JPH0564860A - Resin composite type steel plate - Google Patents

Abstract

PURPOSE:To provide a resin composite type steel plate excellent in bonding strength and/or resistance weldability exerting an influence upon press moldability. CONSTITUTION:In a resin composite type steel plate constituted of two or more steel plates each having iron-zinc alloy layers formed by applying hot dip zinc coating to both surface layers of a steel plate and subsequently continuously heating the plated steel plate to subject the same to alloying treatment and an intermediate layer composed of a viscoelastic substance, said resin composite type steel plate is processed so that the surface collapse ratio of each of the iron-zinc alloy layers is set to the range of 10-80%. When a metal powder is uniformly dispersed in the intermediate layer composed of the viscoelastic substance, resistance weldability is enhanced. When chromate treatment is applied to the surfaces of the iron-zinc alloy layers of the steel plates coming into contact with the intermediate layers composed of the viscoelastic substance, bonding strength can be further enhanced.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a resin composite type steel sheet,
More specifically, a resin that has excellent corrosion resistance against the use environment conditions, and also has excellent adhesive strength that affects press formability, or particularly excellent resistance welding performance represented by spot welding, seam welding, and projection welding. It relates to a composite type steel sheet.

[0002]

2. Description of the Related Art In recent years, there have been increasing demands for quietness and quietness in various fields. In particular, in the field of products that use prime movers such as automobiles and home appliances, or in fields where it is necessary to effectively suppress external vibration and noise, such as building material applications used in buildings, The application of damping steel plates, which are useful for absorbing noise energy, is being actively promoted.

For this purpose, steel plates, various plated steel plates, stainless steel plates, aluminum plates, titanium plates, and further synthetic resin plates are used as the skin material, and a viscoelastic polymer resin is sandwiched between the two skin plates. A so-called restrained composite material (vibration damping material) is applied.

When used as a structural member, the strength of a composite steel sheet is required, and from this point, a steel sheet is generally used as a skin plate. Further, when corrosion resistance under the usage environment is required, surface-treated steel sheets represented by various plated steel sheets are used. In particular, to ensure corrosion resistance,
A hot-dip galvanized steel sheet with a large amount of plating is used.
As seen in Japanese Patent Publication No. 11, a steel sheet subjected to alloying treatment is often used.

[0005]

However, in the resin composite steel sheet using the steel sheet subjected to such alloying treatment, the adhesive strength with the viscoelastic intermediate substance sandwiched between the steel sheets cannot be sufficiently obtained. However, peeling occurs during the molding process, resulting in a fatal defect that the molding process cannot be performed well.

On the other hand, the viscoelastic intermediate material sandwiched between the two steel plates is an electrical insulator, and is a typical technique as a joining technique when a thin material is conventionally applied to a structural member. There is a drawback that resistance welding methods such as spot welding, seam welding, and projection welding cannot be applied as they are.

Recently, in order to impart conductivity to the viscoelastic polymer resin, which is an electric insulator, iron powder (JP-A-57-5)
1453), nickel powder (Japanese Patent Laid-Open No. 63-1880).
For example, a method of adding various metal powders such as JP-A No. 40) and a conductive material such as carbon powder (JP-A-57-163560) is being widely adopted.

According to these methods, it is necessary to add a large amount of the conductive substance in order to prevent the occurrence of welding defects during the welding process. The stability is stabilized and the incidence of welding failure can be reduced, but at the same time, the shear tensile adhesive strength is also reduced ("Iron and Steel" Vol. 63, No. 13, p. 363).

The decrease in adhesive strength causes plate peeling between composite steel sheets during press working, which is a typical method for working thin materials,
It is a fatal defect that it cannot be molded.

Even when the forming process can be carried out, during spot welding in a state in which the parts are not well-fitted due to the occurrence of flange wrinkles, twisting, and warpage during processing, there is a hole associated with sparking and melt fracture of the skin steel sheet. Welding defects such as these occur, and it is a defect that a sound joint strength cannot be secured.

The present invention solves the above-mentioned drawbacks of the prior art,
After hot dip galvanizing on the surface of a steel sheet, resin peeling occurs in a resin composite type steel sheet having a structure in which a viscoelastic material intermediate layer is sandwiched by a skin material having an iron-zinc alloy layer that is continuously heated and alloyed. An object of the present invention is to provide a resin composite-type steel sheet having excellent adhesive strength that enables various forming processes without heat, or excellent resistance weldability to which various resistance welding can be applied, stably and at low cost. It is a thing.

[0012]

Therefore, the present inventors have
As described above, as a result of detailed investigation of the cause of the decrease in the adhesive strength and the cause of the defective welding, the following causes were found.

That is, first, the reason why the adhesive strength is not sufficiently obtained is that the adhesive strength at the time of laminating the vibration-damping steel plate is incomplete, which lowers the adhesive strength between the resin and the steel plate. A more detailed examination shows that the surface of the alloyed plated steel sheet has many fine irregularities, and the resin viscosity is high when the composite steel sheet is laminated, so that the resin can sufficiently follow the irregularities on the steel sheet surface and become compatible with the resin. I can't. As a result, it was found that the real contact area between the polymer resin and the steel plate surface (the area where the steel plate surface and the resin contact each other and contributes to adhesion) decreases, and the adhesive strength that can withstand the molding process cannot be obtained.

In addition, at the interface between the metal powder uniformly dispersed in the polymer resin for imparting conductivity and the steel sheet surface layer,
Since the fine surface irregularities are severe, the resin is not sufficiently removed during lamination, and the polymer resin remains at the interface between the metal powder and the steel sheet surface layer, which frequently interferes with metal contact.
Therefore, it has been found that it does not sufficiently act as a current-carrying circuit during resistance welding and cannot prevent defective welding.

That is, when the metal powder is present in the above-described state, in the initial stage of the energization of resistance welding, the electric current concentrates on the energizing circuit in which the resin is not present at the steel plate / metal powder interface, and the resistance heat is generated by the electric current. The resin is softened and melted by (Joule heat generation), and is removed around the electrode by the pressing force of the electrode. If the calorific value at this time greatly exceeds the heat capacity of the skin steel sheet, a defect that the skin steel sheet melts occurs. Further, it has been found that there is a case in which a rise in internal pressure between the steel plates due to softening, melting and evaporation of the resin cannot be endured and holes are generated in the skin steel plate.

As a measure for preventing such a problem, even if the viscosity of the viscoelastic polymer resin is high in the laminating process, the surface roughness region where the resin can sufficiently follow the irregularities of the surface layer of the surface steel plate It has been revealed that excellent adhesive strength can be obtained by adding the above. Furthermore, it is clear that the number of hydrogen bonds at the steel sheet / resin interface increases and the adhesive strength is further improved by subjecting the steel sheet surface in contact with (reacting with) the polymer resin to surface treatment typified by chromate treatment. Became. Further, by improving the contact condition between the metal powder uniformly dispersed in order to impart conductivity to the viscoelastic intermediate substance that is the electric insulator and the surface layer of the skin steel sheet, in a situation where the steel sheets are not familiar with each other. Even when resistance welding is performed, stable welding work can be performed, and the occurrence of welding defects can be prevented. As a result, it became clear that a sound joint strength can be secured.

The present invention has been completed based on the above findings. That is, the present invention includes two or more steel plates having iron-zinc alloy layers that are continuously heated and alloyed after hot-dip galvanizing both surface layers of the steel plate, and a viscoelastic substance intermediate layer (metal powder). In the resin composite type steel sheet, the crushing rate of the iron-zinc alloy layer surface is processed in the range of 10 to 80%. The main point is steel plate.

The present invention will be described in more detail below.

[Action]

The thickness of the viscoelastic intermediate substance (polymer resin) layer used in the resin composite type vibration damping steel sheet according to the present invention is not particularly limited, but it is 10 to 150 μm, and when vibration damping performance is desired. It is preferably in the range of 30 to 80 μm. When the resin film thickness is 10 μm or less, the vibration damping performance of the resin,
That is, it is not preferable because the effect of converting the vibration energy from the outside into heat energy and dissipating the heat energy is rapidly attenuated and the original characteristics of the vibration damping steel sheet cannot be exhibited. On the other hand, even if the resin film thickness exceeds 150 μm, the vibration damping performance itself does not deteriorate, but the strength difference between the resin itself and the steel plate becomes too large, and the vibration damping steel plate ends at the time of practical forming. The amount of deviation becomes large, which is disadvantageous.

When a metal powder is added to the viscoelastic intermediate substance layer, the metal powder is not particularly limited, but, for example, iron powder having the property proposed in Japanese Patent Laid-Open No. 2-227247 is used. it can. Also, Japanese Patent Application No. 1-18
Metal powders such as nickel powder and stainless powder having the properties proposed in No. 2964 can be used. This is because the hardness (Ph) of the metal powder is 0.6 ≦ with respect to the surface hardness (Sh) of the thin steel plate.
The range of Ph / Sh ≦ 1.1 is such that the flatness of the metal powder after lamination of damping steel sheets is 20% or more.

The present invention is intended to improve the contact state with a resin having a high viscosity at the time of lamination at the interface between a polymer resin (viscous elastic intermediate substance) and a skin steel plate to secure a true contact area. In addition, the surface of the alloying treated material having severe irregularities is processed by rolling or another method, and the crush rate of the steel plate surface (iron-zinc alloy layer surface) is controlled to 10 to 80%.
This allows for the presence of a smooth surface and the average roughness of the center line.
By adjusting (Ra) in the range of 0.3 to 2.0 μm, it becomes possible for the resin with high viscosity to follow the unevenness of the steel plate surface during lamination, the true contact area increases, and high adhesive strength can be obtained. Become. In addition, at this time, the resin does not remain at the interface between the metal powder and the steel sheet surface layer, and the probability of obtaining a sufficient metal contact state is increased.As a result, the electrical conductivity at the beginning of welding is improved and resistance welding is performed even under severe welding conditions. Sex becomes stable.

Here, if the crushing rate of the steel sheet surface is 10% or less, the unevenness on the steel sheet surface cannot be reduced, and the resin with high viscosity cannot follow the unevenness on the surface, so the effect of improving the adhesive strength is not recognized. (See Figure 2). Further, since the area ratio of the smooth surface is also small, the effect of reducing the occurrence rate of welding defects is small and not sufficient. From the viewpoint of weldability, it is sufficient to secure a crushing rate of 10% or more (see FIG. 3).

On the other hand, in order to secure the crushing rate of 80% or more, for example, when it is considered to secure it by rolling, the rolling workability becomes high, cracks occur in the plating layer, and the plating layer itself is destroyed. As a result, the adhesive strength will be decreased on the contrary (see FIG. 2). The relationship between the degree of rolling and the surface roughness at this time is shown in FIG.

In order to increase the contact area between the steel sheet and the resin that contributes to adhesion, it is necessary to increase the true contact area between the steel sheet surface and the resin. To do so, the contact area is small on a smooth surface with little unevenness on the steel plate,
A controlled uneven surface is preferred. Therefore, it is desirable to control Ra defined by the center line average roughness in the range of 0.3 to 2.0 μm. The roughness of the as-alloyed surface is 2.
0 to 4 μm, and on such a rough surface,
Since the resin does not follow the unevenness, the true contact area also decreases and the adhesive strength does not increase. This phenomenon is particularly remarkable when the viscosity of the resin during lamination is high. Specifically, this is an effective method when the resin viscosity is 100 centipoise or more. On the other hand, if the surface roughness is 0.3 μm or less, the unevenness on the surface of the steel sheet will be small, and the anchor effect exhibited by the unevenness will be small, and the true contact area will be small, contributing to adhesion. The contact area between the steel plate and the resin cannot be secured, and the adhesive strength does not increase.

Therefore, the crush rate of the steel plate surface (iron-zinc alloy layer surface) is specified within the range of 10 to 80%. The surface roughness Ra is preferably specified in the range of 0.3 to 2.0 μm. In order to obtain this surface condition, a method such as light rolling (skin pass) that is usually performed on a cold-rolled steel sheet can be considered. Further, in order to obtain the center line roughness Ra within a predetermined range, a method in which the roll surface for rolling is dull-processed by a method such as shot blasting is used and the transfer rate is adjusted so as to have a predetermined roughness. Should be taken.

The thickness of the plating layer is not particularly limited, and can be applied to a range of the basis weight which is usually used for alloying treatment, that is, a wide range of ^{20 to} 80 g / m ² . Moreover, the plate thickness of the steel plate is not particularly limited.

As described above, high adhesion strength can be obtained by controlling the crushing rate and the surface roughness of the plated steel sheet surface. However, by further performing the chromate treatment, the resin surface and the steel sheet surface can be adhered to each other. The number of contributing hydrogen bonds is increased, and more excellent adhesive strength is obtained. When the amount of the chromate-treated film deposited is 5 mg / m ² or less, the effect of increasing the number of hydrogen bonds is small and the effect of improving the adhesive strength is not. Since the chromate-treated film is passive, if the amount of adhesion becomes 50 mg / m ² or more,
5 to 50 mg / m < ² > is preferable since it impedes the electrical conductivity during resistance welding such as spot welding and deteriorates the weldability.

The chromate treatment liquid for improving the adhesive strength is not particularly limited, and any of ordinary chromate liquid and chromic acid may be used. Further, neither the coating type chromate nor the reactive type chromate has any influence in terms of the effect. If a water-soluble or water-dispersible resin is added to the chromate treatment liquid, the adhesive strength can be further improved.

As the viscoelastic intermediate substance, various resins having excellent vibration damping performance can be used, for example, polyolefin type, polyester type, vinyl acetate type, vinyl chloride type, acrylic type resin and the like can be used. Needless to say, a thermosetting resin with a crosslinking reaction and a thermoplastic resin without a crosslinking reaction can be applied, and the resin system is not limited at all.

Next, examples of the present invention will be shown.

[0031]

[Example 1] A continuous cast aluminum killed steel plate having a plate thickness of 0.4 mmt was used, and hot dip galvanizing treatment (plating basis weight 45 g / m ²
After double-sided plating), alloying treatment is performed, and a viscoelastic polymer resin (in this case, a polyolefin resin is used) of 70 μm is used by using a steel plate with the crush rate and surface roughness of the steel plate surface adjusted. It was laminated on the plate, and the shear tensile strength was measured to evaluate the adhesive strength. The adhesion area of the test piece is 35 mm in width and 10 mm in length. These results

[Table 1] Shown in. From Table 1, it can be seen that according to the present invention, the adhesive strength is significantly improved as compared with the conventional example and the comparative example. The condition of the steel plate surface is shown in FIG. 4 (example of the present invention: crush rate 40%).
FIG. 5 (conventional example: collapse rate 0%) is shown.

[0032]

[Example 2] A continuous cast aluminum killed steel plate having a plate thickness of 0.4 mm to 1.2 mmt was used, hot-dip galvanized (double-sided plated material having a coating weight of 60 g / m ² ), and then alloyed. Using a steel plate whose surface crush rate and surface roughness have been adjusted, a viscoelastic polymer resin (in this example, a polyolefin resin is used) is laminated to 70 μm, and shear tensile strength is measured to evaluate the adhesive strength. did. The shape of the test piece is Example 1
The same as the case of. These results

[Table 2] Shown in. From Table 2, it can be seen that in the examples of the present invention, the adhesive strength is excellent even if steel plates having various plate thicknesses are used.

[0033]

[Embodiment 3] A continuous cast aluminum killed steel plate having a plate thickness of 0.8 mmt is used, and hot dip galvanizing treatment (plating basis weight is 45 g / m ²
After performing the alloying treatment, using the steel sheet with the crush rate and surface roughness of the steel sheet surface subjected to chromate treatment, the viscoelastic polymer resin (of this example). In this case, a polyolefin resin was used) was laminated to 70 μm, and the shear tensile strength was measured to evaluate the adhesive strength. The shape of the test piece was the same as in Example 1. These results

[Table 3] Shown in. From Table 3, it can be seen that the adhesion strength is further improved by performing the chromate treatment.

[0034]

[Embodiment 4] A continuous cast aluminum killed steel plate having a plate thickness of 0.4 mmt is used and a hot dip galvanizing treatment (plating basis weight 45 g / m ²
After double-sided plating), an alloying treatment was performed, and a viscoelastic polymer resin in which iron powder was uniformly dispersed using a steel sheet with a crush rate and surface roughness of the steel sheet surface (in this example, a polyolefin-based resin) Resin was used) was laminated to 50 μm, the shear tensile strength was measured, and the adhesive strength was evaluated. The shape of the test piece was the same as in Example 1.

Resistance weldability was evaluated by a method of resistance welding to the end of the test piece using the test piece with a gap shown in FIG. Welding test is 100 sheets under the same conditions,
The appearance of the test piece was visually observed, and the resistance weldability was evaluated by the ratio of the number of welding defects such as perforations on the surface of the steel sheet due to sparking and melt fracture of the skin steel sheet. Welding condition is electrode pressure 15
The welding was carried out at 0 kgf, a welding current of 10 KA, and an energization time of 12 cycles. FIG. 7 shows an example of the condition of the test piece after the welding test.

The results of these tests are

[Table 4] As shown in FIG. 5, it is understood that according to the present invention, the adhesive strength is greatly improved and the resistance weldability is excellent as compared with the conventional example and the comparative example.

[0037]

[Embodiment 5] A continuous cast aluminum-killed steel sheet having a plate thickness of 0.4 to 1.2 mmt is used, and hot dip galvanizing treatment (plating basis weight 4
5g / m ² of double-sided plated material), and then alloying treatment is performed, and a viscoelastic polymer resin (in this example, a polyolefin resin is Used) was laminated to 50 μm, and the shear tensile strength was measured to evaluate the adhesive strength. The shape of the test piece was the same as in Example 1. The result is

[Table 5] As shown in FIG. 5, it can be seen that in the examples of the present invention, the adhesive strength is excellent even when steel sheets having various thicknesses are used.

[0038]

[Example 6] A continuous cast aluminum killed steel plate having a plate thickness of 0.4 mm was used, subjected to hot dip galvanizing treatment (double-sided plated material having a coating weight of 45 g / m ² ), and then subjected to alloying treatment, and the crush rate of the steel plate surface After the chromate treatment is applied to the surface of the steel plate using a steel plate whose surface roughness is adjusted, a viscoelastic polymer resin (in this case, a polyolefin resin is used) is laminated to 50 μm, and the shear tensile strength is measured. Then, the adhesive strength was evaluated. The shape of the test piece was the same as in Example 1. The result is

[Table 6] As shown in (1), it can be seen that when the chromate treatment is performed, the adhesive strength is further improved, and moreover, excellent resistance weldability can be secured by appropriately controlling the chromate adhesion amount.

[0039]

As described in detail above, according to the present invention,
A resin composite steel sheet composed of two or more steel sheets and a viscoelastic intermediate material layer has stable high adhesive strength without causing resin peeling during various forming processes, or has an extremely stable resistance weldability. It is possible to laminate the resin-composite type steel plate that it has.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a skin pass rolling rate and a crush rate of a steel plate surface.

FIG. 2 is a diagram showing a relationship between a crush rate of a steel plate surface of a resin-bonded surface and a shear tensile strength.

FIG. 3 is a diagram showing a relationship between a crushing rate of a steel plate surface of a resin bonding surface and a welding failure occurrence rate.

FIG. 4 is a photograph (× 1000) showing the metal structure (surface condition) of the steel plate surface of the resin composite type steel plate obtained in the example, which is the case of the present invention example.

FIG. 5 is a photograph (× 1000) showing the metal structure (surface condition) of the steel plate surface of the resin composite type steel plate obtained in the example, which is the case of the conventional example.

FIG. 6 is a perspective view showing a test piece used for evaluation of resistance weldability.

FIG. 7 is a perspective view showing a test piece after a resistance welding test.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C23C 22/24 8520-4K

Claims (3)

[Claims] 1. A steel sheet comprising two or more steel sheets each having an iron-zinc alloy layer which has been subjected to hot dip galvanization on both surface layers of the steel sheet and which has been continuously heated and alloyed, and a viscoelastic substance intermediate layer. In the resin composite type steel sheet according to the above, the resin composite type steel sheet is characterized in that the crush rate of the surface of the iron-zinc alloy layer is processed in the range of 10 to 80%. 2. A resistance-weldable resin-composite steel sheet, wherein metal powder is uniformly dispersed in said viscoelastic material intermediate material. 3. The resin composite type steel sheet according to claim 1, wherein the surface of the iron-zinc alloy layer of the steel sheet in contact with the viscoelastic material intermediate layer is chromated.