JPH0142359B2 - - Google Patents
Info
- Publication number
- JPH0142359B2 JPH0142359B2 JP60012057A JP1205785A JPH0142359B2 JP H0142359 B2 JPH0142359 B2 JP H0142359B2 JP 60012057 A JP60012057 A JP 60012057A JP 1205785 A JP1205785 A JP 1205785A JP H0142359 B2 JPH0142359 B2 JP H0142359B2
- Authority
- JP
- Japan
- Prior art keywords
- layer
- plating
- painting
- corrosion resistance
- zinc phosphate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000007747 plating Methods 0.000 claims description 34
- 238000005260 corrosion Methods 0.000 claims description 24
- 230000007797 corrosion Effects 0.000 claims description 22
- 229910000831 Steel Inorganic materials 0.000 claims description 21
- 239000010959 steel Substances 0.000 claims description 21
- 238000010422 painting Methods 0.000 claims description 19
- 239000011701 zinc Substances 0.000 claims description 17
- LRXTYHSAJDENHV-UHFFFAOYSA-H zinc phosphate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LRXTYHSAJDENHV-UHFFFAOYSA-H 0.000 claims description 17
- 229910000165 zinc phosphate Inorganic materials 0.000 claims description 17
- 229910052759 nickel Inorganic materials 0.000 claims description 10
- 239000000956 alloy Substances 0.000 claims description 8
- 229910045601 alloy Inorganic materials 0.000 claims description 8
- 229910018605 Ni—Zn Inorganic materials 0.000 claims description 5
- 239000010410 layer Substances 0.000 description 32
- 239000011248 coating agent Substances 0.000 description 13
- 238000000576 coating method Methods 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 12
- 239000000126 substance Substances 0.000 description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 238000000227 grinding Methods 0.000 description 9
- 238000005275 alloying Methods 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 8
- 238000011156 evaluation Methods 0.000 description 8
- 229910001297 Zn alloy Inorganic materials 0.000 description 5
- 229910000640 Fe alloy Inorganic materials 0.000 description 4
- 238000004070 electrodeposition Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 229910052827 phosphophyllite Inorganic materials 0.000 description 4
- SPDJAIKMJHJYAV-UHFFFAOYSA-H trizinc;diphosphate;tetrahydrate Chemical compound O.O.O.O.[Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O SPDJAIKMJHJYAV-UHFFFAOYSA-H 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- 125000002091 cationic group Chemical group 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 229910017813 Cu—Cr Inorganic materials 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 229910007567 Zn-Ni Inorganic materials 0.000 description 1
- 229910007614 Zn—Ni Inorganic materials 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229920000180 alkyd Polymers 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000006056 electrooxidation reaction Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000007591 painting process Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 description 1
- 229960001763 zinc sulfate Drugs 0.000 description 1
- 229910000368 zinc sulfate Inorganic materials 0.000 description 1
Landscapes
- Electroplating Methods And Accessories (AREA)
Description
〔産業上の利用分野〕
本発明は、自動車用鋼板等として好適な、表面
処理鋼板に関し、特に、塗装後の耐食性に優れた
亜鉛系表面処理鋼板に関する。
〔従来の技術〕
従来より、Znメツキ鋼材は、Znの持つ優れた
防食機能のために自動車、家電製品、建材等に広
く使用されてきたが、Znメツキ表面は一般に塗
装後耐食性に劣り、塗膜の防食機能を十分に利用
できない問題がある。
特に自動車用の塗装工程でカチオン電着に先立
つて下地処理として施されるリン酸亜鉛処理にお
いて、ZnリツチなZn系メツキ鋼板ではアルカリ
に弱いホパイト（Hopeite Zn3（PO4）2・4H2O）
が化成結晶として析出し、電気化学的腐食等に対
して下地被膜として十分に機能しないことが生じ
る。
また、Ni−Zn合金メツキは、裸耐食性では高
耐食性を示し、自動車用防錆鋼板として使用され
ている。ところが、塗装後の耐食性については、
耐水密着性に劣る欠点があり、自動車用途で問題
となるコズメテイツク・コロージヨンにおいて好
ましくない。
これを解決するために、たとえば、Zn−Ni合
金メツキ層の上にFeリツチなFe−Zn合金メツキ
層を形成することにより、比較的アルカリに強い
フオスフオフイライト（phosphophyllite Zn2Fe
（PO4）2・4H2O）なる化成結晶を形成させ、耐水
密着性を改善することが提案されている（特開昭
58−15554号、特開昭58−52483号公報、等）。ま
た、リン酸亜鉛処理性を処理液側から改善する方
法として、リン酸亜鉛処理液中にNi2+等の金属
イオンを添加することが提案されている（たとえ
ば鉄鋼協会 鉄と鋼vol70No.５ S46（1984））。
〔発明が解決しようとする問題点〕
しかしながら、Zn−Ni合金メツキ層の上にFe
リツチなFe−Zn合金メツキ層を形成する方法は、
たしかに耐水密着性を改善することはできるが、
自動車用途においては、飛石等により塗膜傷（ピ
ツチング）が生じるような場合に、傷部分に赤錆
を生じ易いという別の問題が起きる。
一方、リン酸亜鉛化成処理液にNi2+等を添加
する方法は、本発明者らの研究によると、化成被
膜に取り込まれるNi等をいかに供給するかが重
要なポイントであり、化成被膜に取り込まれる
Ni等を所要のものとするためには、相当量の
Ni2+等を化成処理液中に添加しなければならな
い。しかしながら、多量のNi2+等を化成処理液
中に添加すると、液そのものが不安定となり、ま
た、安定したNi供給を行なうためには、液の管
理が極めてむつかしいという問題がある。
そこで、本発明の目的は、上記Ni源等を、効
率的かつ安定的にリン酸亜鉛被膜中に供給するこ
とのできるとともに、特に耐水密着性が良好な塗
装後の耐食性に優れた表面処理鋼板を提供するこ
とにある。
〔問題点を解決するための手段〕
上記問題点を解決するために、本発明によれば
所定量のNi等を鋼板の表層に付着させておき、
塗装前処理であるリン酸亜鉛処理においてNi等
を溶出せしめ、リン酸亜鉛被膜形成時にNi等を
取り込んだ化成被膜を形成することにより、耐水
密着性を改善することが提案される。
すなわち、本発明によれば、塗装前処理として
のリン酸亜鉛化成処理がなされる表面処理鋼板に
おいて、鋼板の少なくとも片面に、第１層とし
て、Znを80wt％以上含み、さらにFeを10wt％を
超えかつ20wt％以下含有するZn−Fe系合金メツ
キを形成し、その上に第２層として、Ni、ある
いはNiとCoおよび／またはMnを合計で30％を超
え80％以下量含有するNi−Zn系合金メツキを0.5
〜５ｇ／m2形成したことを特徴とするものであ
る。
鋼板の少なくとも片面に、第１層として形成さ
れるメツキ層は、それ自体高耐食性を有する安定
したメツキ層である必要があり、裸耐食性に優れ
たZn−（10〜20wt％）Fe合金メツキ（ただし
10wt％を含まない）が用いられる。
また、これらに、微量（１〜5wt％）のCo、
Ni、Mn等をさらに含ましめた高耐食性メツキ被
膜であつてもよい。これらはいずれも、焼付塗装
たとえばカチオン電着の場合で160〜180℃、20分
間の加熱後に、δ1相（Zn−Fe合金）等単相で均
一な被膜を有するものである。
しかしながら、第１層において、Zn以外の元
素、たとえばFe、Ni、Mn等の合計で20wt％以
上であつてはならない。これは、Zn以外の元素
が20wt％以上となると、合金元素の種類にかか
わらず、特に自動車用途においてメツキ鋼板のプ
レス成形等の加工時にパウダリング現象を生じ易
くなるからである。この点において、合金元素は
15wt％以下であることがより好ましく、次に述
べるように第２層にNiリツチなNi−Zn合金メツ
キを施すことによつて合金元素含有率をさらに下
げることも可能である。
第２層としては、第１層上に、Niを30wt％を
超え80wt％以下量含むNi−Zn合金メツキ、ある
いは、NiとCoおよび／またはMn、すなわちNi
＋Co、Ni＋MnまたはNi＋Co＋Mn、を合計でて
30wt％を超え80wt％以下量含むNi−Zn系合金メ
ツキが0.5〜５ｇ／m2施される。
第２層のNi等（Ni、あるいはNi＋Coおよび／
またはMn）の含有率の限定理由は、基本的には
Ni等が多いほどリン酸亜鉛被膜への供給量が多
くなるけれども、第２層のNi等が80wt％を超え
ると、メツキ被膜の溶解性が極端に悪くなり、
Ni等のリン酸亜鉛被膜への供給を十分行うこと
ができず、一方Ni等の含有率が30wt％以下であ
ると、メツキ被膜の溶解性は良好であるが、Ni
等の量が少ないためそのリン酸亜鉛被膜への供給
が不十分となるためであり、また後述するスポツ
ト溶接電極寿命も低下するためでもある。
また、第２層の付着量については、0.5ｇ／m2
に満たない場合には、そのNi等の量が少ないた
め効果を十分発揮できず、５ｇ／m2をこえると、
その効果が飽和し経済的でないので、上記範囲に
限定される。
〔作用〕
本発明において、第２層を、Ni−Zn合金メツ
キ（30＜Ni≦80％、30＜Ni＋Mnおよび／または
Co≦80％）層としたのは、表層に上記範囲の含
有量を有するNi、Ni＋Coおよび／またはMnを
付着させておくことによつて、塗装前処理である
リン酸亜鉛処理においてNi、Coおよび／または
Mnを溶出せしめ、リン酸亜鉛皮膜形成時にNi、
Coおよび／またはMnを取り込んだリン酸亜鉛皮
膜を形成させるためである。このリン酸亜鉛皮膜
によつて、塗装後の耐食性、特に耐水密着性を向
上させることができる。
すなわち、本発明によれば、Ni2+等を化成処
理液中に添加する必要がなく、かつその添加を行
わなくとも第２層中のNi等の溶出によりリン酸
亜鉛の化成処理性が十分なものとなり、塗装後の
耐食性を向上させることができる。なお、この皮
膜は、Ｘ線回析上はHopeite Zn3（PO4）2・4H2O
と同様の回析角度を有しているため、通常リン酸
塩処理性の評価に用いられるPhosphophyllite
Zn2Fe（PO4）2・4H2OとHopeite Zn3（PO4）2・
4H2Oの比率Ｐ／Ｐ＋Ｈは、Ｏである。
さらに、上記したように、第２層により耐水密
着性等の塗装後の耐食性が向上するため、第１層
の合金元素量を減らすことが可能となり、パウダ
リングを抑制できる。しかも、第２層のNi等が
スポツト電極（Cu−Cr合金）のZuとCrとの合金
化を抑制し、電極寿命を著しく向上できる。
総合的にみれば、特有の第１層と第２層との組
み合わせが巧妙に作用し、裸耐食性および塗装後
の耐食性、特に耐水密着性がきわめて良好なもの
となる。
〔実施例〕
鋼板を電解脱脂および酸洗した後、これに、硫
酸亜鉛を主体とする第１表のような浴組成および
メツキ条件で、Zn主体の第１層を形成した。微
量の合金元素を含有させる場合には、硫酸浴中に
Co2+、Mn2+を硫酸塩の形で添加してメツキを行
なつた。
尚、第１層として合金化溶融亜鉛メツキの場合
には、鋼板をNOFで加熱したのち還元炉で還元
後、溶融メツキポツトに浸漬して、溶融メツキし
た。その後、合金化炉にて加熱して合金化させ、
その加熱温度によつてFe含有率を管理した。
第 １ 表
第１層メツキ浴およびメツキ条件
メツキ浴
Zn2+：50ｇ／
Fe2+：50ｇ／
Na2SO4：50ｇ／
CH3COONa・3H2O：20ｇ／
（Co2+、Mn2+はいずれも５〜10ｇ／添加）
PH：２
メツキ浴温：60℃
メツキ条件
電流密度：20〜80A／ｄm2
ついで、この上に、第２表に示すような浴組成
およびメツキ条件で第２層を形成した。微量の合
金元素は第１層と同様に硫酸塩の形で添加した。
第 ２ 表
第２層メツキ浴およびメツキ条件
メツキ浴
Ni2+：60ｇ／
Zn2+：30ｇ／
Na2SO4：50ｇ／
CH3COONa・3H2O：20ｇ／
（Co2+、Mn2+はいずれも５〜10ｇ／添加）
PH：２
メツキ浴温：60℃
メツキ条件
電流密度：20〜80A／ｄm2
上記のようにして得られたメツキ鋼板に対し、
第３表に示す塗装条件で塗装を施した。
第 ３ 表
塗装条件
化成処理液：日本パーカー社製
「BT−3030」
カチオン電着：日本ペイント社製
「パワートツプ Ｕ−30」20μｍ
中・上塗り：市販の焼付型メラミンアルキツド
塗料、各35μｍ
総合膜厚≒90μｍ
塗装後耐食性の評価は、第４表に示す項目、内
容で実施した。塗装後耐食性の評価結果を第５表
に示す。
第 ４ 表
塗装後耐食性評価項目と内容：
Ａ 塩水噴霧テスト（SST）
カチオン電着塗装までの１コート材にカツタ
ーナイフでクロスカツトを入れ、SST600時間
後のクロスカツトからのふくれ巾を評価
Ｂ 耐水密着性
中、上塗り後の３コート材を50℃脱イオン中
で10日間浸漬し、その後２mm間隔のゴバン目を
入れテープ剥離し、塗膜の残存率を評価
Ｃ 耐チツプ耐食性
３コート材をグラベロメーターにて塗膜チツ
ピングしSST240時間後の赤錆発生程度を評価
さらに、パウダリング性の評価として、円筒絞
りによる評価を実施した。結果を第５表に示す。
評価は、円筒絞りされたサンプルの外壁および内
壁について、テープ剥離テストを実施し、その剥
離量で行なつた。
第５表中評価基準は、◎：パウダリングなし、
〇：パウダリング微少、△：パウダリング少、
×：パウダリング大である。
[Industrial Field of Application] The present invention relates to a surface-treated steel sheet suitable as a steel sheet for automobiles, and more particularly to a zinc-based surface-treated steel sheet with excellent corrosion resistance after painting. [Conventional technology] Zn-plated steel materials have been widely used in automobiles, home appliances, building materials, etc. due to Zn's excellent anti-corrosion properties. However, Zn-plated surfaces generally have poor corrosion resistance after painting, and There is a problem that the anti-corrosion function of the membrane cannot be fully utilized. Particularly in the zinc phosphate treatment applied as a base treatment prior to cationic electrodeposition in the automotive painting process, Zn-rich Zn-based plated steel sheets contain alkali-resistant hopeite (Hopeite Zn 3 (PO 4 ) 2.4H 2 O). )
is precipitated as chemical crystals, which may not function satisfactorily as a base film against electrochemical corrosion and the like. In addition, Ni-Zn alloy plating exhibits high corrosion resistance in terms of bare corrosion resistance, and is used as rust-proof steel sheets for automobiles. However, regarding corrosion resistance after painting,
It has the disadvantage of poor water-resistant adhesion, and is not preferred in cosmetic corrosion, which is a problem in automotive applications. To solve this problem, for example, by forming an Fe-rich Fe-Zn alloy plating layer on a Zn-Ni alloy plating layer, phosphophyllite (phosphophyllite Zn 2 Fe
It has been proposed to form chemical crystals (PO 4 ) 2.4H 2 O) to improve water-resistant adhesion (Japanese Patent Application Laid-Open No.
No. 58-15554, Japanese Patent Application Laid-open No. 58-52483, etc.). Additionally, as a method for improving zinc phosphate treatment properties from the treatment solution side, it has been proposed to add metal ions such as Ni 2+ to the zinc phosphate treatment solution (for example, Iron and Steel Institute of Japan, Tetsu-to-Hagane Vol. 70, No. 5). S46 (1984)). [Problems to be solved by the invention] However, Fe
The method for forming a rich Fe-Zn alloy plating layer is as follows:
It is true that water resistant adhesion can be improved, but
In automotive applications, when paint film scratches (pittings) occur due to flying stones or the like, another problem arises in that red rust is likely to form in the scratched areas. On the other hand, in the method of adding Ni 2+ etc. to the zinc phosphate chemical conversion treatment solution, according to the research of the present inventors, the important point is how to supply Ni etc. to be incorporated into the chemical conversion film. It is captured
In order to obtain the necessary amount of Ni etc., a considerable amount of Ni etc.
Ni 2+ etc. must be added to the chemical conversion treatment solution. However, if a large amount of Ni 2+ or the like is added to the chemical conversion treatment solution, the solution itself becomes unstable, and there is a problem in that it is extremely difficult to manage the solution in order to stably supply Ni. Therefore, an object of the present invention is to provide a surface-treated steel sheet that can efficiently and stably supply the above-mentioned Ni source, etc. into a zinc phosphate coating, and that has particularly good water-resistant adhesion and excellent corrosion resistance after painting. Our goal is to provide the following. [Means for solving the problem] In order to solve the above problem, according to the present invention, a predetermined amount of Ni or the like is attached to the surface layer of the steel plate,
It is proposed to improve water-resistant adhesion by eluting Ni etc. during zinc phosphate treatment, which is a pre-painting treatment, and forming a chemical conversion film that incorporates Ni etc. during the formation of the zinc phosphate coating. That is, according to the present invention, in a surface-treated steel sheet subjected to zinc phosphate chemical conversion treatment as a pre-painting treatment, at least one side of the steel sheet contains 80 wt% or more of Zn as a first layer and further contains 10 wt% of Fe. A Zn-Fe alloy plating containing more than 20 wt% is formed, and a second layer is formed on the Zn-Fe alloy plating, which contains Ni, or Ni and Co and/or Mn in a total amount of more than 30% and less than 80%. Zn alloy plating 0.5
~5g/ m2 . The plating layer formed as the first layer on at least one side of the steel plate must be a stable plating layer that itself has high corrosion resistance. however
10wt%) is used. In addition, a trace amount (1 to 5 wt%) of Co,
It may be a highly corrosion-resistant plating film further containing Ni, Mn, etc. All of these have a uniform coating with a single phase such as δ 1 phase (Zn-Fe alloy) after heating at 160 to 180° C. for 20 minutes in the case of baking coating, for example, cationic electrodeposition. However, in the first layer, the total amount of elements other than Zn, such as Fe, Ni, Mn, etc., must not exceed 20 wt%. This is because when the content of elements other than Zn exceeds 20 wt%, powdering tends to occur during processing such as press forming of plated steel sheets, especially in automotive applications, regardless of the type of alloying element. In this respect, the alloying elements
It is more preferable that the content is 15 wt% or less, and it is possible to further reduce the alloying element content by plating the second layer with a Ni-rich Ni--Zn alloy as described below. As the second layer, on the first layer, Ni-Zn alloy plating containing Ni in an amount exceeding 30 wt% and not more than 80 wt%, or Ni and Co and/or Mn, that is, Ni
Add up +Co, Ni+Mn or Ni+Co+Mn.
Ni-Zn alloy plating containing more than 30 wt% and less than 80 wt% is applied at 0.5 to 5 g/ m2 . Second layer Ni etc. (Ni or Ni+Co and/or
The reason for limiting the content rate of (or Mn) is basically
The more Ni, etc., the more the amount supplied to the zinc phosphate coating, but if the Ni, etc. in the second layer exceeds 80wt%, the solubility of the plating coating becomes extremely poor.
If the content of Ni, etc. is less than 30wt%, the solubility of the plating film is good, but Ni
This is because the amount of zinc phosphate is small, so that its supply to the zinc phosphate coating is insufficient, and the life of the spot welding electrode, which will be described later, is also reduced. In addition, the amount of the second layer deposited is 0.5g/m 2
If it is less than 5g/m2, the effect cannot be fully exerted because the amount of Ni etc. is small, and if it exceeds 5g/ m2 ,
Since the effect is saturated and it is not economical, it is limited to the above range. [Function] In the present invention, the second layer is formed by Ni-Zn alloy plating (30<Ni≦80%, 30<Ni+Mn and/or
Co≦80%) layer was created by adhering Ni, Ni+Co and/or Mn having a content in the above range to the surface layer, and by applying Ni, Co and Co in the zinc phosphate treatment which is pre-painting treatment. and/or
When Mn is eluted and zinc phosphate film is formed, Ni and
This is to form a zinc phosphate film incorporating Co and/or Mn. This zinc phosphate film can improve the corrosion resistance after painting, especially the water resistant adhesion. In other words, according to the present invention, there is no need to add Ni 2+ etc. to the chemical conversion treatment solution, and even without the addition, the chemical conversion treatment properties of zinc phosphate are sufficiently improved due to the elution of Ni etc. in the second layer. This makes it possible to improve corrosion resistance after painting. In addition, this film shows Hopeite Zn 3 (PO 4 ) 2・4H 2 O in X-ray diffraction.
Phosphophyllite, which is usually used to evaluate phosphatability because it has a diffraction angle similar to that of Phosphophyllite
Zn 2 Fe (PO 4 ) 2・4H 2 O and Hopeite Zn 3 (PO 4 ) 2・
The ratio P/P+H of 4H 2 O is O. Furthermore, as described above, since the second layer improves the corrosion resistance after coating, such as water-resistant adhesion, it becomes possible to reduce the amount of alloying elements in the first layer, and powdering can be suppressed. Moreover, the Ni etc. in the second layer suppresses alloying of Zu and Cr in the spot electrode (Cu-Cr alloy), thereby significantly improving the life of the electrode. Overall, the unique combination of the first layer and the second layer works well, resulting in extremely good bare corrosion resistance and post-painting corrosion resistance, especially water resistant adhesion. [Example] After a steel plate was electrolytically degreased and pickled, a first layer mainly containing Zn was formed thereon using a bath composition mainly containing zinc sulfate and plating conditions as shown in Table 1. When containing trace amounts of alloying elements, add them to a sulfuric acid bath.
Plating was performed by adding Co 2+ and Mn 2+ in the form of sulfate. In the case of alloyed hot-dip galvanizing as the first layer, the steel plate was heated with NOF, reduced in a reduction furnace, and then immersed in a hot-dip plating pot for hot-dip plating. After that, it is heated and alloyed in an alloying furnace,
The Fe content was controlled by the heating temperature. Table 1 First layer plating bath and plating conditions Plating bath Zn 2+ : 50g/ Fe 2+ : 50g/ Na 2 SO 4 : 50g/ CH 3 COONa・3H 2 O: 20g/ (Co 2+ , Mn 2+ PH: 2 Plating bath temperature: 60°C Plating conditions Current density: 20 to 80 A/dm formed a layer. A trace amount of alloying element was added in the form of sulfate as in the first layer. Table 2 Second layer plating bath and plating conditions Plating bath Ni 2+ : 60g/ Zn 2+ : 30g/ Na 2 SO 4 : 50g/ CH 3 COONa・3H 2 O: 20g/ (Co 2+ , Mn 2+ (5 to 10 g/addition) PH: 2 Plating bath temperature: 60℃ Plating conditions Current density: 20 to 80 A/dm 2 For the plated steel sheet obtained as above,
Painting was performed under the painting conditions shown in Table 3. Table 3 Coating conditions Chemical treatment liquid: "BT-3030" manufactured by Nippon Parker Co., Ltd. Cation electrodeposition: "Power Top U-30" manufactured by Nippon Paint Co., Ltd. 20 μm Medium/top coat: Commercially available baking type melamine alkyd paint, each 35 μm Total film Thickness≒90μm Evaluation of corrosion resistance after painting was carried out using the items and contents shown in Table 4. Table 5 shows the evaluation results of corrosion resistance after painting. Table 4 Corrosion resistance evaluation items and details after painting: A Salt spray test (SST) Cross-cut with a cutter knife on the first coat material up to cationic electrodeposition coating, and evaluate the bulge from the cross-cut after 600 hours of SST B Water resistant adhesion Medium After the top coating, the 3-coat material was immersed in deionized water at 50℃ for 10 days, after which goblets were placed at 2 mm intervals and the tape was peeled off, and the remaining rate of the coating film was evaluated. The coating film was chipped and the degree of red rust generation was evaluated after 240 hours of SST.Furthermore, as an evaluation of powdering property, an evaluation was performed using a cylindrical drawing method. The results are shown in Table 5.
For evaluation, a tape peeling test was performed on the outer and inner walls of the cylindrical drawn sample, and the amount of peeling was determined. The evaluation criteria in Table 5 are: ◎: No powdering;
〇: Slight powdering, △: Slight powdering,
×: Large amount of powdering.
【表】【table】
【表】
＊ 溶融メツキ
第５表から明らかなように、耐食性のよい第１
層、Zn−Fe合金メツキ層の上に、特定量のNi−
Zn合金層を形成させることにより、耐ブリスタ
ー性、耐水密着性、チツプ耐食性、耐パウダリン
グ性を同時に満足する、塗装後耐食性に特に優
れ、かつスポツト溶接における電極寿命を向上さ
せることが可能な表面処理鋼板が得られる。
なお、スポツト溶接の評価試験条件は、第６図
の通りである。[Table] * Melt plating As is clear from Table 5, No. 1 has good corrosion resistance.
layer, a specific amount of Ni− on top of the Zn−Fe alloy plating layer.
By forming a Zn alloy layer, a surface that satisfies blister resistance, water adhesion resistance, chip corrosion resistance, and powdering resistance at the same time, has particularly excellent corrosion resistance after painting, and can improve electrode life in spot welding. A treated steel plate is obtained. The evaluation test conditions for spot welding are as shown in FIG.
【表】
〔発明の効果〕
上記したように、本発明によれば、耐水密着
性、耐ブリスター性、耐チツプ性および耐パウダ
リング性に優れ、しかもスポツト溶接における電
極寿命を著しく延長させることができる、塗装後
の耐食性に優れた表面処理鋼板が提供される。[Table] [Effects of the Invention] As described above, according to the present invention, it is possible to have excellent water resistance, adhesion, blister resistance, chip resistance, and powdering resistance, and to significantly extend the electrode life in spot welding. A surface-treated steel sheet with excellent corrosion resistance after painting is provided.
Claims (1)
る表面処理鋼板において、鋼板の少なくとも片面
に、第１層として、Znを80wt％以上含み、さら
にFeを10wt％を超えかつ20wt％以下含有するZn
−Fe系合金メツキを形成し、その上に第２層と
して、Ni、あるいはNiとCoおよび／またはMn
を合計で30％を超え80％以下量含有するNi−Zn
系合金メツキを0.5〜５ｇ／m2形成したことを特
徴とする塗装後の耐食性に優れた表面処理鋼板。1. In a surface-treated steel sheet that is subjected to zinc phosphate treatment as a pre-painting treatment, Zn containing 80 wt% or more of Zn as a first layer and more than 10 wt% and 20 wt% or less of Fe on at least one side of the steel sheet.
- Form a Fe-based alloy plating, and add Ni, or Ni and Co and/or Mn as a second layer on top of it.
Ni-Zn containing more than 30% but less than 80% in total
A surface-treated steel sheet with excellent corrosion resistance after painting, characterized by forming an alloy plating of 0.5 to 5 g/m 2 .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1205785A JPS61170593A (en) | 1985-01-24 | 1985-01-24 | Zinc surface treated steel sheet having excellent corrosion resistance after painting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1205785A JPS61170593A (en) | 1985-01-24 | 1985-01-24 | Zinc surface treated steel sheet having excellent corrosion resistance after painting |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61170593A JPS61170593A (en) | 1986-08-01 |
| JPH0142359B2 true JPH0142359B2 (en) | 1989-09-12 |
Family
ID=11794970
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1205785A Granted JPS61170593A (en) | 1985-01-24 | 1985-01-24 | Zinc surface treated steel sheet having excellent corrosion resistance after painting |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61170593A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2564524B2 (en) * | 1986-10-06 | 1996-12-18 | 日本鋼管株式会社 | Method for producing electric zinc-nickel alloy plated steel sheet excellent in electrodeposition paintability |
| JPH03158494A (en) * | 1989-11-16 | 1991-07-08 | Nkk Corp | Multi-ply plated steel sheet excellent in lubricity, corrosion resistance and finish coating |
| JPH08218193A (en) * | 1995-02-14 | 1996-08-27 | Sumitomo Metal Ind Ltd | Organic film compositely coated steel sheet |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS586995A (en) * | 1981-07-03 | 1983-01-14 | Kawasaki Steel Corp | Zinc-nickel alloy plated steel plate of superior adhesive strength after working |
| JPS59162292A (en) * | 1983-03-05 | 1984-09-13 | Sumitomo Metal Ind Ltd | Steel sheet having multilayered plating provided with superior corrosion resistance after coating |
| JPS60141894A (en) * | 1983-12-29 | 1985-07-26 | Nippon Steel Corp | Zn-ni alloy double-plated steel sheet having superior workability |
| JPS60215789A (en) * | 1984-04-10 | 1985-10-29 | Nippon Steel Corp | Surface treated steel sheet having superior corrosion resistance and coatability |
-
1985
- 1985-01-24 JP JP1205785A patent/JPS61170593A/en active Granted
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS586995A (en) * | 1981-07-03 | 1983-01-14 | Kawasaki Steel Corp | Zinc-nickel alloy plated steel plate of superior adhesive strength after working |
| JPS59162292A (en) * | 1983-03-05 | 1984-09-13 | Sumitomo Metal Ind Ltd | Steel sheet having multilayered plating provided with superior corrosion resistance after coating |
| JPS60141894A (en) * | 1983-12-29 | 1985-07-26 | Nippon Steel Corp | Zn-ni alloy double-plated steel sheet having superior workability |
| JPS60215789A (en) * | 1984-04-10 | 1985-10-29 | Nippon Steel Corp | Surface treated steel sheet having superior corrosion resistance and coatability |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61170593A (en) | 1986-08-01 |
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