JPH03215686A - Multi-layer plated steel material - Google Patents

Abstract

PURPOSE:To produce a multi-layer plated steel material excellent in adhesion durability by successively laminating an Fe-containing alloying hot dip galvanizing layer, a Cr coating layer, and a ferrous alloy coating layer on a steel sheet under respectively specified conditions. CONSTITUTION:At least, an alloying hot dip galvanizing layer of 5-20wt.% average Fe content having >=0.3mu surface roughness Ra is formed as a lower layer on the surface of a steel material. Subsequently, a coating layer consisting of metal (Cr, Al) or alloy (alloy of one element selected from Cr, Al, Co, and Ni and one or more elements selected from Zn, Mn, and Fe) is formed by 0.01-10g/m<2> coating weight as an intermediate layer. Further, as an upper layer, a coating layer of a ferrous alloy having 90-99.9999wt.% Fe content and containing one or more elements selected from Ni, Co, Mn, B, S, and P as alloy components is formed by 0.01-10g/m<2> coating weight. By this method, the multi-layer plated steel material improved in initial adhesive strength and capable of controlling deterioration in adhesion durability under a corrosive environment to minimum can be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is suitable for use in, for example, automobiles, home appliances, building materials, etc. Furthermore, it relates to multilayer plated steel materials with excellent spot weldability.

(Prior art) Requirements for surface-treated materials have been wide-ranging. For example, surface-treated steel sheets for automobiles require chemical conversion treatment,
Improvements in paint film adhesion, post-painting corrosion resistance, spot weldability, etc.
There is a particular need for improvement. Incidentally, the application of various anticorrosive plated steel sheets to automobile bodies used in particularly severe corrosive environments is being actively promoted. Currently, the most common anti-corrosion plated steel sheets are Zn-based or Zn-N.
Steel sheets having Zn alloy-based plating films, such as i-based, Zn-Fe-based, and Zn-AQ-based, are generally known. However, such anticorrosion-plated steel sheets have insufficient chemical conversion treatment performance, which is a base treatment for painting, and therefore also have insufficient paint film adhesion. Therefore, to solve this problem, it has been proposed to use multiple plating layers. For example, JP-A-56-142885 discloses a two-layer plating material having a sacrificial anti-corrosion coating as the lower layer and an Fe-based continuous coating as the upper layer; The publication proposes a three-layer plating material having a sacrificial anti-corrosion coating as a lower layer, a Ni or Ni-based alloy coating as an intermediate layer, and a Fe or Fe-based alloy coating as an upper layer. It is said that the above problem can be solved by (Intelligence to be Solved by the Invention) These multilayer plated materials are capable of satisfying the above-mentioned performances required for, for example, automobile steel sheets, that is, chemical conversion treatment properties, paint film adhesion, and post-painting corrosion resistance. However, it has not been possible to fully satisfy performance other than these, such as spot weldability and adhesive durability, which will be described later.In other words, it has not been possible to fully satisfy the performance requirements other than these, such as spot weldability and adhesive durability, which will be described later. Therefore, it is possible to increase the thickness of the lower sacrificial anti-corrosion coating layer in this multi-layered plated material, but in this case, deterioration of spot weldability becomes a problem.Also, the elution rate of the lower sacrificial anti-corrosion coating layer increases. This may be due to an increase in the progress of corrosion in the surface direction of the steel material, but multilayer plating also causes problems with the adhesive durability of the steel material. The adhesion strength (i.e., initial adhesion) of the bond interface at the initial stage of adhesion when bonding surface-treated materials such as steel materials used for building materials, etc., or bonding the surface-treated materials and other metal materials, etc. Refers to the adhesion strength (i.e., adhesive durability) of the adhesive interface in a corrosive environment.As adhesive technology improves, the adhesive method can be used as an alternative to welding, or applied to difficult-to-weld materials or areas. Furthermore, this performance has been attracting attention in recent years for reasons such as improving the appearance (welding marks are generated during welding).

In particular, various tests and research have been conducted in recent years regarding the adhesive durability of surface-treated steel sheets. For example, a surface-treated steel sheet such as an electrogalvanized steel sheet, a hot-dip galvanized steel sheet, or an alloyed hot-dip galvanized steel sheet is used as the surface-treated steel sheet, and the surface-treated steel sheet is joined using an adhesive, and a combined corrosion test is performed in parallel. Tests have been conducted to investigate the initial adhesion and adhesion durability of the surface-treated steel sheets by measuring the shear stress of the bonded parts at any time, and the results show that hot-dip galvanized steel sheets are superior to other coated steel sheets. Compared to other galvanized materials, the initial adhesion was consistently strong from the start of the corrosion test, and other galvanized materials had an adhesive strength (initial adhesion) that was equal to or slightly inferior to that of cold-rolled steel sheets at the initial stage of corrosion. However, it has been shown that as corrosion progresses, it shows superior adhesive strength to cold-rolled steel sheets and has superior adhesive durability. However, this test result is only a test result under a combined corrosion test with severe corrosion conditions, and the progress of corrosion is slow under conditions such as actual usage conditions where the corrosion cycle and environment are gentle. Regarding other galvanized materials other than galvanized materials, cold-rolled steel sheets have been superior to galvanized materials for a long time in terms of adhesive strength, and under actual usage conditions, the benefits of using the aforementioned galvanized materials are small. It has become.

In addition, although the use of galvanized materials shows superiority in terms of initial adhesion and adhesive durability in corrosive environments,
This means that it is relatively superior to cold-rolled steel sheets, and even in galvanized materials, the absolute value of the adhesive strength decreases as corrosion progresses, so it is difficult to use in actual use. It was difficult to say that the adhesive durability was sufficient.

By the way, as mentioned above, the reason why the initial adhesion of plated materials is inferior to that of cold-rolled steel sheets can be considered as follows. That is, there is a phlegm in the plating film, for example, the r-phase in the alloyed hot-dip galvanized film, the r-phase in the alloy electrolytic Zn-Ni plating film, and the 6-phase in the alloy electrolytic Zn-Fe plating film. ``If there is a homogeneity, peeling will occur at that site during shear tension, resulting in an apparently low adhesive strength.

Therefore, for such materials, the tensile strength can be increased by reducing the formation of the brittle body as much as possible in hot-dip plating, for example by controlling the heat treatment conditions, and the initial adhesion can be improved. I can do it.

However, with such means, it is not possible to solve the problem of deterioration of adhesive strength that occurs as corrosion progresses, that is, it is not possible to improve adhesive durability.

In recent years, several methods of using plating materials as materials have been proposed as a means to solve this problem of deterioration of adhesive durability, but the level of adhesive strength improved by such means is still insufficient. It was nothing special.

As explained above, when increasing the thickness of the lower sacrificial anticorrosion coating layer of the multilayer plated material for the purpose of imparting high corrosion resistance, there are problems of deterioration of spot weldability and further improvement of adhesive durability. Until now, there has been no means that can achieve both of these challenges.

The purpose of the present invention is to solve the above-mentioned problems and problems, and to provide a material that is suitable for use in, for example, automobiles, home appliances, building materials, etc., and has excellent chemical conversion treatment properties, paint film adhesion, corrosion resistance after painting, etc. Another object of the present invention is to provide a multilayer plated steel material having excellent spot weldability and adhesive durability.

(Means for Solving the Problems) In order to achieve the above object, the present inventors aimed to solve the above-mentioned problems by improving not only initial adhesion but also adhesion with little change in strength over time even in a corrosive environment. Recognizing that the most important thing was to develop a plated rope with excellent durability, we conducted extensive research.

Among the factors that affect the initial adhesion of steel materials,
Factors caused by the steel material include the shape of the coating surface of the steel material (
The present inventors thought that there is a compatibility with the surface roughness of the film, etc.) and the adhesive anatomy. In addition, a factor that particularly affects the adhesive durability of steel materials is thought to be due to the progress of corrosion, and in particular, the progress of corrosion in the plane direction has a negative effect.
The inventors thought about this.

Based on such findings, the present inventors conducted further studies and found that the surface of the steel material to be treated was subjected to alloying hot-dip plating of Zn or a Zn-based alloy having a sacrificial anticorrosion effect as a lower layer, On top of that, a coating of one metal or alloy selected from the group consisting of Cr, Cr-based alloys, AQ, AI2-based alloys, Co-based alloys, and Ni-based alloys is applied as an intermediate phase, and a coating of Fe-based alloy is applied as an upper layer. By using a plated steel material with a three-layer coating structure obtained by applying a coating, it has excellent chemical conversion treatment properties, coating adhesion, and post-painting corrosion resistance, as well as spot weldability and adhesive durability. The present invention was completed by discovering that multilayer plated steel materials can be captured and supplied. Here, the gist of the present invention is to provide at least a lower layer on the surface thereof: an alloyed hot-dip galvanized layer having an average Fe content of 5 to 20% by weight and a surface roughness Ra of 0.3 μm or more. Layer, Intermediate layer: Coating layer of the following metal or alloy with an adhesion amount of 0.01 to 10 g/rrf. Metal: Cr, 8Q Alloy: one selected from the group consisting of Cr, AQ, Co and Ni. , Zn, Mn, and Fe: the deposited amount is 0.01 to 10 g/I, the Fe composition is 90 to 99.9999% by weight, and Ni , C
This is a multilayer plated steel material characterized by having a coating layer of an Fe-based alloy containing one or more elements selected from the group consisting of O, Mn, B, S, and P. In the present invention, "steel" refers to, for example, automobiles, home appliances,
It refers to parts used for building materials, etc., and specifically includes, for example, automobile bodies, interior and exterior panels of building materials, and the bodies of home appliances. Furthermore, in the present invention, the method for coating the intermediate layer or upper layer is as follows:
There are no particular limitations, and the intermediate layer may be coated by electroplating or dry plating, and the upper layer may be coated by electroplating, electroless plating, dry plating, or the like.

In addition, in the present invention, "excellent adhesive durability" means
In combination with the composite corrosion test, the peel tensile strength specified by JIS K 6854 is based on the T-type peel test, and cohesive failure of the adhesive part occurs almost over the entire surface of the peeled surface, that is, the base material and the plating layer. , plating layer one plating layer,
This means that the interfacial adhesion between the plating layer and the adhesive has stronger performance than the cohesive failure of the adhesive. Furthermore, the present invention is not limited to ams having only three layers: a lower layer, an intermediate layer, and an upper layer; for example, between the lower layer and the intermediate layer and/or between the intermediate layer and the upper layer, etc.
It may also be a plated steel material having a multilayer structure of four or five or more layers in total, with a coating layer that does not deteriorate adhesive durability. In the present invention, the word "at least" is used to clarify that such aspects are included. Further, in the present invention, the three layers may be formed on the entire surface or a part of the steel material (especially when the steel material is a steel plate, on both surfaces or one surface).

(Function) The structure and function of the present invention will be explained below.
In addition, in this specification, unless otherwise specified,
"r%" means "% by weight". Briefly, the structure of the present invention has an alloyed hot-dip galvanized layer having a sacrificial anti-corrosion effect as a lower layer, and Cr, Cr-based alloy, AQ, Al-based alloy, Co-based alloy, as an intermediate layer.
Or, it has a coating layer of Ni-based alloy, and further has an F layer as an upper layer.
The plated steel material has a coating layer of at least three layers including a coating layer of an e-based alloy.

First, the lower layer of the multilayer plated steel material according to the present invention will be explained. The reason why an alloyed hot-dip galvanized layer is applied as the lower layer is that the alloyed hot-dip galvanized layer has a sacrificial corrosion protection effect, and a coating that does not have a sacrificial corrosion protection effect will cause significant corrosion on the base metal side, resulting in poor adhesion. This is because significant deterioration of durability cannot be prevented. Furthermore, among the coatings that have a sacrificial anticorrosion effect, the reason for limiting this to the alloyed hot-dip galvanized layer is that, although the reason is unknown, it prevents a significant decrease in adhesive durability with other coatings that have a sacrificial anticorrosion effect. This is because it is impossible to do so. In addition, the alloying degree of this alloyed hot-dip galvanized layer was determined as the average F
Explain the reason why the e content was limited to 5% or more and 20% or less. That is, the present inventors investigated the coating composition and surface morphology of the lower layer alloyed hot-dip galvanized steel sheet using samples in which the coating composition and surface morphology were variously changed, and found that the average Fe content was 5%. 20% or less, and the surface roughness is in the range of 0.3μ snow or more,
It was found that this method was most effective in improving adhesive durability. Note that, taking into account errors in manufacturing conditions, etc., the more desirable average Fe content is 7% or more and 14% or less. The details of this mechanism of action are unknown, but one of the reasons for this is the anchoring effect due to the surface morphology of the steel material, that is, the difference in adhesion between the plating layers and the bonding interface between the plating layers. ．． It is also conceivable that the amount of brittle bodies present is affected by the film composition. The upper limit of the surface roughness is not particularly limited in terms of the effects of the present invention, but considering the clarity of the top coat surface when electrodeposition coating, intermediate coating, and top coating are performed. It is desirable that the fog be 1.8 μm or less, more preferably 1.5 μm or less. In addition to Zn, Fe, and AQ added to the plating bath, the alloying elements of the alloyed hot-dip galvanized layer that is the lower layer include, for example, Si, Nb, Mn, Mg,
No, Ta, Cu, Ni, Co, Sn%Sb,
Ti, Cr%Cd, Pb, TN, In, V, W
, La, P, S, B, etc. may be contained in trace amounts of one or more elements selected from the group consisting of , La, P, S, B, etc., and this does not have any influence on the fourth effect of the present invention. do not have. In addition, in order to apply an alloyed hot-dip galvanized layer as the lower layer of the steel material, it is sufficient to use any currently used well-known means. It is sufficient to adjust the amount of zinc deposited on the plating bath outlet side of the line and immediately lead to a heating furnace maintained at 500 to 650°C, and there are no restrictions at all.

Further, the average Fe content (alloying degree) may be controlled by conventional means, and no restrictions are required.

Next, the intermediate layer and upper layer of the plated steel material having excellent adhesive durability according to the present invention will be explained.

The reason why the surface of the plated steel having the lower layer is coated with an intermediate layer and an upper layer to form at least a three-layer structure is that the intermediate layer is made of Cr, Cr-based alloy, M, Al-based alloy, Co-based alloy, and Ni. Only a coating layer of one metal or alloy selected from the group consisting of alloys, or an upper layer of Fe
The coating layer of the base alloy alone is not sufficiently effective in preventing the significant progress of corrosion, and the interaction (synergistic effect) of having these two coating layers provides satisfactory adhesive durability. This is because it is thought that it will be possible. The reason for this consideration is that the effect of inhibiting the progression of corrosion as described above changes greatly depending on the difference in the amount of adhesion between each coating layer, especially the difference in the amount of adhesion between the upper layer and the intermediate layer.

The components of the intermediate layer coating include Cr, Cr-based alloy, A
Q: Any metal or alloy selected from the group consisting of Al-based alloys, Co-based alloys, and Ni-based alloys is sufficient.
That is, the present invention, briefly stated, aims to improve the adhesive durability of steel materials while sufficiently ensuring the spot weldability of the steel materials as described above. In order to ensure sufficient spot weldability of steel materials, for example, damage (seizing, abrasion, etc.) to the electrode tip of the welding machine should be suppressed as much as possible. Cr or C as an intermediate layer for the purpose of suppressing
r-based alloy, AQ or AQ-based alloy, Co-based alloy, Ni
One type of alloy is applied. As the alloying element, it is necessary to use one or more elements selected from the group consisting of Zn, Mn, and Fe. Although a detailed study has not been conducted, it is thought that applying an excessively aggressive metal layer to the base material cold-rolled steel plate accelerates the corrosion of the base material and deteriorates the adhesive durability. Alloying elements other than those listed above include elements that exhibit a more base potential than the material to be plated, such as Mg, Pb, Cd, and T.
a, Ti, Nb, VSW, Sb, P, B, S
It may contain one or more elements selected from the group consisting of the following.

In addition, the adhesion amount of the intermediate layer film needs to be 0.01 g/rrf or more in order to exhibit its performance, and conversely, if it exceeds 10 g/rrf, the adhesive durability of the entire film deteriorates. ．． Therefore, the adhesion amount is 0.01 to 10g/
Limited to po. In addition, it exhibits stable performance regardless of the manufacturing conditions, and on the other hand, taking into account the high cost and saturation of performance due to thickening, it is more preferably 0.05 to 6 g/po.

Furthermore, there are no particular restrictions on the method of coating the intermediate layer. For example, (i) a so-called electroplating method, or (ii) a CvD method in which a raw material gas is supplied to the surface of the plated steel material having the lower layer and a chemical reaction is caused therein, or the above-mentioned Cr, Cr
One type of metal or alloy selected from the group consisting of AQ, Al-based alloys, CO-based alloys, and Ni-based alloys is heated and evaporated in a vacuum by an appropriate method, and this vapor is converted into a metal containing the lower layer. Vacuum evaporation method for depositing on the surface of plated steel,
The ^r ions made into plasma by glow discharge are converted into the Cr,
Cr-based alloy, 8Q, Al-based alloy, Co-based alloy, and N
Atoms of the target plate are collided at high speed with a target plate of one type of metal or alloy selected from the group consisting of i-based alloys,
A sputtering method involves repelling ions (sputtering) and depositing them on the surface of the plated steel material having the lower layer, and further ionizing low-pressure Ar to transfer the Ar'' to the Cr, Cr.
After purifying the surface by colliding with a plate of one type of metal or alloy selected from the group consisting of AQ, Al-based alloys, CO-based alloys, and Ni-based alloys, and then heating the evaporation source, evaporation occurs. This may be carried out by a so-called dry plating method such as a pvd method such as an ion blating method in which the metal collides with Ar'' and becomes metal ions, which are electrostatically attracted and deposited on the surface of the plated steel material having the lower layer. ．Next, the components of the upper layer coating are alloy elements such as Ni,
It is an Fe-based alloy containing one or more of CoSMn, P, S, B, etc., and the composition has a Fe content of 9
0% or more99. It is sufficient if it is 9999% or less. Among the various performances mentioned above, this is to improve paint film adhesion and chemical conversion treatment properties, which greatly contribute to this performance. Fe as the upper layer
By forming a coating layer of the alloy, the phosphate chemical crystals that form on the surface of the steel material during chemical conversion treatment before painting become dense, resulting in good performance. In addition, although the cause is unknown, in order to improve chemical conversion treatment properties and adhesive durability, it is necessary to add NISCO%ta as an alloy component.
It was found that it is necessary to contain one or more types of ns P 1SSB. In addition to the above alloying elements, impurities such as Zn, Al%
Ta-. Cox Sn, sb, cr, ca,
pb, T I! It may or may not contain 11n, V, W%N, etc., and will not cause any problems with the effects of the present invention. Next, the coating weight of the upper Fe alloy coating layer was reduced to 0.
．． The reason why it is limited to 0.01g/nf or more and 10g/rrf or less is explained below.This is because if it is less than 0.01g/nf, there is no effect of preventing the deterioration of adhesive durability caused by the deterioration of corrosion resistance. This is because this effect appears above /nf. On the other hand, in the case of more than 10 g/rd, although the above-mentioned effect is achieved, the performance is saturated or on the contrary tends to decrease, resulting in the problem of increased cost due to the increase in coating.
Furthermore, the performance deteriorates to almost the same level as when plating only the upper layer without an intermediate layer. Therefore, in the present invention, the amount of coating of the upper layer is set to 0.01 g/r.
Limited to RF or more and 10g#d or less. In addition, in order to exhibit stable performance regardless of variations in manufacturing conditions, and taking into account the increased cost due to thicker coating and saturation in terms of performance, the amount of adhesion of the upper layer should be 0;'05 g/rrf or more6.
g/nf or less is more desirable. Note that there are no particular restrictions on the coating method;
In addition to the aforementioned (i) electroplating method and (ii) dry plating method, there is also (iii) an electroless plating method in which the metal is deposited from a metal salt solution onto the surface of the plated steel material to which the intermediate layer has been applied. etc. can be exemplified. Moreover, the three layers in the multilayer plated steel material according to the present invention do not necessarily need to be formed on both sides of the steel material. For example, l. Either one side of the steel is coated with these three layers and the other side is left bare, or II. By coating only one side of the tl4 material with these three layers, and coating the other side with a coating layer with a different composition than the three layers, for example, with only a plating layer, the desired properties required for the steel material can be achieved. All you have to do is get the performance of In this way, the above 3
The multilayer plated steel material according to the present invention having a layer has excellent retention durability, chemical conversion treatment properties, and! ! It has excellent film adhesion, post-painting corrosion resistance, and spot weldability, and is suitable for use in, for example, automobiles, home appliances, and building materials.

In other words, the multilayer plated steel material according to the present invention has particularly excellent adhesive durability. As mentioned above, the base material factors that affect the initial adhesion and adhesive durability of plated steel include the shape of the coating surface and compatibility with the adhesive, as well as the corrosive environment. The deterioration of adhesive durability at the bottom is thought to be caused by the progress of corrosion, especially the progress of corrosion in the direction of the surface of the steel material. The multilayer plated steel material according to the present invention satisfies these performances, but the exact reason why these performances are satisfied by the present invention is unclear. However, the present inventors have confirmed that these factors have been resolved by the present invention, and in particular, regarding the deterioration of adhesive durability that occurs with the progress of corrosion, as described above, the present invention has resolved these factors. , a sacrificial corrosion protection effect is imparted to the steel material by having an alloyed hot-dip galvanized layer as a lower layer, and Cr, Cr-based alloy, A as an intermediate layer.
Q, a coating layer of one metal or alloy selected from the group consisting of Al-based alloys, Co-based alloys, and Ni-based alloys is provided, and as an upper layer, alloy components Ni, Co, Mn,
By applying a coating layer of an Fe-based alloy containing one or more of B, S, and P, (a) chemical conversion treatment properties are improved, and accordingly, coating film adhesion is improved.

(b) Spot weldability is improved.

(C) It is considered that the adhesive durability can be improved by slowing down the corrosion rate and suppressing the spread of the corroded portion in the planar direction.

Further, the present invention will be explained in detail using examples, but these are merely illustrative of the present invention and do not limit the present invention. Example A cold-rolled steel sheet with a thickness of 0.81 mm was subjected to pretreatment, hot-dip galvanizing, and alloying heat treatment by conventional methods to form the lower alloyed hot-dip galvanized layer.

■Pretreatment and hot-dip galvanizing were performed using conventional methods to form the lower layer, which was the hot-dip galvanizing layer.

■Electrogalvanizing was performed using a conventional method.

The composition, surface roughness, and coating amount of this lower layer were measured, and the results are shown in Table 1. Note that the composition is indicated by the number (% by weight) before each element.

As shown in Table 1, plating methods for the intermediate layer and upper layer include electroplating (EL), electroless plating (N
E) and a dry plating method (DP) as appropriate to form an intermediate layer and an upper layer having the compositions and coating amounts shown in Table 1 to form samples Nα1 to Sample 44 (examples of the present invention) and Samples Nll45 to Sample 64 (comparative example, but sample Nt
163 and sample floor 64 had no lower layer). In addition,
In Table 1, GA indicates the alloyed hot-dip galvanizing method, and Gl indicates the hot-dip galvanizing method.

The plating conditions for the intermediate layer and lower layer, which were used in this example, are shown below.

1. (Electroplating conditions) (i) Intermediate layer plating conditions Plating is basically performed in a pyrophosphate bath, sulfuric acid bath, Watt bath, or Sargent bath. salt, acetate,
Carbonates, molybdates, birophosphates, hypophosphites, organic metal salts, or metals previously dissolved in acid were added to the plating bath to achieve the target composition. The ion concentration of the precipitated metal in the bath is 1 to 2.
It was set as M/1. (ii) Upper layer plating conditions FeSOa4HzO: 250g
/ INazSOa or (NH4) zsOs
: Based on a constant plating bath of 100g/1, alloying elements for alloy plating can be added by adding sulfate, acetate, carbonate, molybdate, hypophosphite, organic metal salt, or This was carried out by adding metal etc. dissolved in acid to the plating bath so as to have the target composition. The conditions during electroplating were as follows.

Current density: 40-150 A/ds+”pH
: 1-2 Bath temperature: 50-60"C Liquid flow rate: 1-3+g/s For electroplating from a molten salt bath, chloride molten salt was used, and the electroplating was carried out at a temperature of 200±10°C. In addition, other conditions were the same as those for the intermediate layer described above. U. (Electroless plating conditions) A commercially available bath containing a reducing agent or a bath for chemical displacement deposition was used. The immersion treatment was performed at a bath temperature of 30 to 80°C, and the amount of adhesion was adjusted by changing the immersion time.

III. [Dry plating conditions] Coating with Zn, AQ, Ti, or an alloy containing these as main components was performed by a PVD method or a CVD method. The processing conditions were known. Thus obtained, the width is 25 mm and the length is 1 mm.
For samples Nα1 to NCL64 having a thickness of 20 mm, the adhesive durability of the coating layer, chemical conversion treatment property, secondary coating adhesion, post-painting corrosion resistance, and spot weldability were evaluated by the following means.

[Adhesive durability evaluation]

In order to evaluate the adhesive properties of the obtained samples, the samples were stacked in two sheets with an adhesive interposed in between and heated and dried under the conditions of 175°C x 30 cm. figure(
A T-peel test was conducted as shown in b).

In addition, similar samples were subjected to the following composite corrosion test, and samples were taken out every 10 cycles and subjected to a T-peel test.
Adhesive durability was investigated. In addition, the tensile speed is 5 m/+
*I went in.

Note that the adhesive includes L-liquid type epoxy-based Araldye.
Using XB3062 (manufactured by Nippon Ciba Gaiki), it was glued so that the sheath had a thickness of 100μ. The adhesive area is Radius
It was set to 100ms. Adhesion was evaluated based on the area ratio of the cohesive failure area of the adhesive on the peeled surface, and the larger this value, the better the adhesiveness. The results are shown in Table 1. The evaluation criteria in Table 1 are summarized below. H1 ■ Keikinbi KeiO ・ ・ ・ 100% Good × × ... Less than 50% Poor In addition, in the evaluation of the adhesive durability described above, the following corrosion cycle was considered as one cycle, and a combined corrosion test was performed in combination. went. (1 cycle) The results of adhesion durability are summarized in Table 1 for O cycle, 10 cycle and 20 cycle.

The bending fatigue test was carried out by holding the sample as schematically shown in Figure 2 and repeatedly bending it alternately in the direction of the arrow. [Evaluation of chemical conversion treatment properties] After degreasing with degreasing agent FC4326-TA (manufactured by Nippon Parkerizing Co., Ltd.) and surface conditioning with PZT (manufacturing by Nippon Parkerizing Co., Ltd.), using PH-L3080 (manufactured by Nippon Parkerizing Co., Ltd.), Chemical conversion treatment was performed depending on the conditions. Regarding the chemical crystals in the chemical conversion coating obtained in this way, phosphophyllite was determined by X-ray analysis.
(100) surface strength (P) of Hopeite and (020)
) The crystal structure was investigated by detecting the surface strength (I1) and calculating the P/(P 〇) ratio (P value). The results are shown in Table 1. According to this evaluation method, a large P value means that a chemical treatment product is good. (Made with secondary coating film adhesion) After applying cationic electrodeposition coating (film thickness 2Gam) to the steel plate that has been subjected to the above chemical conversion treatment, it is further coated with a melamine alkyd resin intermediate coating and top coating to create a coating similar to that of automobile exterior panels. A coating with a total dry film thickness of 80μ was performed.The sample thus obtained was soaked in ion exchange water at 50°C for 10 minutes.
The sample was soaked for a day, and then grids were placed on the surface of the sample so that 100 square grids were formed. Then, adhesive tape was pasted on the goblin and the remaining rate of the paint film was investigated after it was removed. As for the evaluation, those in which there were 5 or more areas where 50% or more of the coating film was peeled off were rated as x, those in 4 to 1 areas were rated as ○, and those in which there was no peeling at all were rated as O. [Corrosion resistance after painting] After the above-mentioned chemical conversion treatment and cationic electrodeposition painting, a cross cut was made to reach the base material, and a salt spray test was conducted for 30 days. After the test, the occurrence of red rust at the cross cut portion was investigated. The results are shown in Table 1. In Table 1, no red rust was given as 20, and red rust was given as ×. [Spot weldability] Two of the above samples were stacked, one spot contact was made continuously, and the number of dots that would maintain the nugget diameter of 4T or more (t: plate thickness) was investigated by observing the cross section of the welded part. The results are shown in Table 1. In Table 1, scores of 5,000 or more RBIs were evaluated as 0, and scores of less than 5,000 RBIs were evaluated as ×. The welding conditions are shown below. Pressure force 7 200kgfit flow: IOKA squeeze time
: 28 cycles energization time : 12 cycles Electrode material: Cu-Cr (commonly used) Electrode shape 2 Cone-shaped, diameter 6.0 steel - The test results are summarized in Table 1.

(Margin below) As is clear from Table 1, the examples of the present invention (Samples Nα1 to Sample No. 44) were compared with the comparative examples (Sample No. 45 to Sample No. 6 4) using similar lower layer plating materials. ■ Initial adhesion properties should be the same or better;
and ■ As the corrosion cycle progresses, the adhesion deteriorates significantly in the comparative example, while the inventive example does not deteriorate much and is much better in terms of adhesive durability. ■ Chemical conversion treatment properties , paint film adhesion and post-painting corrosion resistance are also good, and (2) spot weldability is good not only when the lower sacrificial anticorrosion layer is thin but also when it is thick.

On the other hand, it can be seen that when only the lower plating layer is applied, as in the case of samples Nα45 to 46, all the performances deteriorate.

In addition, in samples such as Sample Nα47 or Sample Nα49, in which the amount of intermediate layer deposited is smaller than the range of the present invention, improvements in chemical conversion treatment properties and secondary coating adhesion are recognized, but the improvement is not sufficient. The performance of the system was also unsatisfactory. In addition, for samples such as Sample No. 48 or Sample N[L50, where the amount of the upper layer deposited is smaller than the range of the present invention, improvements in spot weldability and initial adhesion are recognized, but the adhesive durability in particular is not sufficient. In addition, other performance was insufficient. In addition, in sample 81151, in which the amount of the upper layer was excessively adhered, the adhesive durability deteriorated and the advantage of thickening the film was lost. In this way, when the balance between the middle layer and the upper layer is disrupted, the performance of the steel material decreases, and various properties of the steel material improve, especially with respect to adhesive durability, by creating some kind of synergistic effect between the middle layer and the upper layer. considered to be a thing.

In addition, when an upper layer plating material outside the scope of the present invention is used, such as Samples FkL52 to Sample 54, chemical conversion treatment properties decrease and adhesive durability deteriorates even if the coating amount is within the scope of the present invention. I know it will deteriorate.

In addition, when using an intermediate layer that exhibits a higher potential than the base material to be plated, as in the case of sample layer 55 and sample layer 56, the adhesive durability deteriorates, although this is thought to be due to the rapid progression of corrosion in the plane direction. to degrade. In addition, spot weldability may also deteriorate depending on the plating base material.

In addition, when a lower layer outside the scope of the present invention is used, as in Samples N[L57 to 62, the adhesive durability and post-painting corrosion resistance deteriorate.

In addition, sample NQ63 and sample Arashi 64, which do not have a lower layer,
Also, all performance deteriorates. As described above, in the present invention, the effect of having three multilayer coating layers is clear.

(Effects of the Invention) Since the present invention is configured as described above, by using the multilayer plated steel material according to the present invention,
In addition to being able to improve initial adhesion, it is also possible to minimize deterioration of adhesive durability in a corrosive environment.

Furthermore, the multilayer plated steel material according to the present invention has excellent chemical conversion treatment properties, paint film adhesion, post-painting corrosion resistance, and even spot weldability, making it extremely suitable for use in, for example, automobiles, home appliances, and building materials. It is a suitable plated steel material.

As described above, the significance of the present invention, which has high industrial utility value, is that
This is extremely significant.

[Brief explanation of drawings]

FIG. 1(a) and FIG. 1(b) are schematic explanatory diagrams showing the appearance of the samples used in the adhesive durability evaluation tests conducted in the examples of the present invention for multilayer plated steel materials according to the present invention, respectively. and FIG. 2 are schematic explanatory diagrams showing the state of a bending fatigue test in a composite corrosion test conducted in an example of the present invention.

Claims (1)

[Scope of Claims] At least on the surface thereof, a lower layer: an alloyed hot-dip galvanized layer having an average Fe content of 5 to 20% by weight and a surface roughness Ra of 0.3 μm or more, an intermediate layer: adhesion amount is 0.01 to 10 g/m^2, metal: Cr, Al alloy: one selected from the group consisting of Cr, Al, Co and Ni, and Zn, Mn and Fe An alloy upper layer having one or more selected from the group consisting of: an adhesion amount of 0.01 to 10 g/m^2, and F
e content is 90 to 99.9999% by weight, Ni,
A multilayer plated steel material characterized by having a coating layer of an Fe-based alloy containing one or more selected from the group consisting of Co, Mn, B, S, and P.