JP2008169478A - Hot dip coated steel member and method of producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot dip coated steel member having satisfactory plating appearance, plating adhesion and workability. <P>SOLUTION: The hot dip coated steel member has a plated layer, the plated layer having a composition comprising, by mass, 8 to 60% Al, 1 to 10% Mg and the balance Zn with inevitable impurities and having, at the boundary between the plating and matrix, an Fe-Al compound layer with an average thickness of 0.1 to 5.0 μm. Further, a method of producing a hot dip coated steel member having excellent plating appearance, plating adhesion and workability is characterized in that Cu and Sn are substitution-precipitated on the surface of a steel member, and thereafter, the steel member is dipped into a hot dip plating bath comprising, by mass, 8 to 60% Al and 1 to 10% Mg, and the balance Zn with inevitable impurities. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hot-dip plated steel material having good plating appearance, plating adhesion and workability, and a method for producing the same.

  There are many types of steel materials subjected to rust prevention treatment, but those coated with zinc, aluminum or their alloys or those coated with an organic coating are widely used. Among them, galvanizing is widely used because it has excellent characteristics such as sacrificial anticorrosive property of zinc and can be easily formed into a thick film by a hot dipping method. For hot dip galvanizing, steel sheets other than thin steel plates such as thick steel plates, steel pipes, shaped steels, wire rods, or steel products such as bolts and nuts are used. In addition, there is a method of manufacturing by dipping in a hot dip galvanizing bath after flux treatment (a soaking method).

  Plating by a continuous line is performed by dipping a steel strip with a clean surface heated in a reducing atmosphere in a hot dipping bath. The dipping time is short and the adhesion is high. A plating layer is obtained. Not only zinc plating but many types of hot dip plated steel sheets such as alloy plating with aluminum or magnesium have been put into practical use.

  In the soaking method, the steel material is immersed in an aqueous solution of flux (chloride such as ammonium chloride), dried, and then immersed in a hot dipping bath to form a plating layer. Since this soaking method can cope with various shapes as compared with a continuous line, it is used for manufacturing hot dip galvanized steel pipes, hot dip galvanized bolts and the like. In the soaking method, Zn plating has been mainly used until now, but in recent years, zinc alloy plating containing aluminum, magnesium and the like has been required for the purpose of further improving the corrosion resistance. Here, in the case of plating containing aluminum or magnesium, non-plating occurs in the flux for pure zinc plating, so use flux containing alkali metal chloride as disclosed in Patent Document 1 and Patent Document 2. It has been proposed to do.

  Here, the plating by the continuous line requires a large facility such as a reduction furnace and is not a method suitable for small-scale industrial production. Moreover, although it can apply to a thin steel plate, it is not suitable for correspondence to various shapes. On the other hand, the dobbling method has the advantage that it can be plated regardless of the shape of the material to be plated, but the immersion time in the plating bath is longer than the continuous line method, and the alloy layer grows at the interface, so even with the same zinc plating Compared to thin steel sheets manufactured in line, the iron percentage during plating is higher and the workability is inferior. In addition, when alloying zinc and aluminum or magnesium, the method described in Patent Document 1 and Patent Document 2 uses alkali metal chloride as zinc chloride or ammonium chloride used in pure zinc flux. In comparison, the melting point is high, peeling during plating is not sufficient, and appearance defects may occur. In the case of plating containing magnesium, a compound of magnesium and chlorine is generated, which may cause problems such as poor appearance and poor plating adhesion.

  To prevent this, a method of adding tin chloride to the flux has been proposed (Patent Document 3), but it is effective when the amount of magnesium is small. A compound of magnesium and chlorine is produced. Although this effect can be reduced by increasing the plating bath temperature and lengthening the plating time, it is impossible to suppress the formation of magnesium and chlorine compounds, and the alloy layer grows thickly at the plating layer and the iron ground interface, There are disadvantages such as lower workability and lowering of workability and higher energy cost due to higher temperature of the plating bath.

  Furthermore, a method using fluoride as a flux has also been proposed (Patent Document 4). This method does not produce magnesium and chlorine compounds because there is no chloride. However, compared to the conventional chloride flux, which is an aqueous solution and the temperature is about 60 ° C., fluoride is hardly soluble in water and the melting point is as high as that of the plating bath. This is not an easy process and is an industrially very heavy process. There is also a method of flux treatment by floating fluoride on the plating bath (Patent Document 5), but there is a problem that the flux adheres when the steel material is taken out from the plating bath.

  There is also a two-step plating method (Patent Document 6) in which zinc-aluminum alloy plating is performed after first galvanizing, but an iron-aluminum-zinc-based alloy layer is formed at the interface between the zinc alloy plating layer and the ground iron. It is thick and has the disadvantage of poor workability.

  Because of these problems, the practical application of plating other than galvanization has been delayed.

Japanese Patent Laid-Open No. 3-165557 Japanese Patent No. 2960991 JP 2002-206156 A JP 2002-53942 A Japanese Patent Laid-Open No. 11-350095 Japanese Patent No. 3737316

  In view of the above-described problems, the present invention provides a hot-dip plated steel material excellent in plating appearance, plating adhesion, and workability by a method capable of plating a steel material having various shapes without requiring a large facility. is there.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive studies. As a result, when applying an alloy plating such as zinc-aluminum-magnesium, the iron-aluminum alloy layer generated at the plating layer-base metal interface is optimal. The present invention has been completed by finding a hot-dip galvanized steel material having a sufficient thickness and a method for producing the same, and the gist thereof is as follows.

That is,
(1) The composition of the plating layer is mass%, Al: 8% or more and 60% or less, Mg: 1% or more and 10% or less, the balance consists of Zn and unavoidable impurities, and the average is at the plating layer-base metal interface. A hot-dip plated steel material excellent in plating appearance, plating adhesion, and workability, characterized by having a Fe-Al alloy layer having a thickness of 0.1 μm or more and 5.0 μm or less.

(2) The plating appearance, plating adhesion, (1) characterized in that the amount of Cl in the Fe-Al alloy layer at the plating layer-base metal interface or in the plating layer is 1 g / m ² or less, Hot-dip galvanized steel with excellent workability.

  (3) The hot-dip plated steel material excellent in plating appearance, plating adhesion, and workability according to (1) or (2), wherein the Zn content in the Fe-Al alloy layer is 50% by mass or less .

  (4) The hot-dip plated steel material excellent in plating appearance, plating adhesion and workability according to (1) or (2), wherein the Zn content in the Fe-Al alloy layer is 10% by mass or less .

  (5) The plating appearance, plating adhesion, and workability according to any one of (1) to (4), wherein the plating layer further contains Si in an amount of 0.01% to 2% by mass% Excellent hot-dip galvanized steel.

  (6) The plating appearance according to any one of (1) to (5), wherein the plating layer further contains Cr in an amount of 0.01% to 1% by mass%, Hot-dip galvanized steel with excellent workability.

  (7) After the precipitation of Cu and Sn on the surface of the steel material, the steel material is Al: 8% or more and 60% or less, Mg: 1% or more and 10% or less in mass%, and the balance consists of Zn and inevitable impurities. A method for producing a hot-dip plated steel material excellent in plating appearance, plating adhesion, and workability, characterized by being immersed in a hot-dip plating bath.

(8) The total amount of substitutional precipitation of Cu and Sn is 0.1 g / m ² or more and 10 g / m ² or less, and Sn in the substitutional precipitate is 1% or more and 30% or less by mass%. (7) The method for producing a hot-dip plated steel material having excellent plating appearance, plating adhesion, and workability.

  (9) Melting excellent in plating appearance, plating adhesion, and workability according to (7) or (8), characterized in that a sulfate of Cu and Sn is used in the step of substitutional precipitation of Cu and Sn. Manufacturing method of plated steel.

  (10) The plating appearance and plating adhesion described in any one of (7) to (9) above, wherein the hot dipping bath further contains Si in an amount of 0.01% to 2% by mass. The manufacturing method of hot dipped galvanized steel with excellent workability.

(11) The plating appearance and plating adhesion according to any one of (7) to (10), wherein the molten plating bath further contains Cr in an amount of 0.01% to 1% by mass. The manufacturing method of hot dipped galvanized steel with excellent workability.
It is.

  The present invention can provide hot-dip galvanized-aluminum-magnesium alloy plated steel materials having excellent plating appearance, plating adhesion, and workability in various shapes regardless of large-scale equipment.

  Details of the present invention will be described below. The following “%” means “mass%” unless otherwise specified.

  First, the iron-aluminum alloy layer defined in the present invention will be defined.

  FIG. 1 shows a cross-sectional observation result in the steel material of the present invention. A black portion can be observed at the interface between the plating layer and the ground iron. This black part is an iron-aluminum alloy layer, which can be easily identified by elemental analysis such as EPMA or SEM-EDX. In the case of plating without using a reduction furnace, the surface of the steel sheet is not sufficiently cleaned, and the steel material and the plating must react appropriately in order to ensure adhesion. As a result of the reaction, an iron-aluminum alloy layer is formed. In order to ensure adhesion, an alloy layer having a thickness of at least 0.1 μm is required. On the other hand, if this alloy layer is too thick, it adversely affects workability, so the upper limit of the thickness is set to 5.0 μm. This iron-aluminum alloy layer is also produced by the two-step plating method. In this case, the iron-aluminum alloy layer is formed and grown by the subsequent diffusion of aluminum into the zinc-iron alloy layer, so that the alloy layer contains 50% or more of zinc, and the composition of the alloy layer Is inhomogeneous and tends to be inferior in workability. In contrast, the iron-aluminum alloy layer of the present invention has a zinc content of 50% or less because the base iron and aluminum in the bath react directly. Moreover, the homogeneity of the composition of the alloy layer is also good. A lower zinc content in the iron-aluminum alloy layer is advantageous for workability, and the zinc content in the alloy layer is preferably 10% or less. The amount of zinc in this alloy layer can be analyzed by EPMA.

The plating bath composition defined in the present invention is Al: 8% or more and 60% or less, Mg: 1% or more and 10% or less, the balance is composed of Zn and inevitable impurities, Si: 0.01% or more and 2% or less as required Cr: 0.01% or more and 1% or less. The amount of plating is not particularly specified, but it is preferably 50 g / m ² or more and 500 g / m ² or less per side. Al contributes to the improvement of corrosion resistance, but if it is less than 8%, the effect is not sufficient. Further, as the Al amount increases, the melting point increases and workability decreases, so 60% was made the upper limit. Mg also contributes to improving the corrosion resistance, but if it is less than 1%, the effect is not sufficient. If it exceeds 10%, the effect becomes saturated and dross generation becomes violent, which is not economical. Si forms an alloy with Mg and contributes to further improvement of corrosion resistance. If it is less than 0.01%, the function is not exhibited. Since the effect is saturated when it exceeds 2%, 2% was made the upper limit. Cr has the effect of improving the corrosion resistance of the plating layer. If it is less than 0.01%, the function is not exhibited. The effect is saturated when it exceeds 1%, so 1% was made the upper limit.

The Cl existing in the plating layer will be described. Cl in chloride used for flux treatment, etc., in the case of Zn-Al-Mg plating, reacts with Mg in the plating layer-base metal interface, plating layer, or plating layer surface to form a compound. This compound often causes deterioration of the plating appearance, adhesion, and corrosion resistance. If the amount of Cl is 1 g / m ² or less, it does not affect the deterioration of the appearance or the adhesiveness, so it is important that the amount of Cl is 1 g / m ² or less.

Next, Cu-Sn substitutional precipitation will be described. In displacement precipitation, a metal element that is electrochemically more noble than Fe is replaced by Fe and deposited on the surface. The Cu—Sn substitution precipitation in the present invention can be formed by immersing a steel material in an aqueous solution containing Cu ²⁺ and Sn ²⁺ for 10 seconds or more. If the aqueous solution contains the above ions, Cu-Sn substitutional precipitation can be formed, and it is desirable to use sulfate or chloride. In the case of sulfate, an aqueous solution in which copper sulfate pentahydrate and tin sulfate are dissolved in water and sulfuric acid is added is used as a substitution precipitation bath. Copper sulfate pentahydrate is suitably in the range of 0.1 g / L to 100 g / L, tin sulfate in the range of 1.0 g / L to 100 g / L, and sulfuric acid in the range of 1.0 g / L to 50 g / L. In the case of chloride, dissolve copper chloride dihydrate and tin chloride in water and add hydrochloric acid. The appropriate range is 1.0 g / L to 100 g / L for copper chloride dihydrate, 1.0 g / L to 100 g / L for tin chloride, and 1.0 g / L to 50 g / L for hydrochloric acid. Among them, it is industrially most desirable to use a sulfate having the highest aqueous solution stability and little deterioration with time. There is no need to raise the temperature of the substitutional precipitation bath, and precipitation can be performed without any problem at room temperature. The predetermined deposition amount is usually obtained with an immersion time of about 10 seconds. Even if it is immersed for a long time, there is no particular problem, but since the amount of precipitation is saturated in about 60 minutes, there is not much meaning beyond this.

The effect of Cu-Sn substitution precipitation and the appropriate amount and ratio will be described. Cu has a protective effect on the surface before plating. In particular, it is effective for preventing oxidation immediately before entering the plating bath. Sn dissolves easily in the plating bath, promotes the reaction between the plating bath and the ground iron, and contributes to ensuring adhesion. Although Sn has a low melting point, it has a high boiling point and has a reaction promoting effect. Cu alone has no reaction-promoting effect, and Sn alone has a low antioxidant effect. By depositing both at the same time, it is possible to obtain good plating. When the Sn amount is less than 1% of the substitutional precipitation amount, the effect of promoting the reaction cannot be obtained. If it exceeds 30%, the oxidation-preventing effect is lowered, so that the plating appearance is deteriorated. If the amount of substitutional precipitation is less than 0.1 g / m ² , no effect is observed. Although there is no particular upper limit for the amount of precipitation, the effect is saturated at an amount exceeding 10 g / m ² and is not economical, so 10 g / m ² is the upper limit.

  After precipitation by substitution, it is washed with water or dried as it is. Drying is preferably performed by blowing dry air at room temperature with a blower or the like. After drying, it is immersed in a plating bath of the desired plating composition, taken out after a few seconds to several minutes depending on the shape of the steel material, and after adjusting the amount of plating, cooling and forming the plating, manufacturing the plated steel material of the present invention can do.

  The present invention can be applied to steel materials of any shape, but is most effective particularly for thick steel plates, steel pipes, wire rods, shaped steels, or steel products such as bolts and nuts.

  Next, the effects of the present invention will be specifically described with reference to examples.

(Example 1)
A 0.8 mm thick SPCC (JIS G3141) was degreased and pickled, and then pretreated under the conditions shown below.
<Pretreatment conditions>
Condition 1: ZnCl ₂ (150 g / L), NaCl (50 g / L), SnCl ₂ (10 g / L), HCl (10 g / L) in aqueous solution (temperature 70 ° C) for 10 seconds, then 150 ° C for 5 minutes dry.
Condition 2: After being immersed in an aqueous solution (25 ° C) of CuSO ₄ · 5H ₂ O (2g / L) and H ₂ SO ₄ (30g / L) for 1 minute, blow dry with a blower. Substitution precipitation amount: Cu = 1.1 g / m ² .
Condition 3: Submerged in an aqueous solution (25 ° C) of CuCl ₂ · 2H ₂ O (3.2 g / L), SnCl ₂ (5.0 g / L), HCl (8 g / L) for 1 minute, and then blown dry with a blower. Substitution precipitation amount: Cu = 1.0 g / m ² , Sn = 0.2 g / m ² .
Condition _{4: CuSO 4 · 5H 2 O} (2g / L), SnSO 4 (5.5g / L), after 1 minute immersion in _{H 2 SO 4 (30g / L} ) of an aqueous solution (25 ° C.), is blown dry with a blower . Substitution precipitation amount: Cu = 0.8 g / m ² , Sn = 0.2 g / m ² .

<Plating conditions>
After the pretreatment, Al was 11% by mass, Mg was 3% by mass, and the remainder was dipped in a plating bath consisting of Zn and inevitable impurities for 1 minute to form a plating. After plating, the amount of plating was adjusted to 100 g / m ² per side by gas wiping. Moreover, the peeling test of plating was performed on some test pieces, and it was confirmed that there was no change in bath components.

<Evaluation method>
The test material after plating was evaluated for plating property by appearance observation. The surface was visually marked with no unplating or foreign matter adhered, and the one with x.

  The thickness of the Fe-Al alloy layer was evaluated by observing the cross section and examining the element distribution by EPMA analysis.

  The amount of Cl was identified by dissolving the plating with 10% nitric acid and analyzing the specimen by spectrophotometry.

  The adhesion and workability were evaluated by cutting the test piece into 100 mm × 10 mm and performing a 90 ° bending test with a bending radius of 0.8 mm using a press. The evaluation criteria are as follows. Δ or more was judged good.

◎: No cracking on the surface, no peeling ○: Cracking and peeling of 1% or less by area ratio in the bent part △: Cracking and peeling of 1% or more and less than 5% in the bent part
×: 5% or more of cracks and peeling at the bent part The results are shown in Table 1.

  From Table 1, it can be seen that all of the examples of the present invention are excellent in appearance, adhesion and workability. On the other hand, in the comparative example, the appearance and the adhesion / workability are not compatible.

(Example 2)
A 0.8 mm thick SPCC (JIS G3141) was degreased and pickled, and then pretreated under the conditions shown below.
<Pretreatment conditions>
Condition 1: ZnCl ₂ (150 g / L), NaCl (50 g / L), SnCl ₂ (10 g / L), HCl (10 g / L) in aqueous solution (temperature 70 ° C) for 10 seconds, then 150 ° C for 5 minutes dry.
Condition _{2: CuSO 4 · 5H 2 O} (2g / L), SnSO 4 (5.5g / L), H 2 SO 4 (30g / L) of an aqueous solution (25 ° C.) to 60 minutes after immersion, is blown dry with a blower . Substitution precipitation amount: Cu = 0.8 g / m ² , Sn = 0.2 g / m ² .

<Plating conditions>
After the pretreatment, plating was formed by dipping for 1 minute in a Zn—Al—Mg—Si plating bath having the bath composition shown in Table 2 and pulling it up. The plating amount was adjusted to 135 g / m ² per side by gas wiping. Moreover, the peeling test of plating was performed on some test pieces, and it was confirmed that there was no change in bath components.

<Evaluation method>
The test material after plating was evaluated for plating property by appearance observation. The case where there was no non-plating or foreign matter adhesion on the surface visually was marked with ◯, and the case where there was no mark.

  The thickness of the Fe-Al alloy layer was evaluated by observing the cross section and examining the element distribution by EPMA analysis.

  The amount of Cl was identified by dissolving the plating with 10% nitric acid and analyzing the specimen by spectrophotometry.

  Adhesion and workability were evaluated by cutting a test piece into 100 mm × 10 mm and performing a 90 ° bending test with a bending radius of 0.8 mm using a press. The evaluation criteria are as follows. Δ or more was judged good.

◎: No cracking on the surface, no peeling ○: Cracking and peeling of 1% or less by area ratio in the bent part △: Cracking and peeling of 1% or more and less than 5% in the bent part
×: 5% or more of cracks and peeling at the bent part The results are shown in Table 2.

  From Table 2, it can be seen that all of the examples of the present invention are excellent in appearance, adhesion and workability. On the other hand, in the comparative example, the appearance and the adhesion / workability are not compatible.

(Example 3)
A 0.8 mm thick SPCC (JIS G3141) was degreased and pickled, and then pretreated under the conditions shown below.
<Pretreatment conditions>
Condition 1: ZnCl ₂ (150 g / L), NaCl (50 g / L), SnCl ₂ (10 g / L), HCl (10 g / L) in aqueous solution (temperature 70 ° C) for 10 seconds, then 150 ° C for 5 minutes dry.
Condition _{2: CuSO 4 · 5H 2 O} (2g / L), SnSO 4 (5.5g / L), H 2 SO 4 (30g / L) of an aqueous solution (25 ° C.) to 60 minutes after immersion, is blown dry with a blower . Substitution precipitation amount: Cu = 0.8 g / m ² , Sn = 0.2 g / m ² .

<Plating conditions>
After the pretreatment, the plate was immersed in a Zn—Al—Mg—Cr plating bath having a bath composition shown in Table 3 for 1 minute to form a plating. The plating amount was adjusted to 135 g / m ² per side by gas wiping. Moreover, the peeling test of plating was performed on some test pieces, and it was confirmed that there was no change in bath components.

<Evaluation method>
The test material after plating was evaluated for plating property by appearance observation. The case where there was no non-plating or foreign matter adhesion on the surface visually was marked with ◯, and the case where there was no mark.

  The thickness of the Fe-Al alloy layer was evaluated by observing the cross section and examining the element distribution by EPMA analysis.

  The amount of Cl was identified by dissolving the plating with 10% nitric acid and analyzing the specimen by spectrophotometry.

  Adhesion and workability were evaluated by cutting a test piece into 100 mm × 10 mm and performing a 90 ° bending test with a bending radius of 0.8 mm using a press. The evaluation criteria are as follows. Δ or more was judged good.

◎: No cracking on the surface, no peeling ○: Cracking and peeling of 1% or less by area ratio in the bent part △: Cracking and peeling of 1% or more and less than 5% in the bent part
×: 5% or more of cracks and peeling at the bent part The results are shown in Table 3.

  From Table 3, it can be seen that all of the inventive examples are excellent in appearance, adhesion and workability. On the other hand, in the comparative example, the appearance and the adhesion / workability are not compatible.

(Example 4)
A 0.8 mm thick SPCC (JIS G3141) was degreased and pickled, and then pretreated under the conditions shown below.
<Pretreatment conditions>
Condition 1: After immersion in an aqueous solution of NH ₄ Cl (150 g / L) (temperature 70 ° C.) for 10 seconds, after drying at 150 ° C. for 5 minutes, Zn plating is performed by immersion in a molten Zn bath for 10 seconds. Zn plating amount = 60 g / m ² and 120 g / m ² .
Condition _{2: CuSO 4 · 5H 2 O} (2g / L), SnSO 4 (5.5g / L), H 2 SO 4 (30g / L) of an aqueous solution (25 ° C.) to 60 minutes after immersion, is blown dry with a blower . Substitution precipitation amount: Cu = 0.8 g / m ² , Sn = 0.2 g / m ² .

<Plating conditions>
After the pretreatment, Al was 11% by mass, Mg was 3% by mass, and the remainder was dipped in a plating bath consisting of Zn and inevitable impurities for 1 minute to form a plating. After plating, the amount of plating was adjusted to 100 g / m ² per side by gas wiping. Moreover, the peeling test of plating was performed on some test pieces, and it was confirmed that there was no change in bath components.

<Evaluation method>
The thickness and composition of the Fe-Al alloy layer were evaluated by observing the cross section and examining the element distribution by EPMA analysis.

  Adhesion and workability were evaluated by cutting a test piece into 100 mm × 10 mm and performing a 90 ° bending test with a bending radius of 0.8 mm using a press. The evaluation criteria are as follows. Δ or more was judged good.

◎: No cracking on the surface, no peeling ○: Cracking and peeling of 1% or less by area ratio in the bent part △: Cracking and peeling of 1% or more and less than 5% in the bent part
×: 5% or more of cracks and peeling at the bent part The results are shown in Table 4.

  From Table 4, it can be seen that all of the examples of the present invention are excellent in appearance, adhesion and workability. On the other hand, in the comparative example, the appearance and the adhesion / workability are not compatible.

(Example 5)
A 0.8 mm thick SPCC (JIS G3141) was degreased and pickled, and then pretreated under the conditions shown below.
<Pretreatment conditions>
Condition 1: ZnCl ₂ (150 g / L), NaCl (50 g / L), SnCl ₂ (10 g / L), HCl (10 g / L) in aqueous solution (temperature 70 ° C) for 10 seconds, then 150 ° C for 5 minutes dry.
Condition 2: CuCl ₂ · 2H ₂ O (3.2 g / L), SnCl ₂ (5.0 g / L), and an aqueous solution of HCl (25 ° C) are immersed in air and dried with a blower. The displacement precipitation amount was changed by changing the amount of HCl and the immersion time.

<Plating conditions>
After the pretreatment, Al was 11% by mass, Mg was 3% by mass, and the remainder was immersed in a plating bath (bath temperature: 470 ° C.) consisting of Zn and inevitable impurities for 1 minute to form a plating. The plating amount was adjusted to 100 g / m ² per side by gas wiping. Moreover, the peeling test of plating was performed on some test pieces, and it was confirmed that there was no change in bath components.

<Evaluation method>
The test material after plating was evaluated for plating property by appearance observation. The case where there was no unplating or foreign matter adhesion on the surface visually was marked with ○, the case where the area ratio was 5% or less, Δ, and the case where there was 5% or more, x

  The thickness of the Fe-Al alloy layer was evaluated by observing the cross section and examining the element distribution by EPMA analysis.

  The amount of Cl was identified by dissolving the plating with 10% nitric acid and analyzing the specimen by spectrophotometry.

  Adhesion and workability were evaluated by cutting a test piece into 100 mm × 10 mm and performing a 90 ° bending test with a bending radius of 0.8 mm using a press. The evaluation criteria are as follows. Δ or more was judged good.

◎: No cracking on the surface, no peeling ○: Cracking and peeling of 1% or less by area ratio in the bent part △: Cracking and peeling of 1% or more and less than 5% in the bent part
×: 5% or more of cracks and detachment at the bent portion The results are shown in Table 5.

  From Table 5, it can be seen that all of the inventive examples are excellent in appearance, adhesion and workability. On the other hand, in the comparative example, the appearance and the adhesion / workability are not compatible.

(Example 6)
A 0.8 mm thick SPCC (JIS G3141) was degreased and pickled, and then pretreated under the conditions shown below.
<Pretreatment conditions>
Condition 1: ZnCl ₂ (150 g / L), NaCl (50 g / L), SnCl ₂ (10 g / L), HCl (10 g / L) aqueous solution (temperature 70 ° C) was prepared and left in the air for a predetermined time. After being immersed in the pretreatment liquid for 10 seconds, it is dried at 150 ° C. for 5 minutes.
Condition 2: CuCl ₂ · 2H ₂ O (3.2 g / L), SnCl ₂ (5.0 g / L), HCl aqueous solution (25 ° C) was prepared, and then left for 1 minute in the pretreatment solution left in the atmosphere for 1 minute. After immersion, blow dry with a blower.
Condition _{3: CuSO 4 · 5H 2 O} (2g / L), after creating a SnSO ₄ (5.5g / L), an aqueous solution of _{H 2 SO 4 (30g / L} ) (25 ℃), left at Jo Tokoro time in the air After being immersed in the pretreatment liquid for 1 minute, it is blown dry with a blower.

  The standing time is the standing time of the treatment liquid from the working solution to the treatment, and 0 indicates that an experiment was performed immediately after the creation.

<Plating conditions>
After the pretreatment, Al was 11% by mass, Mg was 3% by mass, and the remainder was immersed in a plating bath (bath temperature: 470 ° C.) consisting of Zn and inevitable impurities for 1 minute to form a plating. The plating amount was adjusted to 100 g / m ² per side by gas wiping. Moreover, the peeling test of plating was performed on some test pieces, and it was confirmed that there was no change in bath components.

<Evaluation method>
The test material after plating was evaluated for plating property by appearance observation. The case where there was no non-plating or foreign matter adhesion on the surface visually was marked with ◯, and the case where there was no mark.

  The thickness of the Fe-Al alloy layer was evaluated by observing the cross section and examining the element distribution by EPMA analysis.

  Adhesion and workability were evaluated by cutting a test piece into 100 mm × 10 mm and performing a 90 ° bending test with a bending radius of 0.8 mm using a press. The evaluation criteria are as follows. Δ or more was judged good.

◎: No cracking on the surface, no peeling ○: Cracking and peeling of 1% or less by area ratio in the bent part △: Cracking and peeling of 1% or more and less than 5% in the bent part
×: 5% or more of cracks and detachment at the bent portion The results are shown in Table 6.

  From Table 6, it can be seen that all of the examples of the present invention are excellent in appearance, adhesion and workability. In addition, the difference in time change is well understood. On the other hand, in the comparative example, the appearance and the adhesion / workability are not compatible.

The figure which shows the cross-section observation result of the plated steel material of this invention.

Claims (11)

  The composition of the plating layer is mass%, Al: 8% or more and 60% or less, Mg: 1% or more and 10% or less, the balance consists of Zn and inevitable impurities, and the average thickness is 0.1μm at the plating layer-base metal interface. A hot-dip plated steel material excellent in plating appearance, plating adhesion, and workability, characterized by having a Fe-Al alloy layer of 5.0 μm or less. The plating appearance, plating adhesion, and workability according to claim 1, wherein the amount of Cl in the Fe-Al alloy layer at the plating layer-base metal interface or in the plating layer is 1 g / m ² or less. Excellent hot-dip galvanized steel.   3. The hot-dip plated steel material excellent in plating appearance, plating adhesion, and workability according to claim 1, wherein the amount of Zn in the Fe—Al alloy layer is 50% by mass or less.   3. The hot-dip galvanized steel material according to claim 1, wherein the Zn content in the Fe—Al alloy layer is 10% by mass or less.   The plating layer according to any one of claims 1 to 4, wherein Si is further contained by 0.01% or more and 2% or less by mass% in the plating layer, and is excellent in plating appearance, plating adhesion, and workability. Hot dipped steel.   In the plating layer, further containing 0.01% or more and 1% or less Cr by mass%, excellent plating appearance, plating adhesion, and workability according to any one of claims 1 to 5 Hot dipped steel.   After substituting and precipitating Cu and Sn on the surface of the steel material, the steel material is, by mass%, Al: 8% or more and 60% or less, Mg: 1% or more and 10% or less, the remainder being hot-dip plated of Zn and inevitable impurities. A method for producing a hot-dip plated steel material excellent in plating appearance, plating adhesion, and workability, characterized by being immersed in a bath. The total amount of substitutional precipitation of Cu and Sn is 0.1 g / m ² or more and 10 g / m ² or less, and Sn in the substitutional precipitate is 1% or more and 30% or less by mass%. 7. A method for producing a hot-dip plated steel material having excellent plating appearance, plating adhesion, and workability.   9. The method for producing a hot-dip galvanized steel material excellent in plating appearance, plating adhesion, and workability according to claim 7 or 8, wherein a sulfate of Cu and Sn is used in the step of precipitation of Cu and Sn. .   10. The plating appearance, plating adhesion, and workability of any one of claims 7 to 9, further comprising 0.01% to 2% by mass of Si in the hot dipping bath. Manufacturing method of hot-dip galvanized steel.   The plating appearance, plating adhesion, and workability according to any one of claims 7 to 10, further comprising 0.01% to 1% by mass of Cr in the hot dipping bath. Manufacturing method of hot-dip galvanized steel.