JPH09249956A - Hot dip zinc-aluminum alloy plated steel excellent in corrosion resistance, phosphating property and blackening resistance and its production - Google Patents
Hot dip zinc-aluminum alloy plated steel excellent in corrosion resistance, phosphating property and blackening resistance and its productionInfo
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- JPH09249956A JPH09249956A JP5933096A JP5933096A JPH09249956A JP H09249956 A JPH09249956 A JP H09249956A JP 5933096 A JP5933096 A JP 5933096A JP 5933096 A JP5933096 A JP 5933096A JP H09249956 A JPH09249956 A JP H09249956A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、耐食性、りん酸塩
処理性及び耐黒変性に優れるＺｎ−Ａｌ系合金溶融めっ
き鋼材及びその製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Zn-Al alloy hot-dip galvanized steel material excellent in corrosion resistance, phosphate treatment property and blackening resistance, and a method for producing the same.
【０００２】[0002]
【従来の技術】鉄鋼材料の耐食性を向上させる方法の一
つに溶融亜鉛めっき法があり、その製品である溶融亜鉛
めっき鋼管、形鋼、鋼線、ボルトナット等の部材は建
築、土木等の構造材料や自動車、機械部品等の幅広い用
途に使用されている。2. Description of the Related Art There is a hot dip galvanizing method as one of the methods for improving the corrosion resistance of steel materials, and the products such as hot dip galvanized steel pipes, shaped steels, steel wires, bolts and nuts are used for construction, civil engineering, etc. It is used in a wide range of applications such as structural materials, automobiles, and machine parts.
【０００３】近年、これらの分野で耐食性を主とした品
質向上が盛んに試みられている。品質向上のために採用
されている方法は、Ｚｎ中へＡｌを主とする金属元素を
添加する方法が殆どであり、添加量の大小により品質は
かなり異なったものになる。In recent years, attempts have been made actively to improve quality mainly in corrosion resistance in these fields. Most of the methods adopted for improving the quality are methods in which a metal element mainly containing Al is added to Zn, and the quality is considerably different depending on the amount of addition.
【０００４】それらの中で従来の溶融亜鉛めっきに近い
条件で製造できるものとして約５％程度のＡｌと第３元
素を添加した溶融Ｚｎ−Ａｌ系合金めっきがある。この
めっきを施すことで鋼材は従来の亜鉛めっきを施したも
のに比べ耐食性が格段に向上した。Among them, there is a hot-dip Zn-Al alloy plating in which about 5% of Al and a third element are added, which can be produced under the conditions close to those of the conventional hot-dip galvanizing. By applying this plating, the corrosion resistance of the steel material was markedly improved compared to the conventional galvanized material.
【０００５】通常、溶融Ｚｎ−Ａｌ系合金めっきのめっ
き層組織は、図１（Ａ）の顕微鏡組織の写真及びその模
式図である図２（Ａ）に示されるように、Ｚｎリッチな
β相（以下、β相と称する）１がめっき皮膜の内部に存
在し、このβ相を囲むように共晶相２が存在する。めっ
き層の共晶相は優れた耐食性を得る上で不可欠である
が、共晶相の存在により、溶融Ｚｎめっきに比べてめっ
き層が黒変化し外観を損なうという問題や、りん酸塩処
理の際に共晶相中のアルミニウムがりん酸処理液中に溶
出して処理液を経時劣化させてりん酸処理性が低下する
という問題がある。また、めっき層中のβ相の存在状態
は耐食性に大きな影響を与え、β相がめっきを貫通する
ような状態で存在する場合、β相が優先的に溶解して耐
食性が劣化するという問題がある。Usually, the plated layer structure of the hot dip Zn-Al alloy plating is a Zn rich β phase as shown in the photograph of the microscopic structure of FIG. 1 (A) and its schematic view of FIG. 2 (A). (Hereinafter, referred to as β phase) 1 exists inside the plating film, and eutectic phase 2 exists so as to surround this β phase. The eutectic phase of the plating layer is indispensable for obtaining excellent corrosion resistance, but the presence of the eutectic phase causes the plating layer to turn black and deteriorates the appearance as compared with hot-dip Zn plating. At this time, there is a problem that aluminum in the eutectic phase elutes in the phosphoric acid treatment liquid and deteriorates the treatment liquid with time, resulting in deterioration of phosphoric acid treatability. Further, the existence state of the β phase in the plating layer has a great influence on the corrosion resistance, and when the β phase exists in a state of penetrating the plating, there is a problem that the β phase is preferentially dissolved and the corrosion resistance deteriorates. is there.
【０００６】これらの問題点を解決するための以下の提
案がなされている。 (1) 特開昭60-110860 号公報には、７重量％以下のＡｌ
を含むＺｎ−Ａｌ系合金めっき浴でめっきした鋼板のめ
っき後の冷却速度を５〜４０℃／秒として、図１（Ｂ）
のめっき層組織の顕微鏡写真及びその模式図である図２
（Ｂ）に示されるように、β相１をめっき層表面近傍に
偏析させることにより、耐食性およびりん酸塩処理液中
へのアルミニウムの溶出を低減してリン酸塩処理性を改
善する技術が開示されている。The following proposals have been made to solve these problems. (1) Japanese Patent Laid-Open No. 60-110860 discloses that Al of 7 wt% or less is used.
1 (B), the cooling rate after plating of the steel sheet plated with the Zn-Al alloy plating bath containing
2 is a photomicrograph of the plating layer structure of FIG.
As shown in (B), by segregating β phase 1 near the surface of the plating layer, there is a technique for improving corrosion resistance and elution of aluminum into the phosphate treatment solution to improve phosphate treatability. It is disclosed.
【０００７】(2) 特開昭58-177447 号公報には、Ａｌが
０．１から２５．０重量％、Ｍｇが０．０５から２．０
重量％、Ｓｂが０．００５から１．５重量％、Ｐｂが
０．０１重量％以下、残部がＺｎ及び不可避不純物から
なるＺｎ−Ａｌ系合金めっきにより、ＳｂをＡｌ−Ｓｂ
化合物としてめっき層の表面全体に分布させ、リン酸塩
処理皮膜生成の際の活性点とすることによって、リン酸
塩処理皮膜の結晶を微細化して塗装性能を改善すること
が開示されている。(2) JP-A-58-177447 discloses that Al is 0.1 to 25.0% by weight and Mg is 0.05 to 2.0.
Wt%, Sb 0.005 to 1.5 wt%, Pb 0.01 wt% or less, the balance Zn-Al alloy plating consisting of Zn and unavoidable impurities, Sb Al-Sb
It is disclosed that a compound is distributed over the entire surface of the plating layer and is used as an active point when a phosphate-treated film is formed, whereby the crystals of the phosphate-treated film are miniaturized to improve the coating performance.
【０００８】(3) 特開平6-158256号公報には、Ａｌを３
から１０重量％、Ｔｉを０．０１から１重量％、残部が
Ｚｎ及び不可避不純物からなるＺｎ−Ａｌ系合金めっき
浴を用いて、めっき層表面にＴｉ酸化物を形成すること
によって、黒変を抑制する技術が開示されている。(3) In Japanese Patent Laid-Open No. 6-158256, Al is mixed with 3
To 10% by weight, 0.01 to 1% by weight of Ti, and the balance Zn and Al inevitable impurities are used to form a Ti oxide on the surface of the plated layer to form a black oxide. Techniques for suppressing are disclosed.
【０００９】(4) 特開昭61-231178 号公報には、Ｚｎ−
Ａｌ系合金めっき鋼板表面に、無電解浸漬処理によりＣ
ｏ−Ｐ合金を被服することによって、耐黒変性、および
リン酸塩処理における大量の微細結晶核の発生ならびに
リン酸塩処理液中のリン酸と反応する際の自己触媒的な
活性点とすることにより化成処理性を改善する技術が開
示されている。(4) JP-A-61-231178 discloses Zn-
C on the surface of Al-based alloy plated steel sheet by electroless dipping treatment
By coating the o-P alloy with blackening resistance, generation of a large amount of fine crystal nuclei in the phosphating treatment, and an autocatalytic active site when reacting with phosphoric acid in the phosphating solution Therefore, a technique for improving the chemical conversion treatment property is disclosed.
【００１０】(5) 特開平1-222065号公報には、Ｚｎ−Ａ
ｌ系合金の溶融めっきを施した後、めっき層の溶融状態
から１７０℃に冷却されるまでの間に、Ｃｏ，Ｎｉ，Ｆ
ｅイオンの少なくとも１種と次亜リン酸塩を含有する無
電解めっき液を噴霧することにより耐黒変性を改善する
技術が開示されている。(5) JP-A 1-222065 discloses Zn-A.
After the hot dip coating of the l-based alloy, Co, Ni, F is added between the molten state of the plating layer and the cooling to 170 ° C.
A technique for improving blackening resistance by spraying an electroless plating solution containing at least one e-ion and hypophosphite is disclosed.
【００１１】[0011]
【発明が解決しようとする課題】しかし、前記した公報
に開示される技術には以下の問題点がある。(1) に開示
される技術による場合、りん酸塩処理性の改善効果は十
分とは言えない。また、裸使用に対する考慮がない。本
発明者らが裸使用において要求される耐黒変性について
調査したところ、耐黒変性は劣っていた。However, the technique disclosed in the above publication has the following problems. In the case of the technique disclosed in (1), the effect of improving the phosphating property is not sufficient. In addition, there is no consideration for naked use. When the present inventors investigated the blackening resistance required for naked use, the blackening resistance was inferior.
【００１２】(2) に開示される技術には、耐黒変性およ
びりん酸塩処理におけるアルミニウムのりん酸塩処理液
中への溶解を防止することにより、りん酸塩処理性を改
善する点について言及がない。本発明者らが調査したと
ころ、耐黒変性は劣っており、リン酸塩処理液中へのア
ルミニウムの溶出量が大きかった。The technique disclosed in (2) is to improve the phosphate treatment property by preventing the blackening resistance and the dissolution of aluminum in the phosphate treatment liquid during the phosphate treatment. There is no mention. As a result of investigation by the present inventors, the blackening resistance was inferior and the amount of aluminum eluted into the phosphate treatment solution was large.
【００１３】(3) に記載される技術には、リン酸塩処理
におけるアルミニウムのリン酸処理液中への溶解を防止
することにより、リン酸塩処理性を改善する点について
言及がない。本発明者らが、リン酸処理液中へのアルミ
ニウムの溶出量を調査したところ、アルミニウムの溶出
量は多かった。[0013] The technique described in (3) does not mention the point that the phosphating property is improved by preventing the dissolution of aluminum in the phosphating solution in the phosphating process. When the present inventors investigated the elution amount of aluminum in the phosphoric acid treatment liquid, the elution amount of aluminum was large.
【００１４】(4) 、(5) に記載される技術の場合、めっ
き後の特別な処理が必要であり、製造コストが増加する
という問題がある。また、リン酸塩処理におけるアルミ
ニウムのリン酸塩処理液中への溶出を防止することによ
り、リン酸塩処理性を改善する点について言及がない。
本発明者らが、リン酸処理液中へのアルミニウムの溶出
量を調査したところ、アルミニウムの溶出量は多かっ
た。In the case of the techniques described in (4) and (5), there is a problem that a special treatment after plating is required and the manufacturing cost increases. Further, there is no mention of improving the phosphate treatment property by preventing the elution of aluminum into the phosphate treatment liquid in the phosphate treatment.
When the present inventors investigated the elution amount of aluminum in the phosphoric acid treatment liquid, the elution amount of aluminum was large.
【００１５】すなわち、前記した技術では、裸使用、塗
装使用の両方の用途に使用することは考慮されていな
い。本発明者らが調査したところ、前記した両方の用途
に使用する場合に要求される耐黒変性とリン酸塩処理液
の経時劣化を防止することによる優れたリン酸塩処理性
とを兼ね備えたものは認められなかった。従って、前記
した技術による場合、裸使用あるいは塗装使用の用途に
応じて予め材料を選択し、その使用形態にあった材料を
使用する必要がある。That is, the above-mentioned technique does not consider use for both naked use and painting use. As a result of investigations by the present inventors, it was found that both the blackening resistance required for use in both of the above-mentioned applications and the excellent phosphating property by preventing the aging of the phosphating solution were prevented. Nothing was found. Therefore, in the case of the above-mentioned technique, it is necessary to select the material in advance according to the purpose of naked use or coating use and use the material suitable for the usage form.
【００１６】本発明は、前記した事情を考慮してなされ
たものであり、りん酸塩処理性と耐黒変性とを兼ね備え
ることにより、裸使用、塗装使用の両方の用途に使用で
きる、耐食性に優れた溶融Ｚｎ−Ａｌ系合金めっき鋼材
及びその製造方法を提供するものである。The present invention has been made in consideration of the above-mentioned circumstances, and by having both the phosphate treatment property and the blackening resistance, it can be used for both naked use and painting use, and has corrosion resistance. An excellent hot-dip Zn-Al alloy plated steel material and a method for producing the same are provided.
【００１７】[0017]
【課題を解決するための手段】本発明者らは、めっき層
のβ相の存在状態がめっき鋼板の品質に大きく影響する
点に着目し、めっき層のβ相の存在状態とめっき品質と
の関係について鋭意検討した。その結果、めっき表層に
β相をリッチ化し、更に、めっき層表面にβ相を露出さ
せると共にその露出率を高めることにより、耐食性、耐
黒変性とリン酸塩処理性とを兼ね備えためっき層を得る
ことができることを知見した。本発明は、この知見に基
づくものであり、その特徴とする構成は以下のとおりで
ある。Means for Solving the Problems The present inventors have focused on the fact that the existence state of the β phase in the plating layer greatly affects the quality of the plated steel sheet, and We studied the relationship diligently. As a result, by enriching the β phase in the plating surface layer, and further exposing the β phase on the surface of the plating layer and increasing the exposure rate, a plating layer having both corrosion resistance, blackening resistance and phosphate treatment property can be obtained. It was found that it can be obtained. The present invention is based on this finding, and the characteristic configuration is as follows.
【００１８】本発明鋼材は、鋼材にＡｌを２重量％以上
６重量％以下を含む溶融Ｚｎ−Ａｌ系合金めっき皮膜を
形成した鋼材（但し、鋼板は除く）において、めっき皮
膜の表層が連続したβ相、又はβ相と共晶相、下層が共
晶相からなり、めっき層表面のβ相の露出面積率が６０
％以上であることを特徴とする耐食性、りん酸塩処理性
及び耐黒変性に優れた溶融Ｚｎ−Ａｌ合金溶融めっき鋼
材である。The steel material of the present invention is a steel material in which a molten Zn-Al based alloy plating film containing 2% by weight or more and 6% by weight or less of Al is formed on the steel material (however, excluding steel plate), the surface layer of the plating film is continuous. The β phase, or the β phase and the eutectic phase, the lower layer consists of the eutectic phase, and the exposed area ratio of the β phase on the plating layer surface is 60
% Or more, which is a hot-dip Zn-Al alloy hot-dip galvanized steel material excellent in corrosion resistance, phosphate treatment property and blackening resistance.
【００１９】本発明の鋼材の製造方法は、めっき浴浴温
度が４２０℃以上５００℃以下で、Ａｌを２重量％以上
６重量％以下を含む溶融Ｚｎ−Ａｌ系合金めっき浴に、
鋼材を浸漬して溶融Ｚｎ−Ａｌ系合金めっきを施した
後、前記鋼材を冷却するに際して、前記鋼材のめっき浴
浸漬時間をｔａ（秒）、初期凝固層消失時間ｔｂ
（秒）、浴温度Ｔbath（℃）、浴融点Ｔmp（℃）、侵入
板温Ｔin（℃）、鋼材表面積Ｓ（ｍ2 ）、鋼材重量Ｗ
（ｋｇ）、めっき後の前記鋼材の４３０℃からめっき層
が凝固するまでの間の冷却速度Ｒ（℃／秒）とした時下
式(1) を満足する浸漬時間ｔａ、初期凝固層消失時間ｔ
ｂ及び冷却速度Ｒでめっきして、めっき皮膜の表層が連
続したβ相、またはβ相と共晶相、下層が共晶相からな
り、めっき層表面のβ相の露出面積率が６０％以上であ
ることを特徴とする耐食性、りん酸塩処理性及び耐黒変
性に優れたＺｎ−Ａｌ系合金溶融めっき鋼材の製造方法
である。The method for producing a steel material according to the present invention comprises a molten Zn-Al alloy plating bath having a plating bath temperature of 420 ° C to 500 ° C and containing Al in an amount of 2% by weight to 6% by weight.
When the steel material is cooled by dipping the steel material and performing the hot dip Zn-Al-based alloy plating, the steel material is immersed in the plating bath for ta (seconds) and the initial solidified layer disappearance time tb.
(Sec), bath temperature Tbath (° C), bath melting point Tmp (° C), penetration plate temperature Tin (° C), steel surface area S (m 2 ), steel weight W
(Kg), when the cooling rate R (° C./sec) from 430 ° C. of the steel material after plating to the solidification of the plating layer is set, the immersion time ta satisfying the following formula (1), the initial solidified layer disappearance time t
b) and cooling rate R, the surface layer of the plating film is continuous β phase, or β phase and eutectic phase, the lower layer is eutectic phase, the exposed area ratio of β phase on the plating layer surface is 60% or more Is a method for producing a Zn-Al alloy hot dip plated steel material excellent in corrosion resistance, phosphate treatment property and blackening resistance.
【００２０】 Ｒ≧31.8-36.196 ｌｏｇ（ｔａ−ｔｂ） （０≦ｔａ−ｔｂ＜５の場合） Ｒ≧6.81×１０-0.004 (ta-tb) （ｔａ−ｔｂ≧５の場合） …(1) 但し，初期凝固層消失時間ｔｂ（秒）は，下式(2) で表
される。R ≧ 31.8-36.196 log (ta-tb) (when 0 ≦ ta-tb <5) R ≧ 6.81 × 10 −0.004 (ta-tb) (when ta-tb ≧ 5) (1) However, the initial solidified layer disappearance time tb (second) is expressed by the following equation (2).
【００２１】 tb＝1.06×｛log （Ｔbath−Ｔin）−log （Ｔbath−Ｔmp)}／ (S/W)…(2) まず、本発明の溶融Ｚｎ−Ａｌ系合金めっき鋼材のめっ
き層組織及び限定理由について説明する。Tb = 1.06 × {log (Tbath-Tin) -log (Tbath-Tmp)} / (S / W) (2) First, the plated layer structure of the molten Zn-Al alloy plated steel material of the present invention and the The reason for limitation will be described.
【００２２】本発明の鋼材のめっき層の状態を従来技術
によるめっき層の状態と対比して図１および図２により
説明する。図１（Ａ）〜（Ｅ）は、６００倍の走査型電
子顕微鏡によるめっき層組織の写真であり、左側の写真
はめっき層の断面組織を示す写真、右側の写真はめっき
層の表面組織を示す写真である。The state of the plated layer of the steel material of the present invention will be described with reference to FIGS. 1 and 2 in comparison with the state of the plated layer according to the prior art. 1 (A) to 1 (E) are photographs of the plating layer structure by a scanning electron microscope at a magnification of 600, where the left-side photo shows the cross-sectional structure of the plating layer and the right-side photo shows the surface structure of the plating layer. It is a photograph shown.
【００２３】また、図２（Ａ）〜（Ｅ）は、それぞれ図
１（Ａ）〜（Ｅ）に対応するめっき層組織のβ相、共晶
相を模式化して示した図である。図１，図２において、
１はβ相、２は共晶相、３は母材の鋼材である。また図
１（Ａ），（Ｂ）の表面組織は全面共晶相、図１（Ｅ）
の表面組織は全面β相であるので、これらについては、
図２の表面組織の模式図を示していない。2A to 2E are schematic views showing the β phase and eutectic phase of the plating layer structure corresponding to FIGS. 1A to 1E, respectively. 1 and 2,
Reference numeral 1 is a β phase, 2 is a eutectic phase, and 3 is a base steel material. In addition, the surface structure of FIGS. 1 (A) and 1 (B) is the entire eutectic phase, and FIG.
Since the surface texture of is the entire β phase,
The schematic diagram of the surface texture of FIG. 2 is not shown.
【００２４】図１（Ａ）、図２（Ａ）は、従来一般に見
られるめっき層組織であり、めっき層内部にβ相が存在
しており、めっき層の表層部には共晶層のみが存在し、
β相は認められない。FIGS. 1 (A) and 2 (A) show a conventional plating layer structure, in which the β phase exists inside the plating layer, and only the eutectic layer is present in the surface layer portion of the plating layer. Exists,
No β phase is observed.
【００２５】図１（Ｂ）、図２（Ｂ）は、先行技術
（１）に記載の方法により製造しためっき鋼板のめっき
層組織であり、めっき層の表層部にβ相が偏析して存在
する。しかし、表面組織によると、めっき相の表面にβ
相が露出していない。これには表面近傍に薄い共晶相の
皮膜が存在しているためと考えられる。FIGS. 1 (B) and 2 (B) show the plating layer structure of the plated steel sheet produced by the method described in the prior art (1), in which the β phase segregates in the surface layer portion of the plating layer. To do. However, according to the surface texture, the β on the surface of the plating phase
Phase is not exposed. This is probably because there is a thin eutectic phase film near the surface.
【００２６】図１（Ｃ）、図２（Ｃ）では、めっき層の
表層部におけるβ相の偏析がより明瞭である。表面組織
によると、めっき層表面にβ相が露出しているがその露
出面積率は低い。In FIGS. 1C and 2C, the segregation of β phase in the surface layer portion of the plating layer is clearer. According to the surface texture, the β phase is exposed on the surface of the plating layer, but the exposed area ratio is low.
【００２７】図１（Ｄ）、図２（Ｄ）では、めっき層の
表層部におけるβ相の偏析がより明瞭であり、表面組織
によると、めっき層表面の６０％以上にβ相の露出が認
められる。In FIGS. 1 (D) and 2 (D), the segregation of the β phase in the surface layer portion of the plating layer is clearer, and according to the surface texture, the β phase is exposed at 60% or more of the surface of the plating layer. Is recognized.
【００２８】図１（Ｅ）、図２（Ｅ）の場合、めっき層
表層部おけるβ相の偏析が顕著であり、めっき層表面に
β相露出面積率は１００％もしくはそれに近い状態にな
っている。In the case of FIGS. 1 (E) and 2 (E), the segregation of β-phase in the surface layer of the plating layer is remarkable, and the β-phase exposed area ratio on the surface of the plating layer is 100% or close to it. There is.
【００２９】本発明のめっき鋼材のめっき層組織は、前
記した図１（Ｄ）、（Ｅ）、図２（Ｄ）、（Ｅ）に示さ
れるような組織であり、β相が表層部に偏析しているこ
とに加えて、その表面にβ相が面積率で６０％以上露出
している点に特徴がある。めっき層表面のβ相の露出面
積率を６０％以上にすることにより、本発明が目的とす
る優れた耐黒変性、りん酸塩処理性を得ることができ
る。めっき層表面のβ相の露出面積率が高くなり、めっ
き層表面の性質が亜鉛めっきに近い性質となったため耐
黒変性が優れると考えられる。また、表層部のβ相の偏
析が大きく、表層部の亜鉛の割合が増加しアルミニウム
の割合が低下しているため、りん酸塩処理においてめっ
き層からりん酸塩処理液中ヘのアルミニウムの溶出が低
減することにより、りん酸塩処理液の劣化が抑制され
る。β相の露出面積率が６０％を下回ると本発明が目的
とする耐黒変性、りん酸塩処理性を得ることができな
い。β相の露出面積率が９５％以上の場合、耐黒変性が
より優れる。The plating layer structure of the plated steel material of the present invention is such a structure as shown in FIGS. 1 (D), (E), 2 (D) and (E), and the β phase is present in the surface layer portion. In addition to segregation, it is characterized in that the β phase is exposed on the surface in an area ratio of 60% or more. By setting the exposed area ratio of the β phase on the surface of the plating layer to 60% or more, it is possible to obtain the excellent blackening resistance and phosphate treatment property which are the objects of the present invention. The exposed area ratio of the β phase on the surface of the plating layer was high, and the properties of the surface of the plating layer were similar to those of zinc plating, so it is considered that the blackening resistance is excellent. In addition, the segregation of the β phase in the surface layer is large, the proportion of zinc in the surface layer is increasing, and the proportion of aluminum is decreasing.Therefore, during the phosphate treatment, the elution of aluminum from the plating layer to the phosphate treatment solution Is reduced, the deterioration of the phosphating solution is suppressed. If the exposed area ratio of the β phase is less than 60%, it is impossible to obtain the blackening resistance and the phosphate treatment property which are the objects of the present invention. When the exposed area ratio of the β phase is 95% or more, blackening resistance is more excellent.
【００３０】また、下層に連続した共晶相が形成されて
いるので、優れた耐食性が得られる。本発明鋼材では、
めっき層中にＡｌを２重量％以上６重量％以下含む必要
がある。Ａｌが２重量％未満の場合、β相の体積分率が
増加して共晶相が連続化できず、一部β相が鋼材界面に
達するため耐食性が低下する。また、Ａｌが６重量％を
超えるとβ相が消失し、本発明の特徴であるめっき相の
表層部においてβ相が偏析しかつ表面にβ相が露出する
めっき層を形成できな＜なる。Further, since a continuous eutectic phase is formed in the lower layer, excellent corrosion resistance can be obtained. In the steel material of the present invention,
It is necessary that the plating layer contain 2% by weight or more and 6% by weight or less of Al. When Al is less than 2% by weight, the volume fraction of the β phase increases, the eutectic phase cannot be continuous, and part of the β phase reaches the steel material interface, so that the corrosion resistance decreases. Further, when Al exceeds 6% by weight, the β phase disappears, and the β layer segregates in the surface layer portion of the plating phase, which is a feature of the present invention, and the plating layer in which the β phase is exposed cannot be formed.
【００３１】なお、めっき層の性状を調整するために、
Ｌａ，Ｃｅ，Ｔｉ，Ｍｇ，Ｓｎ，Ｚｒ，Ｐｂ等の成分元
素を添加する場合がある。本発明のＺｎ−Ａｌ系合金め
っきには、前記目的のための成分元素を１重量％を超え
ない範囲で添加したものを含む。In order to adjust the properties of the plating layer,
In some cases, component elements such as La, Ce, Ti, Mg, Sn, Zr and Pb are added. The Zn-Al-based alloy plating of the present invention includes those in which the constituent elements for the above purpose are added within a range not exceeding 1% by weight.
【００３２】次に、本発明のめっき鋼材の製造方法の限
定理由について説明する。めっき浴のＡｌ濃度は、２重
量％以上６重量％以下とする。めっき浴のＡｌが２重量
％未満の場合、得られためっき層のβ相の体積分率が増
加して共晶相が連続化できず、一部β相が鋼材表面に達
するため耐食性が低下する。また、Ａｌが６重量％を越
えると、得られためっき層のβ相が消失し、めっき層の
表層においてβ相が偏析しかつ表面にβ相が露出しため
っき層が形成できなくなる。めっき浴温は４２０℃以上
５００℃以下にする必要がある。浴温が４２０℃未満に
なると、操業中にめっき浴の一部が凝固し、安定操業が
困難になる。一方、この温度が５００℃を超えると、鋼
材表面でのめっき浴成分との合金化反応が急激に活発化
し、界面合金層が厚く成長して、加工性か劣化するため
である。Next, the reasons for limiting the method for producing a plated steel material according to the present invention will be described. The Al concentration of the plating bath is 2% by weight or more and 6% by weight or less. When the Al content of the plating bath is less than 2% by weight, the volume fraction of the β phase in the obtained plating layer increases and the eutectic phase cannot be continuous, and part of the β phase reaches the surface of the steel material, resulting in reduced corrosion resistance. To do. Further, when Al exceeds 6% by weight, the β phase of the obtained plating layer disappears, the β phase segregates in the surface layer of the plating layer, and the plating layer in which the β phase is exposed cannot be formed. The plating bath temperature must be 420 ° C or higher and 500 ° C or lower. If the bath temperature is lower than 420 ° C., a part of the plating bath is solidified during the operation, which makes stable operation difficult. On the other hand, if this temperature exceeds 500 ° C., the alloying reaction with the plating bath components on the surface of the steel material is rapidly activated, the interface alloy layer grows thick, and the workability deteriorates.
【００３３】浸漬時間ｔａ秒と初期凝固層消失時間ｔｂ
秒との差（ｔａ−ｔｂ）秒と少なくともめっき後の鋼材
の４３０℃からめっき層が凝固するまでの間の冷却速度
Ｒ℃／秒は、浸漬時間と初期凝固層消失時間との差（ｔ
ａ−ｔｂ）秒が５秒未満の場合、Ｒ≧３１．８−３６．
１９６ｌｏｂ（ｔａ−ｔｂ）、浸漬時間と初期凝固層消
失時間との差（ｔａ−ｔｂ）秒が５秒以上の場合、Ｒ≧
６．８１×１０-0.004 (ta-tb) の関係式を満足する必要
がある。ただし、初期凝固層消失時間ｔｂ（秒）はｔｂ
＝１．Ｏ６×｛ｌｏｇ（Ｔbath−Ｔin）−ｌｏｇ（Ｔba
th−Ｔmp）｝／（Ｓ／Ｗ）で表される。この関係式を満
足しない場合、めっき層の表層におけるβ相の偏析とめ
っき層の表層におけるβ相の偏析とめっき層表面へのβ
相の露出面積率を６０％以上にすることができない。Immersion time ta seconds and initial solidified layer disappearance time tb
The difference between the immersion time and the initial solidified layer disappearance time (t-tb) is the difference between the immersion time and the initial solidified layer disappearance time (t).
a-tb) seconds are less than 5 seconds, R ≧ 31.8-36.
196 lob (ta-tb), the difference between the immersion time and the initial solidified layer disappearance time (ta-tb) seconds is 5 seconds or more, R ≧
It is necessary to satisfy the relational expression of 6.81 × 10 −0.004 (ta-tb) . However, the initial solidified layer disappearance time tb (second) is tb
= 1. O6 × {log (Tbath-Tin) -log (Tba
th-Tmp)} / (S / W). If this relational expression is not satisfied, segregation of β phase on the surface of the plating layer and segregation of β phase on the surface of the plating layer and β on the surface of the plating layer
The exposed area ratio of the phase cannot be 60% or more.
【００３４】なお、前記した様に限定した条件におい
て、本発明の構成のめっき層が形成される理由について
は必ずしも明確ではないが、めっき浴における浸漬時間
を十分とったことにより、鋼材界面における極薄い合金
層が形成されて、鋼材界面近傍でのアルミニウムの濃度
低下や前記合金層を通過して鋼材からめっき層中への鉄
の拡散等の結果、溶融状態のめっき層の厚さ方向で、め
っき成分組成の不均一化が起こっており、この状態から
めっき層が急冷、凝固された際、めっき層表面で初晶相
であるβ相が析出しやすくなったことによるのではない
かと考えられる。Although the reason why the plating layer having the constitution of the present invention is formed under the above-mentioned limited conditions is not always clear, it is possible to ensure that the immersion time in the plating bath is long enough to prevent A thin alloy layer is formed, as a result of a decrease in the concentration of aluminum in the vicinity of the steel material interface and diffusion of iron from the steel material into the plating layer through the alloy layer, in the thickness direction of the molten plating layer, The non-uniformity of the composition of the plating components is occurring, and it is considered that when the plating layer was rapidly cooled and solidified from this state, the primary phase β phase was likely to precipitate on the plating layer surface. .
【００３５】[0035]
【発明の実施の形態】本発明のＺｎ−Ａ１系合金めっき
の母材となる鋼材に特に制眼はなく、常法により製造し
た鋼管、鋼線等の鋼材を使用することができる。本発明
の溶融Ｚｎ−Ａｌ系合金めっき鋼材は、常用される溶融
亜鉛めっき設備を利用して、溶融めっき浴成分をＡｌを
２重量％以上６重量％以下含む溶融Ｚｎ−Ａ１系合金め
っき浴により鋼材に浸漬めっきを施して製造する。BEST MODE FOR CARRYING OUT THE INVENTION There is no particular limitation on the steel material used as the base material for the Zn-A1 alloy plating of the present invention, and steel materials such as steel pipes and steel wires manufactured by a conventional method can be used. The hot-dip Zn-Al alloy-plated steel material of the present invention utilizes a hot-dip galvanizing facility that is commonly used, and is obtained by a hot-dip Zn-A1 alloy plating bath containing 2 wt% to 6 wt% of Al as a hot-dip bath component. It is manufactured by applying immersion plating to steel.
【００３６】なお、必要に応じて、めっき層の性状を調
整するために、Ｌａ，Ｃｅ，Ｔｉ，Ｍｇ，Ｓｎ，Ｚｒ，
Ｐｂ等の成分元素を１重量％を超えない範囲でめっき浴
に添加してもよい。If necessary, in order to adjust the properties of the plating layer, La, Ce, Ti, Mg, Sn, Zr,
Component elements such as Pb may be added to the plating bath within a range not exceeding 1% by weight.
【００３７】溶融めっきに際して、めっき浴温度を４２
０〜５００℃、浸漬時間ｔａ秒と初期凝固層消失時間ｔ
ｂ秒との差（ｔａ−ｔｂ）秒と少なくともめっき後の鋼
材の４３０℃からめっき層が凝固するまでの間の冷却速
度Ｒ℃／秒とした時、冷却速度Ｒは、浸漬時間と初期凝
固層消失時間との差（ｔａ−ｔｂ）秒が５秒未満の場
合、Ｒ≧３１．８−３６．１９６ｌｏｇ（ｔａ−ｔ
ｂ）、浸漬時間と初期凝固層消失時間との差（ｔａ−ｔ
ｂ）秒が５秒以上の場合、Ｒ≧６．８１×１０-0.004
(ta-tb) の関係式を満足する範囲で冷却することにより
製造する。ただし、初期凝固層消失時間ｔｂ（秒）はｔ
ｂ＝１．Ｏ６×｛ｌｏｇ（Ｔbath−Ｔin）−ｌｏｇ（Ｔ
bath−Ｔmp）｝／（Ｓ／Ｗ）で表される。In hot dip plating, the plating bath temperature is set to 42
0 to 500 ° C., immersion time ta seconds and initial solidified layer disappearance time t
When the difference (ta-tb) second from b seconds and the cooling rate R ° C./second at least from 430 ° C. of the steel material after plating to the solidification of the plating layer are cooling rates R, the cooling rate R is the immersion time and the initial solidification. If the difference (ta-tb) second from the layer disappearance time is less than 5 seconds, R ≧ 31.8-36.196 log (ta-t
b), the difference between the immersion time and the disappearance time of the initial solidified layer (ta-t
b) When the second is 5 seconds or more, R ≧ 6.81 × 10 −0.004
It is manufactured by cooling within a range satisfying the relational expression (ta-tb) . However, the initial solidified layer disappearance time tb (second) is t
b = 1. O6 × {log (Tbath-Tin) -log (T
bath-Tmp)} / (S / W).
【００３８】めっき浴浸漬時間の調整は、鋼材のライン
走行速度により調整される。初期凝固層消失時間はめっ
き浴条件（めっき組成、めっき浴温度）と鋼材の温度や
形状により決定される値であり、めっき前に予測可能で
ある。The plating bath immersion time is adjusted by the line running speed of the steel material. The disappearance time of the initial solidified layer is a value determined by the plating bath conditions (plating composition, plating bath temperature) and the temperature and shape of the steel material, and can be predicted before plating.
【００３９】めっき後の冷却速度の調整は、冷却用気体
を用いて、鋼材に吹き付ける冷却用気体の吹き付け量の
調整によることができる。また、冷却を、水ミスト冷却
等の気体冷却によらない方法により、冷却速度を調整し
てもよい。また、冷却後、必要に応じて、形状矯正や表
面仕上げ、クロメート処理、塗油を施してもよい。The cooling rate after plating can be adjusted by adjusting the amount of the cooling gas sprayed onto the steel material by using the cooling gas. Further, the cooling rate may be adjusted by a method that does not rely on gas cooling such as water mist cooling. After cooling, if necessary, shape correction, surface finishing, chromate treatment, and oiling may be applied.
【００４０】[0040]
【実施例】以下に実旅例を示す。外径１１４．６ｍｍ
（１２５Ａ）、肉厚４．５ｍｍ、長さ５．５ｍの鋼管
（ＳＴＫ４００）を素地鋼村とし、溶融亜鉛めっき設備
にて、表１，表２に記載の成分組成のＡｌ及び０．Ｏ１
重量％のミッシュメタルと残部がＺｎ及び不可避不純物
からなるめっき浴（Ｎｏ．１〜Ｎｏ．４０）及びこのめ
っき浴に更に微量のＭｇ又はＴｉを添加しためっき浴
（Ｎｏ．４１，Ｎｏ．４２）で合金めっきを行い、めっ
き付着量約１４０ｇ／ｍ2 のＺｎ−Ａｌ合金めっきを行
った。めっき浴成分組成以外のめっき条件についても表
１、表２に記載する。冷却速度は少なくとも４３０〜３
５０℃間の温度範囲における冷却速度である。[Example] An actual travel example is shown below. Outer diameter 114.6 mm
(125A), a steel pipe (STK400) having a wall thickness of 4.5 mm and a length of 5.5 m was used as a base steel village, and Al and 0.1% of the component compositions shown in Table 1 and Table 2 were used in a hot dip galvanizing facility. O1
A plating bath (No. 1 to No. 40) consisting of wt% misch metal and the balance Zn and unavoidable impurities, and a plating bath in which a trace amount of Mg or Ti is further added to this plating bath (No. 41, No. 42). Alloy plating was carried out, and Zn-Al alloy plating having a coating adhesion amount of about 140 g / m 2 was carried out. The plating conditions other than the plating bath composition are also shown in Tables 1 and 2. Cooling rate is at least 430-3
It is the cooling rate in the temperature range between 50 ° C.
【００４１】得られた溶融Ｚｎ−Ａ１系合金めっき鋼材
の任意の位置から試験片を採取し、めっき層構造、めっ
き層表面のβ相の露出面積率は、試験片のめっき層表面
を６００倍に拡大し、その表面組織を顕微鏡観察し、画
像解析により測定した。A test piece was sampled from an arbitrary position of the obtained hot-dip Zn-A1 alloy-plated steel material, and the plating layer structure and the exposed area ratio of β phase on the surface of the plating layer were 600 times those on the surface of the plating layer of the test piece. The surface texture was observed under a microscope and measured by image analysis.
【００４２】めっき層構造は、めっき断面をバフ研磨し
て鏡面に仕上げた後、１％ナイタール腐食液によりエッ
チング処理を施した後β相の偏析状態を顕微鏡観察する
と共に、めっき層表層へのβ相の露出状態の顕微鏡観察
結果を考慮して、その結果に応じて下記のＡ〜Ｅにより
評価した。The plating layer structure was obtained by buffing the cross section of the plating to finish it into a mirror surface, etching it with a 1% Nital etchant, and then observing the segregation state of the β phase under a microscope and the β layer on the surface of the plating layer. Considering the result of microscopic observation of the exposed state of the phase, evaluation was made by the following A to E according to the result.
【００４３】Ａ：図１（Ａ）に見られるように、β相が
めっき層内部に認められ、表層部に偏析が認められない
もの。 Ｂ：図１（Ｂ）に見られるように、β相かめっき層の表
層部に偏析しているが、表面に露出していないもの。A: As shown in FIG. 1 (A), β phase was observed inside the plating layer, and segregation was not observed in the surface layer portion. B: As shown in FIG. 1B, the β phase is segregated in the surface layer portion of the plating layer, but is not exposed on the surface.
【００４４】Ｃ：図１（Ｃ）に見られるように、β相か
めっき層の表層部に偏析し、かつβ相が表面に露出して
いるもので、露出面積率が６０％未満のもの。 Ｄ：図１（Ｄ）に見られるように、めっき層の表層部に
おけるβ相の偏析がより明瞭であり、かつβ相が表面に
露出しているもので、露出面積率が６０％以上９５％未
満のもの。C: As shown in FIG. 1 (C), the β phase is segregated in the surface layer portion of the plating layer and the β phase is exposed on the surface, and the exposed area ratio is less than 60% . D: As seen in FIG. 1D, segregation of β phase in the surface layer portion of the plating layer is more clear, and β phase is exposed on the surface, and the exposed area ratio is 60% or more 95 Less than%.
【００４５】Ｅ：図１（Ｅ）に見られるように、めっき
層の表層部におけるβ相の偏析が顕著であり、かつめっ
き層表面のβ相の露出面積率が９５％以上のもの。 耐食性はＪＩＳ−Ｚ２３７１に規定される塩水噴霧試験
を行い、赤錆が発生するまでの時間により評価した。E: As shown in FIG. 1 (E), the segregation of the β phase in the surface layer portion of the plating layer is remarkable, and the exposed area ratio of the β phase on the plating layer surface is 95% or more. The corrosion resistance was evaluated by performing a salt spray test specified in JIS-Z2371 and by the time until red rust was generated.
【００４６】りん酸塩処理性は、試験片を日本パーカラ
イジング社製の、エナレスクリーナ−２０による脱脂、
ＰＬ−Ｚによる表面調整後、ＰＢ−１３７を用いてりん
酸塩処理を行った際のりん酸塩処理液へのＡ１溶出量に
より評価した。Phosphate treatment was performed by degreasing the test piece with ENALES CLEANER-20 manufactured by Nippon Parkerizing Co., Ltd.
After the surface was adjusted by PL-Z, the amount of A1 eluted into the phosphate treatment liquid when the phosphate treatment was performed using PB-137 was evaluated.
【００４７】耐黒変性は、５０℃、９０％ＲＨの恒温恒
湿槽内に１０日間保持後、試験前後の白色度を測定し、
その変化ΔＬを、ΔＬ＝（試験後の白色度Ｌ１）−（試
験前の白色度Ｌ２）から求めて評価した。The resistance to blackening was determined by measuring the whiteness before and after the test after holding in a constant temperature and humidity chamber at 50 ° C. and 90% RH for 10 days.
The change ΔL was calculated from ΔL = (whiteness L1 after test) − (whiteness L2 before test) and evaluated.
【００４８】加工性はＪＩＳ−ＨＯ４０１に規定される
ハンマー試験によりクラック等の発生程度を目視観察
し、クラックやめっき剥離の観察されないものを○、ク
ラックやめっき剥離の認められたものを×とした。For workability, the degree of occurrence of cracks and the like was visually observed by a hammer test specified in JIS-HO401. When no cracks or plating peeling was observed, the mark was ○, and when cracks or plating peeling was recognized, the mark was x. .
【００４９】調査結果を表３、表４に示す。また、表
３、表４の内、めっき浴温度が４６０℃、めっき浴中Ａ
ｌ濃度が４．５重量％の場合について、浸漬時間と初期
凝固層消失時間の差と冷却速度を変えた場合のめっき層
表面のβ槽の露出面積率を図３に示す。図３のハッチン
グ領域は、本発明の鋼材の製造方法における浸漬時間と
初期凝固層消失時間の差と冷却速度の適正領域を示す。The survey results are shown in Tables 3 and 4. Further, in Tables 3 and 4, the plating bath temperature is 460 ° C.
FIG. 3 shows the exposed area ratio of the β tank on the surface of the plating layer when the difference between the immersion time and the disappearance time of the initial solidified layer and the cooling rate were changed in the case where the 1 concentration was 4.5% by weight. The hatched region in FIG. 3 shows the appropriate region of the cooling rate and the difference between the immersion time and the initial solidified layer disappearance time in the method for manufacturing a steel material of the present invention.
【００５０】本発明例は、いずれもめっき層構造がＤ，
Ｅであり、β相がめっき層の表層部に偏析し、下層は連
続した共晶相であり、更に、めっき層表面のβ相の露出
面積率が６０％以上である。その結果、耐食性、りん酸
塩処理性、耐黒変性試験における白色度の変化ΔＬが−
２以上であり耐黒変性に優れている。In each of the examples of the present invention, the plating layer structure is D,
E, the β phase is segregated in the surface layer portion of the plating layer, the lower layer is a continuous eutectic phase, and the exposed area ratio of the β phase on the plating layer surface is 60% or more. As a result, the change ΔL in whiteness in the corrosion resistance, phosphate treatment and blackening resistance test was −
It is 2 or more and is excellent in blackening resistance.
【００５１】β相の露出面積率が９５％以上の場合、Δ
Ｌが−０．２以上であり、耐黒変性がより優れている。
β相の露出があるものの露出面積率が６０％未満の比較
例は、耐食性、りん酸塩処理液ヘのＡｌ溶出量が多いた
めりん酸塩処理性、また、耐黒変性試験における白色度
の変化ΔＬが−２以下であり、耐黒変性が本発明例に比
べ劣る。When the exposed area ratio of β phase is 95% or more, Δ
L is -0.2 or more, and the blackening resistance is more excellent.
In the comparative example in which the exposed area ratio is less than 60% although the β phase is exposed, the corrosion resistance, the phosphate treatment property due to the large amount of Al eluted in the phosphate treatment liquid, and the whiteness in the blackening resistance test The change ΔL is −2 or less, and the blackening resistance is inferior to the examples of the present invention.
【００５２】Ａｌ量が本発明範囲を下回る比較例Ｎｏ．
３５，Ｎｏ．３６は、めっき層内部のβ相か増加し、下
層の共晶相が不連続になったため、耐食性が劣る。Ａ１
量が本発明範囲を上回る比較例Ｎｏ．３７，Ｎｏ．３８
は、β相が形成されなかったため、りん酸塩処理液への
Ａｌ溶出量が多くりん酸塩処理性、耐黒変性が劣る。め
っき浴温度が本発明の鋼材の製造方法の範囲を外れる比
較例Ｎｏ．３９，４０は、加工性が劣る。めっき浴浸漬
時間と初期凝固層消失時間の差と冷却速度の関係が本発
明の鋼材の製造方法の範囲を外れるＮｏ．１〜３，Ｎ
ｏ．５，Ｎｏ．８，Ｎｏ．１２，Ｎｏ．１７，Ｎｏ．２
１、Ｎｏ．２３、Ｎｏ．２５、Ｎｏ．２７、Ｎｏ．２
９、Ｎｏ．３１は、めっき層の表層部におけるβ相の偏
析が不十分であったり、めっき層表面へのβ相の露出面
積率が６０％未満であったり、めっき層表面にβ相が露
出しないため、りん酸塩処理液へのＡｌ溶出量が多くり
ん酸塩処理性、耐黒変性が劣る。なお、Ｎｏ．１〜３，
５，２１，２７のめっき層構造は従采技術に認められる
めっき層組織に相当する。Comparative Example No. 3 in which the amount of Al was less than the range of the present invention.
35, No. In No. 36, the β phase inside the plating layer increased, and the eutectic phase in the lower layer became discontinuous, resulting in poor corrosion resistance. A1
Comparative Example No. whose amount exceeds the range of the present invention. 37, No. 38
Since the β phase was not formed, the amount of Al eluted into the phosphate treatment solution was large and the phosphate treatment property and blackening resistance were poor. The plating bath temperature is outside the range of the steel material manufacturing method of the present invention. 39 and 40 are inferior in workability. The difference between the immersion time of the plating bath and the disappearance time of the initial solidified layer and the cooling rate are out of the range of the steel material manufacturing method of the present invention. 1-3, N
o. 5, No. 8, No. 12, No. 17, No. Two
1, No. 23, no. 25, no. 27, no. Two
9, No. No. 31, the segregation of the β phase in the surface layer portion of the plating layer is insufficient, the exposed area ratio of the β phase on the surface of the plating layer is less than 60%, or the β phase is not exposed on the surface of the plating layer, A large amount of Al is eluted into the phosphating solution, resulting in poor phosphating property and blackening resistance. In addition, No. 1-3,
The plating layer structures 5, 21, and 27 correspond to the plating layer structure recognized in the subordinate technology.
【００５３】[0053]
【表１】 [Table 1]
【００５４】[0054]
【表２】 [Table 2]
【００５５】[0055]
【表３】 [Table 3]
【００５６】[0056]
【表４】 [Table 4]
【００５７】[0057]
【発明の効果】以上に説明したように、本発明では溶融
Ｚｎ−Ａｌ合金めっき鋼材のめっき皮膜構造を制御し
て、表層が連続したβ相、又はβ相と共晶相、下層が連
続した共晶相とすることにより、耐食性、りん酸塩処理
性および耐黒変性か改善され、建築、土木等の構造材料
や自動車、機械部品等の幅広い用途に対して更に信頼性
が高い、外観の優れた溶融Ｚｎ−Ａｌ合金めっき鋼材を
安価に供給することが可能となる。As described above, in the present invention, the plating film structure of the hot dip Zn-Al alloy plated steel material is controlled so that the surface layer has a continuous β phase, or the β phase has a eutectic phase, and the lower layer has a continuous surface. The eutectic phase improves corrosion resistance, phosphating and blackening resistance, and is more reliable for a wide range of applications such as construction materials, civil engineering structural materials, automobiles, machine parts, etc. An excellent hot-dip Zn-Al alloy plated steel material can be supplied at low cost.
【図１】めっき層の断面組織、表面組織を示す顕微鏡写
真。FIG. 1 is a micrograph showing a cross-sectional structure and a surface structure of a plating layer.
【図２】図１に示した顕微鏡写真のめっき層の組織を説
明するための模式図。FIG. 2 is a schematic diagram for explaining the structure of a plating layer in the micrograph shown in FIG.
【図３】めっき浴温度が４６０℃、めっき浴中Ａｌ濃度
が４．５重量％の場合について、浸漬時間と初期凝固層
消失時間の差，冷却速度，めっき層表面のβ槽の露出面
積率との関係を示す図。FIG. 3 shows the difference between the immersion time and the disappearance time of the initial solidified layer, the cooling rate, and the exposed area ratio of the β tank on the plating layer surface when the plating bath temperature is 460 ° C. and the Al concentration in the plating bath is 4.5% by weight. FIG.
１・・・β相 ２・・・共晶相 ３・・・鋼材 1 ... β phase 2 ... Eutectic phase 3 ... Steel
Claims (2)
以下を含む溶融Ｚｎ−Ａｌ系合金めっき皮膜を形成した
鋼材（但し、鋼板は除く）において、めっき皮膜の表層
が連続したβ相、又はβ相と共晶相、下層が共晶相から
なり、めっき層表面のβ相の露出面積率が６０％以上で
あることを特徴とする耐食性、りん酸塩処理性及び耐黒
変性に優れた溶融Ｚｎ−Ａｌ合金溶融めっき鋼材。1. Al 2% to 6% by weight on the steel surface
In a steel material (however, except for a steel sheet) on which a hot-dip Zn-Al alloy plating film including the following is formed, a surface layer of the plating film is a continuous β phase, or a β phase and a eutectic phase, and a lower layer is a eutectic phase, A hot-dip Zn-Al alloy hot-dip steel material excellent in corrosion resistance, phosphate treatment property and blackening resistance, characterized in that the exposed area ratio of β phase on the surface of the plating layer is 60% or more.
以下で、Ａｌを２重量％以上６重量％以下を含む溶融Ｚ
ｎ−Ａｌ系合金めっき浴に、鋼材を浸漬して溶融Ｚｎ−
Ａｌ系合金めっきを施した後、前記鋼材を冷却するに際
して、前記鋼材のめっき浴浸漬時間をｔａ（秒）、初期
凝固層消失時間ｔｂ（秒）、浴温度Ｔbath（℃）、浴融
点Ｔmp（℃）、侵入板温Ｔin（℃）、鋼材表面積Ｓ（ｍ
2 ）、鋼材重量Ｗ（ｋｇ）、めっき後の前記鋼材の４３
０℃からめっき層が凝固するまでの間の冷却速度Ｒ（℃
／秒）とした時下式(1) を満足する浸漬時間ｔａ、初期
凝固層消失時間ｔｂ及び冷却速度Ｒでめっきして、めっ
き皮膜の表層が連続したβ相、またはβ相と共晶相、下
層が共晶相からなり、めっき層表面のβ相の露出面積率
が６０％以上であることを特徴とする耐食性、りん酸塩
処理性及び耐黒変性に優れたＺｎ−Ａｌ系合金溶融めっ
き鋼材の製造方法。 Ｒ≧31.8-36.196 ｌｏｇ（ｔａ−ｔｂ） （０≦ｔａ−ｔｂ＜５の場合） Ｒ≧6.81×１０-0.004 (ta-tb) （ｔａ−ｔｂ≧５の場合） …(1) 但し，初期凝固層消失時間ｔｂ（秒）は，下式(2) で表
される。 tb＝1.06×｛log （Ｔbath−Ｔin）−log （Ｔbath−Ｔmp)}／ (S/W)…(2)2. The plating bath temperature is 420 ° C. or higher and 500 ° C.
Below, molten Z containing 2 wt% or more and 6 wt% or less of Al
Steel material is immersed in n-Al alloy plating bath to melt Zn-
When the steel material is cooled after being subjected to Al-based alloy plating, the steel material is immersed in the plating bath for ta (second), initial solidified layer disappearance time tb (second), bath temperature Tbath (° C.), bath melting point Tmp ( ℃), penetration plate temperature Tin (℃), steel surface area S (m
2 ), steel weight W (kg), 43 of the steel material after plating
Cooling rate R (° C from 0 ° C until the plating layer solidifies
/ Second), plating is carried out at the immersion time ta, the initial solidified layer disappearance time tb and the cooling rate R satisfying the following equation (1), and the surface layer of the plating film is continuous β phase or β phase and eutectic phase , The lower layer is composed of a eutectic phase, and the exposed area ratio of the β phase on the surface of the plating layer is 60% or more, which is excellent in corrosion resistance, phosphate treatment property and blackening resistance, Zn-Al alloy melting Manufacturing method of plated steel. R ≧ 31.8-36.196 log (ta-tb) (when 0 ≦ ta-tb <5) R ≧ 6.81 × 10 −0.004 (ta-tb) (when ta-tb ≧ 5) (1) However, initial The solidified layer disappearance time tb (second) is expressed by the following equation (2). tb = 1.06 × {log (Tbath-Tin) -log (Tbath-Tmp)} / (S / W) ... (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5933096A JPH09249956A (en) | 1996-03-15 | 1996-03-15 | Hot dip zinc-aluminum alloy plated steel excellent in corrosion resistance, phosphating property and blackening resistance and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5933096A JPH09249956A (en) | 1996-03-15 | 1996-03-15 | Hot dip zinc-aluminum alloy plated steel excellent in corrosion resistance, phosphating property and blackening resistance and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09249956A true JPH09249956A (en) | 1997-09-22 |
Family
ID=13110230
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5933096A Pending JPH09249956A (en) | 1996-03-15 | 1996-03-15 | Hot dip zinc-aluminum alloy plated steel excellent in corrosion resistance, phosphating property and blackening resistance and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09249956A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004315965A (en) * | 2003-03-28 | 2004-11-11 | Jfe Steel Kk | Hot dip galvanized steel sheet having excellent spot weldability and slidability on press working, and production method therefor |
| WO2007052683A1 (en) * | 2005-11-01 | 2007-05-10 | Sanoh Kogyo Kabushiki Kaisha | Steel pipe for automobile piping |
| JP6206995B1 (en) * | 2016-08-04 | 2017-10-04 | 中日本高速道路株式会社 | Method for forming protective film and highly corrosion-resistant steel member having protective film |
| JP2018507321A (en) * | 2014-12-24 | 2018-03-15 | ポスコＰｏｓｃｏ | Zinc alloy plated steel sheet excellent in phosphatability and spot weldability and method for producing the same |
-
1996
- 1996-03-15 JP JP5933096A patent/JPH09249956A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004315965A (en) * | 2003-03-28 | 2004-11-11 | Jfe Steel Kk | Hot dip galvanized steel sheet having excellent spot weldability and slidability on press working, and production method therefor |
| WO2007052683A1 (en) * | 2005-11-01 | 2007-05-10 | Sanoh Kogyo Kabushiki Kaisha | Steel pipe for automobile piping |
| JPWO2007052683A1 (en) * | 2005-11-01 | 2009-04-30 | 三桜工業株式会社 | Steel pipe for automobile piping |
| JP2018507321A (en) * | 2014-12-24 | 2018-03-15 | ポスコＰｏｓｃｏ | Zinc alloy plated steel sheet excellent in phosphatability and spot weldability and method for producing the same |
| US10544497B2 (en) | 2014-12-24 | 2020-01-28 | Posco | Zn alloy plated steel sheet having excellent phosphatability and spot weldability and method for manufacturing same |
| JP6206995B1 (en) * | 2016-08-04 | 2017-10-04 | 中日本高速道路株式会社 | Method for forming protective film and highly corrosion-resistant steel member having protective film |
| JP2018021234A (en) * | 2016-08-04 | 2018-02-08 | 中日本高速道路株式会社 | Formation method of protective film, and high corrosion resistance steel member having protective film |
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