JPS58120795A - High corrosion resistant steel plate as base metal for coating - Google Patents

Abstract

PURPOSE:To obtain a high corrosion resistant steel plate with improved suitability to coating and improved corrosion resistance and weldability after coating as a base metal for coating by forming an Ni-Fe alloy layer and a Zn-Fe alloy layer by plating on the surface of a steel plate. CONSTITUTION:A 2-layered film composed of an Ni-Fe alloy layer as the 1st layer and a Zn-Fe alloy layer as the 2nd layer is formed by plating on at least one side of a steel plate for the external plates of a car body, etc. to obtain a high corrosion resistant steel plate as a base metal for coating. It is preferable to adjust the amount of the Zn-Fe alloy deposited by the plating to 5-50g/m<2> and the amount of the Ni-Fe alloy to 1/50-1/2 of the amount of the Zn-Fe alloy. The Zn-Fe alloy layer has about 5-80wt% Fe content, and the Ni-Fe alloy layer has about 5-90% Fe content. By further forming an Ni-Fe layer on the other side of the steel plate by plating, performance fit for the service environment can be provided.

Description

【発明の詳細な説明】 本発明は塗装後の耐食性および溶接性の優れた表面処理
鋼板に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface-treated steel sheet with excellent corrosion resistance and weldability after painting.

近年、省資源、省エネルギー等の立場から自動車車体の
耐久性向上に対する要望が社会的に高まっている。従来
より自動車車体の内側袋構造部などからの腐食や穴あき
対策として亜鉛めっき鋼板が−熱使用されてきたが、最
近は冬期通路凍結防止用の岩塩や塩化カルシウムを散布
する地域にあける穴あき規制（例、カナダコード）など
厳しい要請に対応するためより耐食性の高い合金めっき
鋼板が使われる雛勢にある。また外板は、従来は化成性
や塗装性の制約から塗装下地めっきは施されていなかっ
たが、擦り疵や砂石の衝突による塗装剥離郡からの錆対
策として何らかの下地表面処理も要望されるようになっ
てきた。In recent years, there has been a growing social demand for improved durability of automobile bodies from the standpoint of resource and energy conservation. Galvanized steel sheets have traditionally been used to prevent corrosion and punctures from the inner bag structure of automobile bodies, but recently they have been used to prevent holes made in areas where rock salt or calcium chloride is sprayed to prevent freezing of passageways in winter. In order to meet the strict requirements of regulations (e.g. Canadian Code), alloy-plated steel sheets with higher corrosion resistance are being used. In addition, conventionally, exterior panels were not coated with a base plating due to restrictions on chemical conversion and paintability, but some type of base surface treatment is now required to prevent rust from peeling off the paint due to scratches or collisions with sand and stones. It's starting to look like this.

このような状勢に対応するためには、単に塗装下地とし
てのめつき厚を厚くしただけでは、耐食性は向上したと
しても部材接合の抵抗溶接性が劣ったり、加工時にめっ
き層が破壊するなどの障害が発生する。そこで、薄目付
で従来以上の耐食性を有しかつ抵抗溶接性や加工性、更
に塗装性も良好な塗装下地表面処理鋼板について鋭意研
究を重ねた結果、鋼板の少なくとも片面に第１層として
Ｎｉ　−Ｆｅ合金めつき層を、第２層としてＺｎ　−Ｆ
ｅ合金めつき層を形成することにより、あるいは鋼板の
片面に上述した二層皮膜を形成し、他の面にＮｉ　−Ｆ
ｅ合金めつき層を形成することにより、所期の目的を達
成することができることを見い出し、本発明に至った。In order to deal with this situation, simply increasing the thickness of the plating as a base for painting may improve corrosion resistance, but it may result in poor resistance weldability when joining parts, or the plating layer may be destroyed during processing. A failure occurs. Therefore, as a result of extensive research into a steel plate with a coating base surface treatment that has a thinner coating weight and better corrosion resistance than conventional ones, and also has good resistance weldability, workability, and paintability, we found that at least one side of the steel plate has Ni - Zn-F with Fe alloy plating layer as the second layer
By forming an e-alloy plating layer, or by forming the above-mentioned two-layer film on one side of the steel plate and Ni-F on the other side.
It was discovered that the intended purpose could be achieved by forming an e-alloy plated layer, leading to the present invention.

自動車用鋼板の内面腐食については、Ｆｅ含有量が５〜
ｓ　ｏ　ｗｔｘのＺｎ　−Ｆｅ合金めっきが亜鉛めっき
より優れた塗装後耐食性を示すが、前述のような苛酷な
条件では必ずしも満足できない。本発明は、この耐食性
を更に改善しようとするものであり、鋼板の少なくとも
片面に第１ノーとしてＮｉ−Ｆｅ合金めつき層、第２層
としてＺｎ　−Ｆｅ合金めつき層からなる二層皮膜、あ
るいは、鋼板の片面に前記二層皮膜を、他の面にＮｉ　
−Ｆｅ合金めっき層を施して得られる表面処理鋼板であ
り、第１〜３図に示すような態様がある。Regarding internal corrosion of automotive steel sheets, Fe content is 5~
Although the Zn-Fe alloy plating of SO Wtx exhibits superior corrosion resistance after painting than zinc plating, it is not necessarily satisfactory under the severe conditions described above. The present invention aims to further improve this corrosion resistance, and includes a two-layer coating consisting of a Ni-Fe alloy plating layer as the first layer and a Zn-Fe alloy plating layer as the second layer on at least one side of the steel plate. Alternatively, the two-layer coating may be applied on one side of the steel plate and the Ni layer may be applied on the other side.
This is a surface-treated steel sheet obtained by applying a -Fe alloy plating layer, and there are embodiments as shown in FIGS. 1 to 3.

第１図に示すものは、素地鋼１の両面にＮｉ　−Ｆｅ合
金めつき層２２よびｚｎ　−Ｆｅ合金めっき層３を形成
したものであり、第２図に示ｆものは、素地鋼ｌの両面
にＮｉ　−Ｆｅ合金めつき層２を形成し、その片面にＺ
ｎ　−Ｆｅ合金めつき層３を形成したものであり、第３
図に示すものは、素地鋼ｌの片面にＮｉ　−Ｆｅ合金め
つき層２およびＺｎ　−Ｆｅ合金めっき層３を形成した
ものである。The one shown in FIG. 1 has a Ni-Fe alloy plating layer 22 and the Zn-Fe alloy plating layer 3 formed on both sides of the base steel 1, and the one shown in FIG. Ni-Fe alloy plating layer 2 is formed on both sides, and Z
n-Fe alloy plating layer 3 is formed, and the third
What is shown in the figure is one in which a Ni--Fe alloy plating layer 2 and a Zn--Fe alloy plating layer 3 are formed on one side of a base steel l.

本発明においては、前述したようにＮｉ　−Ｆｅ合金め
つき層を下地として形成するのであるが、このように下
地めっきとしてＮｉ　−Ｆｅ合金めっきを採用する目的
は以下の通りである。In the present invention, as described above, the Ni-Fe alloy plating layer is formed as the base plating, and the purpose of employing the Ni-Fe alloy plating as the base plating is as follows.

α）Ｚｎ−Ｆｅ合金めつきと素地鋼との間にもう一層の
耐食性の皮膜を施し、同一めっき厚のＺｎ　−Ｆｅ合金
めっき層以上の耐食性を得、またＮｉ　−１ｉ’ｅ単独
めっき面においても安定した鋼板表面状態をつくり、い
ずれの面においても無塗装および塗装後の耐食性の改良
、ならびに塗膜の二次密着性の改良を図ろうとするもの
である。α) Another corrosion-resistant film is applied between the Zn-Fe alloy plating and the base steel to obtain corrosion resistance greater than that of the Zn-Fe alloy plating layer of the same plating thickness, and on the Ni-1i'e single plating surface. The aim is to create a stable surface condition of the steel sheet, improve corrosion resistance on both surfaces, both unpainted and after painting, and improve the secondary adhesion of the paint film.

（２）　Ｎｉ　−Ｆｅ合金を下地とすることによりＦｅ
　成分を素地鋼から最表面まで段階的に積層させること
により、最表面ｚｎ　−Ｆｅ合金めっきの密着性の改良
およびめっき歪の緩和を図ろうとするものである。(2) By using Ni-Fe alloy as a base, Fe
By layering the components in stages from the base steel to the outermost surface, it is intended to improve the adhesion of the outermost surface Zn-Fe alloy plating and to alleviate plating distortion.

０）たとえ素地鋼に至る損傷を受けた場合でも、素地鋼
やＺｎ　−Ｆｅ合金よりも貴であるＮｉ　−Ｆｅ合金が
一位差の大きい最表面のＺｎ　−Ｆｅ合金とのカップル
を優先的につくって素地鋼の腐食を遅延せしめ、かつ安
定なＮｉ　−Ｆｅ合金めつき層に腐食生成物像沈着せし
めることにより、さらに一層素地鋼の腐食を抑制しよう
とするものである。0) Even if the base steel is damaged, the Ni-Fe alloy, which is nobler than the base steel or Zn-Fe alloy, will preferentially couple with the Zn-Fe alloy on the outermost surface, which has a larger difference in rank. The purpose is to further suppress the corrosion of the base steel by delaying the corrosion of the base steel and depositing corrosion product images on the stable Ni--Fe alloy plating layer.

自動車車体の外面（外板）では一般的に、電着塗装、中
塗り、上塗りなどの塗装が施され、上述の苛酷な腐食環
境での耐食性が要求される。これに対して、例えば亜鉛
系めっきの使用が考えられるが、塗装した亜鉛系めっき
鋼板では、チツピングを受けた部分で糸状さびを生じ、
ついには赤錆発生に至る。更には亜鉛系めっき鋼板では
塗装後の色調変化（色むら）が多くなり、このためその
使用が困難であり、一般的には冷延鋼板または片面の表
面処理鋼板が用いられている。本発明では上述のように
このような自動車車体の外板の塗装性、塗装後の耐食性
を著しく改良することができる。The outer surface (outer panel) of an automobile body is generally coated with electrodeposition coating, intermediate coating, top coating, etc., and is required to have corrosion resistance in the above-mentioned severe corrosive environment. To deal with this, for example, the use of zinc-based plating can be considered, but painted galvanized steel sheets may develop filamentous rust in areas that have been chipped.
Eventually, red rust develops. Furthermore, zinc-based plated steel sheets tend to change color tone (color unevenness) after painting, making them difficult to use, and generally cold-rolled steel sheets or single-sided surface-treated steel sheets are used. As described above, the present invention can significantly improve the paintability of the outer panels of such automobile bodies and the corrosion resistance after painting.

本発明は上述の如く鋼板の表裏で異なった環境で使用す
る場合、その使用環境に適合した性能を賦与することを
特長とし、本発明において形成するＮｉ　−Ｆｅ合金め
つき層の耐食性向上効果によりＺｎ−Ｆｅ合金めつき層
の削減ができ、省エネルギー、省資源をはじめ、溶接性
が改良される有利性があ０ 本発明において用いる鋼板の種類、寸法は特に限足され
ないが、Ｎｉ　−Ｆｅ合金付着量は０．１ｆ／−以上が
好ましい。Ｎｉ　−ｐｓｓ付着量が０．１ｆ／ｍｌ以下
では単独においてもＺｎ　−Ｆｅ下地層としても耐食性
の向上はない。また、最適付着量は対応する’ｌｎ　−
Ｆｅ　／Ｉ＃の厚みにより決められ、ムーＦｅ層の５０
分の１から２分の１にするのが好適である。As mentioned above, when the front and back sides of a steel plate are used in different environments, the present invention is characterized by providing performance suitable for the usage environment, and due to the corrosion resistance improvement effect of the Ni-Fe alloy plating layer formed in the present invention. The Zn-Fe alloy plated layer can be reduced, which has the advantage of saving energy and resources as well as improving weldability. Although the type and dimensions of the steel plate used in the present invention are not particularly limited, the Ni-Fe alloy The amount of adhesion is preferably 0.1 f/- or more. If the amount of Ni-pss deposited is less than 0.1 f/ml, there is no improvement in corrosion resistance either alone or as a Zn-Fe underlayer. Moreover, the optimum adhesion amount is the corresponding 'ln −
Determined by the thickness of Fe/I#, 50
It is preferable to reduce the amount by 1/2 to 1/2.

またＮｉ　−１’ｅ層のむ含有量はその加工性の点から
は１０〜５０　ｗｔＸが望ましいが、これに限られるも
のではなく、目的に応じて５ｗｔ％から９０ｗｔＸまで
効果を肩する。Further, the content of the Ni-1'e layer is desirably 10 to 50 wtX from the viewpoint of processability, but is not limited to this, and the effect can be increased from 5 wt% to 90 wtX depending on the purpose.

Ｎｉ　−Ｆｅ合金めつき層を形成した鋼板の少なくとも
一万の面に行なうＺｎ　−Ｆｅ合金めつきの付着量は５
〜５０ｆ／−が好ましく、５ｆ／−未満では高耐食性が
得られず、５０１／ｌを超えると経済的に不利である。The amount of Zn-Fe alloy plating applied to at least 10,000 surfaces of the steel plate on which the Ni-Fe alloy plating layer is formed is 5.
~50 f/- is preferable; if it is less than 5 f/-, high corrosion resistance cannot be obtained, and if it exceeds 501/l, it is economically disadvantageous.

またＺｎ　−Ｆｅ層のｐｅ　含有率は、本発明者等の研
究によると、５〜８０　ｖｙｔＫが塗装後針食性の優れ
ている範囲である。Further, according to research by the present inventors, the PE content of the Zn-Fe layer is within a range of 5 to 80 vytK in which the corrosion resistance after coating is excellent.

本発明に用いられるめっき浴は高ｔｆ１．密度が得られ
、めっき浴の電気伝導度がよいことが望ましく、この観
点から硫酸塩浴、塩化物浴またはこれらの混合浴が用い
られ、電流密［１０Ａ／υ以上、液流速１０ｍ／―以上
での電解が実用的に望ましい。以下、不発Ｆ！Ａを実施
例につき説明する。The plating bath used in the present invention has a high tf1. It is desirable that the plating bath has good electrical conductivity, and from this point of view, a sulfate bath, a chloride bath, or a mixed bath thereof is used. Electrolysis is practically desirable. Below is the unexploded F! A will be explained with reference to an example.

〔実施例１〕 素材５ＰＣＣ，板厚０．７Ｍ、＠１００履、長さ２００
ｍの冷延鋼板を電解脱脂、酸洗を行った後、下記のＮ１
−Ｆｅ合金めっき浴を用いて１５Ａ／ｄｄの電流密度、
浴温６０℃で両面にそれぞれ２ｔ７ｉの付着量となるよ
うにＮｉ　−Ｆｅ合金めつきした。この試料にさらに下
記のＺｎ　−Ｆｅ合金めつき浴を用いて６０Ａ／−の電
流密度、浴温５０℃で表面には１６　ｆ　／　ｄ、裏面
には８ｆｄの付着量となるように表裏差厚のＺｎ　−Ｆ
ｅ合金めつきを行った。[Example 1] Material 5PCC, board thickness 0.7M, @100 shoes, length 200
After electrolytically degreasing and pickling a cold-rolled steel sheet of m, the following N1
- a current density of 15 A/dd using a Fe alloy plating bath;
Ni-Fe alloy was plated on both sides at a bath temperature of 60° C. to a coating weight of 2t7i on each side. This sample was further plated using the following Zn-Fe alloy plating bath at a current density of 60 A/- and a bath temperature of 50°C, so that the coating amount was 16 f/d on the front surface and 8 fd on the back surface. Zn-F
e Alloy plating was performed.

（１）Ｎｉ　−１”ｅ合金めつき浴 ＮｉＳＯ４，６Ｈ，０１０５ｆ／１ ＮｉＣｔｚ　、６Ｈ２０６０ｔ　／　ｌＦｅＳＯ４２０
ｔ　／　ｔ ＨｓＢＯｓ　　　　　　　　　　５０　ｔ　／　ＬｐＨ
３ ■　Ｚｎ　−Ｆｅ合金めつき浴 ムＣＬ２　　　　　　　　１３０　ｆ　／　ＬＦｅＣｔ
２　　　　　　　　１２０　ｆ　／　ｌ。(1) Ni-1”e alloy plating bath NiSO4,6H,0105f/1 NiCtz, 6H2060t/lFeSO420
t/t HsBOs 50 t/LpH
3 ■ Zn-Fe alloy plating bath CL2 130 f / LFeCt
2 120 f/l.

凪Ｃ２６０９／１ Ｃ６Ｈ１１０７１ｆ　／　ｔ ｐＨ２ このようにして得られた本発明の表面処理鋼板、従来の
Ｚｎ　−Ｆｅ合金めつき鋼板および冷延鋼板について以
下に記すような種々の試験を行った。その結果を第１表
に示す。Calm C2609/1 C6H11071f/t pH2 Various tests as described below were conducted on the thus obtained surface-treated steel sheet of the present invention, a conventional Zn-Fe alloy plated steel sheet, and a cold-rolled steel sheet. The results are shown in Table 1.

■　電着塗装後の耐食性 塩水噴霧試験（ＪＩＳ　　Ｚ　　２３７１）３０日後に
おけるカチオン呈電着塗装（１０ｐｍ　）クロスカット
部からの塗膜ふくれ幅（調）■　３スート塗装後の耐食
性 塩水噴霧試験９０日後に２ける３コート塗装（電着中中
塗り十上塗りンクロヌカット部からの塗膜ふくれ幅（關
） 第１表の諸試験結果から、本発明による表面処理鋼板は
従来のものに比して、塗装後の耐食性が著しく改良され
ていることが明らかである。■ Corrosion resistance salt water spray test after electrodeposition coating (JIS Z 2371) Width of cationic electrodeposition coating (10 pm) after 30 days from the cross-cut area (tone) ■ Corrosion resistance salt water spray test after 3 soot coating 90 days From the various test results shown in Table 1, the surface-treated steel sheet according to the present invention has a higher coating thickness than the conventional one. It is clear that the subsequent corrosion resistance is significantly improved.

第１表 〔実施例２〕 素材５ｐｃｃ、板厚０．７ｍ−幅１０Ｑａｇ、長さ２０
０ｍｍの冷延鋼板を実施例１と同様ｌこして電解脱脂１
酸洗を行った後、下記のＮｉ　−Ｆｅ合金めつき浴を用
いて１５Ａ／−の電流密度、浴温６０℃で両面にそれぞ
れ３１／ｄの付着量となるようにＮｉ−１ｉ’ｅ合金め
つきした。さらに、この試料の片面のみに実施例１の■
に示すｚｎ　−１；’ｅ金合金つき浴を用いて５０　Ａ
　／　ｄｓ／の電流密度、浴ｉ！４５℃でｉ　ｓ　ｔ７
ｒｉの付着量となるようにＺｎ　−Ｎｉ合金めつきを行
った。Table 1 [Example 2] Material 5 pcc, plate thickness 0.7 m - width 10 Qag, length 20
A 0 mm cold rolled steel plate was strained and electrolytically degreased in the same manner as in Example 1.
After pickling, using the following Ni-Fe alloy plating bath, at a current density of 15 A/- and a bath temperature of 60°C, Ni-1i'e alloy was coated on both sides with a coating weight of 31/d on each side. I was impressed. Furthermore, on only one side of this sample,
50 A using a bath with gold alloy as shown in zn -1;'e
/ds/ current density, bath i! is t7 at 45℃
Zn-Ni alloy plating was performed so that the coating amount was ri.

＜１）Ｎｉ−Ｆｅ合金めつき浴 ＦｅＣ１−ｚ　・４ＨｘＯ３００ｆ／ＬＮｔＣｚ、・６
迅０　　　　　　　　４０　ｆ／１ＣＦＬＣ１ｘ　　　
　　　　　　　　１８０　ｆ／ＬＰＨ１，０ このようにして得られた本発明の表面処理鋼板、従来の
Ｚｎ　−Ｆｅ合金めつき鋼板および冷延鋼板について実
施例１と同様の諸種の試験および溶接性試験を行った。<1) Ni-Fe alloy plating bath FeC1-z ・4HxO300f/LNtCz, ・6
Speed 0 40 f/1CFLC1x
180 f/LPH1.0 Various tests and weldability tests similar to those in Example 1 were conducted on the surface-treated steel sheet of the present invention, conventional Zn-Fe alloy plated steel sheet, and cold rolled steel sheet thus obtained. .

その結果を第２表に示す。なお、溶接性試験は、本発明
の表面処理鋼板を第４図のように重ね合わせて連続スボ
ツ）ｉｌｌ接を行い、その連続打点数で評価した。！接
電流は９０００Ａ。The results are shown in Table 2. In the weldability test, the surface-treated steel sheets of the present invention were stacked together as shown in FIG. 4, and continuous welding was performed, and the number of continuous welds was evaluated. ! The contact current is 9000A.

加圧力２２０ｋ、溶接時間１２ナイクルである０第２表
の諸試験結果から、Ｎｌ　−Ｆｅ合金めっき上にＺｎ　
−Ｆｅ合金めつき層を施した鋼板では実施例１と同様に
優れた耐食性を示し、またＺｎ　−Ｆｅ合金めつきを施
さなかったＮｉ　−Ｆｅ合金めっきのみの鋼板でも電着
塗装および３コート塗装後の耐食性は著しく優れており
、特に３：１−　）塗装後の耐食性は従来のＺｎ　−Ｆ
ｅ合金めっきおよび冷延鋼板に比べて著しく優れている
ことがわかる。また、本例における片面Ｚｎ　−Ｆｅ合
金めっき鋼板は両面Ｚｎ　−’ｆ；’ｅ合金めつき鋼板
に比べて溶接性の改良効果も大きい。From the test results in Table 2, where the pressure was 220k and the welding time was 12N, it was found that Zn on the Nl-Fe alloy plating
-The steel plate with the Fe alloy plating layer showed excellent corrosion resistance as in Example 1, and the steel plate with only the Ni-Fe alloy plating without the Zn-Fe alloy plating could also be coated with electrodeposition and three coats. The corrosion resistance after coating is extremely excellent, especially after coating with 3:1-) compared to conventional Zn-F.
It can be seen that this is significantly superior to e-alloy plating and cold-rolled steel sheets. Furthermore, the single-sided Zn--Fe alloy-plated steel sheet in this example has a greater weldability improvement effect than the double-sided Zn-'f;'e alloy-plated steel sheet.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図、！２図２よび第３図は本発明の表面処理鋼板の
態様を示す断面図、第４図はスポット溶接試験における
鋼板の重ね合わせ状態を示す線図的部分断面図である０ 符号の説明 １−鋼板、２−Ｎｉ−Ｆｅ合金めつき層、３・−に−Ｆ
ｅ合金めつき層、４−スポット溶接用電極特許出願人　
川崎製鉄株式会社 代理人弁理士　渡　辺　望　稔　′ バ１１１．７Figure 1! 2. FIGS. 2 and 3 are cross-sectional views showing aspects of the surface-treated steel sheet of the present invention, and FIG. 4 is a schematic partial cross-sectional view showing the overlapping state of the steel sheets in a spot welding test.0 Explanation of symbols 1- Steel plate, 2-Ni-Fe alloy plating layer, 3-F
E-alloy plating layer, 4-spot welding electrode patent applicant
Kawasaki Steel Co., Ltd. Representative Patent Attorney Nozomu Watanabe' BA111.7

Claims (1)

【特許請求の範囲】 ０）　　鋼板の少なくとも片面に第１層としてＮｉ−Ｆ
ｅ合金めつき膚、第２層としてＺｎ　−Ｆｅ合金めっき
層からなる二層皮膜を有することを特徴とする＋’−，
ｊ劃食注表側処理鋼板。 （２）　Ｚｎ　−Ｆｃ合金めつきの付着量を５〜５０ｔ
／ｄとし、Ｎｉ　−）’ｅ金合金っきの付着量をｚｎ　
−Ｆｅ合雀めつき−のＶ２Ｏ−Ｖ２とすることを特徴と
する特許請求の範囲第１項に記載の局耐食性表面処理鋼
板・ （３）　　’Ｉｎ−Ｆｅ合金めつきの皮膜組成をｐｅ含
含量量５−８０　ｗｔＸｌＮｉ　−Ｆｅ合金めっきの皮
膜組ｇ’Ｅ−Ｆｂ含イ】！ｔで５〜９Ｑｗｔ％とするこ
とを特徴とする特、？′１″請求の範囲第１項または第
２項に記載の高耐食性表面処理鋼板。 （４）鋼板の片面に第１層としてＮｉ　−）ｉ’ｅ合金
めっき層、１Ｊ４Ｚ２層としてＺｎ　−Ｆｅ合金めっき
層からなる二層皮膜を有し、鋼板の他の面にＮｉ　−Ｆ
ｅ合金めつき層をＭＴることを特徴とする高耐食性表面
処理鋼板。 （５）　　Ｚｎ−Ｆｅ合金めつきの付着量を５〜５０ｆ
／ｉとし、Ｎｉ　−Ｆｅ合金めっきの付！ｊｉをＺｎ　
−Ｆｅ合金めっき量の］１５０〜ｌ／２とすることを特
徴とする特許請求の範囲第４項に記載の高耐食性表面処
理鋼板。 （６）　　Ｚｎ　−Ｆｅ合金めつきの皮膜組成をＦｅ含
含量量５〜８０Ｗ′ｔＸ′）Ｎｉ−Ｆｅ合金めっきの皮
膜組成をＦｅ含含量量５〜９０帆％と１−ることを特徴
とする特許請求の範囲第４項または第５項に記載の高耐
食性表面処理鋼板。[Claims] 0) Ni-F as a first layer on at least one side of the steel plate
+'-, characterized by having a two-layer film consisting of an e-alloy plating layer and a Zn-Fe alloy plating layer as the second layer;
Note: Surface treated steel plate. (2) The amount of Zn-Fc alloy plating applied is 5 to 50 tons.
/d, and the amount of Ni −)'e gold alloy plating is zn
The locally corrosion-resistant surface-treated steel sheet according to claim 1, characterized in that the steel plate is V2O-V2 with -Fe alloy plating. Amount 5-80 wtXlNi -Fe alloy plating film set g'E-Fb included]! A special feature of 5 to 9 Qwt% in t? '1'' Highly corrosion-resistant surface-treated steel sheet according to claim 1 or 2. (4) Ni-)i'e alloy plating layer as the first layer on one side of the steel sheet, and Zn-Fe alloy as the 1J4Z2 layer. It has a two-layer coating consisting of a plating layer, and the other side of the steel plate is coated with Ni-F.
A highly corrosion-resistant surface-treated steel sheet characterized by having an MT e-alloy plating layer. (5) Adjust the amount of Zn-Fe alloy plating to 5 to 50 f.
/i with Ni-Fe alloy plating! ji to Zn
-The highly corrosion-resistant surface-treated steel sheet according to claim 4, characterized in that the amount of the Fe alloy plating is from 150 to 1/2. (6) The film composition of the Zn-Fe alloy plating has a Fe content of 5 to 80 W'tX') The film composition of the Ni-Fe alloy plating has a Fe content of 5 to 90%. A highly corrosion-resistant surface-treated steel sheet according to claim 4 or 5.