JPH04304384A - Production of aluminum sheet having superior press moldability, chemical treatability and weldability - Google Patents

Abstract

PURPOSE:To produce an Al, sheet having superior press moldability chemical treatability and weldability. CONSTITUTION:The surface of an Al sheet is washed and an inorg. coating layer maintaining coating independently of deformation and having adhesion preventing function and rolling lubricative function between dies and a sheet is formed on the washed surface by 2-2,000 mg/m<2> or a ZnO-based oxide film is further formed under the coating layer. The press moldability and chemical treatability of the Al sheet are improved and the weldability can also be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing aluminum plates having excellent press formability, chemical conversion treatment properties, and weldability.

0002

2. Description of the Related Art Recently, attempts have been made to use aluminum plates (hereinafter referred to as "Al plates") for automobile outer panels and the like in order to reduce the weight of automobiles. Such Al plates are inferior to steel plates in press formability, chemical conversion treatment properties, and weldability, and if used also as plated steel plates in the processing line, Al plates (A
A part of l) is eluted and mixed into the processing solution in the line, which has disadvantages such as having an adverse effect on the processing of plated steel sheets.

0003

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an aluminum plate having excellent press formability, chemical conversion treatment properties, and weldability.

0004

[Means for Solving the Problems] The gist of the present invention is as follows. (1) The aluminum plate is cleaned and its surface is equipped with an anti-adhesion function that adheres closely to the aluminum plate surface during press forming and maintains the coating by following its deformation, and a rolling lubrication function between the mold and the plate. Inorganic coating layer 2 to 1000
A method for producing an aluminum plate with excellent press formability, chemical conversion treatment property, and weldability, characterized by forming a metal plate with a total weight of 1.0 mg/m2 (as a metal).

(2) Cleaning the surface of the aluminum plate,
An oxide film with a ZnO content of 30 to 3,000 mg/m2 is formed on the surface, and the upper layer of the oxide film has an anti-adhesion function that adheres to the surface during press molding and maintains the coating by following its deformation. Press formability and chemical conversion treatment properties characterized by forming an inorganic coating layer of 2 to 1000 mg/m2 (as metal) that also has a rolling lubrication function between plates;
A method for manufacturing aluminum plates with excellent weldability.

(3) The aluminum plate is washed and zinc-based plating is applied to the surface thereof, and the upper layer has an anti-adhesion function that adheres to the surface of the plating layer during press molding and maintains the coating by following its deformation; Inorganic coating layer with rolling lubrication function between the mold and the plating layer 2 to 1000 mg/m2
A method for producing an aluminum plate with excellent press formability, chemical conversion treatment properties, and weldability, characterized by forming (as a metal).

(4) Wash the aluminum plate, apply zinc plating to its surface, and coat the top layer with ZnO of 30%.
An oxide film of ~3000mg/m2 is generated, and the upper layer of the oxide film has an anti-adhesion function that adheres to the surface of the plating layer during press molding and maintains the coating by following its deformation, and a rolling lubrication function between the mold and the plating layer. Inorganic coating layer 2 with functions
1000 mg/m2 (as metal) A method for producing an aluminum plate having excellent press formability, chemical conversion treatment property, and weldability.

(5) The film having anti-adhesion function is M
n, Mo, Co, Ni, Ca, Cr, V, W, Ti, A
Mainly composed of one or more metal oxides and/or hydroxides such as Zn and Zn, and the film amount is 1 to 500 mg/m
2 (as a metal), and the film having a rolling lubricating function is mainly composed of one or two types of oxygen acids such as P and B and/or one or more types of oxide colloids of Si, Al, and Ti, The method for producing an aluminum plate having excellent press formability, chemical conversion treatment properties, and weldability according to items 1, 2, 3, and 4 above, wherein the coating amount is 1 to 500 mg/m2 (as metal).

The present invention will be explained in detail below. It is preferable to wash and remove the oxide film present on the surface of the Al plate (0.6 to 5.0 mm) before performing the treatment of the present invention. For example, N
The Al2 O3 based oxide film can be removed by immersion or electrolytic treatment in an aOH 1-5% aqueous solution. In order to clean the Al alloy plate, for example, immersion in an aqueous solution of a weak alkaline cleaning agent based on sodium phosphate or electrolytic treatment can be added. Pickling can be added if necessary. After washing, it is washed with water, and then subjected to an oxide forming treatment that has excellent press formability, chemical conversion treatment properties, and weldability, as described below.

[0010] A film having an adhesion prevention function mainly composed of 1 to 500 mg/m2 (as metal) of metal oxide and/or hydroxide on the surface of the Al plate;
00 mg/m2 (as metal) of oxyacid and/or metal oxide colloid to form a film having a rolling lubrication function. This film has an amorphous structure mainly composed of metal-oxygen bonds, and the film structure with anti-adhesion function and the film structure with rolling lubrication function coexist with each other through oxygen bonds. However, it cannot be separated as a layered structure, but can be identified as a function during press molding.

[0011] During press working, the amorphous metal oxygen bond structure follows the newly formed surface of the deformed Al and forms A via oxygen bonds.
1 and prevents Al from adhering to the mold. On the other hand, part of the film is destroyed and becomes powder, which performs a rolling lubrication function on the sliding surface with the mold, which is the reason why it shows revolutionary lubricity despite being an extremely thin inorganic film. Conceivable.

[0012] As an example, 8mg/m2 of Mn was applied to an Al plate,
The structure of a film formed of an amorphous oxide film containing 5 mg/m2 of P will be described. Although the thin surface film is not visible at all, line analysis using an electron probe microanalyzer confirms the presence of Mn and P as shown in FIG. This A
Figure 2 shows the surface condition of the plate under an electron microscope after it was subjected to a drawbeat sliding test.The surface was rubbed by the mold bead and no trace of the original surface profile remained. In an untreated Al plate, the conditions would cause the plate to break, but when the film of the present invention is formed, the coefficient of friction is 0.17, maintaining a good lubrication state. Figure 3 shows an electron probe microanalyzer line analysis chart after the drawbead sliding test. Although the amounts of both Mn and P in the film have decreased compared to before the sliding test, there are no breaks in the film and they remain almost uniformly. Even if a new Al surface appears due to sliding, it can be understood that the film is being reorganized. Here, when paying attention to the Mn/P ratio, it can be seen that P is relatively reduced compared to before sliding. It is thought that P in the film was selectively destroyed and turned into powder, contributing to rolling lubrication.

[0013] As a film having an adhesion prevention function, Mn
, Mo, Co, Ni, Ca, Cr, V, W, Ti, Al
, Zn, and other metal oxides and/or hydroxides, and has a rolling lubrication function.
Alternatively, it is considered that a structure in which an oxide colloid made of Si, Al, Ti, etc. is bonded to the above-mentioned amorphous structure via an oxygen bond functions mainly. However, since the film formation reaction takes advantage of the pH increase at the interface from an aqueous solution to precipitate as a whole, it is not possible to strictly select the function; some parts of the film have an anti-adhesion function, while others It is more reasonable to understand that a part of it has a rolling lubrication function.

[0014] All of the above-mentioned coating constituents are inorganic substances, do not apply any load to the degreasing solution after pressing, and are dissolved by lowering the pH during chemical conversion treatment, so that a chemical conversion coating can be normally formed. The film can be formed reliably by immersing the Al plate in an acidic aqueous solution containing a film component having an adhesion prevention function and a film component having a rolling lubrication function, or by cathodic electrolytic treatment. In the immersion treatment, when Al dissolves, the pH at the interface increases, and as a result, film components precipitate as hydroxides or oxides. Dissolved Al and other alloy components are also mixed into the film. An oxidation-reduction reaction can also be used, and the dissolution of Al is an oxidation reaction, and correspondingly, oxidized metal ions are precipitated as insoluble reduced oxides. Oxygen acid anions such as phosphoric acid as well as oxidized colloids can be precipitated by increasing the pH at the interface. The cathodic electrolytic treatment has the effect of promoting an increase in pH at the interface. Attempts to control the interfacial reaction by adjusting the thickness of the water film, such as by spraying or coating, can also be applied to the present invention.

[0015] The appropriate amount of the film having both adhesion prevention function and rolling lubrication function is 2 to 1000 mg/m2 based on the metal. If it is less than 2 mg/m2, no clear lubricating effect can be perceived, and if it exceeds 1000 mg/m2, there is a risk that the film will peel off in lumps, and the formation of the chemical conversion film may be adversely affected, which is not preferable. As a form of forming a coating that has both adhesion prevention function and rolling lubrication function,
When forming an amorphous structure film mainly composed of metal oxides and/or hydroxides and an oxyacid and/or metal oxide colloid film, the appropriate amount of the film is 1 to 500 mg/m2 of both metals. It is. 1mg/m2
If the amount is less than 500mg/
If it exceeds m2, there is a risk that the film will peel off in chunks.
Further, it is not preferable because it may have an adverse effect on the formation of a chemical conversion film.

[0016] The amorphous structure film mainly composed of metal oxides and/or hydroxides and the oxyacid and/or metal oxide colloid film are deposited by a chemical reaction at the interface such as the above-mentioned immersion method or cathodic electrolytic treatment method. In some cases, the coating is generally produced as a mixed coating. However, the anti-adhesion function of Al
It is also possible to form a film in a functionally graded manner, with a stronger rolling lubrication function on the surface of the film. By doing this, there is no noticeable effect on the lubrication performance expressed by the friction coefficient, but it does reduce the occurrence of galling when high surface pressure is applied to local areas of the Al plate, such as when pressing difficult-to-form parts. This has the effect of improving the critical surface pressure. Since the so-called press forming load range can be widened, mold design becomes easier in practical use, and pressing work becomes stable, so great benefits can be enjoyed.

The method for producing a functionally graded film takes advantage of the differences in solubility products of metal oxides, etc., and adjusts the ion concentration of each component, flow rate, solution temperature, current density in the case of electrolytic treatment, etc. , consisting of controlling the ion concentration at the interface. For example, in the case of a Mn, P-based film, when potassium permanganate, phosphoric acid, and sulfuric acid are mixed in the treatment solution and reacted with the Al plate, first, as Al dissolves, Mn oxidizes, which has the smallest solubility product. Things precipitate out. The interfacial pH at this time
does not rise rapidly due to the presence of sulfuric acid, and then Mn or Al phosphate precipitates with a delay. The glow discharge spectroscopic analysis in the thickness direction of the film thus formed is shown in FIG.
It can be seen that the film is a functionally graded film in which Mn is rich in the surface layer and Mn is rich in the bottom layer. This figure shows a total of Mn8 on an Al plate.
This is a spectroscopic analysis diagram in the thickness direction of a functionally graded amorphous oxide film of P5mg/m2 and P5mg/m2.A film thickness of 7 nm and a sputtering time of about 0.4 seconds or more indicate Al. .

Next, as a method for forming the above-mentioned oxide film, for example, calcium nitrate, nickel nitrate, cobalt nitrate, and ammonium molybdate each have a concentration of 50 to 8
Phosphoric acid: 5 to 60 g/l is added to 00 g/l, and the Al plate is immersed in an aqueous solution containing an etching aid (sulfuric acid, etc.), or the aqueous solution is sprayed, or the Al plate is electrolyzed in an aqueous solution using the Al plate as a cathode. A desired oxide film can be produced by the treatment.

In addition to improving press formability and chemical conversion treatment properties, in order to improve weldability, for example, 200 to 800 g/l of zinc nitrate must be added before forming the above-mentioned inorganic coating layer. Contact such as immersion or spraying in an aqueous solution for 0.1 to 10 seconds, or electricity amount of 5 to 80 C/dm
2. 20 to 3000 mg/m2 (in ZnO amount) of ZnO-based oxide by cathodic electrolytic treatment for 0.1 to 10 seconds
By generating this, spot weldability can also be reliably improved.

That is, ZnO is placed between the electrode tip and the Al plate.
When the main oxide is present, this oxide layer has the effect of preventing selective alloying of the copper (electrode) and the Al plate, and can delay wear of the electrode tip. In other words, the oxide layer breaks the contact between the electrode tip and the Al plate, prevents chip welding due to the formation of an alloy layer, and also prevents the Zn
The O-based oxide adheres to the tip of the tip and forms a protective film. Even if welding continues, the thickness and shape of the protective film do not change significantly, allowing for good welding at all times and preventing damage to the chip. It is.

[0021] When such an oxide is formed, the above-mentioned inorganic coating layer formed on the oxide can be firmly attached (formed). Like this A
By generating oxides on the surface, in addition to the above-mentioned advantages, for example, even if plated steel sheets and Al sheets are processed together on an automobile manufacturing line, a part of the Al will not be leached into the processing solution, so there will be no adverse effects. This is a big advantage.

It is known that Al plates are susceptible to filiform corrosion when coated, and it is effective to apply Zn or Zn alloy plating to the Al surface in order to prevent filiform corrosion. Additionally, if Al dissolves during chemical conversion treatment and contaminates the treatment solution, a healthy phosphate film may not be formed on the surface of the steel sheet being simultaneously treated, so it is effective to cover the surface of the Al sheet with Zn plating. be. However, like the Al surface, the Zn or Zn alloy plated surface is also a surface with poor press formability and weldability.

In such a case, a Zn-based plating layer is formed on the surface of the Al plate, and an inorganic coating layer having both anti-adhesion and rolling lubrication functions is applied to the upper layer of the film in an amount of 2 to 1000 mg/ml.
m2 (as a metal) can be formed to improve press formability and chemical conversion treatment properties. Furthermore, a Zn-based plating layer is formed on the surface of the Al plate, an oxide film with a ZnO content of 30 to 3000 mg/m2 is formed on the upper layer of the film, and the above-mentioned inorganic coating layer is formed on the oxide film upper layer.
(as a metal) to improve press formability, weldability, and chemical conversion treatment properties.

Almost the same conditions as for the Al surface can be applied to the formation of the above-mentioned inorganic coating layer on the Zn or Zn alloy plated surface. Also, Zn on the Zn or Zn alloy plating surface
Almost the same conditions as for the Al surface can be applied to the formation of the O film. Next, as the above-mentioned zinc-based plating method, for example, hot contact plating method, electroplating method, vapor deposition plating method, electroless plating method, etc. can be used, and as for the plating composition, in addition to Zn, Zn-Fe, Zn -Ni, Zn-Al, Zn-Mn
, Zn-Cr, Zn-Ti, Zn-Mg, Zn-P, Z
Materials containing Zn as a main component, such as n-B and Zn-C, can be used.

[0025] The Al plate to which the present invention is applied is Al-Cu based,
It includes Al alloy plates such as Al-Mg type and Al-Mg-Si type, and can also be applied even if other components such as Fe, Mn, Cr, Zn, and Ti are included.

[0026]

[Examples] Next, Examples of the present invention are listed in Tables 1 to 4 along with comparative examples.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

Note 1) The Al plate used has a thickness of 0.8 mm. Note 2) Al plate cleaning was carried out at 10A/1 in NaOH 5% aqueous solution.
By electrolysis of dm2 x 2.0 seconds. Note 3) Zinc plating is Zn alloy for Zn alloy.
Alloy plating consisting of 85% and remaining alloy as indicated, deposited by electroplating.

Note 4) ZnO-based oxides are expressed in terms of ZnO content. This measurement was performed by dissolving the plating layer with a 5% iodine methanol solution, dissolving the extraction residue with a mixed flux (1 part of nitric acid, 3 parts of sodium carbonate), and then dissolving it with hydrochloric acid to determine the amount of zinc by IC.
Measured by P (infrared spectroscopy). Furthermore, it was measured by GDS (glow discharge spectroscopy). Note 5) The generation of ZnO-based oxide is caused by zinc nitrate (Zn(NO)
3) 6H2O) as the main component, add trace amounts of HNO3 and Fe+++ to make a 350g/l aqueous solution,
It was produced by electrolysis using an L plate as a cathode.

Note 6) Press formability (friction coefficient) sample size: 17mm x 300mm,
Pulling speed: 500mm/min, square beat shoulder R: 1
．． 0/3.0mm, sliding length: 200mm, oiling: Nox Last 530F-40 (Parker Kosan Co., Ltd.) with an oiling amount of 1g/m2, and a surface pressure of 100 to 600kgf.
A several-point test was conducted between the two, the pull-out load was measured, and the coefficient of friction was determined from the slope of the surface pressure and pull-out load.

(Rupture limit load ratio) In the above drawbead test, the surface pressure (presser load) at which the pullout load suddenly increases
The value was taken as the fracture surface pressure, and it was determined from the fracture limit load ratio = fracture surface pressure/tensile strength x plate width x plate thickness.

Note 7) The amount of anti-adhesion film and rolling lubrication film is expressed as the amount of metal. Note that the amount of metal eluted and precipitated from the substrate cannot be measured and is therefore not shown. Note 8) For chemical conversion treatment properties, SD5000 (manufactured by Nippon Paint Co., Ltd.) was used as the chemical conversion treatment solution (zinc-phosphoric acid-fluorine treatment bath), and after degreasing and surface conditioning as prescribed, chemical conversion treatment was performed. Chemical conversion treatment films are judged by SEM (secondary electron beam image): ○ if the film is uniformly formed, △ if the film is partially formed, and △ if the film is not formed. It was judged as ×.

Note 9) The welding conditions are as follows. 1) Electrode pressure: 250 kgf 2) Initial pressure: 40 cycles 3) Current application time: 8 cycles 4) Holding time: 2 cycles 5) Welding current: 15 kA 6) Electrode tip shape: Tip diameter 5.0φ (CF type: 7) Electrode tip material: Cu-Cr (commonly used) 8) Electrode tip life end point determination: Maximum number of dots that can ensure a nugget diameter of 4.0 mm at welding current.

Welding was performed by placing two aluminum plates one on top of the other with one side facing up and the other side facing down, and performing continuous welding.

[0038]

Effects of the Invention According to the present invention, it is possible to provide an Al plate that has improved sliding properties in press molding, eliminates dents during molding, and can also be formed with a chemical conversion coating, so the cost is lower than before. It is of high quality, reduces the burden on the user during the process, improves productivity during press forming, and improves weldability, making it extremely useful industrially.

[Brief explanation of drawings]

FIG. 1 is an electron probe microanalyzer line analysis diagram of the surface of an Al plate with an amorphous oxide film formed thereon.

FIG. 2 is a metallographic electron micrograph showing the surface profile of the Al plate shown in FIG. 1 after being subjected to a drawbead sliding test.

FIG. 3 is an electron probe microanalyzer line analysis diagram of the surface of the Al plate shown in FIG. 2;

FIG. 4 is an explanatory view of glow discharge spectroscopic analysis in the thickness direction of an amorphous oxide film formed on the surface of an Al plate in a functionally graded manner.

Claims (5)

[Claims] Claim 1: An anti-adhesion function that cleans the aluminum plate and maintains the coating by adhering to the surface of the aluminum plate during press molding and following its deformation, and a rolling lubrication function between the mold and the plate. Inorganic coating layers 2 to 1 having both
000mg/m2 (as a metal) A method for producing an aluminum plate having excellent press formability, chemical conversion treatment property, and weldability. 2. The surface of the aluminum plate is washed, an oxide film with a ZnO content of 30 to 3000 mg/m2 is formed on the surface, and the upper layer of the oxide film is adhered to the surface during press molding,
It is characterized by forming an inorganic coating layer of 2 to 1000 mg/m2 (as metal) which has both an anti-adhesion function to maintain the coating following the deformation and a rolling lubrication function between the mold and the plate. A method for manufacturing aluminum plates with excellent press formability, chemical conversion treatment properties, and weldability. [Claim 3] An aluminum plate is washed and zinc-based plating is applied to its surface, and the upper layer has an anti-adhesion function that adheres to the surface of the plating layer during press molding and maintains the coating by following its deformation, and a gold plate. Manufacture of an aluminum plate with excellent press formability, chemical conversion treatment property, and weldability, characterized by forming an inorganic coating layer of 2 to 1000 mg/m2 (as metal), which also has a rolling lubrication function between the mold and the plating layer. Method. 4. Wash the aluminum plate, apply zinc plating to the surface, and coat the upper layer with ZnO of 30 to 30%.
00mg/m2 of oxide film, and the upper layer of the oxide film has an anti-adhesion function that adheres to the surface of the plating layer during press molding and maintains the coating by following its deformation, and a rolling lubrication function between the mold and the plating layer. Inorganic coating layer 2 to 100 having
0 mg/m2 (as a metal) A method for producing an aluminum plate having excellent press formability, chemical conversion treatment property, and weldability. [Claim 5] The film having an adhesion prevention function is made of Mn, M
o, Co, Ni, Ca, Cr, V, W, Ti, Al, Z
Mainly composed of one or more metal oxides and/or hydroxides of n, and has a film amount of 1 to 500 mg/m2 (
(as a metal), and the coating having a rolling lubricating function is composed of one or two types of oxygen acids of P and B and/or Si,
Press formability according to claims 1, 2, 3 and 4, which is mainly composed of one or more oxide colloids of Al and Ti, and has a film amount of 1 to 500 mg/m2 (as metal);
A method for manufacturing aluminum plates with excellent chemical conversion treatment and weldability.