JP2007262544A - Method for manufacturing hot-dip galvanized steel sheet - Google Patents
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本発明は、めっき付着量が55g/m2以上の厚目付な溶融亜鉛めっき鋼板の製造方法に関し、特に不めっきのない美麗な表面外観を有しめっき密着性に優れた溶融亜鉛めっき鋼板、また不めっきのない美麗な表面外観を有し耐パウダリング性に優れた合金化溶融亜鉛めっき鋼板を経済的にかつ高い生産性を有して製造する方法に関する。 The present invention relates to a method for producing a thick galvanized steel sheet having a coating weight of 55 g / m 2 or more, and in particular, a hot dip galvanized steel sheet having a beautiful surface appearance without unplating and excellent plating adhesion, The present invention relates to a method of producing an alloyed hot-dip galvanized steel sheet having a beautiful surface appearance free of non-plating and having excellent powdering resistance, economically and with high productivity.
近年、自動車、家電、建材等の分野においては、素材鋼板に防錆性を付与した表面処理鋼板、中でも安価に製造できかつ防錆性に優れた溶融亜鉛めっき鋼板（以下、ＧＩと称することもある）、合金化溶融亜鉛めっき鋼板（以下、ＧＡと称することもある）が使用されている。 In recent years, in the fields of automobiles, home appliances, building materials, etc., surface-treated steel sheets provided with rust preventive properties, especially hot dip galvanized steel sheets (hereinafter referred to as GI) that can be manufactured at low cost and have excellent rust preventive properties. In other words, an alloyed hot-dip galvanized steel sheet (hereinafter sometimes referred to as GA) is used.
一般的に、溶融亜鉛めっき鋼板は、以下の方法にて製造される。まず、スラブを熱延、冷延あるいは熱処理した薄鋼板を用いて、母材鋼板表面を前処理工程にて脱脂および／または酸洗して洗浄するか、あるいは前処理工程を省略して予熱炉内で母材鋼板表面の油分を燃焼除去した後、非酸化性雰囲気中あるいは還元性雰囲気中で加熱することで再結晶焼鈍を行う。その後、非酸化性雰囲気中あるいは還元性雰囲気中で鋼板をめっきに適した温度まで冷却して、大気に触れることなく微量Ａｌ（０．１〜０．２％程度）を添加した溶融亜鉛浴中に浸漬する。
また合金化溶融亜鉛めっき鋼板は、溶融亜鉛めっき後、引き続き、鋼板を合金化炉内で熱処理することで製造される。
さらに、自動車用に使用される場合、上記溶融亜鉛めっき鋼板もしくは合金化溶融亜鉛めっき鋼板の耐食性を向上させるため、副資材と呼ばれる防錆材が表面に塗布される。
Generally, a hot dip galvanized steel sheet is manufactured by the following method. First, using a thin steel plate obtained by hot-rolling, cold-rolling or heat-treating the slab, the base steel plate surface is degreased and / or pickled and cleaned in the pretreatment step, or the pretreatment step is omitted. After the oil on the surface of the base steel plate is burned and removed, recrystallization annealing is performed by heating in a non-oxidizing atmosphere or a reducing atmosphere. Then, the steel sheet is cooled to a temperature suitable for plating in a non-oxidizing atmosphere or a reducing atmosphere, and in a molten zinc bath to which a small amount of Al (about 0.1 to 0.2%) is added without being exposed to the air Immerse in.
An alloyed hot-dip galvanized steel sheet is produced by subsequently heat-treating the steel sheet in an alloying furnace after hot-dip galvanizing.
Furthermore, when used for automobiles, in order to improve the corrosion resistance of the hot dip galvanized steel sheet or alloyed hot dip galvanized steel sheet, a rust preventive material called an auxiliary material is applied to the surface.
ところで、近年、自動車用鋼板のさらなる防錆性向上が求められており、防錆性向上の有力な一つの手段としてめっき付着量を増加させる方法がある。現在の主流はめっき付着量が30〜45g/m2程度の合金化溶融亜鉛めっき鋼板であるが、上記要望を受けて、耐食性、防錆性能を向上させるため、55g/m2以上の厚目付溶融めっき鋼板が開発された。しかしながら、55g/m2以上の厚目付の溶融亜鉛めっき鋼板および合金化溶融亜鉛めっき鋼板は以下の問題がある。 Incidentally, in recent years, there has been a demand for further improvement in rust prevention of steel sheets for automobiles, and there is a method of increasing the amount of plating adhesion as one effective means for improving rust prevention. Although the current mainstream coating weight is galvannealed steel sheet of about 30~45g / m 2, by receiving the request, the corrosion resistance, to improve the rust performance, 55 g / m 2 or more thick basis weight Hot dipped steel sheet was developed. However, hot dip galvanized steel sheets and galvannealed steel sheets having a thickness of 55 g / m 2 or more have the following problems.
合金化溶融亜鉛めっき鋼板の場合には、めっき付着量の増加に伴い、溶融亜鉛めっき後の合金化過程における合金化反応が遅延する。その結果、生産性を著しく阻害したり、生産性を確保するために過剰に高温で合金化処理すると耐パウダリング性の劣化を招くという問題があり、高い生産性と良好な耐パウダリング性を両立させることが困難となる。 In the case of an alloyed hot dip galvanized steel sheet, the alloying reaction in the alloying process after hot dip galvanization is delayed with an increase in the amount of plating. As a result, there is a problem that if the alloying process is performed at an excessively high temperature in order to ensure productivity, the resistance to powdering will be deteriorated, resulting in high productivity and good powdering resistance. It becomes difficult to achieve both.
溶融亜鉛めっき鋼板の場合には、厚目付とすることによりめっき密着性が悪化する傾向にあり、めっき密着性が十分な厚目付溶融亜鉛めっき鋼板は得られない。さらに、厚目付とすることにより耐食性を向上させて、上述の副資材の塗布を省略することが考えられるが、副資材の塗布を省略できる程の耐食性向上は得られておらず、副資材の塗布省略を可能とする程度の耐食性向上が厚目付鋼板に求められている。 In the case of a hot dip galvanized steel sheet, the plating adhesion tends to be deteriorated by making it thick, and a thick galvanized steel sheet with sufficient plating adhesion cannot be obtained. Furthermore, it is conceivable to improve the corrosion resistance by making it thicker and omit the application of the above-mentioned secondary material, but the corrosion resistance improvement that can omit the application of the secondary material has not been obtained, There is a demand for thickened steel sheets to improve corrosion resistance to the extent that application can be omitted.
このような問題に対して、予め酸化性雰囲気中で鋼板を加熱して表面に酸化鉄を形成した後加熱することで還元焼鈍を行い、溶融亜鉛との濡れ性及び反応性を改善する方法が開示されている（特許文献1）。
また、溶融めっきに先立って硫黄または硫黄化合物をＳ量として0.1〜1000mg/m2付着させた後、予熱工程を弱酸化性雰囲気で行い、その後、水素を含む非酸化性雰囲気中で焼鈍する方法が開示されている（特許文献2）。
For such a problem, there is a method in which a steel sheet is heated in an oxidizing atmosphere in advance to form iron oxide on the surface and then subjected to reduction annealing to improve wettability and reactivity with molten zinc. It is disclosed (Patent Document 1).
In addition, after depositing sulfur or a sulfur compound as an S amount in an amount of 0.1 to 1000 mg / m 2 prior to hot dipping, a preheating step is performed in a weakly oxidizing atmosphere, followed by annealing in a non-oxidizing atmosphere containing hydrogen. Is disclosed (Patent Document 2).
上記方法により、溶融亜鉛めっき時の溶融亜鉛と鋼板との濡れ性は向上し、めっき密着性の向上効果はある。また、めっき層の合金化を行う場合には、合金化反応の遅延抑制効果も期待できる。しかし、厚目付の溶融亜鉛めっきを行うと、合金化溶融亜鉛めっき鋼板の場合には耐パウダリング性が、溶融亜鉛めっき鋼板の場合にはめっき密着性が未だ不十分である。さらに、耐食性の問題については、上述の副資材の塗布を省略するレベルまでには到底至っていない。
本発明はかかる事情に鑑みてなされたものであって、めっき付着量が55g/m2以上の不めっきのない美麗な表面外観を有し、耐食性にも優れた溶融亜鉛めっき鋼板、あるいはさらに耐パウダリング性にも優れた合金化溶融亜鉛めっき鋼板を経済的にかつ高い生産性を有して製造する方法を提供することを目的とする。 The present invention has been made in view of such circumstances, and is a hot dip galvanized steel sheet having a beautiful surface appearance free of unplating with a plating adhesion amount of 55 g / m 2 or more, and excellent corrosion resistance, or more An object of the present invention is to provide a method for producing an alloyed hot-dip galvanized steel sheet excellent in powdering properties economically and with high productivity.
前述したように、めっき付着量が55ｇ/m2以上の厚目付の場合、従来技術によるめっき−合金化手段のみでは、合金化溶融亜鉛めっき鋼板においては、合金化が遅延する。さらには、パウダリング性が劣化する。溶融亜鉛めっき鋼板においては、耐食性が不十分であり、めっき密着性が劣化する。そこで、発明者らは、これらの問題を解決するために、めっき処理条件について、詳細に検討を行った。
その結果、鋼板をめっき浴へ浸入する際の板温（以下、浸入板温と称す）を通常の460℃程度から500〜600℃まで上昇させることにより、厚目付な溶融亜鉛めっき鋼板ながら合金化速度が増加させることに成功した。また、溶融亜鉛めっき鋼板においては密着性が向上した。
また、めっき浴中Al濃度を最適化し、0.15〜0.3%にすることで、パウダリング性を劣化させるΓ相の形成を抑制し、厚目付な合金化溶融亜鉛めっき鋼板ながら耐パウダリング性を向上させることに成功した。また、めっき層中に取り込まれるAl量が増加した事で、耐食性に優れた溶融亜鉛めっき鋼板が得られた。
さらに溶融亜鉛めっき処理を施すに先立ち、鋼板表面に特定の元素を付着させておくことによって、Γ相が過剰に生成することなく合金化反応を促進させることに成功し、合金化温度を低減させることに成功した。また、表面が活性化され、めっき浴中におけるFeとZnの初期合金化が促進されることで、溶融亜鉛めっき鋼板においてめっき密着性が向上した。
本発明は、以上の知見に基づきなされたもので、その要旨は以下のとおりである。
［１］C≦0.25mass%を含有する冷延鋼板に溶融亜鉛めっき処理を施すに際し、浸入板温を500〜600℃、浴中Al濃度を0.15〜0.3wt%として溶融亜鉛めっき処理を施し、めっき付着量を55g/m2以上とすることを特徴とする溶融亜鉛めっき鋼板の製造方法。
［２］前記［１］において、前記溶融亜鉛めっき処理を施すに先立ち、まず、元素XとしてS、Cl、Na、K、Ni、C、N、B、Se、Brの少なくとも１種以上を含有する化合物を、下記（１）式を満足するように鋼板表面に付着させ、次いで、再結晶焼鈍することを特徴とする溶融亜鉛めっき鋼板の製造方法。
〔X〕≧（1/600）×〔M〕 ―――（１）
〔X〕：Xの量単位mg/m2 〔M〕：めっき付着量単位g/m2
［３］前記［１］または［２］において、溶融亜鉛めっき処理後に合金化処理することを特徴とする溶融亜鉛めっき鋼板の製造方法。
As described above, when the coating weight is 55 g / m 2 or more, alloying is delayed in the galvannealed steel sheet only by the plating-alloying means according to the prior art. Furthermore, the powdering property is deteriorated. In the hot dip galvanized steel sheet, the corrosion resistance is insufficient and the plating adhesion deteriorates. Therefore, the inventors have studied in detail the plating process conditions in order to solve these problems.
As a result, by increasing the plate temperature when the steel plate enters the plating bath (hereinafter referred to as the intrusion plate temperature) from about 460 ° C to 500-600 ° C, it is alloyed with a thick hot-dip galvanized steel plate. Succeeded to increase speed. Moreover, the adhesiveness improved in the hot dip galvanized steel sheet.
In addition, by optimizing the Al concentration in the plating bath to 0.15 to 0.3%, the formation of the Γ phase, which degrades powdering properties, is suppressed, and the powdering resistance is improved while using thick alloyed hot-dip galvanized steel sheets. I succeeded in making it happen. Moreover, the hot dip galvanized steel plate excellent in corrosion resistance was obtained by having increased the amount of Al taken in in a plating layer.
Furthermore, prior to the hot dip galvanizing treatment, by adhering specific elements to the surface of the steel sheet, the alloying reaction was successfully promoted without excessive formation of the Γ phase, and the alloying temperature was reduced. Succeeded. Further, the surface was activated and the initial alloying of Fe and Zn in the plating bath was promoted, thereby improving the plating adhesion in the hot dip galvanized steel sheet.
The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] When hot-dip galvanizing treatment is performed on a cold-rolled steel sheet containing C ≦ 0.25 mass%, the hot-dip galvanizing treatment is performed with an intrusion plate temperature of 500 to 600 ° C. and an Al concentration in the bath of 0.15 to 0.3 wt%. A method for producing a hot dip galvanized steel sheet, characterized in that the coating weight is 55 g / m 2 or more.
[2] In the above [1], prior to performing the hot dip galvanizing treatment, first, the element X contains at least one of S, Cl, Na, K, Ni, C, N, B, Se, and Br The manufacturing method of the hot dip galvanized steel sheet characterized by making the compound to adhere to the steel plate surface so that the following (1) formula may be satisfied, and then recrystallizing annealing.
[X] ≧ (1/600) × [M] ――― (1)
[X]: X quantity unit mg / m 2 [M]: Plating adhesion quantity unit g / m 2
[3] The method for producing a hot dip galvanized steel sheet according to [1] or [2], wherein an alloying treatment is performed after the hot dip galvanizing treatment.
本発明によれば、不めっきのなく美麗な表面外観を有しめっき密着性に優れた溶融亜鉛めっき鋼板、および不めっきのない美麗な表面外観を有しかつ耐パウダリング性に優れた合金化溶融亜鉛めっき鋼板が得られる。また、溶融亜鉛めっき鋼板においては、充分な耐食性が得られるため、上述の副資材の塗布を省略することが可能となる。また、合金化遅延等の問題も解消され、高い生産性の下、製造することが可能となる。 According to the present invention, a hot-dip galvanized steel sheet having a beautiful surface appearance without plating and excellent plating adhesion, and an alloying having a beautiful surface appearance without plating and excellent powdering resistance. A hot dip galvanized steel sheet is obtained. Moreover, since sufficient corrosion resistance is obtained in the hot dip galvanized steel sheet, it becomes possible to omit application of the above-mentioned auxiliary materials. In addition, problems such as alloying delay can be solved, and manufacturing can be performed with high productivity.
以下、本発明について具体的に説明する。
まず、本発明の最も重要な要件の一つである浸入板温について説明する。本発明では、浸入板温を500℃以上600℃以下とする。これにより、溶融めっき時に形成されるFe-Alの合金層を、後述するように合金化処理時にΓ相の形成を抑制でき、かつ、FeとZnの初期合金化反応を阻害しない程度とすることができる。その結果、めっき浴中におけるFeとZnの初期合金化も促進され、めっきと下地鋼板との密着性が良好な溶融亜鉛めっき鋼板が得られる。また、溶融めっき後の合金化時においては、FeとZnの合金化速度の遅く、めっき付着量が55g/m2以上の厚目付のめっき鋼板の場合でも合金化を促進させることが可能となる。
浸入板温が500℃未満の場合、本発明による効果が発現しない。また、600℃を超える場合、溶融亜鉛めっき時に部分的に合金化反応が進行してしまい、溶融亜鉛めっき後合金化ムラが発生し、めっき外観が損なわれる。
Hereinafter, the present invention will be specifically described.
First, the infiltration plate temperature, which is one of the most important requirements of the present invention, will be described. In the present invention, the immersion plate temperature is set to 500 ° C. or more and 600 ° C. or less. As a result, the Fe-Al alloy layer formed during hot dipping should be able to suppress the formation of the Γ phase during the alloying process, as will be described later, and not to inhibit the initial alloying reaction of Fe and Zn. Can do. As a result, initial alloying of Fe and Zn in the plating bath is also promoted, and a hot dip galvanized steel sheet having good adhesion between the plating and the base steel sheet is obtained. In addition, when alloying after hot dipping, the alloying speed of Fe and Zn is slow, and it is possible to promote alloying even in the case of a plated steel sheet with a coating weight of 55 g / m 2 or more. .
When the penetration plate temperature is less than 500 ° C., the effect of the present invention is not exhibited. On the other hand, when the temperature exceeds 600 ° C., the alloying reaction partially proceeds during hot dip galvanizing, resulting in uneven galvanizing after hot dip galvanizing, and the plating appearance is impaired.
次いで、本発明において、もう一つの重要な要件である、めっき浴中のAl濃度について説明する。本発明ではめっき浴中のAl濃度を0.15％以上0.3%以下とする。これにより、めっき層中に取り込まれるAl量が増加し、耐食性に優れた溶融亜鉛めっき鋼板が得られることになる。これは、めっきの表層においてAlが不働態化し、0.1μm以下の薄い酸化皮膜を形成したためと考えられる。また、めっき後の合金化時に形成され、パウダリング性を劣化させるΓ相の形成を抑制する。その結果、耐パウダリング性が飛躍的に向上する。
浴中のAl濃度が、0.15%未満では溶融亜鉛めっき時のめっき表面にAlの不働態皮膜が充分に形成せず、耐食性が劣化する。さらに、合金化時のΓ相の形成の抑制効果が認められない。一方、0.3%を超えてAl濃度を大きくしても、溶融亜鉛めっき時のめっき表面に形成されるAlの不働態皮膜量は増加せず飽和する。また、合金化時のΓ相の形成抑制効果も飽和するため、経済的観点からも0.3%を上限とする。
さらに、本発明においては、上記要件に加え、前記溶融亜鉛めっき処理を施すに先立ち、まず、元素XとしてS、Cl、Na、K、Ni、C、N、B、Se、Brの少なくとも１種以上を含有する化合物を、下記（１）式を満足するように鋼板表面に付着させ、次いで、再結晶焼鈍することが好ましい。
〔X〕≧（1/600）×〔M〕 ―――（１）
〔X〕：Xの量単位mg/m2
〔M〕：めっき付着量単位g/m2
上記めっき前の処理は、還元処理後の表面を活性化させてFeとZnの反応性を促進させるために行う。上記の特定の元素を鋼板表面に付着させることで表面が活性化され、めっき浴中におけるFeとZnの初期合金化が促進され、めっき密着性に極めてすぐれた溶融亜鉛めっき鋼板が得られる。また、溶融めっき後の合金化時においては、FeとZnの合金化速度の遅く、めっき付着量が55g/m2以上の厚目付のめっき鋼板の場合でも合金化を飛躍的に促進させることが可能となる。
上記の特定元素を付着させることで表面が活性化させる理由は明らかでないが、例えばNOF（無酸化炉）やDFF（直下炉）型焼鈍炉での酸化では表面状態を変化させることで表面の酸化が促進され、次工程の還元時に鋼板表面に生成する反応性に富む還元鉄の量が増加すると考えられる。また、RTF（ラジアントチューブ炉）型の焼鈍炉では、鋼板表層での再結晶時に鋼中の易酸化元素や不可避的不純物の表面への濃化を抑制する効果があると考えられる。ここで特定元素Xとして使用可能な化合物の例としては以下のようなものがあげられる。
水酸化ナトリウム(NaOH)、硫酸ナトリウム(Na2SO4)、硫化ナトリウム(Na2S)、チオ硫酸ナトリウム(Na2S2O3)、塩化ナトリウム(NaCl)、炭酸ナトリウム(Na2CO3)、クエン酸ナトリウム(Na3C6H5O7)、シアン酸ナトリウム(NaCNO)、酢酸ナトリウム(CH3COONa)、リン酸水素ナトリウム(Na2HPO4)、リン酸ナトリウム(Na3PO4)、フッ化ナトリウム(NaF)、炭酸水素ナトリウム(NaHCO3)、硝酸ナトリウム(NaNO3)、シュウ酸ナトリウム((COONa)2)、四ほう酸ナトリウム(Na2B4O7)、酸化ナトリウム(Na2O)等のＮａ含有化合物、
水酸化カリウム(KOH)、酢酸カリウム(CH3COOK)、ほう酸カリウム(K2B4O7)、炭酸カリウム(K2CO3)、塩化カリウム(KCl)、シアン酸カリウム(KCNO)、クエン酸水素カリウム(KH2C6H5O7)、フッ化カリウム(KF)、モリブデン酸カリウム(K2MoO4)、硝酸カリウム(KNO3)、過マンガン酸カリウム(KMnO4)、リン酸カリウム(K3PO4)、硫酸カリウム(K2SO4)、チオシアン酸カリウム(KSCN)、シュウ酸カリウム((COOK)2)等のＫ含有化合物、
塩酸(HCl)、塩化ナトリウム(NaCl)、塩化アンモニウム(NH4Cl)、塩化アンチモン(SbCl3)、塩化カリウム(KCl)、塩化鉄(FeCl2、FeCl3)、塩化チタン(TiCl4)、塩化銅(CuCl)、塩化バリウム(BaCl2)、塩化モリブデン(MoCl5)、塩素酸ナトリウム(NaClO3)等のＣｌ含有化合物、臭化鉄等のBr含有化合物
硫酸(H2SO4)、硫酸ナトリウム(Na2SO4)、亜硫酸ナトリウム(Na2SO3)、硫化ナトリウム(Na2S)、硫酸アンモニウム((NH4)2SO4)、硫化アンモニウム((NH4)2S)、チオ硫酸ナトリウム(Na2S2O3)、硫酸水素ナトリウム(NaHSO4)、硫酸水素アンモニウム(NH4HSO4)、硫酸カリウム(K2SO4)、硫酸鉄(FeSO4、Fe2(SO4)3)、硫酸アンモニウム鉄（Fe(NH4)2(SO4)2、FeNH4(SO4)2）、硫酸バリウム(BaSO4)、硫化アンチモン(Sb2S3)、硫化鉄(FeS)、チオ尿素(H2NCSNH2)、二酸化チオ尿素((NH2)2CSO2)、ＳＣＨ基のチオフェン酸塩類、ＳＣＮ基を有するチオシアン酸塩類 等のＳ含有化合物、セレン酸カリウムなどのSe含有化合物等が上げられる
タンニン酸、アジピン酸等のカルボン酸含有化合物、糖類、フマル酸、フタル酸、フェノール、アニリン、安息香酸等の芳香族環含有化合物、グリシン、アラニンなどのアミノ酸、エチレングリコール、アセチレングリコール等の多価アルコール類、アクリル酸、ポリエステル、エポキシ、それらの変性化合物等の樹脂類等のC含有化合物が挙げられる。
なお、上記は代表的な例を示したのであって、上記以外のNa、K、Ni、C、N、B、Se、Brを含有する化合物を使用しても本発明の効果を好適に得られることは言うまでもない。
Next, the Al concentration in the plating bath, which is another important requirement in the present invention, will be described. In the present invention, the Al concentration in the plating bath is 0.15% or more and 0.3% or less. As a result, the amount of Al taken into the plating layer is increased, and a hot-dip galvanized steel sheet having excellent corrosion resistance is obtained. This is presumably because Al was passivated on the surface layer of the plating, and a thin oxide film of 0.1 μm or less was formed. Further, the formation of a Γ phase which is formed during alloying after plating and deteriorates powdering properties is suppressed. As a result, the powdering resistance is greatly improved.
When the Al concentration in the bath is less than 0.15%, a passive film of Al is not sufficiently formed on the plating surface during hot dip galvanization, and the corrosion resistance is deteriorated. Furthermore, the effect of suppressing the formation of the Γ phase during alloying is not recognized. On the other hand, even if the Al concentration is increased beyond 0.3%, the amount of the passive film of Al formed on the plating surface during hot dip galvanizing does not increase and is saturated. In addition, since the effect of suppressing the formation of the Γ phase at the time of alloying is saturated, the upper limit is set to 0.3% from the economical viewpoint.
Further, in the present invention, in addition to the above requirements, prior to performing the hot dip galvanizing treatment, first, the element X is at least one of S, Cl, Na, K, Ni, C, N, B, Se, and Br. It is preferable to adhere the compound containing the above to the surface of the steel sheet so as to satisfy the following formula (1), and then to perform recrystallization annealing.
[X] ≧ (1/600) × [M] ――― (1)
[X]: X quantity unit mg / m 2
[M]: Plating adhesion unit g / m 2
The treatment before plating is performed to activate the surface after the reduction treatment and promote the reactivity of Fe and Zn. By adhering the specific element to the surface of the steel sheet, the surface is activated, the initial alloying of Fe and Zn in the plating bath is promoted, and a hot dip galvanized steel sheet with excellent plating adhesion can be obtained. Also, during alloying after hot dipping, the alloying rate of Fe and Zn is slow, and even in the case of thick plated steel sheets with a coating weight of 55 g / m 2 or more, alloying can be dramatically accelerated. It becomes possible.
The reason why the surface is activated by attaching the above specific elements is not clear, but for example, oxidation in NOF (non-oxidation furnace) or DFF (direct furnace) type annealing furnace changes the surface state to oxidize the surface. It is considered that the amount of reduced iron rich in reactivity generated on the steel sheet surface during the reduction in the next step is increased. In addition, in an RTF (radiant tube furnace) type annealing furnace, it is considered that there is an effect of suppressing the concentration of easily oxidizable elements and unavoidable impurities in the steel surface during recrystallization on the steel sheet surface layer. Examples of compounds that can be used as the specific element X include the following.
Sodium hydroxide (NaOH), sodium sulfate (Na2SO4), sodium sulfide (Na2S), sodium thiosulfate (Na2S2O3), sodium chloride (NaCl), sodium carbonate (Na2CO3), sodium citrate (Na3C6H5O7), sodium cyanate (NaCNO) ), Sodium acetate (CH3COONa), sodium hydrogen phosphate (Na2HPO4), sodium phosphate (Na3PO4), sodium fluoride (NaF), sodium bicarbonate (NaHCO3), sodium nitrate (NaNO3), sodium oxalate ((COONa) 2), Na-containing compounds such as sodium tetraborate (Na2B4O7), sodium oxide (Na2O),
Potassium hydroxide (KOH), potassium acetate (CH3COOK), potassium borate (K2B4O7), potassium carbonate (K2CO3), potassium chloride (KCl), potassium cyanate (KCNO), potassium hydrogen citrate (KH2C6H5O7), potassium fluoride ( KF), potassium molybdate (K2MoO4), potassium nitrate (KNO3), potassium permanganate (KMnO4), potassium phosphate (K3PO4), potassium sulfate (K2SO4), potassium thiocyanate (KSCN), potassium oxalate ((COOK) 2) K-containing compounds such as
Hydrochloric acid (HCl), sodium chloride (NaCl), ammonium chloride (NH4Cl), antimony chloride (SbCl3), potassium chloride (KCl), iron chloride (FeCl2, FeCl3), titanium chloride (TiCl4), copper chloride (CuCl), chloride Cl-containing compounds such as barium (BaCl2), molybdenum chloride (MoCl5), sodium chlorate (NaClO3), Br-containing compounds such as iron bromide sulfuric acid (H2SO4), sodium sulfate (Na2SO4), sodium sulfite (Na2SO3), sodium sulfide (Na2S), ammonium sulfate ((NH4) 2SO4), ammonium sulfide ((NH4) 2S), sodium thiosulfate (Na2S2O3), sodium hydrogensulfate (NaHSO4), ammonium hydrogensulfate (NH4HSO4), potassium sulfate (K2SO4), iron sulfate (FeSO4, Fe2 (SO4) 3), ammonium iron sulfate (Fe (NH4) 2 (SO4) 2, FeNH4 (SO4) 2), barium sulfate (BaSO4), antimony sulfide (Sb2S3), iron sulfide (FeS), thiourea (H2NCSNH2), thiourea dioxide ((NH2) 2CSO2), thiophene salts of SCH group, S-containing compounds such as phosphates, Se-containing compounds such as potassium selenate, carboxylic acids-containing compounds such as tannic acid and adipic acid, fragrances such as saccharides, fumaric acid, phthalic acid, phenol, aniline and benzoic acid C-containing compounds such as aromatic ring-containing compounds, amino acids such as glycine and alanine, polyhydric alcohols such as ethylene glycol and acetylene glycol, and resins such as acrylic acid, polyester, epoxy, and modified compounds thereof.
The above shows a representative example, and the effects of the present invention can be suitably obtained even if a compound containing Na, K, Ni, C, N, B, Se, or Br other than the above is used. Needless to say.
上述したように、前記特定元素を含む化合物の付着量は、特定元素量として式（1）を満たすように付着させることが望ましい。
〔X〕≧（1/600）×〔M〕―――（１）
ここで〔X〕：Xの量単位mg/m2、〔M〕：めっき付着量単位g/m2
下限を式（1）のように規定したのは、これ未満であれば特定元素Xを塗布しない場合と変わらず、塗布することによる大幅なめっき密着性向上効果、及び飛躍的な合金化促進効果が発現しないためである。めっき付着量の増加に伴い、溶融亜鉛めっき時のめっきと鋼板の密着性は劣化する傾向にあるため、良好な密着性を示す溶融亜鉛めっき鋼板を得るためには前記特定元素の付着量を増加させFeとZnの初期合金化を促進させる必要がある。さらに、めっき後合金化時においても、めっき付着量の増加に伴い、合金化速度は遅延するため、前記特定元素の付着量を増加させ、FeとZnの合金化を促進させる必要がある。一方、上限は特には設けないが、前期特定元素の付着量が1000mg/m2を超える場合には本発明の効果が飽和して経済的に不利になる。よって、1000mg/m2以下が望ましい。
なお、本発明においては、この特定元素Xを塗布しない場合でも、本発明の主要な要件である浸入板温およびめっき浴中のAl濃度が本発明範囲内であれば、めっき密着性、合金化特性は良好となる。そして、さらに、特定元素Xを上式の条件で塗布することで、めっき密着性、合金化特性いずれの特性も極めて良好となる。
As described above, it is desirable that the amount of the compound containing the specific element be adhered so as to satisfy the formula (1) as the specific element amount.
[X] ≧ (1/600) × [M] ――― (1)
Here, [X]: X quantity unit mg / m 2 , [M]: Plating adhesion quantity unit g / m 2
The lower limit is defined as in formula (1), and if it is less than this, it is the same as the case where the specific element X is not applied. This is because is not expressed. As the adhesion amount of plating increases, the adhesion between the hot dip galvanizing and the steel sheet tends to deteriorate, so in order to obtain a hot dip galvanized steel sheet with good adhesion, the adhesion amount of the specific element is increased. It is necessary to promote the initial alloying of Fe and Zn. Furthermore, even during alloying after plating, the alloying speed is delayed with an increase in the amount of plating deposited, so it is necessary to increase the amount of the specific element deposited to promote alloying of Fe and Zn. On the other hand, although there is no particular upper limit, when the adhesion amount of the specific element in the previous period exceeds 1000 mg / m 2 , the effect of the present invention is saturated, which is economically disadvantageous. Therefore, 1000 mg / m 2 or less is desirable.
In the present invention, even when this specific element X is not applied, if the infiltration plate temperature and the Al concentration in the plating bath, which are the main requirements of the present invention, are within the range of the present invention, the plating adhesion, alloying The characteristics are good. Furthermore, by applying the specific element X under the above conditions, both the plating adhesion and the alloying characteristics are extremely good.
前記した特定元素を含む化合物を鋼板表面に付着させる方法としては特に限定するものではない。物理的に付着させればよいので、例えば、前記化合物を水または有機溶剤等に溶解し、またはこれらと混合したものを用い、この中に鋼板を浸漬させる方法、スプレー等で噴霧する方法、ロールコーター等で塗布する方法を用いることができる。また、その後に乾燥させても本発明の効果は変わらない。その他、化合物を直接塗布しても同様に本発明の効果を得ることができる。前記化合物を付着させる前に必要に応じて電解脱脂や酸洗等の従来から用いられている前処理を施しても本発明の効果を得ることができる。また、前記化合物を付着させた後に必要に応じて電解脱脂や酸洗等の従来から用いられている前処理を施したとしても、前記化合物が鋼板上に付着していれば本発明の効果を得ることができる。さらに、前記化合物を含む圧延油を用いて圧延時に付着させる方法を用いてもよい。いずれにしても、鋼板を酸化させる際に前記特定元素を含む化合物が鋼板表面に付着していれば良い。 It does not specifically limit as a method to adhere the compound containing an above described specific element to the steel plate surface. Since it only has to be physically attached, for example, a method in which the above compound is dissolved in water or an organic solvent, or a mixture thereof, a method of immersing a steel plate in this, a method of spraying with a spray or the like, a roll A coating method using a coater or the like can be used. Moreover, even if it dries after that, the effect of this invention does not change. In addition, the effect of the present invention can be obtained in the same manner by directly applying the compound. The effect of the present invention can be obtained even if a conventional pretreatment such as electrolytic degreasing or pickling is performed as necessary before the compound is attached. Moreover, even if the pretreatment conventionally used, such as electrolytic degreasing and pickling, is performed as needed after making the said compound adhere, if the said compound adheres on the steel plate, the effect of the present invention will be achieved. Obtainable. Furthermore, you may use the method of making it adhere at the time of rolling using the rolling oil containing the said compound. In any case, it is sufficient that the compound containing the specific element adheres to the surface of the steel sheet when oxidizing the steel sheet.
鋼板表面に付着させた特定元素量の定量方法としては、湿式分析法により測定することができる。すなわち、素材鋼板を含んだ全特定元素量から鋼中の特定元素量を差し引くことで容易に定量することができる。 As a method for quantifying the specific element amount adhered to the steel sheet surface, it can be measured by a wet analysis method. That is, it can be easily quantified by subtracting the specific element amount in the steel from the total specific element amount including the raw steel plate.
鋼板表面に特定元素を含有する化合物を付着させた後、鋼板を再結晶焼鈍することが好ましい。再結晶焼鈍は通常、還元雰囲気下で行うが、NOFやDFF型CGLのように、加熱帯において酸化させた後、還元処理してもよい。還元方法は従来から使用されている方法に準じて行えばよく、特に限定するものではない。例えば、放射加熱方式の焼鈍炉で水素を含む還元性雰囲気中で６００〜９００℃程度の温度で還元処理するのが一般的ではあるが、特に限定するものではない。加熱帯で酸化した場合には、鋼板表面の酸化皮膜を還元することができる方法であれば本発明の効果を妨げるものではない。また雰囲気は水素-窒素系が好ましく、水素は1〜90%が好ましい。1%未満の場合還元が不十分であり、90%以上は経済的に不利な場合がある。 It is preferable to recrystallize the steel sheet after attaching the compound containing the specific element to the steel sheet surface. The recrystallization annealing is usually performed in a reducing atmosphere, but may be reduced after being oxidized in a heating zone like NOF or DFF type CGL. The reduction method may be performed in accordance with a conventionally used method and is not particularly limited. For example, the reduction treatment is generally performed at a temperature of about 600 to 900 ° C. in a reducing atmosphere containing hydrogen in a radiant heating type annealing furnace, but is not particularly limited. When oxidized in a heating zone, the effect of the present invention is not hindered by a method that can reduce the oxide film on the surface of the steel sheet. The atmosphere is preferably a hydrogen-nitrogen system, and hydrogen is preferably 1 to 90%. If it is less than 1%, the reduction is insufficient, and if it is more than 90%, it may be economically disadvantageous.
前記還元処理後に、非酸化性あるいは還元性雰囲気中で500〜600℃まで冷却され、めっき浴中に浸漬してめっきする。この時、前述した通り、浸入板温は500〜600℃、浴中Al濃度は0.15〜0.3wt%とする。また、それ以外の条件として、めっき浴温は440〜600℃程度が好ましい。また、製品の使用用途によってはめっき浴組成を変更する場合があるが、めっき浴組成の違いは本発明の効果に何ら害するものではなく、特に限定するものではない。例えば、めっき浴中にＡｌ以外にＰｂ、Ｓｂ、Ｆｅ、Ｍｇ、Ｍｎ、Ｎｉ、Ｃａ、Ｔｉ、Ｖ、Ｃｒ、Ｃｏ、Ｓｎ等の元素が混入していても本発明の効果は何ら変わらない。 After the reduction treatment, it is cooled to 500 to 600 ° C. in a non-oxidizing or reducing atmosphere, and immersed in a plating bath for plating. At this time, as described above, the infiltration plate temperature is 500 to 600 ° C., and the Al concentration in the bath is 0.15 to 0.3 wt%. As other conditions, the plating bath temperature is preferably about 440 to 600 ° C. Moreover, although the plating bath composition may be changed depending on the intended use of the product, the difference in the plating bath composition does not impair the effects of the present invention and is not particularly limited. For example, even if elements such as Pb, Sb, Fe, Mg, Mn, Ni, Ca, Ti, V, Cr, Co, and Sn other than Al are mixed in the plating bath, the effect of the present invention is not changed.
めっき後のめっき付着量を調整する方法は特に限定するものではないが、一般的にガスワイピングが使用され、ガスワイピングのガス圧、ワイピングノズル／鋼板間距離等により調整される。このとき、めっき付着量は55g/m2以上とする。上限は特に限定するものではないが、55〜150g/m2が好ましい。55ｇ/ｍ2未満では防錆性が充分得られない。一方、150ｇ/ｍ2を超える付着量では防錆性が飽和して、一方で加工性、経済性を損なうため、150ｇ/ｍ2以下が好ましい。 A method for adjusting the plating adhesion amount after plating is not particularly limited, but gas wiping is generally used, and is adjusted by a gas pressure of gas wiping, a wiping nozzle / steel plate distance, and the like. At this time, the plating adhesion amount is 55 g / m 2 or more. The upper limit is not particularly limited, but 55 to 150 g / m 2 is preferable. If it is less than 55 g / m 2 , sufficient rust prevention properties cannot be obtained. On the other hand, when the adhesion amount exceeds 150 g / m 2 , the rust prevention property is saturated, and on the other hand, the workability and the economical efficiency are impaired, so 150 g / m 2 or less is preferable.
次いで、合金化溶融亜鉛めっき鋼板を得る場合、前記溶融亜鉛めっき後に合金化処理を施す。前述のように本発明によれば、めっき付着量が55ｇ/ｍ2以上の厚目付な溶融亜鉛めっき鋼板でも、著しい合金化遅延という従来技術での問題を解消することができる。その結果、55ｇ/ｍ2以上の厚目付な耐パウダリング性に優れた合金化溶融亜鉛めっき鋼板を、生産性を阻害することなく製造することができる。さらに合金化温度の低温下により機械的特性が改善する効果も得られる。合金化処理方法はガス加熱、インダクション加熱や通電加熱等の従来から行われているどのような加熱方法を用いてもよく、特に限定するものではない。 Next, when obtaining an galvannealed steel sheet, an alloying treatment is performed after the galvanizing. As described above, according to the present invention, even in the case of a thick hot dip galvanized steel sheet having a coating adhesion amount of 55 g / m 2 or more, it is possible to solve the problem in the prior art that a significant alloying delay occurs. As a result, an alloyed hot-dip galvanized steel sheet excellent in powdering resistance of 55 g / m 2 or more can be produced without impairing productivity. Furthermore, the effect of improving the mechanical properties can be obtained by lowering the alloying temperature. The alloying treatment method may be any heating method conventionally used, such as gas heating, induction heating, and current heating, and is not particularly limited.
また、合金化処理条件は特に限定するものではなく、例えば合金化処理板温は４６０〜６００℃程度、合金化保持時間は５〜６０秒程度とするのが一般的ではあるが、合金化処理条件の違いが本発明の効果を妨げるものではない。 The alloying treatment conditions are not particularly limited. For example, the alloying treatment plate temperature is generally about 460 to 600 ° C., and the alloying holding time is about 5 to 60 seconds. The difference in conditions does not hinder the effects of the present invention.
なお、本発明が対象とする鋼板は、特に鋼種を限定するものではない。ただし、Cについては0.25mass％以下含有することとする。Cが0.25mass％を超えて含有すると鋼板自体が硬くなりすぎ脆化する。その他の添加元素については本発明の効果を妨げるものではなく、特に限定するものではない。例えば、素材に必要とされる特性、品質等を考慮してSi、Mn、Ｐ、Ａｌ等の元素を１種あるいは２種以上含有することができる。含有量としては、Si：3.0mass％以下、Ｍｎ：0.01〜5 mass %、Ｐ：0.005〜0.2 mass %、Ａｌ：0.01〜5 mass %が好ましい。なお、これらの元素は本発明の効果とは無関係に、素材に必要とされる特性、品質等から適宜選定することができるのは言うまでもなく、上記以外の元素についても同様である。 In addition, the steel plate which this invention makes object does not specifically limit a steel type. However, about C, it shall contain 0.25 mass% or less. If C exceeds 0.25 mass%, the steel sheet itself becomes too hard and becomes brittle. Other additive elements do not impede the effects of the present invention and are not particularly limited. For example, one or more elements such as Si, Mn, P, and Al can be contained in consideration of characteristics, quality, and the like required for the material. As content, Si: 3.0 mass% or less, Mn: 0.01-5 mass%, P: 0.005-0.2 mass%, Al: 0.01-5 mass% are preferable. It goes without saying that these elements can be appropriately selected from the characteristics, quality, etc. required for the material irrespective of the effects of the present invention, and the same applies to other elements.
以下、本発明を、実施例に基づいて具体的に説明する。 Hereinafter, the present invention will be specifically described based on examples.
表１に示したような鋼組成のスラブを加熱炉で1260℃、60分加熱し、引き続き2.8mmまで熱間圧延をして540℃で巻き取った。その後、酸洗で黒皮スケールを除去して、1.6mmまで冷間圧延した。得られた鋼板の表面にロールコーター法で薬剤の水溶液を塗布し、オーブンで乾燥し、ラジアントチューブ型（RTF）CGLまたは直火型（DFF）CGLで850℃で再結晶焼鈍したあと引き続き溶融亜鉛めっきを行い溶融亜鉛めっき鋼板（GI）を得た。さらに、同様にして溶融亜鉛めっきを行った後、合金化して合金化溶融亜鉛めっき鋼板（GA）も得た。特定元素の塗布量は、20mass%NaOH-10mass%トリエタノールアミン水溶液195ccと35mass%過酸化水素溶液7ccの混合溶液にめっき鋼板を浸漬してめっき層を溶解し、溶解液中の元素XをICP法で定量し、片面単位当たり面積の付着量として求めた。付着量の制御は、水溶液濃度を変化させることで実施した。その後、850℃で加熱することで焼鈍した後引き続き、浸入板温500〜600℃、浴温460℃、めっき浴中のＡｌ濃度0.15〜1%のZnにて溶融亜鉛めっきを施した。付着量はガスワイピングにより調節した。合金化処理は540℃で行い、時間を変化させることで必要に応じて合金化度を変化させた。 A slab having a steel composition as shown in Table 1 was heated in a heating furnace at 1260 ° C. for 60 minutes, subsequently hot-rolled to 2.8 mm and wound up at 540 ° C. Thereafter, the black scale was removed by pickling and cold rolled to 1.6 mm. The obtained steel sheet is coated with an aqueous solution of chemicals using a roll coater method, dried in an oven, recrystallized and annealed at 850 ° C in a radiant tube type (RTF) CGL or direct flame type (DFF) CGL, and then molten zinc Plating was performed to obtain a hot dip galvanized steel sheet (GI). Further, hot dip galvanizing was performed in the same manner, and then alloyed to obtain an alloyed hot dip galvanized steel sheet (GA). The coating amount of the specified element is determined by immersing the plated steel sheet in a mixed solution of 195cc of 35mass% NaOH-10mass% triethanolamine aqueous solution and 7cc of 35mass% hydrogen peroxide solution to dissolve the plating layer, and the element X in the solution is ICP The amount was determined by the method and determined as the amount of adhesion per unit on one side. The amount of adhesion was controlled by changing the concentration of the aqueous solution. Then, after annealing by heating at 850 ° C., hot dip galvanization was performed with Zn having an intrusion plate temperature of 500 to 600 ° C., a bath temperature of 460 ° C., and an Al concentration of 0.15 to 1% in the plating bath. The amount of adhesion was adjusted by gas wiping. The alloying treatment was performed at 540 ° C., and the degree of alloying was changed as necessary by changing the time.
以上により得られた溶融亜鉛めっき鋼板（GI）および合金化溶融亜鉛めっき鋼板（GA）に対して、下記に示す方法にて下記に示す特性を調査した。得られた結果を条件と併せて表２に示す。 With respect to the hot dip galvanized steel sheet (GI) and the alloyed hot dip galvanized steel sheet (GA) obtained as described above, the following characteristics were investigated by the method described below. The obtained results are shown in Table 2 together with the conditions.
＜めっき外観＞
得られためっき鋼板について、まず外観性として、不めっきがない場合は良好、不めっきある場合には不良と判定した。合金化処理する場合には合金化遅延による外観ムラの有無も加味し、ムラのない場合には良好、ある場合には不良とした。
○：外観良好
×：外観不良
＜溶融亜鉛めっき鋼板のめっき密着性＞
ボールインパクト試験を行い、テープ剥離した際のめっき剥離状態を評価した。試験条件は直径1/2インチの半球状突起の上に載せた溶融亜鉛めっき鋼板上に、2.8kgの重りを1mの高さから落下させた後、凸側をテープ剥離を実施した。
○：めっき剥離あり（良好）
△：めっき剥離僅かにあり（概ね良好）
×：めっき剥離なし（不良）
＜合金化溶融亜鉛めっき鋼板の耐パウダリング性＞
合金化溶融亜鉛めっき鋼板の耐パウダリング性はめっき鋼板にセロテープ（登録商標）を貼りテープ面を90℃曲げ戻しを行った場合の単位長さ当たりの剥離量を蛍光X線によりZnカウント数を測定し、表１の基準に照らしてランク１、２、３のものを良好（○）、４のものを概ね良好（△）、５の物を不良（×）として評価した。
蛍光Ｘ線カウント数 ランク
0-500 1(良)
500-1000 2
1000-3000 3
3000-5000 4
5000以上 5（劣）
＜耐食性＞
JIS Z 2371に基づく塩水噴霧試験を3日間行い、腐食生成物をクロム酸を用いて洗浄除去し、試験前後のめっき腐食減量（g/m2・日）を重量法にて測定し、下記基準で評価した。
○（良好）：20 g/m2・日未満
×（不良）：20g/m2・日以上
＜機械的特性＞
機械的特性の評価は、JIS5号引張試験片を採取し、引張試験を行って測定した引張強さTS（MPa）及び伸びEl（%）より、TS×Elの値が20000MPa・%以上である場合を良好な強度延性バランスを示すとして、機械的特性良好（○）とした．
○＝TS×Elの値が20000MPa・%以上
×＝TS×Elの値が20000MPa・%未満
<Plating appearance>
Regarding the obtained plated steel sheet, as the appearance, first, it was determined that it was good when there was no unplating and was defective when there was non-plating. In the case of alloying treatment, the presence or absence of appearance unevenness due to alloying delay was taken into consideration, and when there was no unevenness, it was judged good, and when there was, it was judged as defective.
○: Appearance is good ×: Appearance is poor <Plating adhesion of hot-dip galvanized steel sheet>
A ball impact test was performed to evaluate the plating peeling state when the tape was peeled off. Test conditions were as follows: a 2.8 kg weight was dropped from a height of 1 m onto a hot dip galvanized steel sheet placed on a hemispherical protrusion having a diameter of 1/2 inch, and then the tape was peeled from the convex side.
○: Plating peeling (good)
△: Slightly peeled (generally good)
×: No plating peeling (defect)
<Powdering resistance of galvannealed steel sheet>
The powdering resistance of alloyed hot-dip galvanized steel sheet is the number of Zn counts measured by fluorescent X-rays when the tape surface is bent 90 ° C and the tape surface is bent 90 ° C. According to the criteria of Table 1, those of ranks 1, 2, and 3 were evaluated as good (◯), those of 4 were generally good (Δ), and those of 5 were evaluated as bad (×).
X-ray fluorescence count rank
0-500 1 (good)
500-1000 2
1000-3000 3
3000-5000 4
5000 or more 5 (poor)
<Corrosion resistance>
A salt spray test based on JIS Z 2371 was conducted for 3 days. Corrosion products were washed away with chromic acid, and plating corrosion weight loss (g / m 2 · day) before and after the test was measured by the gravimetric method. It was evaluated with.
○ (good): less than 20 g / m 2 · day × (defect): 20 g / m 2 · day or more <Mechanical properties>
The mechanical properties are evaluated by taking a JIS No. 5 tensile test piece and measuring the tensile strength TS (MPa) and elongation El (%) measured by a tensile test. The value of TS x El is 20000 MPa ·% or more. In this case, the mechanical properties were good (O), indicating a good balance of strength and ductility.
○ = TS x El value is 20000 MPa ·% or more x = TS x El value is less than 20000 MPa ·%
表2から明らかなように、本発明例の（合金化）溶融亜鉛めっき鋼板は付着量が55g/m2以上の厚目付であるにも関わらず、いずれも耐食性およびめっき密着性に優れている。さらに合金化温度が低減可能であるために耐パウダリング性が良好であり、機械的特性にも優れるものである。特に、溶融亜鉛めっき処理を施すに先立ち、特定の元素を含有する化合物を鋼板表面に付着させた本発明例では、より一層、めっき密着性および耐パウダリング性が優れている。 As is apparent from Table 2, the (alloyed) hot-dip galvanized steel sheets of the examples of the present invention are excellent in corrosion resistance and plating adhesion, although the adhesion weight is 55 g / m 2 or more. . Furthermore, since the alloying temperature can be reduced, the powdering resistance is good and the mechanical properties are also excellent. In particular, in the present invention example in which a compound containing a specific element is adhered to the steel sheet surface prior to the hot dip galvanizing treatment, the plating adhesion and the powdering resistance are further improved.
機械的特性が良好な上、溶融亜鉛めっき鋼板では、耐食性に優れ、かつ、めっき外観、めっき密着性にも優れているため、また、合金化溶融亜鉛めっき鋼板では、耐食性に優れ、かつ、耐パウダリング性にも優れているため、自動車、家電、建材等の分野を中心に、幅広い用途での使用が見込まれる。 In addition to excellent mechanical properties, hot-dip galvanized steel sheet has excellent corrosion resistance, and also has excellent plating appearance and plating adhesion, and alloyed hot-dip galvanized steel sheet has excellent corrosion resistance and resistance. Because it has excellent powdering properties, it is expected to be used in a wide range of applications, especially in the fields of automobiles, home appliances, and building materials.
Claims (3)
浸入板温を500〜600℃、浴中Al濃度を0.15〜0.3wt%として溶融亜鉛めっき処理を施し、めっき付着量を55g/m2以上とすることを特徴とする溶融亜鉛めっき鋼板の製造方法。 When performing hot-dip galvanizing treatment on cold-rolled steel sheets containing C ≦ 0.25 mass%,
Hot-dip galvanized steel sheet manufacturing method characterized by performing hot-dip galvanizing treatment with an intrusion plate temperature of 500-600 ° C and an Al concentration in the bath of 0.15-0.3 wt%, and a coating amount of 55 g / m 2 or more .
まず、元素XとしてS、Cl、Na、K、Ni、C、N、B、Se、Brの少なくとも１種以上を含有する化合物を、下記（１）式を満足するように鋼板表面に付着させ、
次いで、再結晶焼鈍することを特徴とする請求項１に記載の溶融亜鉛めっき鋼板の製造方法。
〔X〕≧（1/600）×〔M〕 ―――（１）
〔X〕：Xの量単位mg/m2
〔M〕：めっき付着量単位g/m2 Prior to performing the hot dip galvanizing process,
First, a compound containing at least one of S, Cl, Na, K, Ni, C, N, B, Se, and Br as element X is attached to the steel sheet surface so as to satisfy the following formula (1). ,
Subsequently, recrystallization annealing is performed, The manufacturing method of the hot dip galvanized steel plate of Claim 1 characterized by the above-mentioned.
[X] ≧ (1/600) × [M] ――― (1)
[X]: X quantity unit mg / m 2
[M]: Plating adhesion unit g / m 2
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010156029A (en) * | 2009-01-05 | 2010-07-15 | Nippon Steel Corp | Method for manufacturing hot-dip galvanized high-tensile steel plate |
| CN111763907A (en) * | 2020-08-12 | 2020-10-13 | 北京天仁道和新材料有限公司 | Salt bath nitriding agent for metal workpiece surface treatment and metal workpiece surface treatment method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010156029A (en) * | 2009-01-05 | 2010-07-15 | Nippon Steel Corp | Method for manufacturing hot-dip galvanized high-tensile steel plate |
| CN111763907A (en) * | 2020-08-12 | 2020-10-13 | 北京天仁道和新材料有限公司 | Salt bath nitriding agent for metal workpiece surface treatment and metal workpiece surface treatment method |
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