JP4102144B2 - Hot-dip galvanized steel material excellent in uniform paintability and corrosion resistance and method for producing the same - Google Patents
Hot-dip galvanized steel material excellent in uniform paintability and corrosion resistance and method for producing the same Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、塗装性と耐食性に優れた溶融メッキ鋼材およびその製造法に属し、建材、自動車、家電製品等の耐食性を必要とする工業製品に広く使用することができる。
【０００２】
【従来の技術】
亜鉛メッキ鋼材は、亜鉛メッキの優れた犠牲防食作用と塗装性により広く用いられている。犠牲防食作用は、亜鉛が鉄よりも電気化学的に卑であることを利用したものであり、亜鉛メッキ層が優先的に溶解することで耐食性を発揮する。従って、耐食性の向上には、メッキ付着量を増加して溶解時間の延長を図る考え方と、添加元素によりメッキ層の電気化学的な活性度を低下させて溶解時間を延長させる考え方の二通りがある。ここで、メッキ付着量の増大は、溶接性の低下、プレス加工性の劣化、外観の悪化、製造コストの増大といった弊害が生じるため実用的な観点からは好ましくない。一方、メッキ層中にＮｉやＣｏ、Ｃｒなどの金属を添加する方法も提案されているが、電気メッキ法での製造に限定されてしまい、製造プロセスが複雑になったり、合金コストが高くなったりなどの弊害がある．さらに電気メッキ法では、電力コストがメッキ付着量に比例するためにメッキ付着量を溶融メッキ法と比べて大幅に抑制する必要があり、たとえ合金添加を行っても耐食性の発現が十分でない場合がある。
【０００３】
溶融メッキ法で製造するＺｎ−Ａｌ−Ｍｇ合金メッキ鋼板は、ＡｌとＭｇの効果で耐食性の向上が望めるために付着量の低減が図れる上に、たとえメッキ付着量を増大してもコスト上昇が小さいために有効な技術である。従来技術としては、耐食性および表面外観の良好な溶融Ｚｎ−Ａｌ−Ｍｇメッキ鋼板およびその製造方法がある（例えば特許文献１）。本技術は、従来のＺｎメッキと比較すると耐食性の向上作用は認められるが、浴中にＭｇを１から４質量％も添加するために、ドロスと称するＭｇを含有する酸化物や合金がメッキ浴の内部や表層に生成し、メッキの操業性を劣化させる。また、メッキ層は、Ａｌ相、Ｚｎ相、三元共晶相が生成するために、メッキ組織の制御が難しく均一な品質の製品の製造を困難にしている。さらに、メッキ表層は、三元共晶やＡｌ相による凹凸が生じてしまい、塗装後も塗膜の平滑性が低下して外観を損なう問題がある。また、耐食性の更なる向上を目的とした溶融Ｚｎ−Ａｌ−Ｍｇメッキ鋼板がある（例えば特許文献２）。本技術は、Ｚｎ−Ａｌ−Ｍｇ合金メッキ層にさらにＳｉを０．０１から２質量％添加したものである。溶融メッキ浴にＳｉを添加することにより、メッキ層中でＭｇ2Ｓｉが析出し、これが耐食性の向上に寄与する。しかしながら、本技術は、Ａｌの含有率が２０％以下のＺｎ−Ａｌ浴ではＳｉの溶解量がわずかであり、大幅な耐食性の向上は望めない。Ｓｉの溶解量を増大させるためには、浴中のＡｌ含有率を増大させればよいが、その場合は、メッキ金属と地鉄層との合金化反応が促進されてメッキ密着性が劣化したり、メッキ鋼材を抵抗溶接する際の電極の損耗が早くなるといった弊害、亜鉛の含有率が減ることで犠牲防食作用が不足してしまう欠点が発生する。さらには、本技術においては、メッキ浴に溶解したＳｉは、メッキ後の冷却の過程でＭｇ2Ｓｉとなって析出するために、その形態、サイズは冷却状態に応じて変化する。Ｍｇ2Ｓｉは初晶として析出するために、１μｍ以上になってしまうのが普通である。この析出物がメッキ層の表層に存在すると、塗装後の平滑性や外観に弊害を生じることがある。また、Ａｌ相や三元共晶相の存在によるメッキ表層の凹凸を回避することもできず、塗装後平滑性を低下させる。
【０００４】
【特許文献１】
特開平１０−２２６８６５号公報
【特許文献２】
特開２０００−１０４１５４号公報
【０００５】
【発明が解決しようとする課題】
本発明は、溶融Ｚｎ−Ａｌメッキ鋼板の耐食性を向上させて、少ないメッキ付着量で良好な耐食性、溶接性、プレス加工性、塗装後均一外観性を達成することも目的としている。そのために、粒径が０．９μｍ以下の微細で高度の耐食性を発現する防錆性金属間化合物をメッキ層中に均一に分散させたメッキ鋼材およびその製造方法を提供することをその課題としている。
【０００６】
【課題を解決するための手段】
本発明者らは、これらの課題を解決すべく鋭意検討した結果、Ｓｉを必須元素とした金属間化合物が０．９μｍ以下という極めて微細な形状でメッキ層に分散すれば塗装後の外観を損なう事は無く、耐食性を著しく向上させ、溶接性やプレス成形性をも向上させることを見出した。さらに、これらの微細金属は、Ｚｎ系浴の融点よりも高温側に有るために、浴中では微粒子の状態で存在し、メッキ層が凝固する過程では結晶析出の核となり結晶の微細化が生じることも判明した。メッキ組織の微細化はメッキ表面を平滑化させ塗装後の均一外観性を向上させることを見出した。これらの知見をもとに本発明を完成させた。さらには、本発明の微細な金属間化合物の製造法や浴中での安定性についても種々検討し、浴組成の最適化を図ることで達成した。その要旨とするところは、以下の通りである。
【０００７】
（１） Ａｌを０．０１から１５質量％含有し残部がＺｎおよび不可避的不純物からなるメッキ層中に、Ａｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる粒径が０．９μｍ以下の金属間化合物の１種または２種以上を合計で０．００１から１０質量％含有することを特徴とする均一塗装性と耐食性に優れた亜鉛メッキ鋼材。
【０００８】
（２） Ａｌが０．０１から１５質量％、Ｍｇが０．０１から１．０質量％で残部がＺｎおよび不可避的不純物からなるメッキ層中に、Ａｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる粒径が０．９μｍ以下の金属間化合物の１種または２種以上を合計で０．００１から１０質量％含有することを特徴とする均一塗装性と耐食性に優れた亜鉛メッキ鋼材。
【０００９】
（３） Ａｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる金属間化合物がＢａＳｉ、ＢａＳｉ2、ＣａＳｉ、ＣａＳｉ2、Ｃａ2Ｓｉ、Ｃａ3Ａｌ2Ｓｉ2、ＣａＡｌ2Ｓｉ2、ＣａＡｌ1-xＳｉ1+x、Ｃａ3Ａｌ6Ｓｉ2、Ｃａ2Ａｌ4Ｓｉ3、Ｃｅ2Ｓｉ、ＣｅＳｉ2、Ｍｇ2Ｓｉ、ＡｌＦｅＳｉ、ＡｌＦｅＭｇＳｉ、Ｓｒ2Ｓｉ、ＳｒＳｉ2、ＴｉＳｉ2、ＴｉＳｉ、Ｔｉ5Ｓｉ4、Ｔｉ3Ｓｉ、Ｓｉ3Ｗ5、Ｓｉ2Ｗ、ＳｉＺｒ3、ＳｉＺｒ2、Ｓｉ2Ｚｒ3、Ｓｉ4Ｚｒ5、ＳｉＺｒ、Ｓｉ2Ｚｒの１種または２種以上であることを特徴とする前記（１）または（２）に記載の均一塗装性と耐食性に優れた亜鉛メッキ鋼材。
【００１０】
（４） Ａｌが０．０１から１５質量％で残部がＺｎおよび不可避的不純物からなる溶融亜鉛メッキ浴に、更に、Ａｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる粒径が０．９μｍ以下の金属間化合物の１種または２種以上を合計で０．００１から１０質量％添加したメッキ浴を用いてメッキすることを特徴とする、前記（１）または（３）に記載の均一塗装性と耐食性に優れた亜鉛メッキ鋼材の製造方法。
【００１１】
（５） Ａｌが０．０１から１５質量％、Ｍｇが０．０１から１．０質量％で残部がＺｎおよび不可避的不純物からなる溶融亜鉛メッキ浴に、更に、Ａｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる粒径が０．９μｍ以下の金属間化合物の１種または２種以上を合計で０．００１から１０質量％添加したメッキ浴を用いてメッキすることを特徴とする、前記（２）または（３）に記載の均一塗装性と耐食性に優れた亜鉛メッキ鋼材の製造方法。
【００１２】
（６） Ａｌが０．０１から１５質量％で残部がＺｎおよび不可避的不純物からなる溶融亜鉛メッキ浴に鋼材を浸漬し、引き抜いた後、メッキ層が溶融状態の間にＡｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる粒径が０．９μｍ以下の金属間化合物の１種または２種以上をガスもしくは水と共に鋼材に吹き付けることを特徴とする、前記（１）または（３）に記載の均一塗装性と耐食性に優れた亜鉛メッキ鋼材の製造方法。
【００１３】
（７） Ａｌが０．０１から１５質量％、Ｍｇが０．０１から１．０質量％で残部がＺｎおよび不可避的不純物からなる溶融亜鉛メッキ浴に鋼材を浸漬し、引き抜いた後、メッキ層が溶融状態の間にＡｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる粒径が０．９μｍ以下の金属間化合物の１種または２種以上をガスもしくは水と共に鋼材に吹き付けることを特徴とする、前記（２）または（３）に記載の均一塗装性と耐食性に優れた亜鉛メッキ鋼材の製造方法。
【００１４】
（８） 上記（４）または（５）に記載の製造方法において、Ａｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる粒径が０．９μｍ以下の金属間化合物をＡｌマトリクス中に微分散させた後にメッキ浴に添加することを特徴とする均一塗装性と耐食性に優れた亜鉛メッキ鋼材の製造方法。
【００１５】
（９） 上記（４）または（５）に記載の製造方法において、ＡｌとＢａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる溶融金属を１００℃／秒以上で急冷凝固させＡｌマトリックス中に粒径が０．９μｍ以下の金属間化合物を形成させることを特徴とする均一塗装性と耐食性に優れた亜鉛メッキ鋼材の製造方法。
【００１６】
（１０） 上記（６）または（７）に記載の製造方法において、Ａｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる溶融金属を不活性ガスと共に噴霧することで超急冷し粒径が０．９μｍ以下の金属間化合物を形成させることを特徴とする均一塗装性と耐食性に優れた亜鉛メッキ鋼材の製造方法。
【００１７】
【発明の実施の形態】
以下、本発明について詳しく説明する。メッキ鋼材の塗装後の均一外観性は、塗装の膜厚、塗装方法、メッキ表面形状の影響を受ける。このうち、膜厚は厚いほど平滑性が向上し好ましい。しかし、膜厚の増大は塗料代の増大や塗装性の低下を生じて好ましくなく、薄い膜厚で外観の確保できるメッキ鋼材が求められている。また、塗装方法は、静電塗装、電着塗装法、ロールコーティング法、カーテンフローコーティング法、紛体塗装法等があり塗料種、塗装材形態、要求品位に応じて使い分けられている。
【００１８】
このように、塗装後の均一外観性は、種々の因子の影響を受けるが、メッキ表面に凹凸があると、最適な塗装方法においても塗装後の外観に下地の凹凸が浮き上がり、平滑性を低下する場合がある。また、車体の下地塗装として必須であるカチオン電着塗装において、メッキ中の微粒子がメッキ表面に顔をだしていると電着塗装時にガスピンと称する塗装欠陥を生じやすくなる。これは、微粒子部に電流集中が生じやすくなり、水素ガス発生が生じ塗膜欠陥になるものと推定されている。このような知見をもとに各種塗料と各種塗装法を種々検討したうえでメッキ層の最適化を試みた結果、メッキ層中に微粒子を含有する場合には、微粒子の粒径が極めて重要であり、その粒径を０．９μｍ以下であればよいことを見出した。
【００１９】
０．９μｍ超ではメッキ表層に頭をだした微粒子による表面形状の凸凹化や電流集中によるガスピンの発生が生じやすくなり、塗装時の塗膜欠陥が発生するようになる。また、車体塗装で一般的な１００μｍ程度の多層塗装（カチオン電着−静電塗装（中塗り）−静電塗装（上塗り））では、粒径が０．９μｍ超では、微粒子の近傍の塗膜厚が不均一となり、平滑外観が得られなくなる。
【００２０】
次に、メッキ層の組成は、鋼材に対する犠牲防食性を維持するためにＺｎを主体の組成とする。純亜鉛浴に鋼材を浸漬すると鉄と亜鉛との合金化反応が急速に生じてしまい好ましくなく、Ａｌを添加することが望ましい。Ａｌが０．０１質量％未満ではＺｎ−Ｆｅ合金反応抑制の効果が無く、Ａｌ添加量を増大すると耐食性が向上するが１５質量％超では、メッキ層と地鉄層との界面近傍にＦｅ−Ａｌ系の合金反応が生じ、メッキ密着性が著しく低下するため好ましくない。また、Ｚｎ−Ａｌ系の合金は共晶反応系であり、Ａｌはメッキ層中ではＺｎと分離して凝固している。
【００２１】
Ａｌ含有率が、Ｚｎ−Ａｌの共晶組成以上であるとＡｌが初晶として析出するようになり、この初晶の成長が促進されるとメッキ層表層の粗度を大きくする。その結果、塗装後の外観均一性や鮮鋭性を低下させる。この初晶は、結晶を多数析出させれば１個あたりの結晶サイズが小さくなり成長が抑制され塗装均一性にとって好ましいものとなる。
【００２２】
本発明で添加する金属間化合物は、いずれも融点がメッキ浴の融点より高く浴中で微粒子として浮遊しているため、初晶の凝固する過程で凝固の核となり、結晶の生成数を増加させ初晶のサイズを小さくする効果を有している。これは、いわゆる接種効果と呼ばれるものに相当すると推定されるが、粒径が大きいとその効果が無く、０．９μｍ以下で効果が発現する。
【００２３】
以上のことから、本発明の微粒子の添加とＺｎ−Ａｌ合金の組成を規定することでメッキ層表層が平滑化し塗装後の均一外観性が向上させる事ができる。
【００２４】
次に、浴中に添加する微粒子は、粒径が０．９μｍ以下で溶解しないものならばいずれでも良いわけではなく、腐食抑制作用を有するものでなければならない。種々の微粒子を検討した結果、Ａｌ、Ｂａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素とＳｉからなる粒径が０．９μｍ以下の金属間化合物が腐食抑制効果が高いことを確認した。これらの微粒子は、より具体的には、ＢａＳｉ、ＢａＳｉ2、ＣａＳｉ、ＣａＳｉ2、Ｃａ2Ｓｉ、Ｃａ3Ａｌ2Ｓｉ2、ＣａＡｌ2Ｓｉ2、ＣａＡｌ1-xＳｉ1+x、Ｃａ3Ａｌ6Ｓｉ2、Ｃａ2Ａｌ4Ｓｉ3、Ｃｅ2Ｓｉ、ＣｅＳｉ2、Ｍｇ2Ｓｉ、ＡｌＦｅＳｉ、ＡｌＦｅＭｇＳｉ、Ｓｒ2Ｓｉ、ＳｒＳｉ2、ＴｉＳｉ2、ＴｉＳｉ、Ｔｉ5Ｓｉ4、Ｔｉ3Ｓｉ、Ｓｉ3Ｗ5、Ｓｉ2Ｗ、ＳｉＺｒ3、ＳｉＺｒ2、Ｓｉ2Ｚｒ3、Ｓｉ4Ｚｒ5、ＳｉＺｒ、Ｓｉ2Ｚｒがあげられる。これら微粒子の腐食抑制作用のメカニズムについては不明であるが、腐食環境下において一部が溶出してＺｎとの複合腐食性生物を形成し、腐食反応を抑制するためと推定される。
【００２５】
これら微粒子の添加量は、０．００１質量％未満では耐食性向上の効果が無く、１０質量％超では、耐食性の効果が飽和するだけでなく、浴中での微粒子の凝集やメッキ層中での微粒子の過多による表面形状の高粗度化が生じ電着塗装板のガスピン性塗装板の均一塗装性が悪化することから望ましくない。
【００２６】
メッキ浴の組成は、前述したＺｎとＡｌのほかにＭｇを微量添加すると耐食性がさらに向上する．Ｍｇが０．０１質量％未満では耐食性向上効果が無く、１．０質量％超では効果が飽和するばかりでなく浴中で安定に存在できなくなり酸化物等のドロスとして浴表面に析出したり浴の粘度を増大させてメッキ品位を低下させる。
【００２７】
メッキ層の付着量は特に限定しないが、１０ｇ／ｍ2〜２００ｇ／ｍ2の範囲が望ましい。１０ｇ／ｍ2未満であれば耐食性の発現が十分でなく、また、溶融メッキ法で付着量を１０ｇ／ｍ2未満に下げることは難しく現実的でない。２００ｇ／ｍ2超では、耐食性の効果はさらに向上するもののプレス加工時のメッキ損傷、抵抗溶接性の低下、塗装後の品位の低下が生じ好ましくない。自動車車体用として、現状の自動車製造メーカーの工程能力を考慮すると、メッキ付着量は２０〜１００ｇ／ｍ2が望ましい。
【００２８】
次に、本発明の製造方法は、溶融メッキ法が最適である。まず、Ｚｎ、Ａｌ、ＭｇもしくはＺｎ、Ａｌからなる溶融メッキ浴に本発明で規定した金属間化合物の微粒子を分散させた浴を用いてメッキを施せばよい。鋼帯のメッキであれば、メッキの前に余熱炉で６００〜９００℃に加熱、還元処理を行った後メッキ浴に浸漬する方法、いわゆるゼンジミア法が最適であり、鋼帯にＮｉを電気メッキ法で０．１〜１０ｇ／ｍ2程度施したのち６００℃程度の還元性雰囲気で加熱処理したのちメッキ浴に浸漬する方法でもよい。また、メッキ浴に浸漬する前にフラックス処理を行ったのちメッキ浴に浸漬しても良い。このような方法でメッキを行うことで微粒子が分散したメッキ鋼材を得ることができる。また、鋼材は冷延鋼板、熱延鋼板のみならず線材でもよく、また、切板、棒鋼、管材でもよい。
【００２９】
微粒子は、メッキ浴に直接添加する方法以外にも、溶融メッキ後のメッキが凝固する前に微粒子を水またはＡｒ、Ｈｅ、Ａｉｒガスとともに吹き付けることで得ることも可能である。
【００３０】
微粒子の製造方法は、ＡｌとＢａ、Ｃａ、Ｃｅ、Ｆｅ、Ｍｇ、Ｓｒ、Ｔｉ、Ｗ、Ｚｒの１種または２種以上の元素からなる溶融状態の金属を毎秒１００℃以上の冷却速度で凝固することでＡｌマトリックス中にＢａＳｉ、ＢａＳｉ2、ＣａＳｉ、ＣａＳｉ2、Ｃａ2Ｓｉ、Ｃａ3Ａｌ2Ｓｉ2、ＣａＡｌ2Ｓｉ2、ＣａＡｌ1-xＳｉ1+x、Ｃａ3Ａｌ6Ｓｉ2、Ｃａ2Ａｌ4Ｓｉ3、Ｃｅ2Ｓｉ、ＣｅＳｉ2、Ｍｇ2Ｓｉ、ＡｌＦｅＳｉ、ＡｌＦｅＭｇＳｉ、Ｓｒ2Ｓｉ、ＳｒＳｉ2、ＴｉＳｉ2、ＴｉＳｉ、Ｔｉ5Ｓｉ4、Ｔｉ3Ｓｉ、Ｓｉ3Ｗ5、Ｓｉ2Ｗ、ＳｉＺｒ3、ＳｉＺｒ2、Ｓｉ2Ｚｒ3、Ｓｉ4Ｚｒ5、ＳｉＺｒ、Ｓｉ2Ｚｒの微粒子を得ることができる．それらの粒径は冷却速度を速めるほど微細化する。本発明の０．９μｍ以下を得るための冷却速度は合金種により異なり一概には云えないがおおよそ毎秒１００℃以上であれば良い。このような急冷凝固させる方法としては、回転ドラムに溶湯を注ぐ方法（単ドラム、双ドラム急冷）や滴下金属を金属板ではさみつける方法、溶融金属を水や油に滴下する方法等がある。
【００３１】
これらの凝固金属は、ＡｌをマトリックスとしているためＺｎ系のメッキ浴に添加するとＡｌが溶出し微粒子状の合金が浴中に分散する。
【００３２】
一方、本発明の微粒子を直接溶融メッキ材に吹き付ける場合には、求める合金成分の溶融金属を不活性ガスと共に噴霧することで急冷することで微粒子を得ることができる。
【００３３】
【実施例】
実施例をもとに本発明をさらに詳細に説明する。溶融メッキは、実験室の溶融メッキシュミレータを用いた。本設備は、鋼板のメッキを行う装置であり、雰囲気制御が可能な加熱炉と溶融メッキポットが縦位置に連結されており、鋼板は縦２００ｍｍ、巾１００ｍｍに切断し、予め油分を脱脂した。次に加熱炉に入れられ、１０％水素残窒素ガス雰囲気下で８００℃１０分加熱後５００℃まで冷却したのち溶融メッキ浴に浸漬する。２秒間浸漬したのち引き上げ、直ちに窒素ガスワイピングにより所定の付着量にする。その後は放冷し、鋼板温度が２００℃以下になったところで系外に取り出す。メッキの付着量は、ガスワイピング圧の調整で行った。また、メッキ浴温は４６０℃とした。
【００３４】
次に、金属間化合物を付与する方法であるが、吹き付ける場合は、鋼板をメッキ浴から引き上げガスワイピングしたのち、直ちにメッキ表面に均一に水と共に吹き付け冷却した。また別の例として、金属間化合物をＨｅ、Ｎ2、Ａｉｒガスと共に吹き付けた後冷却した。
【００３５】
また、金属間化合物を直接メッキ浴に添加する場合は、Ａｌをマトリックス金属とし、さらに必要な金属を添加した溶融金属を１００℃／ｓ以上の冷却速度で急冷することで０．９μｍ以下の析出金属をＡｌマトリックス中に得る方法がある。
【００３６】
また、微粒子を得る方法として、溶融金属を不活性ガスと共に噴霧することで急冷させて凝固させる方法がある。
得られた鋼材は、各種塗装処理を施した。自動車外板用の塗装処理は、リン酸塩処理（日本パーカーライジング（株）製、ＰＢ３８００）２．０ｇ／ｍ2、電着塗装（日本ペイント（株）製パワートップＵ５０）２０μｍを行った。得られた塗装板のガスピン性は、鋼板一枚あたりの気泡状の表面欠陥の個数で判断した。鋼板１枚当たり０ヶを良好（○）、１ヶから５ヶをやや不良（△）、それ以上を不良（×）とした。良好のみを合格とした。さらに、静電塗装タイプの中塗り、上塗り（関西ペイント（株）製）をそれぞれ３５μｍ施した。得られた塗装板の均一塗装性は、ＰＧＤ計（財団法人日本色彩研究所製）を用いた。Ｇｄ値が０．７以上を合格、それ以下を不合格とした。さらに、触針式粗度計（東京精密製サーフコム５５０Ａ、触針径５μｍＲ）を用いてＷｃａを測定した．得られたＷｃａが０．６μｍ以下を合格、それ以上を不合格とした。
【００３７】
次に、耐食性の評価として、電着および中・上塗り塗装したサンプルにカッターでクロスカットを施し、複合環境サイクル試験（ＪＩＳ Ｚ２３７１号の塩水噴霧２時間、乾燥（６０℃ＲＨ３０％）４時間、湿潤（５０℃ＲＨ９５％）２時間）を２００サイクル行い、クロスカット部の片側最大ふくれ巾を評価した。電着塗装材の場合は、３ｍｍ以下を合格、それ以上を不合格、中・上塗り塗装材の場合は、１．５ｍｍ以下を合格、それ以上を不合格とした。表１〜７の実施例１から２４９の本発明材に於いては、電着塗装時のガスピン性、塗装板の均一塗装性（ＰＧＤ値）、表面粗度（Ｗｃａ）、耐食性（塗装後のＣＣＴ後クロスカット部ふくれ巾）のいずれも優れており合格レベルとなっている。
【００３８】
一方、本発明の範囲外の材料は表８に示すとおおり、ガスピン性に劣ったり均一塗装性、表面粗度、耐食性のいずれかが劣っている。したがって、本発明材は、均一塗装性と耐食性の両者を両立し優れたメッキ鋼材であり、自動車、家電、電機機械等の広い用途の工業製品に適用が可能である。
【００３９】
【表１】
【表２】
【表３】
【表４】
【表５】
【表６】
【表７】
【表８】
【発明の効果】
本発明によれば、溶融Ｚｎ−Ａｌメッキ鋼板の耐食性を向上させて、少ないメッキ付着量で良好な耐食性、溶接性、プレス加工性、塗装後均一外観性を達成することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a hot-dip plated steel material excellent in paintability and corrosion resistance and a manufacturing method thereof, and can be widely used for industrial products that require corrosion resistance, such as building materials, automobiles, and home appliances.
[0002]
[Prior art]
Galvanized steel is widely used due to the excellent sacrificial anticorrosive action and paintability of galvanization. The sacrificial anticorrosive action utilizes the fact that zinc is electrochemically lower than iron, and exhibits corrosion resistance by preferentially dissolving the galvanized layer. Therefore, there are two ways to improve corrosion resistance: the idea of increasing the amount of plating adhesion and extending the dissolution time, and the concept of reducing the electrochemical activity of the plating layer by the additive element and extending the dissolution time. is there. Here, an increase in the adhesion amount of plating is not preferable from a practical point of view because it causes adverse effects such as a decrease in weldability, a deterioration in press workability, a deterioration in appearance, and an increase in manufacturing cost. On the other hand, a method of adding a metal such as Ni, Co, or Cr to the plating layer has also been proposed, but it is limited to the electroplating method, which complicates the manufacturing process and increases the alloy cost. There are harmful effects such as. Furthermore, in the electroplating method, since the power cost is proportional to the amount of plating applied, it is necessary to significantly reduce the amount of plating applied compared to the hot dipping method. Even if an alloy is added, the corrosion resistance may not be sufficiently developed. is there.
[0003]
The Zn-Al-Mg alloy-plated steel sheet manufactured by the hot dipping method can improve the corrosion resistance due to the effects of Al and Mg, so that the adhesion amount can be reduced, and even if the plating adhesion amount is increased, the cost increases. This is an effective technology because of its small size. As a conventional technique, there is a molten Zn—Al—Mg plated steel sheet having good corrosion resistance and surface appearance and a method for producing the same (for example, Patent Document 1). Although this technique has an effect of improving the corrosion resistance as compared with the conventional Zn plating, since 1 to 4% by mass of Mg is added to the bath, an oxide or alloy containing Mg called dross is used as the plating bath. Produced on the inside and surface of the steel, it degrades the operability of plating. Moreover, since the Al layer, the Zn phase, and the ternary eutectic phase are generated in the plating layer, it is difficult to control the plating structure, and it is difficult to manufacture a product of uniform quality. Further, the plating surface layer has irregularities due to ternary eutectic and Al phase, and there is a problem that the smoothness of the coating film is lowered after coating and the appearance is impaired. Moreover, there exists a hot-dip Zn-Al-Mg plated steel plate for the purpose of further improving corrosion resistance (for example, Patent Document 2). In the present technology, 0.01 to 2 mass% of Si is further added to the Zn—Al—Mg alloy plating layer. By adding Si to the hot dipping bath, Mg 2 Si is precipitated in the plating layer, which contributes to improvement of corrosion resistance. However, in the present technology, in a Zn-Al bath having an Al content of 20% or less, the amount of Si dissolved is small, and a significant improvement in corrosion resistance cannot be expected. In order to increase the dissolution amount of Si, the Al content in the bath may be increased. In this case, the alloying reaction between the plating metal and the ground metal layer is promoted, and the plating adhesion deteriorates. In addition, there are disadvantages that the electrode wears out faster when resistance welding the plated steel material, and that the sacrificial anticorrosive action is insufficient due to a decrease in the zinc content. Furthermore, in the present technology, since Si dissolved in the plating bath is precipitated as Mg 2 Si in the cooling process after plating, the form and size change according to the cooling state. Since Mg 2 Si precipitates as primary crystals, it is usually 1 μm or more. If this deposit is present on the surface layer of the plating layer, it may have a negative effect on the smoothness and appearance after coating. Moreover, the unevenness | corrugation of the plating surface layer by presence of Al phase or a ternary eutectic phase cannot be avoided, and smoothness after coating is reduced.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-226865 [Patent Document 2]
Japanese Patent Laid-Open No. 2000-104154
[Problems to be solved by the invention]
Another object of the present invention is to improve the corrosion resistance of a hot-dip Zn-Al plated steel sheet and achieve good corrosion resistance, weldability, press workability, and uniform appearance after coating with a small amount of plating. Therefore, it is an object to provide a plated steel material in which a rust-proof intermetallic compound having a particle size of 0.9 μm or less and expressing a high degree of corrosion resistance is uniformly dispersed in a plating layer, and a method for producing the same. .
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve these problems, the present inventors impair the appearance after coating if an intermetallic compound containing Si as an essential element is dispersed in a plated layer in an extremely fine shape of 0.9 μm or less. It was found that the corrosion resistance was remarkably improved and the weldability and press formability were also improved. Furthermore, since these fine metals are on the higher temperature side than the melting point of the Zn-based bath, they exist in the state of fine particles in the bath, and in the process of solidification of the plating layer, the crystals become the nucleus of crystal precipitation, resulting in finer crystals. It was also found out. It has been found that the refinement of the plating structure smoothes the plating surface and improves the uniform appearance after coating. The present invention has been completed based on these findings. Furthermore, the present invention has been achieved by variously examining the production method of the fine intermetallic compound of the present invention and the stability in the bath and optimizing the bath composition. The gist is as follows.
[0007]
(1) One type of Al, Ba, Ca, Ce, Fe, Mg, Sr, Ti, W, Zr in the plating layer containing 0.01 to 15% by mass of Al and the balance being Zn and inevitable impurities Or uniform coating properties and corrosion resistance characterized by containing one or more intermetallic compounds composed of two or more elements and Si having a particle size of 0.9 μm or less in a total amount of 0.001 to 10 mass% Excellent galvanized steel.
[0008]
(2) Al, Ba, Ca, Ce, Fe, Mg in the plating layer of 0.01 to 15% by mass of Al, 0.01 to 1.0% by mass of Mg and the balance of Zn and inevitable impurities Contains 0.001 to 10% by mass in total of one or more intermetallic compounds having a particle size of 0.9 μm or less, consisting of one or more of Sr, Ti, W, Zr and Si and a particle size of 0.9 μm or less A galvanized steel with excellent uniform paintability and corrosion resistance.
[0009]
(3) Al, Ba, Ca , Ce, Fe, Mg, Sr, Ti, W, 1 kind or intermetallic compound consisting of two or more elements and Si and Zr is BaSi, BaSi 2, CaSi, CaSi 2, Ca 2 Si, Ca 3 Al 2 Si 2 , CaAl 2 Si 2 , CaAl 1-x Si 1 + x , Ca 3 Al 6 Si 2 , Ca 2 Al 4 Si 3 , Ce 2 Si, CeSi 2 , Mg 2 Si, AlFeSi , AlFeMgSi, Sr 2 Si, SrSi 2, TiSi 2, TiSi, Ti 5 Si 4, Ti 3 Si, Si 3 W 5, Si 2 W, SiZr 3, SiZr 2, Si 2 Zr 3, Si 4 Zr 5, SiZr The galvanized steel material excellent in uniform paintability and corrosion resistance as described in (1) or (2) above, which is one or more of Si 2 Zr.
[0010]
(4) A hot dip galvanizing bath composed of 0.01 to 15% by mass of Al and the balance of Zn and unavoidable impurities is further added to Al, Ba, Ca, Ce, Fe, Mg, Sr, Ti, W, and Zr. Plating using a plating bath to which one or two or more intermetallic compounds having a particle size of 0.9 μm or less composed of one or more elements and Si are added in a total amount of 0.001 to 10% by mass. The method for producing a galvanized steel material excellent in uniform paintability and corrosion resistance as described in (1) or (3) above.
[0011]
(5) To a hot dip galvanizing bath comprising Al of 0.01 to 15% by mass, Mg of 0.01 to 1.0% by mass and the balance of Zn and inevitable impurities, Al, Ba, Ca, Ce, 0.001 to 10 in total of one or more intermetallic compounds having a particle size of 0.9 μm or less composed of one or more elements of Fe, Mg, Sr, Ti, W, Zr and Si The method for producing a galvanized steel material excellent in uniform paintability and corrosion resistance as described in (2) or (3) above, wherein plating is carried out using a plating bath added by mass%.
[0012]
(6) The steel material is immersed in a hot dip galvanizing bath composed of 0.01 to 15% by mass of Al and the balance of Zn and inevitable impurities, and after being drawn, Al, Ba, Ca, Steel materials together with one or more intermetallic compounds having a particle size of 0.9 μm or less composed of one or more elements of Ce, Fe, Mg, Sr, Ti, W, Zr and Si, together with gas or water The method for producing a galvanized steel material excellent in uniform paintability and corrosion resistance as described in (1) or (3) above, wherein
[0013]
(7) A steel layer is immersed in a hot dip galvanizing bath composed of 0.01 to 15% by mass of Al, 0.01 to 1.0% by mass of Mg and the balance of Zn and unavoidable impurities, and then extracted, and then a plating layer Of an intermetallic compound having a particle size of 0.9 μm or less, comprising one or more elements of Al, Ba, Ca, Ce, Fe, Mg, Sr, Ti, W, Zr and Si and Si in a molten state The method for producing a galvanized steel material excellent in uniform paintability and corrosion resistance as described in (2) or (3) above, wherein one or more types are sprayed onto the steel material together with gas or water.
[0014]
(8) In the manufacturing method according to the above (4) or (5), it comprises Si, one or more elements of Al, Ba, Ca, Ce, Fe, Mg, Sr, Ti, W, and Zr. A method for producing a galvanized steel material excellent in uniform paintability and corrosion resistance, wherein an intermetallic compound having a particle size of 0.9 μm or less is finely dispersed in an Al matrix and then added to a plating bath.
[0015]
(9) In the manufacturing method according to the above (4) or (5), Al and Ba, Ca, Ce, Fe, Mg, Sr, Ti, W, Zr and one or more elements are composed of Si. A method for producing a galvanized steel material excellent in uniform paintability and corrosion resistance, characterized in that a molten metal is rapidly solidified at 100 ° C./second or more to form an intermetallic compound having a particle size of 0.9 μm or less in an Al matrix.
[0016]
(10) In the manufacturing method according to the above (6) or (7), Si, one or more elements of Al, Ba, Ca, Ce, Fe, Mg, Sr, Ti, W, and Zr and Si are included. A method for producing a galvanized steel material excellent in uniform paintability and corrosion resistance, characterized in that molten metal is sprayed together with an inert gas to form an intermetallic compound having a particle size of 0.9 μm or less.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below. The uniform appearance after coating of plated steel is affected by the coating thickness, coating method, and plated surface shape. Among these, the thicker the film thickness, the better the smoothness is. However, an increase in the film thickness is undesirable because it causes an increase in paint cost and a decrease in paintability, and there is a need for a plated steel material that can ensure an appearance with a thin film thickness. In addition, there are electrostatic coating, electrodeposition coating method, roll coating method, curtain flow coating method, powder coating method, and the like as the coating method, and they are properly used according to the type of paint, the form of the coating material, and the required quality.
[0018]
In this way, the uniform appearance after painting is affected by various factors, but if the plating surface has irregularities, even under the optimal coating method, the irregularities of the foundation will rise to the appearance after painting, reducing smoothness. There is a case. Further, in cationic electrodeposition coating, which is essential as a base coating for a vehicle body, if a fine particle being plated has a face on the plating surface, a coating defect called a gas pin is likely to occur during electrodeposition coating. This is presumed that current concentration tends to occur in the fine particle portion, hydrogen gas generation occurs, and a coating film defect occurs. Based on this knowledge, various coating materials and various coating methods were examined and various attempts were made to optimize the plating layer. As a result, when the plating layer contains fine particles, the particle size of the fine particles is extremely important. It was found that the particle size should be 0.9 μm or less.
[0019]
If it exceeds 0.9 μm, irregularities in the surface shape due to fine particles protruding on the surface of the plating surface and generation of gas pins due to current concentration are likely to occur, resulting in coating film defects during painting. In multilayer coating (cationic electrodeposition-electrostatic coating (intermediate coating) -electrostatic coating (top coating)) of about 100 μm, which is common in vehicle body coating, when the particle size exceeds 0.9 μm, the coating film near the fine particles The thickness becomes uneven and a smooth appearance cannot be obtained.
[0020]
Next, the composition of the plating layer is mainly composed of Zn in order to maintain sacrificial anticorrosive properties for the steel material. When steel material is immersed in a pure zinc bath, an alloying reaction between iron and zinc occurs rapidly, which is not preferable, and it is desirable to add Al. If the Al content is less than 0.01% by mass, there is no effect of suppressing the Zn—Fe alloy reaction, and if the Al content is increased, the corrosion resistance is improved, but if it exceeds 15% by mass, the Fe— This is not preferable because an Al-based alloy reaction occurs and the plating adhesion is remarkably lowered. The Zn-Al alloy is a eutectic reaction system, and Al is separated from Zn and solidified in the plating layer.
[0021]
When the Al content is equal to or higher than the eutectic composition of Zn—Al, Al begins to precipitate as the primary crystal. When the growth of the primary crystal is promoted, the roughness of the plating layer surface layer is increased. As a result, the appearance uniformity and sharpness after coating are reduced. In this primary crystal, if a large number of crystals are precipitated, the crystal size per one is reduced, the growth is suppressed, and this is preferable for coating uniformity.
[0022]
All of the intermetallic compounds added in the present invention have a melting point higher than the melting point of the plating bath and float as fine particles in the bath, so that they become solidification nuclei in the process of solidification of the primary crystal and increase the number of crystals formed. It has the effect of reducing the primary crystal size. This is presumed to correspond to what is called an inoculation effect, but if the particle size is large, there is no effect, and the effect is manifested at 0.9 μm or less.
[0023]
From the above, by adding the fine particles of the present invention and defining the composition of the Zn-Al alloy, the surface layer of the plating layer can be smoothed and the uniform appearance after coating can be improved.
[0024]
Next, the fine particles to be added to the bath are not limited as long as the particle diameter is 0.9 μm or less and do not dissolve, and must have a corrosion-inhibiting action. As a result of studying various fine particles, it was found that between one or more elements of Al, Ba, Ca, Ce, Fe, Mg, Sr, Ti, W, Zr and a metal having a particle size of 0.9 μm or less composed of Si. It was confirmed that the compound has a high corrosion inhibitory effect. These fine particles, more specifically, BaSi, BaSi 2, CaSi, CaSi 2, Ca 2 Si, Ca 3 Al 2 Si 2, CaAl 2 Si 2, CaAl 1-x Si 1 + x, Ca 3 Al 6 Si 2 , Ca 2 Al 4 Si 3 , Ce 2 Si, CeSi 2 , Mg 2 Si, AlFeSi, AlFeMgSi, Sr 2 Si, SrSi 2 , TiSi 2 , TiSi, Ti 5 Si 4 , Ti 3 Si, Si 3 W 5 Si 2 W, SiZr 3 , SiZr 2 , Si 2 Zr 3 , Si 4 Zr 5 , SiZr, and Si 2 Zr. Although the mechanism of the corrosion inhibitory action of these fine particles is unknown, it is presumed that a part of the fine particles are eluted in a corrosive environment to form a complex corrosive organism with Zn and suppress the corrosion reaction.
[0025]
If the amount of these fine particles added is less than 0.001% by mass, the effect of improving the corrosion resistance is not obtained, and if it exceeds 10% by mass, the effect of the corrosion resistance is not only saturated, but also the aggregation of the fine particles in the bath or in the plating layer. This is not desirable because the surface roughness is increased due to the excessive amount of fine particles and the uniform coating property of the gas pinned coating plate of the electrodeposited coating plate is deteriorated.
[0026]
As for the composition of the plating bath, the corrosion resistance is further improved by adding a small amount of Mg in addition to the aforementioned Zn and Al. If Mg is less than 0.01% by mass, there is no effect of improving corrosion resistance, and if it exceeds 1.0% by mass, the effect is not only saturated but also cannot be stably present in the bath and deposited on the surface of the bath as dross such as oxide. The viscosity of the steel is increased to lower the plating quality.
[0027]
Adhesion amount of the plating layer is not particularly limited, but a range of 10g / m 2 ~200g / m 2 is desirable. If it is less than 10 g / m 2 , the development of corrosion resistance is not sufficient, and it is difficult and impractical to reduce the adhesion amount to less than 10 g / m 2 by the hot dipping method. If it exceeds 200 g / m 2 , the corrosion resistance effect is further improved, but plating damage during press working, resistance weldability, and quality after coating are undesirably caused. For automobile bodies, the amount of plating adhesion is preferably 20 to 100 g / m 2 considering the process capability of current automobile manufacturers.
[0028]
Next, the hot-dip plating method is optimal for the manufacturing method of the present invention. First, plating may be performed using a bath in which fine particles of an intermetallic compound defined in the present invention are dispersed in a hot dipping bath made of Zn, Al, Mg or Zn, Al. For steel strip plating, the most suitable method is the so-called Sendzimir method, in which the steel strip is heated to 600-900 ° C. in a preheating furnace before plating and subjected to a reduction treatment and then immersed in a plating bath. Alternatively, it may be applied by 0.1 to 10 g / m 2 by the method, followed by heat treatment in a reducing atmosphere at about 600 ° C. and then dipping in a plating bath. Moreover, after immersing in a plating bath, after performing a flux process, you may immerse in a plating bath. By plating by such a method, a plated steel material in which fine particles are dispersed can be obtained. Further, the steel material may be not only a cold-rolled steel plate and a hot-rolled steel plate but also a wire material, or a cut plate, a bar steel, and a pipe material.
[0029]
In addition to the method of adding the fine particles directly to the plating bath, the fine particles can be obtained by spraying the fine particles together with water or Ar, He, or Air gas before the plating after the hot dipping is solidified.
[0030]
The method for producing fine particles is to solidify a molten metal composed of Al and one or more elements of Ba, Ca, Ce, Fe, Mg, Sr, Ti, W, and Zr at a cooling rate of 100 ° C. or more per second. BaSi in the Al matrix by, BaSi 2, CaSi, CaSi 2 , Ca 2 Si, Ca 3 Al 2 Si 2, CaAl 2 Si 2, CaAl 1-x Si 1 + x, Ca 3 Al 6 Si 2, Ca 2 Al 4 Si 3 , Ce 2 Si, CeSi 2 , Mg 2 Si, AlFeSi, AlFeMgSi, Sr 2 Si, SrSi 2 , TiSi 2 , TiSi, Ti 5 Si 4 , Ti 3 Si, Si 3 W 5 , Si 2 W , SiZr 3 , SiZr 2 , Si 2 Zr 3 , Si 4 Zr 5 , SiZr, Si 2 Zr fine particles can be obtained. Their particle size becomes finer as the cooling rate is increased. The cooling rate for obtaining 0.9 μm or less of the present invention varies depending on the alloy type and cannot be generally specified, but it may be approximately 100 ° C. or more per second. Examples of such a rapid solidification method include a method of pouring a molten metal into a rotating drum (single drum, twin drum rapid cooling), a method of sandwiching dripped metal with a metal plate, a method of dripping molten metal into water or oil, and the like.
[0031]
Since these solidified metals use Al as a matrix, when they are added to a Zn-based plating bath, Al is eluted and a fine-particle alloy is dispersed in the bath.
[0032]
On the other hand, when the fine particles of the present invention are directly sprayed on a hot dipped plating material, the fine particles can be obtained by rapidly cooling by spraying a molten metal of a desired alloy component together with an inert gas.
[0033]
【Example】
The present invention will be described in more detail based on examples. For the galvanization, a laboratory galvanizing simulator was used. This equipment is a device for plating a steel plate, and a heating furnace capable of controlling the atmosphere and a hot dipping pot are connected in a vertical position. The steel plate was cut into a length of 200 mm and a width of 100 mm, and oil was degreased in advance. Next, it is put in a heating furnace, heated at 800 ° C. for 10 minutes in a 10% hydrogen residual nitrogen gas atmosphere, cooled to 500 ° C., and then immersed in a hot dipping bath. After being immersed for 2 seconds, it is pulled up and immediately brought to a predetermined adhesion amount by nitrogen gas wiping. Thereafter, it is allowed to cool, and is taken out of the system when the steel plate temperature becomes 200 ° C. or lower. The amount of plating was adjusted by adjusting the gas wiping pressure. The plating bath temperature was 460 ° C.
[0034]
Next, in the method of applying an intermetallic compound, in the case of spraying, the steel sheet was pulled up from the plating bath, gas-wiped, and then immediately sprayed uniformly with water on the plating surface and cooled. As another example, the intermetallic compound was sprayed with He, N 2 , and Air gas and then cooled.
[0035]
In addition, when the intermetallic compound is added directly to the plating bath, Al is used as the matrix metal, and the molten metal to which the necessary metal is added is rapidly cooled at a cooling rate of 100 ° C./s or more to precipitate 0.9 μm or less. There are methods for obtaining metal in an Al matrix.
[0036]
Moreover, as a method for obtaining fine particles, there is a method in which molten metal is sprayed together with an inert gas to be rapidly cooled and solidified.
The obtained steel material was subjected to various coating treatments. The coating treatment for the automobile outer plate was a phosphate treatment (Nihon Parker Rising Co., Ltd., PB3800) 2.0 g / m 2 , and electrodeposition coating (Nihon Paint Co., Ltd. Power Top U50) 20 μm. The gas pin property of the obtained coated plate was judged by the number of bubble-like surface defects per steel plate. 0 pieces per steel plate were good (◯), 1 to 5 pieces were slightly bad (△), and more than that was bad (x). Only good was accepted. Furthermore, an electrostatic coating type intermediate coating and top coating (manufactured by Kansai Paint Co., Ltd.) were applied to each 35 μm. The uniform coating property of the obtained coated plate was a PGD meter (manufactured by Nippon Color Research Institute). A Gd value of 0.7 or higher was accepted and less than that was rejected. Furthermore, Wca was measured using a stylus type roughness meter (Surfcom 550A manufactured by Tokyo Seimitsu, stylus diameter 5 μmR). The obtained Wca passed 0.6 μm or less, and more than it was rejected.
[0037]
Next, as an evaluation of corrosion resistance, the electrodeposited and intermediate / top-coated samples were cross-cut with a cutter, combined environmental cycle test (JIS Z2371 salt spray 2 hours, dried (60 ° C RH 30%) 4 hours, wet) (50 ° C RH 95%) 2 hours) was performed 200 cycles to evaluate the maximum blister width on one side of the cross-cut portion. In the case of an electrodeposition coating material, 3 mm or less was passed, more than that was rejected, and in the case of middle / top coating material, 1.5 mm or less was passed, and more than that was rejected. In the inventive materials of Examples 1 to 249 of Tables 1 to 7, the gas pinability during electrodeposition coating, the uniform coating property of the coated plate (PGD value), the surface roughness (Wca), the corrosion resistance (after coating) All of the post-CCT cross-cut portion blister widths are excellent and are at a pass level.
[0038]
On the other hand, materials outside the scope of the present invention are shown in Table 8, and are inferior in gas pinability or in any of uniform paintability, surface roughness, and corrosion resistance. Therefore, the material of the present invention is an excellent plated steel material that achieves both uniform paintability and corrosion resistance, and can be applied to a wide range of industrial products such as automobiles, home appliances, and electric machines.
[0039]
[Table 1]
[Table 2]
[Table 3]
[Table 4]
[Table 5]
[Table 6]
[Table 7]
[Table 8]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the corrosion resistance of a hot-dip Zn-Al plating steel plate can be improved, and good corrosion resistance, weldability, press workability, and uniform appearance after coating can be achieved with a small amount of plating.
Claims (10)
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| JP4528149B2 (en) * | 2004-04-09 | 2010-08-18 | 新日本製鐵株式会社 | Hot-dip plated steel and coated steel plate with excellent corrosion resistance |
| JP4751206B2 (en) * | 2005-02-10 | 2011-08-17 | 新日本製鐵株式会社 | High corrosion resistance plated steel material and method for producing the same |
| JP5014594B2 (en) * | 2005-06-03 | 2012-08-29 | 新日本製鐵株式会社 | Surface treated steel |
| CA2646554C (en) * | 2006-03-20 | 2011-08-02 | Nippon Steel Corporation | High corrosion resistance hot dip galvanized steel material |
| JP5092512B2 (en) * | 2007-04-13 | 2012-12-05 | 新日本製鐵株式会社 | Alloyed hot-dip galvanized steel sheet with excellent corrosion resistance and plating adhesion |
| JP5600398B2 (en) * | 2009-04-28 | 2014-10-01 | Ｊｆｅ鋼板株式会社 | Hot-dip galvanized steel sheet |
| CN101818316B (en) * | 2010-05-11 | 2011-12-07 | 昆明理工大学 | Zinc-based multi-element alloy for hot dipping and preparation method thereof |
| CN102400141B (en) * | 2010-09-07 | 2014-05-07 | 鞍钢股份有限公司 | Manufacturing method of alloyed galvanized steel sheet and alloyed galvanized steel sheet thereof |
| CN106591717B (en) * | 2016-12-01 | 2019-02-22 | 首钢集团有限公司 | A kind of method of potassium steel platability in improvement |
| KR102281201B1 (en) * | 2019-12-19 | 2021-07-26 | 주식회사 포스코 | Galvanized steel sheet with excellent liquid metal embrittlement resistance and hydrogen embrittlement resistance and method for manufacturing thereof |
| KR102413245B1 (en) * | 2020-09-15 | 2022-06-27 | 주식회사 포스코 | Galvanized steel sheet with excellent corrosion resistance in chloride containing environment and method for manufacturing thereof |
| KR20240080732A (en) * | 2022-11-30 | 2024-06-07 | 현대제철 주식회사 | Plated steel sheet and method of manufacturing the same |
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| JPS54139839A (en) * | 1978-04-24 | 1979-10-30 | Nippon Parkerizing Co Ltd | Pulverizing method for spangles of galvanized steel sheet |
| JPS63157849A (en) * | 1986-12-19 | 1988-06-30 | Nippon Steel Corp | Manufacture of steel sheet hot-dip-galvanized with zn or zn alloy inhibiting growth of spangle pattern |
| JPH04160142A (en) * | 1990-10-23 | 1992-06-03 | Mitsubishi Heavy Ind Ltd | Hot dip galvanizing steel sheet and its manufacture |
| JP3179401B2 (en) * | 1996-12-13 | 2001-06-25 | 日新製鋼株式会社 | Hot-dip Zn-Al-Mg plated steel sheet with good corrosion resistance and surface appearance and method for producing the same |
| JP3149129B2 (en) * | 1997-03-04 | 2001-03-26 | 日新製鋼株式会社 | Hot-dip Zn-Al-Mg-based coated steel sheet with good corrosion resistance and surface appearance and method for producing the same |
| JP3212977B2 (en) * | 1999-08-27 | 2001-09-25 | 新日本製鐵株式会社 | Hot-dip galvanized steel with excellent workability |
| JP4102035B2 (en) * | 2000-04-18 | 2008-06-18 | 新日本製鐵株式会社 | Plating product with excellent corrosion resistance and manufacturing method thereof |
| JP2002004017A (en) * | 2000-06-15 | 2002-01-09 | Nippon Steel Corp | HOT-DIP Zn-Al-Mg-Si PLATED STEEL MATERIAL EXCELLENT IN SURFACE CHARACTERISTIC AND ITS PRODUCTION METHOD |
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