JP5194702B2 - Method for producing galvannealed steel sheet - Google Patents
Method for producing galvannealed steel sheet Download PDFInfo
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本発明は、合金化遅延がなく、耐パウダリング性に優れた合金化溶融亜鉛めっき鋼板の製造方法に関する。 The present invention relates to a method for producing a galvannealed steel sheet having no alloying delay and excellent powdering resistance.
近年、自動車、家電、建材等の分野において素材鋼板に防錆性を付与した表面処理鋼板として、安価に製造できかつ防錆性に優れた合金化溶融亜鉛めっき鋼板が使用されている。 In recent years, alloyed hot-dip galvanized steel sheets that can be manufactured at low cost and have excellent rust prevention properties have been used as surface-treated steel sheets that impart rust prevention properties to raw steel sheets in fields such as automobiles, home appliances, and building materials.
一般的に、合金化溶融亜鉛めっき鋼板は、スラブを熱延、冷延あるいは熱処理した薄鋼板を母材とし、この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焼鈍され、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質量％程度）を添加した溶融亜鉛浴中に浸漬して溶融亜鉛めっきし、引き続いて合金化炉内で合金化処理し、めっき層をFe-Zn合金化することで製造される。 Generally, an alloyed hot dip galvanized steel sheet is a thin steel sheet obtained by hot-rolling, cold-rolling or heat-treating a slab as a base material, and the surface of the base steel sheet is cleaned by degreasing and / or pickling in a pretreatment process. Or after removing the oil on the surface of the base steel plate in the preheating furnace by omitting the pretreatment step, it is annealed by heating in a non-oxidizing atmosphere or a reducing atmosphere, and then a non-oxidizing atmosphere. In a medium or reducing atmosphere, the steel sheet is cooled to a temperature suitable for plating and immersed in a hot dip galvanized bath with a slight amount of Al (0.1 to 0.2% by mass) added to it without touching the air. The alloying process is performed in an alloying furnace, and the plating layer is made into an Fe-Zn alloy.
ところで、近年、自動車用鋼板はさらなる防錆性向上が求められており、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。これまでは、30〜45g/m2（片面あたり、以下同じ）程度のめっき付着量の合金化溶融亜鉛めっき鋼板が主流であるが、耐食性、防錆性能を向上させるため、50g/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、50g/m2以上の厚目付の合金化溶融亜鉛めっき鋼板には以下の問題がある。 Incidentally, in recent years, steel plates for automobiles have been required to further improve rust prevention, and there is a method for increasing the amount of plating adhesion as one effective means. Up to now, alloyed hot-dip galvanized steel sheets with a coating weight of about 30 to 45 g / m 2 (same for each side) are the mainstream, but in order to improve corrosion resistance and rust prevention performance, 50 g / m 2 or more A heavy duty hot dip galvanized steel sheet was developed. However, the alloyed hot-dip galvanized steel sheet with a thickness of 50 g / m 2 or more has the following problems.
めっき付着量の増加に伴い、溶融亜鉛めっき後の合金化処理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する問題や、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。 The alloying reaction in the alloying process after hot dip galvanization is delayed with the increase in the amount of plating adhesion. As a result, there are problems that significantly impede productivity, and problems that cause deterioration of powdering resistance when alloyed at an excessively high temperature to ensure productivity, achieving both high productivity and good powdering resistance. It becomes difficult to make it.
このような問題に対して、予め酸化性雰囲気中で加熱して鋼板表面に酸化鉄を形成した後加熱して還元焼鈍を行うことにより、溶融亜鉛との濡れ性及び反応性が改善されることが知られている（特許文献１参照）。 For such problems, the wettability and reactivity with molten zinc are improved by heating in an oxidizing atmosphere in advance and forming iron oxide on the steel sheet surface, followed by reduction annealing. Is known (see Patent Document 1).
また、特許文献２には、溶融めっきに先立って鋼板表面に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ことで、耐パウダリング性を向上できることが開示されている。 Further, Patent Document 2 discloses that a preheating step is performed in a weakly oxidizing atmosphere after sulfur or a sulfur compound is deposited as an S amount in an amount of 0.1 to 1000 mg / m 2 on the steel plate surface prior to hot dipping. It is disclosed that the powdering resistance can be improved by annealing in an oxidizing atmosphere.
しかし、特許文献１、２に記載の方法では、めっき付着量が50ｇ/m2以上の厚目付の場合、合金化が遅延する問題、耐パウダリング性が劣化する問題が発生する。
本発明は、めっき付着量が50g/m2以上の厚目付であっても合金化処理の際に合金化遅延を防止し、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高い生産性を有して製造する方法を提供することを課題とする。 The present invention prevents alloying delay during alloying treatment even when the coating weight is 50 g / m 2 or more, and provides high productivity for alloyed hot-dip galvanized steel sheets with excellent powdering resistance. It is an object of the present invention to provide a method for manufacturing a product having a problem.
また本発明は、鋼中にSi、Mn、P、Al等の鋼高強度化元素が添加され高強度合金化溶融亜鉛めっき鋼板においても合金化処理の際に合金化遅延を防止し、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高い生産性を有して製造する方法を提供することを課題とする。 In addition, the present invention provides a steel-resistant element such as Si, Mn, P, Al, etc. added to steel to prevent alloying delay in alloying treatment even in a high-strength alloyed hot-dip galvanized steel sheet. It is an object of the present invention to provide a method for producing an alloyed hot-dip galvanized steel sheet excellent in ringability with high productivity.
本発明者らは、前記課題を解決すべく鋭意検討した。その結果、焼鈍前に、（イ）HCl、H2SO4、HNO3及びH2O2の中から選ばれる２種以上の水溶液、又は、（ロ）HCl、H2SO4、HNO3及びH2O2の中から選ばれる１種以上と、タンニン酸、アジピン酸、フマル酸、フタル酸、安息香酸、CH3COOHの中から選ばれるカルボキシル基（-COOH）をもつ化合物、アルカリ金属の硝酸塩、アルカリ土類金属の硝酸塩及びH2Sの中から選ばれる１種以上の水溶液を鋼板に接触させ、しかる後に、焼鈍した後、溶融亜鉛めっきし、その後合金化処理を行うと、合金化処理の際の合金化遅延を防止でき、合金化溶融亜鉛めっき鋼板の耐パウダリング性の劣化を防止できることを見出した。 The present inventors diligently studied to solve the above problems. As a result, before annealing, (ii) two or more aqueous solutions selected from HCl, H 2 SO 4 , HNO 3 and H 2 O 2 , or (b) HCl, H 2 SO 4 , HNO 3 and One or more selected from H 2 O 2 and a compound having a carboxyl group (—COOH) selected from tannic acid, adipic acid, fumaric acid, phthalic acid, benzoic acid, and CH 3 COOH, an alkali metal One or more aqueous solutions selected from nitrates, alkaline earth metal nitrates and H 2 S are brought into contact with the steel sheet, then annealed, hot dip galvanized, and then alloyed to form an alloy. It has been found that the alloying delay during the treatment can be prevented and the deterioration of the powdering resistance of the galvannealed steel sheet can be prevented.
本発明は、この知見に更に検討を加えることでなされたものである。上記課題を解決する本発明の手段は次の通りである。 The present invention has been made by further studying this finding. Means of the present invention for solving the above problems are as follows.
（１）鋼板を、（ロ）下記第I分類の中から選ばれる化合物の１種以上と下記第II分類の中から選ばれる化合物の１種以上を、各々の化合物を濃度0.10質量％以上で含有する溶液に、２秒以上接触させる接触工程を行い、その後、焼鈍した後、溶融亜鉛めっきし、その後合金化処理することを特徴とする合金化溶融亜鉛めっき鋼板の製造方法。
第I分類：HCl、H2SO4、HNO3、H2O2
第II分類：アジピン酸、安息香酸、アルカリ金属の硝酸塩
（２）溶融亜鉛めっき時のめっき付着量を片面当たり50g/m2以上とすることを特徴とする（１）の合金化溶融亜鉛めっき鋼板の製造方法。
(1) Steel plate (b) One or more compounds selected from the following class I and one or more compounds selected from the following class II, each compound having a concentration of 0.10 % by mass or more The manufacturing method of the galvannealed steel plate characterized by performing the contact process made to contact the solution to contain for 2 second or more, after annealing, hot-dip galvanizing, and alloying after that.
Class I: HCl, H 2 SO 4 , HNO 3 , H 2 O 2
Class II: Adipic acid, benzoic acid, nitrates of alkali metals (2) Alloyed hot-dip galvanized steel sheet according to (1), characterized in that the coating weight during hot-dip galvanizing is 50 g / m 2 or more per side Manufacturing method.
（３） （１）又は（２）の合金化溶融亜鉛めっき鋼板の製造方法において、接触工程を行った後焼鈍する前に、下記Xの中から選ばれる１種以上の元素を含有する化合物の１種以上を、下記式（１）を満足するように鋼板表面に付着させることを特徴とする合金化溶融亜鉛めっき鋼板の製造方法。
X：S、Cl、Na、K、Ni、C、N、B、Se、Br
〔X〕≧（1/600）×〔M〕 …（１）
ただし、
〔X〕：Xの元素の片面あたり合計付着量(mg/m2)
〔M〕：片面あたりめっき付着量(g/m2)
(3) In the method for producing an alloyed hot-dip galvanized steel sheet according to (1) or (2), before annealing after performing the contact step, the compound containing one or more elements selected from the following X One or more types are made to adhere to the steel plate surface so that following formula (1) may be satisfied, The manufacturing method of the galvannealed steel plate characterized by the above-mentioned.
X: S, Cl, Na, K, Ni, C, N, B, Se, Br
[X] ≧ (1/600) × [M] (1)
However,
[X]: Total adhesion amount per side of X element (mg / m 2 )
[M]: Plating adhesion amount per side (g / m 2 )
本発明によれば、良好な耐パウダリング性を有する50g/m2以上の厚目付の合金化溶融亜鉛めっき鋼板を、高い生産性で製造することができるようになる。また、本発明によれば、鋼中にSi、Mn、P、Al等の鋼高強度化元素が添加され高強度合金化溶融亜鉛めっき鋼板であっても、合金化処理の際に合金化遅延を防止し、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高い生産性で製造することができるようになる。 According to the present invention, an alloyed hot-dip galvanized steel sheet having a thickness of 50 g / m 2 or more and having good powdering resistance can be produced with high productivity. In addition, according to the present invention, even in the case of a high-strength alloyed hot-dip galvanized steel sheet in which steel-strengthening elements such as Si, Mn, P, and Al are added to the steel, alloying delays This makes it possible to produce an alloyed hot-dip galvanized steel sheet having excellent powdering resistance with high productivity.
以下、本発明について具体的に説明する。 Hereinafter, the present invention will be specifically described.
本発明では、鋼板を、（ロ）下記第I分類の中から選ばれる化合物の１種以上と下記第II分類の中から選ばれる化合物の１種以上を、各々の化合物を濃度0.10質量％以上で含有する溶液に、２秒以上接触させる接触工程を行い、その後、焼鈍した後、溶融亜鉛めっきし、その後合金化処理する。
第I分類：HCl、H2SO4、HNO3、H2O2
第II分類：アジピン酸、安息香酸、アルカリ金属の硝酸塩
鋼板を、（イ）第I分類の中から選ばれる化合物の２種以上を含有する溶液、又は、（ロ）第I分類の中から選ばれる化合物の１種以上と第II分類の中から選ばれる化合物の１種以上を含有する溶液に2秒以上接触させることにより、その詳細な理由は解明されていないが、鋼板表面に微小な凹凸が形成される。この微小な凹凸が形成される効果により、溶融めっき時に鋼板と溶融亜鉛との接触面積が増大し、めっき浴中におけるFeとZnの初期合金化が促進され、合金化処理を行うと合金化反応を促進させることができる。背景技術で説明したように、従来技術では、めっき付着量が50g/m2以上の厚めっきになると合金化反応の遅延が顕著になり、高い生産性と良好な耐パウダリング性を両立できなかった。本発明によれば、合金化処理で合金化反応が促進されるため、めっき付着量が50g/m2以上の厚めっきであっても過剰に高温で合金化処理する必要がなくなるので、耐パウダリング性が劣化することがない。また生産性を損なうことがないので、高い生産性と良好な耐パウダリング性を両立できる。合金化遅延に伴う外観ムラの発生を防止する効果もある。
In the present invention, the steel plate is (b) one or more compounds selected from the following class I and one or more compounds selected from the following class II, each compound having a concentration of 0.10 % by mass or more. The contact process is performed for 2 seconds or more with the solution contained in the above, and after annealing, hot dip galvanizing is performed, followed by alloying treatment.
Class I: HCl, H 2 SO 4 , HNO 3 , H 2 O 2
Class II: Adipic acid, benzoic acid, nitrates of alkali metals Select a steel plate from (b) a solution containing two or more compounds selected from Class I, or (b) Class I Although the detailed reason has not been elucidated by contacting with a solution containing one or more compounds selected from Group II and one or more compounds selected from Group II for 2 seconds or more, minute irregularities on the steel sheet surface Is formed. Due to the effect of the formation of the micro unevenness, the contact area between the steel sheet and the molten zinc is increased during hot dipping, and the initial alloying of Fe and Zn in the plating bath is promoted. Can be promoted. As explained in the background art, in the conventional technology, when the plating adhesion amount is 50 g / m 2 or more, the alloying reaction delay becomes remarkable, and it is not possible to achieve both high productivity and good powdering resistance. It was. According to the present invention, since the alloying reaction is promoted by the alloying treatment, it is not necessary to perform the alloying treatment at an excessively high temperature even when the plating adhesion amount is 50 g / m 2 or more. Ring property does not deteriorate. Moreover, since productivity is not impaired, both high productivity and good powdering resistance can be achieved. There is also an effect of preventing the appearance unevenness accompanying the alloying delay.
ただし、前記（イ）及び前記（ロ）において、各化合物の濃度が0.10質量％未満の場合、上記効果が発現しないので、化合物の濃度は、各々が0.10質量％以上であることが必要である。また、化合物の合計濃度が30質量％を超えると合、本発明の効果が飽和して経済的に不利になる。よって、化合物の合計濃度は30質量％以下が望ましい。 However, in the above (a) and (b), when the concentration of each compound is less than 0.10% by mass, the above effect is not exhibited, and therefore the compound concentration needs to be 0.10% by mass or more. . Further, if the total concentration of the compounds exceeds 30% by mass, the effect of the present invention is saturated, which is economically disadvantageous. Therefore, the total concentration of the compounds is desirably 30% by mass or less.
また、接触時間が2秒未満の場合、上記効果が発現しない。また、50秒を超える場合、本発明の効果が飽和して経済的に不利になる。よって、接触時間は2秒以上50秒以下が望ましい。接触方法は限定されない。例えば、溶液中へ浸漬する方法、溶液をスプレー等で塗布した後絞りロールを通過させる方法、ロールコーター等で塗布する方法等を採用できる。 In addition, when the contact time is less than 2 seconds, the above effect is not exhibited. Moreover, when it exceeds 50 seconds, the effect of this invention is saturated and it becomes economically disadvantageous. Therefore, the contact time is desirably 2 seconds or more and 50 seconds or less. The contact method is not limited. For example, a method of immersing in a solution, a method of applying the solution by spray or the like and then passing through a squeeze roll, a method of applying by a roll coater or the like can be employed.
また、接触工程の処理温度（溶液温度）は特に規定するものではないが、概ね5℃〜90℃程度が望ましい。これは、5℃未満及び90℃を超える場合、温度の管理が困難であり、経済的に不利になるためである。 The treatment temperature (solution temperature) in the contacting step is not particularly specified, but is preferably about 5 ° C to 90 ° C. This is because when the temperature is lower than 5 ° C and higher than 90 ° C, it is difficult to control the temperature, which is economically disadvantageous.
また、本発明においては、還元処理後の鋼板表面を活性化させてFeとZnの反応性を促進させるため、前記接触工程後、焼鈍前に、鋼板表面に下記Xの中から選ばれる元素の少なくとも１種以上を含有する化合物の１種以上を下記式（１）を満足するように付着させる処理を行うことが好ましい。
X：S、Cl、Na、K、Ni、C、N、B、Se、Br
〔X〕≧（1/600）×〔M〕 …（１）
ここで、
〔X〕：Xの元素の片面あたり合計付着（mg/m2）
〔M〕：片面あたりめっき付着量（g/m2）
鋼板表面に前記Xの中の１種以上の元素を含む化合物の１種以上を付着させることで鋼板表面が活性化され、溶融亜鉛めっきの際にめっき浴との濡れ性が良好になり、めっき浴中におけるFe-Al金属間化合物の生成が促進され、溶融めっき後の合金化時において、Γ相が過剰に生成することなく合金化反応が促進される。またFeとZnの合金化反応を促進するため、FeとZnの合金化速度の遅い、めっき付着量が50ｇ/m2以上の厚目付であっても合金化反応を促進させることが可能となる。合金化処理は過剰に高温にして行わずともよいので、耐パウダリング性が劣化することがない。また生産性を損なうことがないので、高い生産性と良好な耐パウダリング性を両立できる。合金化遅延に伴う外観ムラの発生を防止する効果もある。
Further, in the present invention, in order to activate the steel sheet surface after the reduction treatment and promote the reactivity of Fe and Zn, after the contact step, before annealing, an element selected from the following X on the steel sheet surface: It is preferable to perform a treatment for adhering at least one compound containing at least one compound so as to satisfy the following formula (1).
X: S, Cl, Na, K, Ni, C, N, B, Se, Br
[X] ≧ (1/600) × [M] (1)
here,
[X]: Total adhesion per side of X element (mg / m 2 )
[M]: Plating adhesion amount per side (g / m 2 )
By attaching one or more compounds containing one or more elements in X to the steel sheet surface, the steel sheet surface is activated, and the wettability with the plating bath is improved during hot dip galvanizing. Formation of the Fe—Al intermetallic compound in the bath is promoted, and the alloying reaction is promoted without excessive generation of the Γ phase during alloying after hot dipping. Moreover, since the alloying reaction of Fe and Zn is promoted, the alloying reaction can be promoted even when the alloying rate of Fe and Zn is slow and the coating weight is more than 50 g / m 2. . Since the alloying treatment does not have to be performed at an excessively high temperature, the powdering resistance does not deteriorate. Moreover, since productivity is not impaired, both high productivity and good powdering resistance can be achieved. There is also an effect of preventing the appearance unevenness accompanying the alloying delay.
鋼板表面にこれら元素を付着させることで鋼板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（直火炉）型焼鈍炉での酸化では鋼板の表面状態を変化させることで表面の酸化が促進され、次工程の還元焼鈍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ためと考えられる。また、RTF（ラジアントチューブ炉）型の焼鈍炉では、焼鈍時に鋼中の易酸化元素や不可避的不純物の鋼板表面への濃化を抑制する効果があるためと考えられる。そのため、めっきの母材鋼板が、鋼の高強度化のために、鋼中に、Si、Mn、P、Alの１種以上を添加した冷延鋼板であっても、前記作用効果が発現される。 The reason why the steel sheet surface is activated by attaching these elements to the steel sheet surface is not clear, but for example, oxidation in a NOF (non-oxidation furnace) or DFF (direct-fired furnace) type annealing furnace changes the surface condition of the steel sheet. This is thought to be due to the fact that the oxidation of the surface is promoted and the amount of reduced iron rich in reactivity generated on the steel sheet surface during the subsequent reduction annealing is increased. Further, it is considered that the RTF (radiant tube furnace) type annealing furnace has an effect of suppressing the concentration of easily oxidizable elements and unavoidable impurities in the steel on the steel sheet surface during annealing. Therefore, even if the base steel sheet for plating is a cold-rolled steel sheet in which one or more of Si, Mn, P, and Al are added to the steel in order to increase the strength of the steel, the above-mentioned effects are exhibited. The
ここで、Xの元素を含む化合物としては、例えば以下の化合物を使用できる。
（１）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
（２）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
（３）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
（４）臭化鉄等のBr含有化合物
（５）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
（６）セレン酸カリウムなどのSe含有化合物
（７）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
（８）Ni3O4、NiOOH（オキシ水酸化ニッケル）、NiCl2、LiNiO2、Ni(OH)2、Ni(OH)3等のNi含有化合物
（９）NH3、HNO3、HNO2、ピクリン酸、NCl3、BN、ALN、I3N等のN含有化合物
（１０）BN、ホウ酸、ホウ砂、ジボラン等のB含有化合物
なお、上記は代表的な化合物を示したのであって、上記以外のS、Cl、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。
Here, as a compound containing the element of X, the following compounds can be used, for example.
(1) Sodium hydroxide (NaOH), sodium sulfate (Na 2 SO 4 ), sodium sulfide (Na 2 S), sodium thiosulfate (Na 2 S 2 O 3 ), sodium chloride (NaCl), sodium carbonate (Na 2 CO 3 ), sodium citrate (Na 3 C 6 H 5 O 7 ), sodium cyanate (NaCNO), sodium acetate (CH 3 COONa), sodium hydrogen phosphate (Na 2 HPO 4 ), sodium phosphate (Na 3 PO 4), sodium fluoride (NaF), sodium bicarbonate (NaHCO 3), sodium nitrate (NaNO 3), sodium oxalate ((COONa) 2), sodium tetraborate (Na 2 B 4 O 7) , sodium oxide Na-containing compounds such as (Na 2 O) (2) Potassium hydroxide (KOH), potassium acetate (CH 3 COOK), potassium borate (K 2 B 4 O 7 ), potassium carbonate (K 2 CO 3 ), potassium chloride (KCl), potassium cyanate (KCNO), potassium hydrogen citrate (KH 2 C 6 H 5 O 7), potassium fluoride (KF), potassium molybdate (K 2 MoO 4), nitric Potassium (KNO 3), potassium permanganate (KMnO 4), potassium phosphate (K 3 PO 4), potassium sulfate (K 2 SO 4), potassium thiocyanate (KSCN), potassium oxalate ((COOK) 2) K-containing compounds such as (3) hydrochloric acid (HCl), sodium chloride (NaCl), ammonium chloride (NH 4 Cl), antimony chloride (SbCl 3 ), potassium chloride (KCl), iron chloride (FeCl 2 , FeCl 3 ), Cl-containing compounds such as titanium chloride (TiCl 4 ), copper chloride (CuCl), barium chloride (BaCl 2 ), molybdenum chloride (MoCl 5 ), sodium chlorate (NaClO 3 ) (4) Br-containing compounds such as iron bromide (5) Sulfuric acid (H 2 SO 4 ), sodium sulfate (Na 2 SO 4 ), sodium sulfite (Na 2 SO 3 ), sodium sulfide (Na 2 S), ammonium sulfate ((NH 4 ) 2 SO 4 ), ammonium sulfide ((NH 4) 2 S) , sodium thiosulfate (Na 2 S 2 O 3) , sodium bisulfate (NaHSO 4), ammonium hydrogen sulfate (NH 4 HSO 4), potassium sulfate (K 2 SO 4), Iron (FeSO 4, Fe 2 (SO 4) 3), ammonium iron (Fe (NH 4) 2 ( SO 4) 2, FeNH 4 (SO 4) 2), barium sulfate (BaSO 4), antimony sulfide (Sb 2 S 3 ), iron sulfide (FeS), thiourea (H 2 NCSNH 2 ), thiourea dioxide ((NH 2 ) 2 CSO 2 ), SCH group thiophenates, thiocyanates having SCN groups, etc. Containing compounds (6) Se-containing compounds such as potassium selenate (7) Carboxylic acid-containing compounds such as tannic acid and adipic acid, aromatic ring-containing compounds such as saccharides, fumaric acid, phthalic acid, phenol, aniline, benzoic acid, C-containing compounds such as amino acids such as glycine and alanine, polyhydric alcohols such as ethylene glycol and acetylene glycol, resins such as acrylic acid, polyester, epoxy, and modified compounds thereof (8) Ni 3 O 4 , NiOOH (oxy nickel hydroxide), NiCl 2, LiNiO 2, Ni (OH) 2, Ni (OH) 3 , etc. Ni-containing compound (9) NH 3, HNO 3 , HNO 2, picric acid, NCl 3, BN, ALN, I 3 N -containing compounds such as N (10) BN, boric acid, borax, B-containing compound such as diborane Note that the above shows representative compounds, and the effects of the present invention can be achieved by using compounds containing S, Cl, Na, K, Ni, C, N, B, Se, and Br other than those described above. Needless to say, is preferably obtained.
前記元素を含む化合物を鋼板に付着させる方法は特に限定するものではなく、例えば物理的に付着させればよいので、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、この溶解液又は混合液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。また、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。 The method for attaching the compound containing the element to the steel sheet is not particularly limited. For example, it may be physically attached, so that the compound is dissolved in water or an organic solvent, or a mixture thereof is used. A method of immersing a steel plate in the solution or mixed solution, a method of spraying with a spray, a method of applying with a roll coater or the like can be used. Moreover, even if it dries after that, the effect of this invention does not change. Moreover, the effect of this invention can be acquired similarly even if it apply | coats a compound directly. The effect of the present invention can be obtained even if a conventional pretreatment such as electrolytic degreasing and 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. Can be obtained. Furthermore, you may use the method of making it adhere at the time of rolling using the rolling oil containing the said compound.
また、処理温度は特に規定するものではないが、概ね5℃〜90℃程度が望ましい。これは、5℃未満及び90℃を超える場合、温度の管理が困難であり、経済的に不利になるためである。いずれにしても、鋼板を酸化させる際に前記元素を含む化合物が鋼板表面に付着していれば良い。 Further, the treatment temperature is not particularly specified, but is preferably about 5 ° C to 90 ° C. This is because when the temperature is lower than 5 ° C and higher than 90 ° C, it is difficult to control the temperature, which is economically disadvantageous. Anyway, the compound containing the said element should just adhere to the steel plate surface when oxidizing a steel plate.
前記Xの元素を含む化合物の付着量は、Xの元素の合計付着量が下記式（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）
ただし、〔X〕：Xの元素の片面あたり合計付着量（mg/m2）、〔M〕：片面あたりめっき付着量（g/m2）である。
The adhesion amount of the compound containing the X element is desirably adhered so that the total adhesion amount of the X element satisfies the following formula (1).
[X] ≧ (1/600) × [M] (1)
However, [X] is the total adhesion amount per side of the element of X (mg / m 2 ), and [M] is the plating adhesion amount per side (g / m 2 ).
めっき付着量の増加に伴い、合金化処理の合金化反応は遅延する。Xの元素の付着量を増加させると、めっき浴中でのFe-Al金属間化合物の生成を促進し、Γ相の過剰生成を防ぎつつ、合金化処理の合金化反応を促進させることができる。Xの元素の合計付着量〔X〕の下限を式（１）のように規定したのは、Xの元素の合計付着量〔X〕が式（１）を満足しないと、本発明で意図するXの元素を含む化合物を鋼板表面に付着させることによる合金化処理における合金化反応促進効果が発現されないためである。Xの元素の合計付着量〔X〕の上限は特に規定しないが、Xの元素の合計付着量が1000mg/m2を超えると本発明の効果が飽和して経済的に不利になる。よって、Xの元素の合計付着量〔X〕の上限は1000mg/m2以下が望ましい。 As the amount of plating is increased, the alloying reaction of the alloying process is delayed. Increasing the amount of X element can promote the formation of Fe-Al intermetallic compounds in the plating bath, and promote the alloying reaction of the alloying process while preventing excessive formation of the Γ phase. . The lower limit of the total deposition amount [X] of the elements of X is defined as in the formula (1). The present invention intends that the total deposition amount [X] of the elements of X does not satisfy the formula (1). This is because the effect of promoting the alloying reaction in the alloying treatment by attaching the compound containing the element X to the steel sheet surface is not exhibited. The upper limit of the total deposition amount [X] of X elements is not particularly defined, but if the total deposition amount of X elements exceeds 1000 mg / m 2 , the effect of the present invention is saturated, which is economically disadvantageous. Therefore, the upper limit of the total amount [X] of X elements is preferably 1000 mg / m 2 or less.
鋼板表面に付着させたXの元素の付着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、Xの元素を含む化合物を付着させた鋼板（母材鋼板を含む）のXの元素の合計量から母材鋼板中のXの元素の合計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 amount of X element deposited on the steel sheet surface, it can be measured by a wet analysis method. That is, it can be easily quantified by subtracting the total amount of X elements in the base steel plate from the total amount of X elements in the steel plate (including the base steel plate) to which the compound containing the X element is attached. .
本発明では、（あ）前記第I分類の中から選ばれる１種以上の化合物と前記第II分類の中から選ばれる１種以上の化合物を含有する溶液に、２秒以上接触させる処理を行った後、若しくは、（い）前記（あ）の処理の後、前記Xの中から選ばれる元素の１種以上含有する化合物を鋼板表面に付着させる処理を行った後、鋼板を焼鈍する。 In the present invention, the process of contacting (A) before SL in a solution containing one or more compounds selected from among the first II classified as one or more compounds selected from among the I classification, more than 2 seconds After the treatment, or (ii) after the treatment (a), the steel plate is annealed after a treatment for adhering a compound containing one or more elements selected from X to the steel plate surface.
焼鈍は通常、還元雰囲気下で鋼板を再結晶温度以上の温度に加熱して行うので、同時に還元処理される。NOF型CGL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鋼板を600〜900℃程度の温度に加熱し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1〜90vol％が好ましい。1vol％未満の場合還元が不十分であり、90vol％以上は経済的に不利である。 Annealing is usually performed by heating the steel sheet to a temperature higher than the recrystallization temperature in a reducing atmosphere, and thus the reduction treatment is performed simultaneously. Like NOF type CGL and DFF type CGL, reduction may be performed after oxidation in the heating zone. The reduction method may be performed in accordance with a conventionally used method and is not particularly limited. For example, it is common to perform a reduction treatment by heating a steel sheet to a temperature of about 600 to 900 ° C. in a reducing atmosphere containing hydrogen in a radiant heating type annealing furnace, but there is no particular limitation. When oxidized in a heating zone, the effect of the present invention is not hindered if the method 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 vol%. If it is less than 1 vol%, the reduction is insufficient, and if it is 90 vol% or more, it is 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。溶融亜鉛めっき処理は従来から行われている方法に従えばよい。例えば、めっき浴温は440〜520℃程度、鋼板のめっき浴浸漬温度はほぼめっき浴温に等しくし、亜鉛めっき浴中のAl濃度は0.1〜0.2質量％とするのが一般的ではあるが、特に限定するものではない。また、めっき鋼板の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寄与するものではなく、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. The hot dip galvanizing process may be performed according to a conventionally performed method. For example, the plating bath temperature is about 440 to 520 ° C., the plating bath immersion temperature of the steel plate is approximately equal to the plating bath temperature, and the Al concentration in the galvanizing bath is generally 0.1 to 0.2% by mass, There is no particular limitation. The plating bath composition may be changed depending on the use of the plated steel sheet, but the difference in the plating bath composition does not contribute to 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30〜150g/m2が好ましいが、耐食性の観点から50〜150g/m2が理想的である。30g/m2未満では防錆性が不良となる。50g/m2未満では十分な防錆性が得られない。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 coating weight is preferably 30 to 150 g / m 2, from the viewpoint of corrosion resistance 50 to 150 g / m 2 is ideal. If it is less than 30 g / m 2 , the rust resistance is poor. If it is less than 50 g / m 2 , sufficient rust resistance cannot be obtained. 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.
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50g/m2以上の厚目付であっても、合金化遅延を防止することができる。その結果、50g/m2以上の厚目付で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。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。 Alloying treatment is performed after hot dip galvanization. As described above, according to the present invention, it is possible to prevent a delay in alloying even if the plating adhesion amount is 50 g / m 2 or more. As a result, an alloyed hot-dip galvanized steel sheet with a weight per unit area of 50 g / m 2 or more and excellent powdering resistance can be produced without impairing productivity. 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.
本発明に使用する鋼板の成分組成について説明する。 The component composition of the steel sheet used in the present invention will be described.
近年、自動車用鋼板では、車体の軽量化等のために、高強度合金化溶融亜鉛めっき鋼板が使用されるようになってきた。この高強度合金化溶融亜鉛めっき鋼板では、鋼板に必要とされる特性、品質等に応じて、鋼成分として、C：0.0001〜0.5質量％を含有する。また高強度合金化溶融亜鉛めっき鋼板に必要とされる特性、品質等に応じて、鋼成分として、C：0.01〜0.5質量％に限定し、および／または、Si：0.01〜3.0質量％、Mn：0.01〜5質量％、P：0.005〜0.2質量％、Al：0.01〜5質量％の元素の１種または２種以上を含有又は添加する。前記組成範囲のSi、Mn、P、Alの１種又は２種以上を添加した高強度合金化溶融亜鉛めっき鋼板では、合金化遅延の問題や耐パウダリング性劣化の問題がより顕在化している。 In recent years, high strength alloyed hot dip galvanized steel sheets have been used for automobile steel sheets in order to reduce the weight of the vehicle body. This high-strength alloyed hot-dip galvanized steel sheet contains C: 0.0001 to 0.5 mass% as a steel component depending on the properties, quality, and the like required for the steel sheet. Also, depending on the properties, quality, etc. required for high-strength galvannealed steel sheets, the steel components are limited to C: 0.01 to 0.5 mass%, and / or Si: 0.01 to 3.0 mass%, Mn : 0.01 to 5% by mass, P: 0.005 to 0.2% by mass, Al: 0.01 to 5% by mass of one or more elements. In high-strength galvannealed steel sheets to which one or more of Si, Mn, P, and Al in the above composition range are added, problems of alloying delay and powdering resistance deterioration are more obvious. .
前記成分組成を有する高強度合金化溶融亜鉛めっき鋼板を本発明法によって製造すると、合金化遅延の問題を解消し、耐パウダリング性劣化の問題を防止できる。 When a high-strength galvannealed steel sheet having the above composition is produced by the method of the present invention, the problem of alloying delay can be solved and the problem of deterioration of powdering resistance can be prevented.
本発明は、対象とする鋼板の鋼種を特に限定するものではないが、以上の理由から、高強度合金化溶融亜鉛めっき鋼板を製造する場合は、以下に記載する成分組成が好ましい。 Although this invention does not specifically limit the steel type of the steel plate made into object, when manufacturing a high intensity | strength galvannealed steel plate from the above reason, the component composition described below is preferable.
C：0.01〜0.5質量％
Cは、鋼板の高強度化に有効な元素であり、さらに残留オーステナイトや低温変態相の生成に効果があり、強度延性バランスの向上（TS×El値の向上）に有効な元素である。しかし、C含有量が0.01質量％未満では所望の機械特性(TS×El値)を得難い。一方、C含有量が0.5質量％を超えると、溶接性の劣化を招く。以上より、C含有量は0.01質量％以上0.5質量％以下の範囲が好ましい。
C: 0.01-0.5% by mass
C is an element effective for increasing the strength of a steel sheet, and further effective for generating retained austenite and a low-temperature transformation phase, and is an element effective for improving the strength-ductility balance (improving the TS × El value). However, if the C content is less than 0.01% by mass, it is difficult to obtain desired mechanical properties (TS × El value). On the other hand, when the C content exceeds 0.5% by mass, weldability is deteriorated. From the above, the C content is preferably in the range of 0.01% by mass to 0.5% by mass.
さらに、本発明では、強度延性バランスの向上を有効に発現させるために、Mn、SiおよびAlのうちから選ばれる１種または２種以上を以下のように含有させることが好ましい。 Furthermore, in the present invention, in order to effectively improve the strength ductility balance, it is preferable to contain one or more selected from Mn, Si and Al as follows.
Mn：0.01〜5.0質量％
Mnは、固溶強化により鋼を強化するとともに、鋼の焼入性を向上し、さらに残留オーステナイトや低温変態相の生成を促進する作用を有し、良好な材質を得るために有効な元素である。このような作用は、Mn含有量が0.01質量％以上で認められる。一方、5.0質量％を超えて含有しても効果が飽和し、含有量に見合う効果が期待できなくなりコストの上昇を招く。以上より、Mn含有量は、0.01質量％以上5.0質量％以下の範囲が好ましい。
Mn: 0.01-5.0 mass%
Mn strengthens the steel by solid solution strengthening, improves the hardenability of the steel, further promotes the formation of retained austenite and low-temperature transformation phase, and is an effective element for obtaining a good material. is there. Such an effect is recognized when the Mn content is 0.01% by mass or more. On the other hand, if the content exceeds 5.0% by mass, the effect is saturated, and an effect commensurate with the content cannot be expected, resulting in an increase in cost. From the above, the Mn content is preferably in the range of 0.01% by mass to 5.0% by mass.
Si：0.01〜3.0質量％
Siは、固溶強化により鋼を強化するとともに、炭化物の生成を抑制し、オーステナイトを安定化し、残留オーステナイト相の生成を促進する作用を有し、良好な材質を得るために有効な元素である。このような作用は、Si含有量が0.01質量％以上で認められる。一方、3.0質量％以上を超えて含有すると、めっき性が顕著に劣化する弊害が生じる。以上より、Si含有量は0.01質量％以上3.0質量％以下が好ましい。
Si: 0.01-3.0 mass%
Si strengthens steel by solid solution strengthening, suppresses the formation of carbides, stabilizes austenite, promotes the formation of residual austenite phase, and is an effective element for obtaining a good material . Such an effect is recognized when the Si content is 0.01% by mass or more. On the other hand, when it contains more than 3.0 mass%, the bad effect that plating property will deteriorate remarkably will arise. From the above, the Si content is preferably 0.01% by mass or more and 3.0% by mass or less.
P：0.005〜0.2質量％
Pは不可避的に含有されるものであり、セメンタイトの析出を遅延させ変態の進行を遅らせるため、0.005%以上が好ましい。一方、0.2％を超えると溶接性が劣化するだけでなく、表面品質が劣化するため、非合金化時にはめっき密着性が劣化し、合金化処理時には合金化温度が上昇し、延性が劣化すると同時に合金化めっき皮膜の密着性が劣化する場合がある。よって、含有する場合、P量は0.005%以上0.2％以下とする。
P: 0.005-0.2 mass%
P is unavoidably contained, and is preferably 0.005% or more in order to delay the precipitation of cementite and delay the progress of transformation. On the other hand, if it exceeds 0.2%, not only the weldability deteriorates, but also the surface quality deteriorates, so that the adhesion of the plating deteriorates at the time of non-alloying, the alloying temperature rises at the time of alloying treatment, and at the same time the ductility deteriorates. The adhesion of the alloyed plating film may deteriorate. Therefore, when contained, the P content is 0.005% or more and 0.2% or less.
Al：0.01〜5.0質量％
Alは、Siと同様に炭化物の生成を抑制し、残留オーステナイト相の生成を促進する作用を有し、良好な材質を得るために有効な元素である。このような作用は、Al含有量が0.01質量％以上で認められる。一方、5.0質量％以上を超える含有は、鋼中の介在物量を増加させ、延性を低下させる。以上より、Al含有量は0.01質量％以上5.0質量％以下が好ましい。
Al: 0.01-5.0 mass%
Al, like Si, suppresses the formation of carbides and promotes the formation of retained austenite phase, and is an effective element for obtaining a good material. Such an effect is recognized when the Al content is 0.01% by mass or more. On the other hand, the content exceeding 5.0% by mass increases the amount of inclusions in the steel and lowers the ductility. Accordingly, the Al content is preferably 0.01% by mass or more and 5.0% by mass or less.
以上の添加元素により、本発明の合金化溶融亜鉛めっき鋼板は目的とする特性が得られるが、上記の添加元素に加えて、所望の特性に応じて以下の元素を含有することができる。 Although the alloyed hot-dip galvanized steel sheet of the present invention has the desired characteristics by the above additive elements, it can contain the following elements according to desired characteristics in addition to the additive elements described above.
Cr：0.01〜2.0質量％、Mo：0.01〜1.0質量％、B：0.001〜0.01質量％の１種または２種以上
鋼の焼入性を向上し、低温変態相の生成を促進する作用を有する元素である。このような作用は、Cr：0.01質量％以上、Mo：0.01質量％以上、B：0.001質量％以上含有して認められる。一方、Cr：2.0質量％、Mo：1.0質量％、B：0.01質量％を超えて含有しても効果が飽和し、含有量に見合う効果を期待できず、経済的に不利となる。以上より、含有する場合、Crは0.01質量％以上2.0質量％以下、Moは0.01質量％以上1.0質量％以下、Bは0.001質量％以上0.01質量％以下が好ましい。
One or more of Cr: 0.01-2.0 mass%, Mo: 0.01-1.0 mass%, B: 0.001-0.01 mass% Improves the hardenability of the steel and has the effect of promoting the formation of a low-temperature transformation phase It is an element. Such an action is recognized by containing Cr: 0.01% by mass or more, Mo: 0.01% by mass or more, and B: 0.001% by mass or more. On the other hand, even if the content exceeds Cr: 2.0% by mass, Mo: 1.0% by mass, and B: 0.01% by mass, the effect is saturated and an effect commensurate with the content cannot be expected, which is economically disadvantageous. Accordingly, when contained, Cr is preferably 0.01% by mass or more and 2.0% by mass or less, Mo is 0.01% by mass or more and 1.0% by mass or less, and B is preferably 0.001% by mass or more and 0.01% by mass or less.
V：0.001〜0.1質量％、Nb：0.001〜0.1質量％、Ti：0.001〜0.1質量％の１種または２種以上
炭窒化物を形成し、析出硬化により鋼を高強度化する作用を有する元素であり、必要に応じて添加できる。このような作用は、V：0.001質量％以上、Nb：0.001質量％以上、Ti：0.001質量％以上含有して認められる。一方、V：0.1質量％、Nb：0.1質量％、Ti：0.1質量％を超えて含有する場合、過度に高強度化し、延性が劣化してしまう。以上より、含有する場合、Vは0.001質量％以上0.1質量％以下、Nbは0.001質量％以上0.1質量％以下、Tiは0.001質量％以上0.1質量％以下が好ましい。
V: 0.001 to 0.1% by mass, Nb: 0.001 to 0.1% by mass, Ti: 0.001 to 0.1% by mass, one or more elements that form carbonitrides and have the effect of increasing the strength of steel by precipitation hardening And can be added as needed. Such an action is recognized by containing V: 0.001 mass% or more, Nb: 0.001 mass% or more, and Ti: 0.001 mass% or more. On the other hand, when it contains exceeding V: 0.1 mass%, Nb: 0.1 mass%, and Ti: 0.1 mass%, it will become high strength too much and ductility will deteriorate. Accordingly, when contained, V is preferably 0.001% by mass to 0.1% by mass, Nb is preferably 0.001% by mass to 0.1% by mass, and Ti is 0.001% by mass to 0.1% by mass.
Cu：0.01〜2.0質量％、Ni：0.01〜2.0質量％、W：0.001〜0.1質量％の１種または２種以上
Si、Mnと複合添加することにより、Γ相の生成を抑制し、めっき密着性を向上させる効果がある。このような作用はCu：0.01質量％以上、Ni：0.01質量％以上、W：0.001質量％以上含有して認められる。一方、Cu：2.0質量％、Ni：2.0質量％、W：0.1質量％を超えて含有しても効果が飽和し、含有量に見合う効果を期待できず、経済的に不利となる。以上より、含有する場合、Cuは0.01質量％以上2.0質量％以下、Niは0.01質量％以上2.0質量％以下、Wは0.001質量％以上0.1質量％以下が好ましい。
One or more of Cu: 0.01-2.0 mass%, Ni: 0.01-2.0 mass%, W: 0.001-0.1 mass%
The combined addition with Si and Mn has the effect of suppressing the formation of the Γ phase and improving the plating adhesion. Such an effect is recognized by containing Cu: 0.01% by mass or more, Ni: 0.01% by mass or more, and W: 0.001% by mass or more. On the other hand, even if it contains Cu: 2.0 mass%, Ni: 2.0 mass%, and W: more than 0.1 mass%, an effect will be saturated, the effect corresponding to content cannot be expected, and it becomes economically disadvantageous. Accordingly, when contained, Cu is preferably 0.01% by mass to 2.0% by mass, Ni is 0.01% by mass to 2.0% by mass, and W is preferably 0.001% by mass to 0.1% by mass.
なお、本発明に用いる鋼板は、上記した化学成分以外は、残部Feおよび不可避的不純物からなる。不可避的不純物としては、S：0.02質量％以下が許容できる。 In addition, the steel plate used for this invention consists of remainder Fe and an unavoidable impurity except the above-mentioned chemical component. As an inevitable impurity, S: 0.02 mass% or less is acceptable.
なお、本発明において、めっきの素材鋼板は特に限定されない。熱間圧延後酸洗工程で脱スケール処理された熱延鋼板、冷延圧延された冷延鋼板のいずれでもよい。前記鋼板の製造方法も限定されず、常法によって製造されたものでもよい。 In the present invention, the material steel plate for plating is not particularly limited. Any of a hot-rolled steel sheet descaled in the pickling process after hot rolling and a cold-rolled steel sheet cold-rolled may be used. The manufacturing method of the said steel plate is not limited, either, It may be manufactured by a conventional method.
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に示した鋼組成を有し、残部Fe及び不可避的不純物からなる鋼スラブを加熱炉で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。 A steel slab having the steel composition shown in Table 1 and the balance Fe and inevitable impurities was heated in a heating furnace at 1260 ° C. for 60 minutes, subsequently hot-rolled to 2.8 mm and wound at 540 ° C. Thereafter, the black scale was removed by pickling and cold rolled to 1.6 mm.
前記で作製した冷延鋼板を脱脂処理した後、本発明の第I分類の化合物の水溶液（液温は常温）中に又は第I分類の化合物と第II分類の元素を含有する化合物の水溶液（液温は常温）中に浸漬接触する処理（以下、接触処理と記載する。）を行った後、または前記処理を行った後鋼板表面にロールコーター法で本発明のXの元素を含有する化合物の水溶液を塗布し、オーブンで乾燥した（以下、塗布処理と記載する。）後、ラジアントチューブ型（RTF）CGLまたは直火型（DFF）CGLで、850℃で焼鈍した後、引き続き溶融亜鉛めっき、合金化処理した。 After degreasing the cold-rolled steel sheet prepared above, the aqueous solution of the compound of the class I of the present invention (liquid temperature is room temperature) or the aqueous solution of the compound containing the compound of the class I and the element of the class II ( A compound containing the element X of the present invention by a roll coater method after performing a dipping contact process (hereinafter referred to as a contact process) in a liquid temperature (normal temperature) or after performing the above-described process. After coating with an aqueous solution of the above and drying in an oven (hereinafter referred to as coating process), annealing with radiant tube type (RTF) CGL or direct fire type (DFF) CGL at 850 ° C, followed by hot dip galvanization And alloyed.
Xの元素の付着量の制御は、Xの元素を含有する化合物の濃度を変化させることで実施した。 The amount of the X element deposited was controlled by changing the concentration of the compound containing the X element.
溶融亜鉛めっきは、浸入板温500〜600℃、浴温460℃の0.15〜1質量％Al含有Zn浴にて行い、めっき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、処理時間を調整してFe濃度が10質量％になるようにした。 Hot dip galvanization was performed in a Zn bath containing 0.15 to 1% by mass of Al having an intrusion plate temperature of 500 to 600 ° C. and a bath temperature of 460 ° C., and the coating amount was adjusted by gas wiping. Alloying treatment was performed at 540 ° C., and the treatment time was adjusted so that the Fe concentration was 10% by mass.
接触処理条件、塗布処理条件、CGL焼鈍炉タイプ、亜鉛めっき量を表２〜表９に記載する。 Tables 2 to 9 show the contact treatment conditions, coating treatment conditions, CGL annealing furnace type, and zinc plating amount.
Xの元素の塗布量は、20質量％NaOH-10質量％トリエタノールアミン水溶液195ccと35質量％過酸化水素溶液7ccの混合溶液に塗布処理後の鋼板を浸漬して塗付層を溶解し、溶解液中の元素XをICP法で定量し、片面単位面積当たりの付着量として求めた。 The coating amount of the element X is 20% by weight NaOH-10% by weight triethanolamine aqueous solution 195cc and 35% by weight hydrogen peroxide solution 7cc mixed solution soaking the coated steel plate, Element X in the solution was quantified by the ICP method and determined as the amount deposited per unit area on one side.
前記で作製した合金化溶融亜鉛めっき鋼板のめっき外観、耐パウダリング性、耐食性、機械特性について評価した。評価方法を以下に記載する。また評価結果を表２〜表１０に記載する。 The plating appearance, powdering resistance, corrosion resistance, and mechanical properties of the alloyed hot-dip galvanized steel sheet produced above were evaluated. The evaluation method is described below. The evaluation results are shown in Tables 2 to 10.
＜めっき外観＞
合金化処理後のめっき外観を目視観察し、不めっき有無および合金化遅延による外観ムラの有無を評価した。合金化遅延による外観ムラについては、ムラがないものは良好、ムラがあるものは不良とした。さらに、両方の評価がいずれも良好なものは、○：外観良好と判定し、少なくともいずれか一方が不良のものは、×：外観不良と判定した。
<Plating appearance>
The appearance of plating after the alloying treatment was visually observed, and the presence or absence of non-plating and the presence or absence of appearance unevenness due to alloying delay were evaluated. As for the appearance irregularity due to the alloying delay, those having no unevenness were good, and those having the unevenness were bad. Further, when both evaluations were good, it was judged that ◯: good appearance, and at least one of them was bad, x: judged as poor appearance.
＜耐パウダリング性＞
耐パウダリング性は、寸法70mm×150mmのめっき鋼板に粘着テープを貼り、テープ貼り付け面を内側にして曲げ半径1.6mmで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、下記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のものを不良（×）として評価した。○、◎が合格である。
蛍光X線カウント数：ランク
０−５００未満 ：１（良）
５００−１０００未満 ：２
１０００−３０００未満：３
３０００−５０００未満：４
５０００以上 ：５（劣）
<Powdering resistance>
For powdering resistance, the amount of peel per unit length when fluorescent tape is applied to a 70 mm x 150 mm galvanized steel sheet and bent back at 90 ° with a bend radius of 1.6 mm with the tape affixed inside is fluorescent. Measure the Zn count with X-rays, and rank 1, 2, and 3 are good (◎), 4 are generally good (○), and 5 are bad (×) according to the following criteria. did. ○ and ◎ are acceptable.
X-ray fluorescence count: Rank 0 to less than 500: 1 (good)
Less than 500-1000: 2
Less than 1000-3000: 3
Less than 3000-5000: 4
5000 or more: 5 (poor)
＜耐食性＞
寸法70mm×150mmの合金化溶融亜鉛めっき鋼板について、JIS Z 2371(2000)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（濃度200g/L、80℃）を用いて１分間洗浄除去し、試験前後のめっき腐食減量（片面あたり；g/m2・日）を重量法にて測定し、下記基準で評価した。○、◎が合格である。
◎（良好）：15g/m2・日未満
○（概ね良好）：15g/m2・日〜20 g/m2・日未満
×（不良）：20g/m2・日以上
<Corrosion resistance>
A 70 mm x 150 mm alloyed hot dip galvanized steel sheet is subjected to a salt spray test based on JIS Z 2371 (2000) for 3 days, and the corrosion product is washed with chromic acid (concentration 200 g / L, 80 ° C) for 1 minute. The weight loss of plating before and after the test (per one side; g / m 2 · day) was measured by a weight method and evaluated according to the following criteria. ○ and ◎ are acceptable.
◎ (good): 15g / m less than 2 day ○ (generally good): 15g / m 2 day ~20 g / m less than 2 day × (bad): 20g / m 2 · day or more
＜機械的特性＞
機械的特性の評価は、合金化処理溶融亜鉛めっき鋼板から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、機械的特性は良好（○）とし、TS×Elの値が20000MPa・％未満である場合を機械的特性は不良（×）とした。これはTS×Elの値が20000MPa・％以上であれば、自動車用用途として十分な強度・伸びバランスを有すると考えられるためである。
<Mechanical properties>
Mechanical properties were evaluated by taking a JIS No. 5 tensile test specimen from an alloyed hot-dip galvanized steel sheet and measuring the tensile strength TS (MPa) and elongation El (%) measured by tensile test. When the value is 20000 MPa ·% or more, the mechanical properties are good (○), indicating a good balance of strength and ductility, and when the TS × El value is less than 20000 MPa ·%, the mechanical properties are poor (× ). This is because if the value of TS × El is 20000 MPa ·% or more, it is considered that the balance of strength and elongation is sufficient for automotive applications.
表２〜表１０から明らかなように、本発明法範囲を満足する方法で製造された実施例の合金化溶融亜鉛めっき鋼板は、めっき付着量が50ｇ/m2以上の厚目付であっても、またさらに、該合金化溶融亜鉛めっき鋼板の母材鋼板がSiを0.25〜1.5％含有する鋼（鋼Ｂ〜Ｚ、Ｚ１〜Ｚ３）であっても、耐パウダリング性が良好であり、また良好なめっき外観が得られている。また、合金化温度を高温にせずに合金化処理できることで、強度伸びバランスの優れた高強度鋼板が得られている。 As is apparent from Tables 2 to 10, the alloyed hot-dip galvanized steel sheets of Examples manufactured by the method satisfying the scope of the present invention have a coating weight of 50 g / m 2 or more. Furthermore, even if the base steel sheet of the galvannealed steel sheet is a steel containing 0.25 to 1.5% Si (steel B to Z, Z1 to Z3), the powdering resistance is good, Good plating appearance is obtained. Moreover, the high-strength steel plate excellent in the strength-elongation balance is obtained because the alloying process can be performed without increasing the alloying temperature.
本発明法で製造された実施例のめっき鋼板のうちでは、請求項３に係る発明範囲を満足するものは、耐パウダリング性がより良好である。 Among the plated steel sheets of the examples manufactured by the method of the present invention, those satisfying the invention scope according to claim 3 have better powdering resistance .
一方、本発明法範囲を満足しない比較例の合金化溶融亜鉛めっき鋼板は、耐パウダリング性が劣る。 On the other hand, the alloyed hot-dip galvanized steel sheet of the comparative example that does not satisfy the scope of the present invention has poor powdering resistance.
本発明は、めっき付着量が50ｇ/m2以上の厚目付で、耐パウダリング性に優れた合金化溶融亜鉛めっき鋼板の製造方法として利用することができる。 INDUSTRIAL APPLICABILITY The present invention can be used as a method for producing an alloyed hot-dip galvanized steel sheet having a coating weight of 50 g / m 2 or more and excellent powdering resistance.
Claims (3)
第I分類：HCl、H2SO4、HNO3、H2O2
第II分類：アジピン酸、安息香酸、アルカリ金属の硝酸塩 (B) A solution containing one or more compounds selected from the following class I and one or more compounds selected from the following class II at a concentration of 0.10 % by mass or more. A method for producing an alloyed hot-dip galvanized steel sheet, comprising: performing a contact step for 2 seconds or more, annealing, hot-dip galvanizing, and then alloying.
Class I: HCl, H 2 SO 4 , HNO 3 , H 2 O 2
Class II: Adipic acid, benzoic acid, alkali metal nitrates
X：S、Cl、Na、K、Ni、C、N、B、Se、Br
〔X〕≧（1/600）×〔M〕 …（１）
ただし、
〔X〕：Xの元素の片面あたり合計付着量(mg/m2)
〔M〕：片面あたりめっき付着量(g/m2) In the manufacturing method of the galvannealed steel plate of Claim 1 or 2, before annealing after performing a contact process, 1 or more types of the compound containing 1 or more types of elements chosen from following X are included. The manufacturing method of the galvannealed steel plate characterized by making it adhere to the steel plate surface so that following formula (1) may be satisfied.
X: S, Cl, Na, K, Ni, C, N, B, Se, Br
[X] ≧ (1/600) × [M] (1)
However,
[X]: Total adhesion amount per side of X element (mg / m 2 )
[M]: Plating adhesion amount per side (g / m 2 )
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