surface as in the bonde treatment, in the vicinity of the surface before and after press working. FIG. 1A is a cross-sectional view schematically showing a state near the surface of the steel sheet before press working, and FIG. 1B is a cross-sectional view schematically showing a state near the surface of the steel sheet during press working. FIG. 1C is a cross-sectional view schematically showing the state of the vicinity of the surface of the steel sheet after press working.

As shown in FIG. 1A, at this time, the phosphate crystals 130a are directly precipitated from the steel plate 110a, and a soap layer 140a containing a metal soap is further formed on the surface of the steel plate 110a. When the steel sheet is pressed, as shown in FIG. 1B, the phosphate crystals 130a directly deposited on the surface of the steel sheet 110a are phosphorus due to contact with the sliding die 210a and deformation of the steel sheet. It is easily broken by the stress applied to the phosphate crystal and easily peeled from the surface of the steel sheet 110a. Therefore, when the steel sheet after this processing is further processed (processing of the second and subsequent stages), seizure occurs due to the exposed steel sheet coming into contact with the mold and being rubbed due to the peeling of the phosphate crystals. There is.

FIG. 2 is a cross-sectional view schematically showing the state of the zinc-based plated steel sheet according to the present embodiment in the vicinity of the surface before and after press working. FIG. 2A is a cross-sectional view schematically showing the state of the vicinity of the surface of the steel sheet before press working, and FIG. 2B is a cross-sectional view schematically showing the state of the vicinity of the surface of the steel sheet during press working. FIG. 2C is a cross-sectional view schematically showing the state of the vicinity of the surface of the steel sheet after press working.

As shown in FIG. 2A, in the present embodiment, the zinc-based plating layer 120b is formed on the surface of the steel sheet 110b, and the phosphate crystals 130b are precipitated from the surface of the zinc-based plating layer 120b. Further, a lubricating film 140b is further formed on the surface of the zinc-based plating layer 120b. When this steel sheet is pressed, as shown in FIG. 2B, the zinc-based plating layer 120b is deformed to absorb the stress on the phosphate crystal 130b, so that the steel sheet comes into contact with the sliding die 210b. Phosphate crystals 130b are not easily broken and peeled off by friction. At this time, since the thickness of the zinc-based plating layer 120b is not so large, even if the phosphate crystal 130b enters the zinc-based plating layer 120b, the head of the phosphate crystal 130b is from the surface of the zinc-based plating layer 120b. It remains prominent. Therefore, as shown in FIG. 2C, the zinc-based plating layer 120b and the phosphate crystal 130b are likely to remain on the surface of the processed steel sheet 110b. Even when the processed steel sheet is further processed (processing of the second and subsequent stages), the phosphate crystals 130b remain on the surface of the steel sheet 110b, so that the lubricity and galling resistance are maintained. ..

FIG. 3 schematically shows a state in the vicinity of the surface before and after press working when a phosphate crystal and a lubricating film are formed on the surface of the zinc-based plating layer by increasing the thickness of the zinc-based plating layer. It is sectional drawing which shows. FIG. 3A is a cross-sectional view schematically showing the state of the vicinity of the surface of the steel sheet before press working, and FIG. 3B is a cross-sectional view schematically showing the state of the vicinity of the surface of the steel sheet during press working. FIG. 3C is a cross-sectional view schematically showing the state of the vicinity of the surface of the steel sheet after press working.

As shown in FIG. 3A, at this time, a zinc-based plating layer 120c having a thicker layer thickness is formed on the surface of the steel sheet 110c, and phosphate crystals 130c are precipitated from the surface of the zinc-based plating layer 120c. There is. Further, a lubricating film 140c is further formed on the surface of the zinc-based plating layer 120c. When this steel sheet is pressed, as shown in FIG. 3B, phosphate crystals 130c are formed in the relatively soft zinc-based plating layer 120c due to contact and friction with the sliding die 210c. It gets in and the phosphate crystal 130c is buried. If the mold 210c further slides in this state, the mold 210c and the zinc-based plating layer 120c come into contact with each other and are rubbed. Therefore, as shown in FIG. 2C, seizure 150 is likely to occur on the surface of the processed zinc-based plating layer 120c.

If the amount of phosphate crystals adhered (H) is sufficiently large (H / M is sufficiently large) with respect to the layer thickness (M) of the zinc-based plating layer, phosphorus to the zinc-based plating layer during processing is sufficient. Since other phosphate crystals inhibit the entry of the phosphate crystals, it is considered that the occurrence of seizure due to the burial of the phosphate crystals is unlikely to occur. On the contrary, when the amount of phosphate crystals adhered (H) is small (H / M is small) with respect to the layer thickness (M) of the zinc-based plating layer, phosphate crystals are formed on the zinc-based plating layer during processing. Since it is easy to penetrate, it is considered that seizure is likely to occur due to the burial of phosphate crystals.

By appropriately adjusting the layer thickness (M) of the zinc-based plating layer and the amount of phosphate crystals adhered (H) in this way, phosphate crystals during processing can be suppressed and seizure can occur. Occurrence can also be suppressed.

FIG. 4 is a cross-sectional view schematically showing the state of the vicinity of the surface before and after press working when the amount of the lubricating film adhered is increased. FIG. 4A is a cross-sectional view schematically showing a state near the surface of the steel sheet before press working, and FIG. 4B is a cross-sectional view schematically showing a state near the surface of the steel sheet during press working. FIG. 4C is a cross-sectional view schematically showing the state of the mold after press working.

As shown in FIG. 4A, in the present embodiment, the zinc-based plating layer 120d is formed on the surface of the steel sheet 110d, and the phosphate crystals 130d are precipitated from the surface of the zinc-based plating layer 120d. Further, a large amount of lubricating film 140d is further formed on the surface of the zinc-based plating layer 120d. When this steel sheet is pressed, as shown in FIG. 4B, when the lubricating film 140d and the lower phosphate crystal 130d slide in contact with the mold 210d, a part of the lubricating film 140d is removed. It may be torn and peeled off. When the lubricating film 140d peeled off by processing is a thick film, as shown in FIG. 4C, a large film-like film strip 160 tends to adhere to the surface of the processed mold 210d. When such processing is continuously performed, the film strip 160 adheres to the surface of the mold 210d and accumulates. Then, the deposited film strip 160 is likely to cause pushing against the work piece during further processing. Further, if a large film strip 160 is generated during processing, it is necessary to increase the cleaning frequency of the mold in order to remove the film strip 160, which increases the processing cost.

On the other hand, by appropriately adjusting the amount of the lubricating film adhered to the volume of the phosphate crystals, it is possible to suppress the generation of large flakes of the lubricating film during processing, and to suppress the occurrence of pushing and the increase in cost. Therefore, the workability can be further improved.

The zinc-based plating layer, phosphate crystals, and lubricating film may be formed on only one side of the surface (front side surface and back side surface) of the steel sheet, or may be formed on both sides. When formed on only one side, none of these layers may be formed on the other surface, or only part of these layers (eg, only the zinc-based plating layer) may be formed. Good.

1-1. Steel sheet The steel sheet may be a steel sheet capable of forming a zinc-based plating layer, and may be made of alloy steel such as low carbon steel, medium carbon steel, high carbon steel, and chromium molybdenum steel, and the above surface-treated zinc-based plated steel sheet. It can be selected according to the application. For example, when good press formability is required, it is preferable to use a steel plate for deep drawing such as low carbon Ti-added steel and low-carbon Nb-added steel. The steel sheet may be a high-strength steel sheet to which P, Si, Mn and the like are added.

1-2. Zinc-based plating layer The zinc-based plating layer is a plating layer containing zinc as a main component. The plating constituting the zinc-based plating layer includes Zn plating (pure zinc plating), Zn-Al-based alloy plating, Zn-Mg alloy plating, Zn-Ni alloy plating, Zn-Al-Mg-based alloy plating, and the like. It can be selected according to the application of the surface-treated zinc-based plated steel sheet.

Of these, from the viewpoint of making the zinc-based plating softer and making it easier for the plating layer to follow the deformation of the steel sheet during processing, the zinc-based plating layer is composed of pure zinc plating composed of zinc and unavoidable impurities. It is preferably a layer. When phosphate crystals are deposited on the surface of the pure galvanized layer, even if the steel sheet is deformed during processing, the plating layer and phosphate crystals easily follow the above deformation, causing destruction and peeling of the phosphate crystals. Hateful.

Further, the zinc-based plating layer may be a plating layer formed by any known method such as an electroplating method, a hot-dip plating method, and a vapor deposition plating method. Of these, from the viewpoint of forming the zinc-based plating layer more uniformly on the surface of the steel sheet, the zinc-based plating layer is wider on the surface of the steel sheet by etching the surface of the steel sheet in a plating solution having a low pH (about pH 2). It is preferably a plating layer formed by an electroplating method, in which the area is activated and plated. In particular, when the steel sheet contains easily oxidizable elements such as Si and Mn, an uneven oxide layer is likely to be formed on the surface of the steel sheet. Even in such a case, according to the electroplating method, plating can be performed while etching the oxide layer or removing the oxide layer (and other foreign substances) by hydrogen foaming by energization, so that more uniform zinc can be obtained. A system plating layer can be formed. Further, according to the electroplating method, it is easy to form a thinner zinc-based plating layer as described later. The zinc-based plating layer formed by the electroplating method is directly arranged on the surface of the steel sheet without interposing an alloy layer of zinc and iron between the steel sheets.

Zn, which is the main component of the zinc-based plating layer, is more easily etched than Fe, which is the main component of the steel sheet, at the pH (about pH 3 to 4) at the time of phosphate treatment. Therefore, the zinc-based plating layer makes it easier to precipitate phosphate crystals on the surface of the zinc-based plating layer during the phosphate treatment for precipitating phosphate crystals by utilizing the increase in pH due to etching, and phosphoric acid. The time required for salt treatment can be significantly reduced.

Further, when the above-mentioned uneven oxide layer is formed on the surface of the steel plate, if phosphate crystals are to be deposited directly on the surface of the steel plate, phosphate is formed between the surface of the steel plate and the surface of the oxide layer. Since the easiness of crystal precipitation is different, the distribution of phosphate crystals tends to be uneven. Therefore, in order to uniformly precipitate the phosphate crystals, a longer time of phosphate treatment is required. In addition, if an attempt is made to shorten the bond processing time, the distribution of phosphate crystals will also become uneven, and in the portion where the phosphate crystals are not sufficiently precipitated, between the steel plate and the mold during processing. Insufficient lubricity and processing defects are likely to occur. On the other hand, when the phosphate crystals are precipitated on the surface of the zinc-based plating layer, the influence of the uneven distribution of the oxide layer on the steel plate surface is less likely to occur, so that even a short-time phosphate treatment is performed with the phosphate. The crystals can be distributed more evenly. For example, when the phosphate crystals are directly deposited on the surface of the steel sheet as in the bonde treatment, a treatment time of about 10 minutes is required, and even then, the treatment unevenness of the phosphate treatment may occur. .. On the other hand, when the phosphate crystals are precipitated on the surface of the zinc-based plating layer, the phosphate crystals can be uniformly precipitated even with a treatment time of 10 seconds or less.

The layer thickness (M) of the zinc-based plating layer is 0.05 μm or more and 1.5 μm or less. When the layer thickness (M) is 0.05 μm or more, the zinc-based plating layer is easily deformed during processing of the steel sheet to easily absorb stress, so that the phosphate crystals are less likely to be destroyed or peeled during processing. When the layer thickness (M) is 1.5 μm or less, the phosphate crystals are less likely to be buried in the zinc-based plating layer during processing of the steel sheet, so that the mold and the zinc-based plating layer are in contact with each other and rubbed during processing. As a result, seizure on the surface of the zinc-based plating layer is unlikely to occur. From the above viewpoint, the layer thickness (M) is preferably a thickness that does not allow the phosphate crystals to be buried and can absorb stress during deformation, and is, for example, 0.07 μm or more and 1.12 μm or less. Is more preferable, 0.14 μm or more and 0.84 μm or less is more preferable, 0.21 μm or more and 0.7 μm or less is further preferable, and 0.28 μm or more and 0.7 μm or less is particularly preferable.

The layer thickness (M) of the zinc-based plating layer can be a value measured by observing a scanning electron microscope (SEM) image of a cross section of the zinc-based plating layer in the thickness direction.

From the same viewpoint, the adhesion amount of the zinc-based plating layer is preferably less than 0.30 g / ^{m 2} or more ^{10.75g / m 2, 0.50g / m} 2 or more 8.00 g / ^m of less than ² more preferably, more preferably more preferably less than 1.00 g / ^{m 2} or more 6.00 g / ^{m 2,} is less than 1.50 g / ^{m 2} or more 5.00 g / ^{m 2,} 2 It is particularly preferable that the amount is 0.00 g / m ² or more and less than 5.00 g / m ^2.

The amount of adhesion of the zinc-based plating layer is determined by immersing a test piece prepared by covering the back surface of a plated steel sheet with a seal and punching it to a predetermined size (for example, 45 mmφ) and immersing it in 10% hydrochloric acid for 5 minutes. It can be a value calculated from the weight difference before and after immersion. When measuring the amount of adhesion of the zinc-based plating layer on a zinc-based plated steel sheet on which a phosphate film is formed, an aqueous ammonium dichromate solution (ammonium dichromate: 20 g / L, concentrated ammonium dichromate) should be measured in advance. : 480 g / L) may be immersed in the steel sheet for 15 minutes to remove phosphate crystals, and then the amount of adhesion of the zinc-based plated layer may be calculated by the above method.

The relationship between the layer thickness (M) of the zinc-based plating layer and the amount of adhesion differs depending on the type of plating (atomic ratio), etc., but for pure zinc plating, for example, the layer thickness (M) is 1 μm thicker (M) ( As it becomes thinner (or thinner), the amount of adhesion becomes larger (or smaller) ^{by about 7.16 g / m 2.}

1-3. Phosphate film The phosphate film is a film containing phosphate crystals formed on the surface of the zinc-based plating layer.

The phosphate film is a compound having a phosphate anion, in which a plurality of phosphate crystals composed of compounds capable of forming poorly water-soluble crystals are arranged on the surface of the zinc-based plating layer. .. Examples of phosphate crystals include magnesium phosphate, manganese phosphate, zinc phosphate, iron phosphate, zinc iron phosphate, calcium zinc phosphate and the like. The phosphate film may contain metal elements such as Ni, Mn, Mg, Ca, Co and Fe, aliphatic amines and the like as other components.

The adhesion amount (H) of the phosphate crystals is 0.5 g / m ² or more and 3.5 g / m ² or less. When the adhesion amount (H) is 0.5 g / m ² or more, the phosphate crystals sufficiently cover the surface of the zinc-based plating layer, so that the mold and the zinc-based plating layer come into contact with each other during processing. Burning to the surface of the zinc-based plating layer due to friction is unlikely to occur. Further, when the adhesion amount (H) is 3.5 g / m ² or less, it is possible to prevent the phosphate crystals from being coagulated and broken during processing. From the above viewpoint, the adhesion amount (H) is ^{preferably 0.5 g / m 2} or more and 2.8 g / m ² or less.

The amount (H) of the phosphate crystals attached is surface-treated when the phosphate crystals are dissolved in an aqueous solution of ammonium dichromate (ammonium dichromate: 20 g / L, concentrated ammonium: 480 g / L). It can be a value calculated from the amount of change in the mass of the zinc-based plated steel sheet before and after melting.

The coverage of the phosphate crystals with respect to the surface area of the zinc-based plating layer is preferably 75% or more. When the coverage is 75% or more, the phosphate crystals sufficiently cover the surface of the zinc-based plating layer, so that the mold and the zinc-based plating layer are in contact with each other and rubbed during processing, resulting in zinc. Seizure on the surface of the system plating layer is unlikely to occur. From the above viewpoint, the coverage is preferably 80% or more, and preferably 85% or more. The upper limit of the coverage can be 100%, but it is preferably 98% or less from the viewpoint of shortening the phosphate treatment.

The coverage can be a value obtained by analyzing an SEM image obtained by imaging the surface of a surface-treated galvanized steel sheet with known image analysis software.

The ratio (H / M) of the amount (H) of the phosphate crystals attached to the thickness (M) of the zinc-based plating layer is 0.90 or more. When the above ratio (H / M) is 0.90 or more, a sufficient amount of phosphate crystals are formed with respect to the zinc-based plating layer, so that phosphoric acid is formed inside the zinc-based plating layer during processing. It is difficult for salt crystals to enter, and the zinc-based plating layer is less likely to be seized on the surface due to contact and friction between the mold and the zinc-based plating layer during processing. The ratio (H / M) is preferably 3.00 or more and 20.00 or less, more preferably 3.50 or more and 15.00 or less, and 4.00 or more and 12.00 or less. Is even more preferable.

The size of the phosphate crystals is not limited as long as the above-mentioned adhesion amount (H) and ratio (H / M) can be satisfied, but the average value of the long sides is preferably 5.0 μm or more and 30 μm or less. When the average value of the long sides is 5.0 μm or more, the phosphate crystals sufficiently cover the surface of the zinc-based plating layer, so that the mold and the zinc-based plating layer are in contact with each other and rubbed during processing. As a result, seizure on the surface of the zinc-based plating layer is unlikely to occur. Further, when the average value of the lengths of the long sides is 30 μm or less, even if the steel sheet is deformed during processing, the phosphate crystals easily follow the deformation, and the phosphate crystals are less likely to be broken or peeled off. .. From the above viewpoint, the average value of the long sides is more preferably 5 μm or more and 25 μm or less, and further preferably 5 μm or more and 20 μm or less.

Similarly, the size of the phosphate crystal is preferably such that the average value of the short sides is 0.5 μm or more and 2.5 μm or less. When the average value of the short sides is 0.5 μm or more, the phosphate crystals sufficiently cover the surface of the zinc-based plating layer, so that the mold and the zinc-based plating layer are in contact with each other and rubbed during processing. As a result, seizure on the surface of the zinc-based plating layer is unlikely to occur. Further, when the average value of the lengths of the long sides is 2.5 μm or less, even if the steel sheet is deformed during processing, the phosphate crystals easily follow the deformation, and the phosphate crystals are broken and peeled off. It is unlikely to occur. From the above viewpoint, the average value of the short sides is more preferably 0.5 μm or more and 2.0 μm or less, and further preferably 0.5 μm or more and 1.5 μm or less.

In this embodiment, the ratio (H / M) of the amount of phosphate crystals attached (H) and the amount of phosphate crystals attached (H) to the thickness (M) of the zinc-based plating layer is adjusted. Therefore, it is preferable to attach a surface conditioner to the surface of the zinc-based plating layer before the phosphate treatment.

The surface conditioner can impart a large number of fine particles that serve as nuclei for the growth of phosphate crystals to the surface of the zinc-based plating layer. After that, when phosphate treatment is performed, phosphate crystals grow around the large number of fine particles as nuclei, so that the phosphate crystals are relatively small in size and easily follow the deformation even if the steel plate is deformed during processing. , Can be formed in large numbers. In addition, the phosphate treatment time can be shortened.

Examples of the surface conditioner include titanium colloid and phosphate fine particles.

1-4. Lubricating film The lubricating film is an organic resin film containing a lubricant or an inorganic film containing a lubricant.

The lubricating film itself enhances the lubricity of the surface-treated galvanized steel sheet, and also acts as a binder to further suppress the peeling of phosphate crystals. Further, since the lubricating film is arranged between the zinc-based plating layer and the mold during processing, seizure can be suppressed by suppressing the contact between the zinc-based plating layer and the mold.

Further, unlike the soap layer formed by the bonde treatment, the lubricating film does not easily adhere to the manufacturing apparatus and the processing apparatus (slitter, shirring, etc.) during processing. Therefore, unlike the soap layer formed by the bonde treatment, the lubricating film is contaminated by the adhered soap layer material adhering to the processed product to be subsequently processed using the same device. It is not necessary to frequently clean the device in order to suppress the above-mentioned adhesion.

In the present embodiment, the amount of the lubricating film adhered is 35% by volume or more and 500% by volume or less with respect to the volume of the phosphate crystals. When the amount of adhesion is 35% by volume or more with respect to the volume of the phosphate crystals, the effect of suppressing the peeling of the phosphate crystals and the suppression of the contact between the zinc-based plating layer and the mold are suppressed. However, it is played enough. If the amount of adhesion is 500% by volume or less with respect to the volume of the phosphate crystal, the amount of the lubricating film adhered to the phosphate crystal is not too large, so that only the lubricating film comes into contact with the mold during processing and rubs. It is possible to suppress the generation of large film-like film strips due to the peeling. From the above viewpoint, the amount of the lubricating film adhered is preferably 35% by volume or more and 300% by volume or less, and more preferably 50% by volume or more and 300% by volume or less with respect to the volume of the phosphate crystal. It is more preferably 80% by volume or more and 250% by volume or less.

If large film flakes are generated during processing, the film flakes may adhere to the mold and accumulate during continuous processing, causing pushing into the work piece. In addition, if large film flakes are generated during processing, it is necessary to increase the frequency of cleaning the mold in order to remove the film flakes, which may lead to an increase in processing cost. On the other hand, in the present embodiment, by setting the amount of the lubricating film adhered within the above range, it is possible to suppress the peeling and seizure of the phosphate crystals, while suppressing the pressing into the work piece and the increase in the frequency of cleaning. be able to.

The amount of the lubricant adhered ^{is preferably 0.1 g / m 2} or more and 3.0 g / m ² or less. When the adhesion amount is 0.1 g / m ² or more, the lubricity of the surface-treated galvanized steel sheet can be further improved. Further, since the adhesion amount may ^{be saturated when it exceeds 3.0 g / m 2} , if the adhesion amount is 3.0 g / m ² or less, the production cost of the surface-treated galvanized steel sheet is increased. While suppressing it, the amount of film residue generated during processing can be further reduced.

The lubricant may be any known lubricant that is applied to the surface of the plated steel sheet to impart lubricity. Examples of the above-mentioned lubricants include organic lubricants such as polymer-based synthetic waxes including fluorine-based waxes, polyethylene-based waxes and styrene-based waxes, and inorganic-based lubricants including silica, molybdenum disulfide, talc and graphite. Includes lubricants and the like.

Of these, from the viewpoint of further improving workability, the organic resin preferably has good ductility, and is preferably an organic lubricant (organic resin film containing a lubricant).

The lubricant is arranged on the outer side (opposite side of the steel sheet) of the surface-treated galvanized steel sheet from the zinc-based plating layer using an organic resin or an inorganic component as a base component as a binder.

Examples of the above-mentioned base component which is an organic resin include urethane-based resin, epoxy-based resin, acrylic-based resin, olefin-based resin including polyethylene, polypropylene and ethylene-acrylic acid copolymer, and styrene-based resin containing polystyrene and the like. Polystyrene-based resins and copolymers thereof are included. These organic resins may be modified products.

Of these, from the viewpoint of further improving workability, the organic resin preferably has a good balance between strength and ductility, and is preferably a urethane-based resin.

The urethane-based resin usually has a structural unit derived from an isocyanate compound and a structural unit derived from a polyol compound.

Examples of the structural unit derived from the isocyanate compound include a structural unit derived from an aliphatic diisocyanate and a structural unit derived from an alicyclic diisocyanate. Examples of the aliphatic diisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate and naphthalene diisocyanate. Examples of the alicyclic diisocyanate include cyclohexane diisocyanate, isophorone diisocyanate, norbornane diisocyanate, xylylene diisocyanate and tetramethylxylylene diisocyanate.

Examples of the structural unit derived from the above-mentioned polyol compound include a structural unit derived from a polyolefin polyol. Examples of the polyolefin polyols include polyester polyols, polyether polyols, polycarbonate polyols, polyacetal polyols, polyacrylate polyols and polybutadiene polyols.

The urethane resin preferably has a tensile fracture elongation rate of 10% or less as measured according to JIS K 7161. The tensile breakdown elongation is the type of the structural unit derived from the isocyanate compound, the type of the structural unit derived from the polyol compound, the type of the structural unit derived from the monomer having a carboxyl group to be copolymerized, the type of the chain extender, and each of them. It can be adjusted according to the ratio of.

The urethane resin preferably has a tensile fracture elongation of 10% or less when the film thickness is 100 μm. Such urethane-based resin is easy to peel off into smaller flakes during processing, and suppresses the occurrence of scratches on the processed product due to the lubricating film peeled off in the form of a film adhering to the processed product or mold. be able to. From the same point of view, the lubricating film containing the urethane-based resin was subjected to a close-contact bending test in accordance with JIS Z 2248 (2014), and then scanning electron electrons were arbitrarily selected at five locations in the bent portion. The average value of the crack generation area ratio calculated from the image taken by the microscope (SEM) is preferably 15% or more. The crack-generated area ratio means the ratio of the area of the portion of the image imaged by the SEM where the underlying zinc-based plating layer or the steel plate is exposed due to the cracking in the organic resin film. .. The tensile fracture elongation and the crack occurrence rate of the urethane resin can be adjusted by adjusting the amount of the film forming aid added when forming the lubricating film.

The organic resin film is one or more compounds selected from the group consisting of an oxide of a valve metal, a hydroxide of a valve metal, or a fluoride of a valve metal (hereinafter, also simply referred to as a "valve metal compound"). ) Etc. may be included. The valve metal compound can impart an excellent barrier action to the organic resin film while reducing the environmental load. The valve metal is a metal whose oxide exhibits high insulation resistance. Examples of the valve metal include one kind or two or more kinds of metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Mo and W. A known valve metal compound may be used.

Further, by including the soluble fluoride of the valve metal in the organic resin film, it is possible to impart a self-repairing action to the organic resin film. After being dissolved in the moisture in the atmosphere, the fluoride of the valve metal is reprecipitated as a sparingly soluble oxide or hydroxide on the surface of the plated steel sheet exposed from the film defect portion, and the film defect portion is formed. Can be filled.

Further, the organic resin film may further contain a soluble or sparingly soluble metal phosphate or composite phosphate in addition to the soluble fluoride of the valve metal. Soluble phosphate elutes from the organic resin film into the film defect and reacts with the metal of the galvanized steel sheet to become insoluble phosphate, which can complement the self-healing action of the soluble fluoride of valve metal. it can. Further, the poorly soluble phosphate can be dispersed in the organic resin film to improve the film strength.

Examples of the base component, which is an inorganic component, include sodium silicate, sodium metasilicate, and metal salts such as zirconium carbonate.

The ratio between the base component and the lubricant is preferably a ratio in which the content of the lubricant with respect to the total amount of the base component and the lubricant is 4% by mass or more and 30% by mass or less. When the content of the lubricant is 4% by mass or more, the lubricity of the surface-treated galvanized steel sheet can be further improved. Further, when the content of the lubricant is 30% by mass or less, the production cost of the surface-treated galvanized steel sheet can be suppressed.

The lubricating film is in contact with the surface of the phosphate crystal and is arranged outside the zinc-based plating layer. The lubricating film may be arranged outside the phosphate film, or may enter the gaps between the phosphate crystals and be arranged in contact with the zinc-based plating layer (see FIG. 2A).

The film thickness of the lubricating film is preferably 0.2 μm or more and 5.0 μm or less, more preferably 0.2 μm or more and 2.5 μm or less, and further preferably 0.2 μm or more and 2.0 μm or less. preferable.

2. Method for manufacturing surface-treated zinc-based plated steel sheet The above-mentioned surface-treated zinc-based plated steel sheet has a zinc-based plated layer having a layer thickness (M) of 0.11 μm or more and 1.6 μm or less. (Step S110) and the amount (H) of phosphate crystals adhering to the surface of the zinc-based plating layer is 0.5 g / m ² or more and 3.5 g / m ² or less. A step of forming a phosphate film (step S120), wherein the ratio (H / M) of the adhesion amount (H) of the phosphate crystals to the layer thickness (M) of the zinc-based plating layer is 0.90 or more. ) And the step of forming a lubricating film in contact with the phosphate film (step S130).

2-1. Preparation of galvanized steel sheet (process S110)
FIG. 5 is a workflow showing a method for manufacturing the galvanized steel sheet. The zinc-based plated steel sheet may be any zinc-based plated steel sheet having the above-mentioned zinc-based plating layer.

The plating constituting the zinc-based plating layer is any of Zn plating (pure zinc plating), Zn-Al-based alloy plating, Zn-Mg alloy plating, Zn-Ni alloy plating, Zn-Al-Mg-based alloy plating, and the like. However, pure zinc plating is preferable.

Further, the zinc-based plating layer may be a plating layer formed by any known method such as an electroplating method, a hot-dip plating method, and a vapor deposition plating method. Of these, from the viewpoint of uniformly forming a zinc-based plating layer having a thinner layer thickness (M) on the surface of the steel sheet, a plating layer formed by an electroplating method is preferable.

The layer thickness (M) of the zinc-based plating layer is 0.11 μm or more and 1.6 μm or less. The layer thickness (M) is preferably 0.11 μm or more and 0.8 μm or less, more preferably 0.11 μm or more and 0.4 μm or less, and further preferably 0.11 μm or more and 0.3 μm or less. preferable.

Further it, the adhesion amount of the zinc-based plating layer is more preferably less than 0.75 g / ^{m 2} or more 11.5 g / ^{m 2,} is less than 0.75 g / ^{m 2} or more 5.73 g / ^{m 2} Is more preferably 0.75 g / m ² or more and less than 2.86 g / m ² , and particularly preferably 0.75 g / m ² or more and less than 2.15 g / m ^2.

The layer thickness (M) and the amount of adhesion of the zinc-based plating layer are the layer thickness (M) and the amount of adhesion after the phosphate film is formed. Since the zinc-based plating layer is partially dissolved when the phosphate film is formed, the thickness of the zinc-based plating layer of the prepared galvanized steel sheet is slightly thickened (adhesion amount) in anticipation of the above-mentioned dissolution amount. Is a little more).

The zinc-based plated steel sheet may be prepared in advance, or may be produced by subjecting the surface of the steel sheet to a zinc-based plating treatment in this step. The zinc-based plating treatment can be performed by known methods such as an electroplating method, a hot-dip plating method, and a thin-film deposition plating method, but from the viewpoint of uniformly forming a zinc-based plating layer having a thinner layer thickness (M) on the surface of the steel sheet. Therefore, it is preferable to use the electroplating method.

2-2. Formation of phosphate film (step S120)
The phosphate film can be formed by bringing the phosphate treatment solution into contact with the surface of the zinc-based plating layer to precipitate phosphate crystals, and then washing and drying with water. Examples of contacting methods include dipping and spraying.

At this time, the adhesion amount (H) of the phosphate crystals is 0.5 g / m ² or more and 3.5 g / m ² or less, and the phosphate crystals have a thickness (M) relative to the zinc-based plating layer. A phosphate film is formed while adjusting the ratio (H / M) of the adhesion amount (H) to 0.90 or more.

For example, the amount of phosphate crystals adhered (H) is adjusted by the amount of surface conditioner applied, the particle size of the surface conditioner acting as a nucleating agent, and the phosphate treatment method (such as time for immersion and spraying). can do.

Further, from the viewpoint of further suppressing seizure on the surface of the zinc-based plating layer during processing, the phosphate treatment covers 75% or more of the surface area of the zinc-based plating layer with phosphate crystals. It is preferably carried out until 80% or more is covered with the phosphate crystal, and more preferably 85% or more is carried out until it is covered with the phosphate crystal. The upper limit of the coverage can be 100%, but it is preferably 98% or less from the viewpoint of shortening the phosphate treatment.

The phosphate treatment solution can be prepared by dissolving the above-mentioned phosphate in an aqueous solvent, or dissolving a metal salt capable of producing phosphoric acid and a metal ion described later in an aqueous solvent. From the viewpoint of precipitating a sufficient number of phosphate crystals and suppressing the generation of sludge due to the aggregation of phosphates, the concentration of phosphate ions in the phosphate treatment solution is 0.03. It is preferably mol / L or more and 0.5 mol / L or less.

The phosphate treatment solution may contain a polyamine-based organic inhibitor having at least one functional group of _{-NH 2 or = NH.} The polyamine-based organic inhibitor is _{adsorbed on the surface of the plating layer by the action of -NH 2} or = NH, and non-polar groups such as hydrocarbon groups oriented to the outside (treatment liquid side) form a monomolecular film by intermolecular force. It is formed and inhibits the contact between the etching component contained in the phosphate treatment liquid and the surface of the plating layer. As a result, the phosphate crystal particles can be precipitated at appropriate intervals, and the phosphate crystal particles can be made finer.

Examples of polyamine-based organic inhibitors include aliphatic polyamines including polyethylamine, polyethyleneimine, polyetheramine and polyaminoacrylate, and aromatic polyamines including polyaniline and the like. From the viewpoint of enhancing the stability in the phosphate treatment solution, the polyamine-based organic inhibitor is preferably an aliphatic polyamine.

From the viewpoint of appropriately adjusting the amount of precipitated phosphate crystals, the number average molecular weight of the polyamine-based organic inhibitor is preferably 200 or more and 30,000 or less. Further, from the viewpoint of appropriately adjusting the amount of precipitated phosphate crystals, the concentration of the polyamine-based organic inhibitor in the phosphate treatment liquid is preferably 0.01% by mass or more and 5% by mass or less.

The phosphate treatment solution may further contain nitrate ions. Nitrate ions promote the precipitation of phosphate.

From the viewpoint of appropriately adjusting the amount of precipitated phosphate crystals, the concentration of nitrate ions in the phosphate treatment solution is preferably 0.01 mol / L or more and 1.0 mol / L or less.

The phosphate treatment solution may further contain fluoride. In particular, when a phosphate film is formed on the surface of a plating layer containing Al, Al eluted from the plating layer may prevent the precipitation of phosphate, but by adding fluoride to the phosphate treatment solution, The adverse effect of this eluted Al can be suppressed. Examples of the fluoride include sodium fluoride, potassium fluoride, sodium hydrogen fluoride and the like. From the viewpoint of appropriately adjusting the amount of precipitated phosphate crystals, the concentration of fluoride in the phosphate treatment solution is preferably 0.001 mol / L or more and 0.5 mol / L or less.

The method for applying the phosphate treatment liquid is not particularly limited, and may be appropriately selected from known methods in which the phosphate treatment liquid is brought into contact with the surface of the plating layer. Examples of the above coating method include a spray method, a dipping pulling method, and the like.

The temperature of the phosphate treatment liquid when applying the phosphate treatment liquid is preferably 40 ° C. or higher and 80 ° C. or lower. When a phosphate treatment solution heated to 40 ° C. or higher and 80 ° C. or lower is used, a large number of fine phosphate crystals can be stably precipitated in a short time.

For example, when a phosphate treatment solution heated to 40 ° C. or higher and 80 ° C. or lower is applied by a spray method, phosphate crystals are precipitated and a phosphate film is formed in about 2 to 6 seconds. Further, when a phosphate treatment solution heated to 40 ° C. or higher and 80 ° C. or lower is applied by a dipping and pulling method, phosphate crystals are precipitated and a phosphate film is formed in about 3 to 9 seconds. Even if the treatment time is longer than the above time, there is no particular problem because the precipitation of phosphate is saturated.

In order to promote the precipitation of phosphate, the zinc-based plating layer may be surface-adjusted with a known surface conditioner before applying the phosphate treatment solution.

Examples of the surface conditioner include titanium colloid and phosphate fine particles.

The amount of the surface conditioner applied ^{is preferably 5 mg / m 2} or more and 80 mg / m ² or less, more preferably 10 mg / m ² or more and 60 mg / m ² or less, and 20 mg / m ² or more and 50 mg / m. It is more preferably ^{2 or less.}

2-3. Formation of lubricating film (step S130)
The lubricating film can be formed by applying a lubricating liquid containing the above-mentioned lubricant and base component to the surface of the phosphate film and drying it.

The amount of the lubricant adhered is 35% by volume or more and 500% by volume or less with respect to the volume of the phosphate crystal. Further, from the viewpoint of further improving the lubricity of the produced surface-treated galvanized steel sheet, it is preferably ^{0.1 g / m 2} or more and 3.0 g / m ^{2 or less.} The amount of the lubricant adhering can be adjusted within the above range depending on the type (solid component amount) of the lubricating liquid to be applied, the application method, and the like.

Further, the ratio between the base component and the lubricant is the content of the lubricant with respect to the total amount of the base component and the lubricant from the viewpoint of further enhancing the lubricity of the produced surface-treated galvanized steel sheet. The amount is preferably a ratio of 4% by mass or more and 30% by mass or less.

The method for applying the lubricating liquid is not particularly limited, and may be appropriately selected from known methods for applying the phosphate treatment liquid to the surface of the plating layer. Examples of the above coating method include a spray method, coating with a bar coater, a dipping pulling method, and the like.

The method for drying the applied lubricating liquid is not particularly limited, and may be natural drying, or may be, for example, drying in a drying furnace in which the furnace temperature is 100 ° C. or higher and 200 ° C. or lower.

[Example 1]
The following experiments were conducted to investigate the effects of the thickness of the zinc-based plated layer and the amount of phosphate crystals attached on the lubricity and galvanizing resistance of the surface-treated galvanized steel sheet.

As the base steel plate, chrome molybdenum steel (SCM415) having a plate thickness of 1.1 mm was used. The alloy composition is shown in Table 1.

1. 1. Production of Surface-treated Galvanized Steel Sheet The above-mentioned base steel sheet is subjected to plating treatment, phosphate treatment and formation of a lubricating film in this order by the following methods, and the surface treatment of the surface-treated galvanized steel sheet is performed. Galvanized steel sheets 1 to surface-treated galvanized steel sheets 38 were produced. At this time, the layer thickness of the zinc-based plated layer, the amount of phosphate crystals adhered, and the presence or absence of each treatment of phosphate treatment and formation of a lubricating film were changed for each surface-treated plated steel sheet to be produced.

Further, the base steel sheet was plated only by the following method to produce a plated steel sheet 39 without phosphate treatment and formation of a lubricating film.

1-1. Zinc plating (pretreatment)
The base steel sheet was alkali degreased by electrolysis, and then pickled and washed with a sulfuric acid aqueous solution having a concentration of 50 g / L for 10 seconds.

(Electrogalvanization)
Then, the base steel sheet was electroplated using a liquid circulation type electroplating experimental device. The plating solution was a sulfuric acid acidic plating bath containing 350 g / L of zinc sulfate heptahydrate, 80 g / L of sodium sulfate, and sulfuric acid having a pH of 1.3. The above-mentioned sulfuric acid acidic plating at 60 ° C. By immersing the base steel plate in a bath, the relative flow velocity between the plating bath and the base steel plate is 1.0 m / s, the current density is 30 A / dm ² , and the energization time is changed to make pure zinc of various thicknesses. A plating layer was formed.

1-2. Phosphate treatment (surface adjustment)
The surface of the plated steel sheet was adjusted by immersing it in a surface conditioner (Preparen X (“Preparen” is a registered trademark of Nihon Parkerizing Co., Ltd.) or Preparen 4028 manufactured by Nihon Parkerizing Co., Ltd.) for 5 seconds. In order to change the amount of phosphate crystals attached, the concentration of the surface conditioner was changed and each of the above plated steel sheets was immersed.

(Phosphate treatment)
Palbond 3312M manufactured by Nihon Parkerizing Co., Ltd. was diluted with water to a concentration of 50 g / L to prepare a phosphate treatment solution. The surface-adjusted plated steel sheet is immersed in the phosphate treatment solution having a treatment temperature of 60 ° C., and phosphate treatment is performed until 75% or more of the surface of the plated steel sheet is covered with phosphate crystals. It was.

1-3. Formation of lubricating film (preparation of lubricating liquid)
The base components and lubricants shown in Table 2 are added to pure water at the ratios shown in Table 2 (the numerical values in Table 2 represent the blending amount of each component with respect to the total mass in parts by mass), and the mixture is stirred. And further diluted to 20% of the solid component to prepare eight kinds of lubricating liquids.

The urethane resin used as the base component is ADEKA BONTITER HUX232 manufactured by ADEKA CORPORATION. The acrylic resin used as the base component is Boncoat 40-418EF manufactured by DIC Corporation. The epoxy resin used as the base component is ADEKA Resin EM-0180 manufactured by ADEKA CORPORATION. Also. The polyethylene wax used as the lubricant is MYE-35G manufactured by Maruyoshi Chemical Co., Ltd. The polypropylene wax used as the lubricant is P-5800 manufactured by Toho Chemical Industry Co., Ltd.

(Formation of lubricating film)
One of the above lubricating liquids was applied to a phosphate-treated plated steel sheet with a bar coater and dried in a drying oven at a furnace temperature of 390 ° C. for 10 seconds to form a lubricating film. In order to change the volume fraction of the lubricating film, the coating amount of the lubricating liquid was changed by changing the count of the bar coater and the amount of the solid component of the lubricating liquid to form the lubricating film.

1-4. Measurement (thickness of plating layer)
The formed surface-treated plated steel sheet was cut in the cross-sectional direction, the cross section in the thickness direction of the pure galvanized layer was observed by SEM, and the layer thickness (M) (μm) of each pure galvanized layer was measured.

(Volume ratio of lubricating film to phosphate crystals)
A portion of the formed surface-treated galvanized steel sheet having an average surface shape was cut at three points, the cross section was mirror-polished, and then the film cross section was observed by SEM. At this time, in order to clearly observe the boundary between each film (the boundary between the phosphate crystal and the lubricating film), the cross section was mechanically polished and then finish-polished by ion milling or the like. After polishing, the average part on the film side from the cross section was photographed with SEM at 5000 times in 5 fields, the areas of the phosphate crystal and the lubricating film were calculated from each image, and the ratio of these to the phosphate crystal was calculated. The volume ratio of the lubricating film was used.

2. Evaluation 2-1. Lubricity In order to evaluate the lubricity of the flat surface of the lubricated steel sheet during press working, the dynamic friction coefficient of the surface-treated plated steel sheet 1 to the surface-treated plated steel sheet 39 was measured using a flat plate sliding test. For the test pieces of 300 mm in length and 30 mm in width collected from each surface-treated galvanized steel sheet, a processing oil (Daido Chemical Industry Co., Ltd. Daillustrat RX-900V) ^{of 1.5 g / m 2 was applied to the surface thereof.} After that, a flat plate sliding test was performed under the conditions shown below, and the dynamic friction coefficient (pulling force / pressing load) was measured.
(Test condition)
Die shape: 30 mm L x 50 mm W long plane (SKD11 mold)
Pressing load: 900N / mm ²
Pull-out speed: 100 mm / min Sliding length: 100 mm
Test temperature: Room temperature Judgment criteria: Dynamic friction coefficient by flat plate sliding test

From the obtained dynamic friction coefficient, the lubricity of the surface-treated galvanized steel sheet 1 to the surface-treated galvanized steel sheet 39 was evaluated according to the following criteria.
(Evaluation criteria)
⊚: Dynamic friction coefficient is 0.15 or less ○: Dynamic friction coefficient is more than 0.15 and 0.25 or less Δ: Dynamic friction coefficient is more than 0.25 and is 0.35 or less ×: Dynamic friction coefficient is 0. Over 35

2-2. Gnawing resistance (during drawing)
In order to evaluate the galling resistance during drawing, the surface of a 76 mmφ disk-shaped test piece collected from the surface-treated galvanized steel sheet 1 to the surface-treated galvanized steel sheet 39 is processed in an amount of ^{1.5 g / m 2.} After applying oil (Daido Kagaku Kogyo Co., Ltd. Da Illust RX-900V), 3-stage cylindrical drawing is performed, and galvanizing resistance is visually observed from the appearance of the vertical wall after the 2nd and 3rd-stage drawing. Gender was evaluated.
(Test condition)
1st stage punch diameter: 50mm
Punch shoulder: 5mmR
Die diameter: 53 mm
Dice shoulder: 5mmR
Aperture ratio: 1.52
Wrinkle presser pressure: 2.8 kN
2nd stage punch diameter: 40mm
Punch shoulder: 5mmR
Die diameter: 43 mm
Dice shoulder: 5mmR
3rd stage punch diameter: 33mm
Punch shoulder: 5mmR
Die diameter: 35 mm
Dice shoulder: 5mmR

The area ratio of the galvanized portion in the vertical wall portion after the second and third stages of drawing is visually calculated, and the galvanizing resistance of the surface-treated plated steel sheet 1 to the surface-treated plated steel sheet 39 is determined according to the following criteria, respectively. evaluated.
(Evaluation criteria)
⊚: Area ratio is 5% or less ○: Area ratio is more than 5% and 15% or less Δ: Area ratio is more than 15% and is 25% or less ×: Area ratio is more than 25%

2-3. Gnawing resistance (during bending)
In order to evaluate the galvanizing resistance during press working with bending back deformation at high surface pressure, a draw bead test was carried out on the surface-treated plated steel sheets 1 to 39. For the test pieces of 300 mm in length and 30 mm in width collected from each surface-treated galvanized steel sheet, a processing oil (Daido Kagaku Kogyo Co., Ltd. Daillustrat RX-900V) ^{of 1.5 g / m 2 was applied to the surface thereof.} After that, the draw bead test was repeated under the conditions shown below. The galling resistance was visually evaluated from the appearance of the sample when the number of repetitions was 1 and 5 times.

(Test condition)
Die shape: One-sided convex type (bead R: 0.5 mm, bead height: 4 mm),
Single-sided concave type (shoulder R: 2 mm), 50 mmW
Pressing load: 900N / mm ²
Pull-out speed: 100 mm / min Sliding length: 100 mm
Test temperature: Room temperature Judgment criteria: Visually evaluate the area ratio of the galling occurrence part after the draw bead test

The area ratio of the galvanized part in the machined part after bending at the time when the number of repetitions was 1 and 5 times was visually calculated, and the surface-treated plated steel sheet 1 to the surface-treated plated steel sheet 39 were calculated according to the following criteria, respectively. The galvanizing resistance was evaluated.
(Evaluation criteria)
⊚: Area ratio is 5% or less ○: Area ratio is more than 5% and 15% or less Δ: Area ratio is more than 15% and is 25% or less ×: Area ratio is more than 25%

2-4. Phosphate Crystal Peeling Suppression 30 mm square samples were cut out from the test pieces before and after the galling resistance test (the number of repetitions was 1), and the fluorescent X-ray intensity of phosphorus was measured by fluorescent X-ray analysis. Calculate the reduction rate ((fluorescent X-ray intensity before test-fluorescent X-ray intensity after test) / fluorescent X-ray intensity before test) (%) before and after the test to determine the rate of inhibition of phosphate crystal peeling. evaluated.

(Evaluation criteria)
⊚: Decrease rate is 10% or less ○: Decrease rate is over 10% and 25% or less Δ: Decrease rate is over 25% and 40% or less ×: Decrease rate is over 40%

2-5. Size of film debris after processing From the film debris peeled from the surface-treated steel sheet that occurred after the first test of galling resistance (during bending), select 3 large pieces and the size of the debris. The average value (the size of the square in which the debris fits) was calculated. From the average value of the obtained debris size, the debris size was evaluated according to the following criteria.
(Evaluation criteria)
⊚: The average value of the size of the flakes is 1 mm square or less ○: The average value of the size of the flakes is more than 1 mm square and 3 mm square or less Δ: The average value of the size of the flakes is more than 3 mm square and 5 mm square The following ×: The average value of the size of the flakes exceeds 5 mm square.

With respect to the layer thickness (M) of the zinc plating layer, the amount of phosphate crystals adhered to the phosphate film (H), and the layer thickness (M) of the zinc-based plating layer of the surface-treated plated steel sheets 1 to 39. The ratio (H / M) of the amount of phosphate film adhered (H), the type of lubricating liquid used to form the lubricating film, the amount of lubricating film adhered to the volume of phosphate crystals (volume ratio), and Tables 3 to 5 show the evaluation results of lubricity, galling resistance (during drawing and bending), suppression of peeling of phosphate crystals, and size of film fragments after processing.

As shown in Tables 3 to 5, the thickness (M) of the zinc-based plating layer is 0.05 μm or more and 1.5 μm or less, and the adhesion amount (H) of the phosphate crystals on the phosphate film is determined. It is 0.5 g / m ² or more and 3.5 g / m ² or less, and the ratio (H / M) of the adhesion amount (H) of the phosphate crystals to the thickness (M) of the zinc-based plating layer is 0.90. As described above, the amount of the lubricating film adhered is 35% by volume or more and 500% by volume or less with respect to the volume of the phosphate crystal, surface-treated plated steel sheet 4, surface-treated plated steel sheet 7, surface-treated plated steel sheet 9 to surface. Treated plated steel plate 14, surface treated plated steel plate 16, surface treated plated steel plate 18 to surface treated plated steel plate 20, surface treated plated steel plate 22 to surface treated plated steel plate 24, surface treated plated steel plate 26, surface treated plated steel plate 27, surface treated plating The steel plate 30, the surface-treated plated steel plate 31, the surface-treated plated steel plate 35, and the surface-treated plated steel plate 37 all have good lubricity and galling resistance, and the film is less likely to peel off, and even if peeled off, large film fragments Was hard to occur.

In particular, the amount of the lubricating film adhered is 35% by volume or more and 300% by volume or less with respect to the volume of the phosphate crystal, surface-treated plated steel plate 4, surface-treated plated steel plate 7, surface-treated plated steel plate 9, surface-treated plating. Steel plate 10, surface-treated plated steel plate 12, surface-treated plated steel plate 14, surface-treated plated steel plate 16, surface-treated plated steel plate 18 to surface-treated plated steel plate 20, surface-treated plated steel plate 23, surface-treated plated steel plate 24, surface-treated plated steel plate 26 , The surface-treated plated steel plate 27, the surface-treated plated steel plate 30, the surface-treated plated steel plate 31, and the surface-treated plated steel plate 37 were less likely to generate large film fragments.

Further, the lubricating film is an organic resin film containing a lubricant, which is a surface-treated plated steel plate 4, a surface-treated plated steel plate 7, a surface-treated plated steel plate 9, a surface-treated plated steel plate 11 to a surface-treated plated steel plate 13, and a surface-treated plating. Steel plate 16, surface-treated plated steel plate 19, surface-treated plated steel plate 20, surface-treated plated steel plate 22 to surface-treated plated steel plate 24, surface-treated plated steel plate 27, surface-treated plated steel plate 30, surface-treated plated steel plate 31, surface-treated plated steel plate 35 The surface-treated plated steel plate 37 had better galling resistance during multiple machining.

Further, the lubricating film is an organic resin film containing a urethane resin, surface-treated plated steel plate 4, surface-treated plated steel plate 7, surface-treated plated steel plate 11, surface-treated plated steel plate 12, surface-treated plated steel plate 16, surface-treated. The plated steel plate 19, the surface-treated plated steel plate 20, the surface-treated plated steel plate 24, the surface-treated plated steel plate 27, the surface-treated plated steel plate 30, the surface-treated plated steel plate 31, the surface-treated plated steel plate 35, and the surface-treated plated steel plate 37 are processed many times. The galling resistance at the time was better.

On the other hand, the surface-treated plated steel sheets 1 to 3 having a zinc-based plated layer having a thickness (M) of less than 0.05 μm had low galvanizing resistance. This is because the zinc-based plating layer was too thin to be sufficiently deformed during the processing (draw bead) of the steel sheet and could not absorb the stress during the processing, resulting in the destruction and peeling of the phosphate crystals during the processing. It is thought that it depends.

Further, the surface-treated plated steel sheet 38 having a zinc-based plating layer thickness (M) larger than 1.5 μm had low galvanizing resistance. This is because the phosphate crystals are buried in the zinc-based plating layer during processing of the steel sheet, and the mold and the zinc-based plating layer are in contact with each other and rubbed during processing, so that the zinc-based plating layer is exposed to the surface. It is probable that the burning occurred.

Further, the surface-treated plated steel sheet 1, the surface-treated plated steel sheet 2, and the surface-treated plated steel sheet 5 having a phosphate crystal adhesion amount (H) of ^{less than 0.5 g / m 2 in the phosphate film have galvanizing resistance.} It was low. This is because the phosphate crystals cannot sufficiently coat the surface of the zinc-based plating layer, and the mold and the zinc-based plating layer not covered with the phosphate crystals come into contact with each other and are rubbed during processing. It is probable that the zinc-based plating layer was seized on the surface.

Further, in the surface-treated galvanized steel sheet 6 in which the amount (H) of the phosphate crystals adhered to the phosphate film was ^{more than 3.5 g / m 2} , the phosphate crystals were likely to be peeled off. .. It is considered that this is because the amount of the phosphate crystals attached was large and the phosphate crystals were agglomerated and broken during processing.

Further, the surface-treated plated steel sheet 25 and the surface-treated plated steel sheet 32 to the surface in which the ratio (H / M) of the adhesion amount (H) of the phosphate crystals to the thickness (M) of the zinc-based plated layer is less than 0.90. The treated plated steel sheet 34 had low galvanizing resistance. This is because a sufficient amount of phosphate crystals are not formed on the zinc-based plating layer, so that the phosphate crystals get inside the zinc-based plating layer during processing, and the mold and zinc are processed during processing. It is probable that the zinc-based plating layer was seized on the surface due to contact and friction with the system-based plating layer.

Further, the surface-treated plated steel sheet 8, the surface-treated plated steel sheet 15, and the surface-treated plated steel sheet 28, in which the amount of the lubricating film adhered is less than 35% by volume with respect to the volume of the phosphate crystals, have low galvanizing resistance. Moreover, peeling of phosphate crystals was likely to occur. It is considered that this is because the lubricating film does not easily act as a binder and the effect of suppressing the contact between the zinc-based plating layer and the mold by the lubricating film is not exhibited.

Further, in the surface-treated plated steel sheet 21 and the surface-treated plated steel sheet 36 in which the amount of the lubricating film adhered was more than 500% by volume with respect to the volume of the phosphate crystals, large film fragments were likely to be generated during processing. It is considered that this is because only the lubricating film came into contact with the mold during processing and was rubbed and peeled off.

Further, the surface-treated plated steel sheet 39 in which neither the phosphate treatment nor the formation of the lubricating film was performed had low lubricity and galling resistance.

According to the present invention, there is provided a surface-treated galvanized steel sheet that can be surface-treated in a short time and that does not easily cause peeling of phosphate crystals during processing. Further, unlike the bonde treatment, the surface-treated galvanized steel sheet provided by the present invention needs to be able to perform the surface treatment in a short time and to wash the processing apparatus frequently at the time of processing. Absent. Therefore, the present invention is expected to contribute to the further spread of plated steel sheets.

110a, 110b, 110c, 110d Steel plate 120b, 120c, 120d Zinc-based plating layer 130a, 130b, 130c, 130d Phosphate crystal 140a Soap layer 140b, 140c, 140d Lubrication film 150 Burnt 160 film flakes 210a, 210b, 210c, 210d mold

Claims (8)

A steel sheet, a zinc-based plating layer arranged on at least one surface of the steel sheet, a phosphate film containing a phosphate crystal arranged in contact with the surface of the zinc-based plating layer, and the phosphate. A surface-treated galvanized steel sheet having a lubricating film arranged in contact with the film.
The layer thickness (M) of the zinc-based plating layer is 0.05 μm or more and 1.5 μm or less.
The adhesion amount (H) of the phosphate crystals is 0.5 g / m ² or more and 3.5 g / m ² or less.
The ratio (H / M) of the adhesion amount (H) of the phosphate crystals to the layer thickness (M) of the zinc-based plating layer is 0.90 or more.
The amount of the lubricating film adhered is 35% by volume or more and 500% by volume or less with respect to the volume of the phosphate crystals.
Surface-treated galvanized steel sheet. The surface-treated galvanized steel sheet according to claim 1, wherein the amount of the lubricating film adhered is 35% by volume or more and 300% by volume or less with respect to the volume of the phosphate crystals. The surface-treated galvanized steel sheet according to claim 1 or 2, wherein the lubricating film is an organic resin film containing a lubricant. The surface-treated galvanized steel sheet according to any one of claims 1 to 3, wherein the lubricating film is an organic resin film containing a urethane resin. A step of preparing a zinc-based plated steel sheet having a zinc-based plated layer having a layer thickness (M) of 0.11 μm or more and 1.6 μm or less, and
The amount (H) of phosphate crystals adhering to the surface of the zinc-based plating layer is 0.5 g / m ² or more and 3.5 g / m ² or less, and the layer thickness of the zinc-based plating layer ( A step of forming a phosphate film, wherein the ratio (H / M) of the amount (H) of the phosphate crystals attached to M) is 0.90 or more.
A step of forming a lubricating film which is in contact with the surface of the phosphate film and which is 35% by volume or more and 500% by volume or less with respect to the volume of the phosphate crystals.
A method for producing a surface-treated galvanized steel sheet, including. The surface-treated zinc-based material according to claim 5, wherein the step of forming the lubricating film is a step of forming a lubricating film having a volume of 35% by volume or more and 300% by volume or less with respect to the volume of the phosphate crystal. Manufacturing method of plated steel sheet. The method for producing a surface-treated galvanized steel sheet according to claim 5 or 6, wherein the lubricating film is an organic resin film containing a lubricant. The method for producing a surface-treated galvanized steel sheet according to any one of claims 5 to 7, wherein the lubricating film is an organic resin film containing a urethane resin.

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