JP2017190499A - Black plated member for vehicle and black plated steel sheet for member for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a black plated member for a vehicle and black plated steel sheet for a member for a vehicle capable of obtaining black appearance without coating and having excellent sustainability of black appearance after processing.SOLUTION: There is provided a member for a vehicle using a plated steel sheet as a raw material having a black plated layer which: is formed on the surface of a base steel member; has a molten Al/Mg-containing galvanized layer which contains 0.1 to 22.0 mass% of Al and 0.1 to 10.0 mass% of Mg and in which a black oxide of Zn is distributed in a plating layer; and exhibits black appearance in which the surface of the molten Al/Mg-containing galvanized layer has lightness L* value of 60 or less. There is provided a member for a vehicle which may be a member used for a vehicle including an automobile, for example, a bracket member, an underbody member, a structural member, a protective member, an interior member, an exterior member and a member for a vehicle, irrespective of shape and irrespective of whether the member is used outside or inside a vehicle.SELECTED DRAWING: None

Description

The present invention relates to a vehicle member and a black plated steel sheet for a vehicle member in which the surface of a base steel material is plated with a black appearance.

  Steel members made of steel such as plain steel, structural steel, and high-strength steel are plated or painted. However, steel coated with steel has a tendency to corrode the steel material easily in areas where the paint film is thin or where the paint film is wrinkled. From the above, those plated with high corrosion resistance are mainly used.

However, when the color tone of the appearance is required, there are cases where the plated one is further coated or a coated steel plate is used. Among these, the black appearance is particularly used for a vehicle member and its peripheral hardware because it can give an impression that the strength is high and is difficult to notice in the shade.
However, when it is applied to a plated product, it tends to be expensive. Furthermore, since the base plating is silver white, in order to obtain a black appearance, it is necessary to cover the base color by increasing the thickness of the coating film, which increases the coating cost. In addition, there is a problem that welding cannot be performed because the coating film is thick after coating. In the case of a coated steel plate, the base may be visible at cracks or wrinkled portions of the coating film due to processing or the like, and white may be exhibited.

Japanese Patent No. 5097305

  The present invention has been made in view of the above points, and is a vehicle member on which a black appearance is obtained without painting and a highly corrosion-resistant black plating is provided that is excellent in retaining the black appearance even after processing. And it aims at providing the black plating steel plate for members for vehicles.

The above-mentioned object is that the base steel material and the surface of the base steel material contain Al: 0.1 to 22.0 mass%, Mg: 0.1 to 10.0 mass%, and the black oxide of Zn For vehicles with black plating, which has molten Al and Mg-containing Zn plating layers distributed in the plating layer, and the surface brightness of the molten Al and Mg-containing Zn plating layers is L * value of 60 or less This can be achieved with a member. Here, the black oxide of Zn may be an oxide of Zn derived from a Zn ₂ Mg phase. Here, in the plating layer includes both the surface of the plating layer and the inside of the plating layer. “Oxide” is a generic term for oxides, hydroxides, or both.

The vehicle members of the present invention are, for example, bracket members, suspension members, structural members, protective members, interior members, exterior members, and vehicle body members. Specifically, electrical components, engine surroundings, piping, actuators and other bracket members, arms, suspensions and other suspension members, joists, aggregates, floor boards, members, body frames and other structural members, motors Protective members such as covers, engine covers, sensor covers, sealing caps, hub caps, safety belt hooks, airbag parts, pedals (brake pedals, accelerator pedals, foot brake pedals, clutches), side brakes, sunroofs, etc. Car body parts for inner and outer plates such as parts, carrier parts, wheel caps, exhaust parts, wiper parts, etc., door modules, door sashes, pillars (front pillars, center pillars, rear pillars), bodies, etc. is there. In addition, fuel system members such as fuel supply pipes, AT mission bottom case, oil pan, fuel tank, insulator, mulder member, cable clamp, filler pipe, window regulator, plate, washer, metal fittings, hinge, clip, jack, There are pallets for transportation.
In addition, since the surface of the plating layer of the vehicle member of the present invention has a black appearance, the cationic electrodeposition coating, which has been performed to give a black appearance to the parts in the conventional vehicle member, is performed. It is possible to omit a special chemical conversion process called “Chemical conversion”.

Moreover, the black-plated steel sheet for vehicle members of the present invention has a base steel material and a surface of the base steel material, Al: 0.1 to 22.0 mass%, Mg: 0.1 to 10.0 mass%. And having a molten Al, Mg-containing Zn plating layer in which a black oxide of Zn is distributed in the plating layer,
The lightness of the surface of the molten Al and Mg-containing Zn plating layer is a black plated steel sheet for vehicle members having an L * value of 60 or less.

According to the present invention, a vehicle member and a vehicle member having a black appearance excellent in design without being painted and having a high corrosion resistance black plating excellent in retention of the black appearance after processing are applied. A black-plated steel sheet can be provided.

(Embodiment 1) Vehicle member to which black plating is applied A vehicle member to which black plating of the present invention is applied is a base steel material, a molten Al, Mg-containing Zn plating layer (hereinafter also referred to as “plating layer”). ). The upper layer of the black plating of the present invention may further have an inorganic, organic or inorganic-organic composite chromium-containing or chromium-free film.

In the vehicle member to which the black plating of the present invention is applied, 1) the black oxide of Zn is distributed in the plating layer, and 2) the lightness of the surface of the plating layer is L ^* value of 60 or less (preferably Is 40 or less, more preferably 35 or less). The lightness (L ^* value) of the surface of the plating layer is measured by a spectral reflection measurement method based on JIS K 5600 using a spectral color difference meter. Furthermore, the black oxide of Zn may be an oxide of Zn derived from a Zn ₂ Mg phase.

[Base material]
The kind of base steel material is not particularly limited. For example, steel materials such as low carbon steel, medium carbon steel, high carbon steel, and alloy steel can be used. When good press formability is required, a steel material excellent in workability made of low carbon Ti-added steel, low carbon Nb-added steel, or the like is preferable. Moreover, you may use the high strength steel which added P, Si, Mn, etc. The shape of the base steel material is not limited, and may be a strip steel such as a hot-rolled steel sheet or a cold-rolled steel sheet, or a steel material after being processed after performing shape steel such as H-shaped steel or C-shaped steel or press forming. It may be.

[Molded Al, Mg-containing Zn plating layer]
The plating layer of the present invention includes Al: 0.1 to 22.0% by mass, Mg: 0.1 to 10.0% by mass, and a black oxide is distributed in the plating layer. It is a containing Zn plating layer. When the Al content or the Mg content is smaller than the lower limit of the above range, sufficient corrosion resistance cannot be obtained. On the other hand, when it is larger than the upper limit value, the generation of oxide (dross) is excessive on the surface of the plating bath in the plating step, and a beautiful plating layer cannot be obtained.

  Further, Si in the range of 0.005 to 2.0 mass% may be added to the plating layer in order to improve the adhesion between the plating layer and the base steel material. Further, Ti, B, Ti—B alloy, Ti-containing compound or B-containing compound may be added to the plating layer. The addition amount of these compounds is preferably set so that B is in the range of 0.0005 to 0.045% by mass such that Ti is in the range of 0.001 to 0.1% by mass. .

  Although the thickness of a plating layer is not specifically limited, The inside of the range of 3-100 micrometers is preferable. When the thickness of the plating layer is less than 3 μm, wrinkles that reach the base steel material are likely to enter during handling, which may reduce the black appearance retention and corrosion resistance. On the other hand, when the thickness of the plating layer exceeds 100 μm and is processed after plating, the plating layer and the base steel material are separated at the processed portion because the plating layer and the base steel material when subjected to compression are different. There is a fear.

[Black oxide]
The black plating layer of the present invention contains a black oxide of Zn distributed in the plating layer. Here, in the plating layer includes both the surface of the plating layer and the inside of the plating layer. In addition, the “oxide” in the present specification is a generic term for oxide, hydroxide, or both.

  The distribution of the black oxide in the black plating layer can be confirmed by observing the cross section of the plating layer with an optical microscope or the like. The presence of Zn oxide can be confirmed by electron beam microanalyzer (EPMA) from a cross section, X-ray diffraction from the surface, or the like.

  In the plating layer of the vehicle member to which the black plating of the present invention is applied, a black oxide imparting a black color tone is present not only on the surface of the plating layer but also inside. Therefore, the vehicle member to which the black plating of the present invention is applied can maintain a black appearance even if the surface of the plating layer is shaved, and has excellent black appearance retention.

  Further, since the vehicle member subjected to the black plating of the present invention does not form a coating film, welding such as spot welding is also possible.

The member for a vehicle to which the black plating of the present invention is applied may be any member that is used for a vehicle including an automobile regardless of its shape and regardless of whether the part used is outside or inside the automobile.
Specifically, electrical components, engine surroundings, piping, actuators and other bracket members, arms, suspensions and other suspension members, joists, aggregates, floor boards, members, body frames and other structural members, motors Protective members such as covers, engine covers, sensor covers, sealing caps, hub caps, safety belt hooks, airbag parts, pedals (brake pedals, accelerator pedals, foot brake pedals, clutches), side brakes, sunroofs, etc. Car body parts for inner and outer plates such as parts, carrier parts, wheel caps, exhaust parts, wiper parts, etc., door modules, door sashes, pillars (front pillars, center pillars, rear pillars), bodies, etc. is there. In addition, fuel system members such as fuel supply pipes, AT mission bottom case, oil pan, fuel tank, insulator, mulder member, cable clamp, filler pipe, window regulator, plate, washer, metal fittings, hinge, clip, jack, Suitable for transportation pallets and the like that require a black appearance.
In addition, since the surface of the plating layer of the vehicle member of the present invention has a black appearance, the cationic electrodeposition coating, which has been performed to give a black appearance to the parts in the conventional vehicle member, is performed. It is possible to omit a special chemical conversion process called “Chemical conversion”.

(Embodiment 2) Manufacturing method of vehicle member subjected to black plating The manufacturing method of a vehicle member subjected to black plating according to the present invention includes 1) a step of performing molten Al and Mg-containing Zn plating, and 2) molten Al. And a step of bringing the steel material subjected to Mg-containing Zn plating into contact with water vapor in a sealed container. Further, the processing for the vehicle member may be performed before the plating step, after the plating, or after the step of contacting with water vapor. Further, it may have a step of applying an inorganic, organic or inorganic-organic composite chromium-containing or chromium-free film, and may be performed after plating, or after contact with water vapor. It may be before processing or after processing.

[Step of plating]
The vehicle member subjected to black plating according to the present invention includes a Zn alloy plating bath containing 0.1 to 22.0% by mass of Al and 0.1 to 10.0% by mass of Mg with respect to the base steel material. It is manufactured by performing the hot dipping used. In this way, Al: from 0.1 to 22.0 wt%, Mg: 0.1 to 10.0 consists Zn containing mass%, and by _Zn 2 Mg phase is distributed in the plating layer A plating layer can be formed. Further, Si, Ti, B, Ti—B alloy, Ti-containing compound, and B-containing compound may be added to the alloy plating bath. Further, the hot dipping method may be a general continuous hot dipped galvanized steel plate manufacturing method or a batch dipping method referred to as dopping. For example, in the case of a continuous hot-dip galvanized steel sheet manufacturing method, the plating bath temperature is 430 ° C., the cooling after plating is an air cooling method, and the average cooling rate from the plating bath temperature to the solidification of the plating layer is 11 ° C./second. Thus, a molten Al, Mg-containing Zn-plated steel sheet can be produced. Depending on the plating method, there may be a case where Zn ₁₁ Mg ₂ which is an intermetallic compound is precipitated in the plating layer depending on the case where the cooling rate cannot be sufficiently secured or depending on the plating composition. Since black plating can be obtained even in the plating layer on which this Zn ₁₁ Mg ₂ is deposited, it is within the scope of the present invention, and its performance does not change.

  Moreover, the value of content of each component in the plating layer is expressed as a percentage obtained by dividing the mass of each metal component contained in the plating layer by the mass of all metals contained in the plating layer. That is, the masses of oxygen, water, and hydrogen contained in the oxide are not included as components in the plating layer. Therefore, when the elution of the metal component does not occur during the blackening treatment for blackening by bringing it into contact with water vapor, the value of the content of each component in the plating layer does not change before and after the blackening treatment.

[Step of contacting with water vapor]
In this step, by bringing the plating layer into contact with water vapor in a sealed container, the lightness (L ^* value) of the surface of the plating layer is reduced to 60 or less (preferably 40 or less, more preferably 35 or less) to blacken the surface. It is a step to do. Hereinafter, this step is also referred to as blackening processing. The lightness (L ^* value) of the surface of the plating layer is measured using a spectroscopic color difference meter.

  By bringing the plating layer into contact with water vapor in a sealed container, a black oxide of Zn is generated in the plating layer, and a black appearance is obtained. The mechanism is not clear, but the inventors consider as follows. However, the present invention is not limited to these.

By bringing the plating layer into contact with water vapor in a sealed container, each metal component in the plating layer is oxidized or hydroxylated. Hereinafter, oxidation (products) and hydroxylation (products) are collectively referred to as “oxidation (products)”. At this time, among the components in the plating layer, Al and Mg, which are relatively easily oxidized, take oxygen from the oxide of Zn. The oxide of Zn deprived of oxygen becomes non-stoichiometric, and becomes an oxygen-deficient oxide such as ZnO _1-x . When a non-stoichiometric oxide is generated in this manner, light is trapped in the defect level, and the oxide exhibits a black appearance, and black plating is obtained. In addition, since Al and Mg are easily oxidized, Al and Mg existing inside the plating layer are also oxidized, and this becomes an oxygen penetration path into the plating layer, so that Zn inside the plating layer is also oxidized. As a result, the non-stoichiometric oxide as described above is formed. For this reason, since non-stoichiometric oxides exhibiting black color are distributed not only on the surface of the plating layer but also inside the plating layer, even if wrinkles or the like are attached to the surface of the plating layer, the black appearance is retained. It can be secured.

Among the plating layer, Zn 2 _Mg particularly easily oxidized, because of the close proximity further Zn and Mg, to promote the formation of stoichiometric oxide of Zn. As described above, the same effect can be obtained with Zn ₁₁ Mg ₂ .

  In the blackening treatment by contact with water vapor, blackening does not occur when there is no water vapor. Moreover, when there is much oxygen in the atmosphere which performs blackening process, blackening will not occur and it is preferable that the oxygen concentration for performing a stable process is 13% or less. For this reason, it is preferable to perform a blackening process in an airtight container.

  The temperature of the blackening treatment is preferably in the range of 50 to 350 ° C. When temperature is less than 50 degreeC, the blackening speed | rate is slow and productivity falls. On the other hand, when the temperature is higher than 350 ° C., the blackening speed becomes very fast and the control becomes difficult. In addition, since the plating layer melts or alloying between the steel material and the plating layer occurs, it is difficult to obtain a beautiful black plating layer.

  The relative humidity of the blackening water vapor is preferably in the range of 30 to 100% RH. When the relative humidity of the water vapor is less than 30% RH, the blackening speed is very slow and the productivity is lowered. The treatment time for the blackening treatment is appropriately set according to the temperature, relative humidity, pressure, oxygen concentration, the composition of the plating layer (concentration of Al or Mg), the required brightness, and the like.

(Embodiment 3) Manufacturing method of vehicle member subjected to black plating The method of processing and forming the base steel material subjected to black plating into a vehicle member is not particularly limited. For example, a method of slitting a coiled steel plate and processing it by roll forming, a method of punching and forming it by a press molding machine, a method of cutting it into a cut plate shape by shearing etc. and then bending it by a press brake etc. Can be used.

  When assembling these vehicle members, sub-joining members such as bolts, nuts, screws and rivets may be used, or they may be mechanically joined by caulking, or bonded using an adhesive or adhesive tape. You may join. Moreover, when using the joining submembers, such as a volt | bolt, a nut, a screw, and a rivet, what performed processing, such as black coating and black plating, can also be used.

  Moreover, since these vehicle members are not coated on the surface, welding can be used to assemble or join them. Therefore, a spot welder, an arc welder, a projection welder, a laser welder, or the like can be used. When welding is used, the welded part and the vicinity thereof are white as the plated metal melts and adheres to the surface of the black plating layer, the black oxide disappears, or the base steel is exposed. There is a case. In that case, touch-up (repair) with black paint or the like may be performed.

(Embodiment 4) Black-plated steel sheet for vehicle member The black-plated steel sheet for vehicle member of the present invention is the [Step of applying plating] described in Embodiment 2 with respect to [Substrate steel material] described in Embodiment 1. Then, [Step of contacting with water vapor] is performed in this order. The black plated steel sheet for a vehicle member manufactured in this way is a molten Al, Mg-containing Zn plating layer in which [black oxide] is distributed in the plating layer, and the brightness of the surface of the plating layer is Since the L * value is 60 or less, a black appearance is exhibited.

Claims (4)

Base steel, and
Melting containing Al: 0.1 to 22.0 mass%, Mg: 0.1 to 10.0 mass% on the surface of the base steel material, and a black oxide of Zn being distributed in the plating layer Al, Mg containing Zn plating layer,
The member for vehicles by which the blackness which the brightness of the surface of the said fusion | melting Al and Mg containing Zn plating layer is 60 or less by L * value was given. _{2. The} vehicle member subjected to black plating according to claim 1, wherein the Zn black oxide is an oxide of Zn derived from a Zn ₂ Mg phase.   The vehicle with black plating according to claim 1 or 2, wherein the vehicle member is a bracket member, a suspension member, a structural member, a protective member, an interior member, an exterior member, or a vehicle body member. Materials. Base steel, and
Melting containing Al: 0.1 to 22.0 mass%, Mg: 0.1 to 10.0 mass% on the surface of the base steel material, and a black oxide of Zn being distributed in the plating layer Al, Mg containing Zn plating layer,
The brightness | luminance of the said molten Al and Mg containing Zn plating layer surface is a black plating steel plate for members for vehicles which is 60 or less by L * value.