JP2732398B2

JP2732398B2 - High corrosion resistant zinc-aluminum alloy plated steel wire

Info

Publication number: JP2732398B2
Application number: JP62096249A
Authority: JP
Inventors: 純一関; 寿佳高沢; 雄三松平; 重治松田; 益雄汐谷; 和久山木
Original assignee: Nippon Telegraph and Telephone Corp; Tokyo Seiko Co Ltd
Current assignee: Nippon Telegraph and Telephone Corp; Tokyo Seiko Co Ltd
Priority date: 1987-04-21
Filing date: 1987-04-21
Publication date: 1998-03-30
Anticipated expiration: 2013-03-30
Also published as: JPS63262451A

Description

【発明の詳細な説明】【産業上の利用分野】本発明は耐食性の極めて良好なZn-Al合金めっき鋼ワ
イヤに関する。【従来の技術】腐食環境、例えば、海岸地帯や海洋で使用されるワイ
ヤ製品は、高耐食性を得るためにZn、Cd、Al等の単体で
被覆されるか、あるいは、Zn-Mg系、Zn-3〜20％Al系等
の合金めっきが施されている。【発明が解決しようとする問題点】しかし、Znめっきでは耐食性の不足、Cdめっきでは毒
性、Al被覆では局部腐食の発生等の難点がある。また、
近年開発が進んでいるZn系合金による溶融めっきも耐食
性が十分とはいえず、ワイヤ製品の長寿命化の要望が強
い今日、要求を完全に満足させ得ないという問題があっ
た。本発明は前記問題を解決するためになされたものであ
り、その目的は高耐食性の鋼ワイヤを提供することにあ
る。【問題点を解決するための手段】本発明は鋼ワイヤに関する発明であって、めっき構造
が、上層がZn固溶体とAl固溶体の混合体で、下層が実質
的にFe-Zn-Al3元金属間化合物である亜鉛−アルミニウ
ム合金めっき鋼ワイヤにおいて、鋼ワイヤにめっき温度
440〜460℃、浸漬時間５〜10秒で溶融Znめっきを施し、
引続き、めっき温度420〜450℃、浸漬時間５〜30秒で溶
融Zn-Al系合金めっきを施して形成した前記下層の厚さ
が２〜10μｍであることを特徴としている。本発明者は、Zn-Al系合金めっきの高耐食性に着目
し、ワイヤ等への適用を検討してきた。この過程でZn-A
l系合金めっきを施したワイヤの塩水噴霧試験（以下SST
という）において、めっき上層に比べ、めっき下層の腐
食減量速度が小さいことを見出した。この原因を追究す
るため、めっき層の分析を進めた結果、耐食性が高いめ
っき下層部分にはFe-Zn-Alを主成分とする金属間化合物
層が形成されていることを確認した。更に、めっき下層に当たる「Fe-Zn-Alを主成分とする
金属間化合物」とめっき上層部に当る「Zn固溶体−Al固
溶体混合相合金」の腐食試験サンプルをそれぞれ製造し
SSTを行ったところ、前者の腐食減量速度が後者の1/2以
下であることが認められた。本発明は上記の発見に基づき、Fe-Zn-Alを主成分とす
る金属間化合物の高耐食性を積極的に活用して長寿命な
ワイヤ製品を得ようとするものであり、従来のZn固溶体
−Al固溶体混合相合金の耐食性を利用したZn-Al系合
金、例えば、Zn-5％Al-0.03％La-0.025％Ce合金、Zn-5
％Al-0.1％Mg合金等を１層めっきした製品と異なる。本発明において、金属間化合物層の厚さを２〜10μｍ
としたのは、２μｍ未満の場合２層めっきによる耐食性
向上効果が少なくなり、10μｍを超す金属間化合物層が
あるとワイヤの曲げ加工時にひび割れを生じやすく、か
つワイヤのねじり特性の低下が見られるためである。上述の２層構造めっきは、後記の実施例に示すよう
に、ワイヤに溶融Znめっきを施したのち、更にZn-Al系
合金溶融めっきを施せば実現することができる。なお、本発明のワイヤあるいはその撚合体の表面に３
層目として樹脂被覆やクロム酸、タンニン酸などの化学
処理、又は他金属、例えば鉛、アルミニウム等を被覆す
ることも可能で耐食性、耐疲労性を高めることができ
る。【実施例】以下、本発明を実施例により更に具体的に説明する
が、本発明はこれら実施例に限定されない。なお、各例における％は重量％を意味する。【実施例１】 2.3mm径の硬鋼線に最初、純Znめっきを施した後、更
に、その上にAl濃度が4.2％、残りがZnを主成分とするZ
n-Al系合金めっきを施した。硬鋼線材JIS G 3506 SWRH62Aを原料とする2.3mm径の
ワイヤに最初、純Znめっきを浴温440〜460℃、浸漬時間
５〜10秒で施した後、更に、その上にAl濃度が4.2％、
残りがZnを主成分とするZn-Al系合金めっきを浴温420〜
450℃、浸漬時間５〜30秒で施した。このプロセスにより、ワイヤ地金に接する部分には厚
さが６μｍのFe-Zn-Alを主成分とする金属間化合物層、
その上に厚さ37μｍのZn固溶体−Al固溶体混合層の２層
めっき構造を有するめっきワイヤを得た。第１表は、この２層めっきワイヤあるいはこれを７本
撚合させた撚線の耐食性及び機械的性質を、Zn-Al系合
金を１層めっきしたワイヤあるいはこれを７本撚合せた
撚線と比較した結果である。また、第２表は、２層めっ
き７本撚線を更に３本撚合せロープを形成し、これを海
岸道路に１年間架設して通常のZnめっきを施したロープ
と実用比較試験した結果である。これらの結果から明らかなように、本発明の２層めっ
きのワイヤあるいはこれから成る撚合体は、Zn-Al系一
層合金めっきあるいはZnめっきの製品に比較して高度な
耐食性を有し、機械的性質に関してもそん色がない。なお、Zn-5％Al-0.5％ミッシュメタル合金、Zn-5％
Al-0.5％Mg合金を用いて上記実施例と同様な比較試験を
行った結果、２層化による耐食性の改善効果が認められ
た。また、耐曲げ疲労試験を行った結果、下層厚さが９
μｍ以下では100万回の曲げに対しても素線の断線が発
生しないが、下層厚さが15μｍ以上では10万回程度の曲
げでも素線が断線するものが見られた。【発明の効果】以上説明したように、本発明による２層めっきワイヤ
あるいはこれから成る撚合体を腐食環境で使用した場
合、従来の製品に比べ長寿命が期待されるため、海洋、
海岸地帯、温泉地帯でケーブル吊線、電柱支線、架空地
線、金網、ガードロープ、じゃかご、かき養殖用ワイヤ
等に使用すれば経済化を図ることができる。とくに風圧
により繰り返し曲げ変形を受けるケーブル吊線に対して
長寿命が期待できる。また、ぶどう棚用のワイヤ等厳し
い腐食環境で使用されるワイヤ類にも極めて有効であ
る。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Zn-Al alloy plated steel wire having extremely good corrosion resistance. 2. Description of the Related Art Wire products used in corrosive environments such as coastal areas and oceans are coated with Zn, Cd, Al or the like in order to obtain high corrosion resistance, or Zn-Mg, Zn, etc. -3 to 20% Al-based alloy plating is applied. [Problems to be Solved by the Invention] However, Zn plating has disadvantages such as insufficient corrosion resistance, Cd plating has toxicity, and Al coating has local corrosion. Also,
Hot-dip coating of a Zn-based alloy, which has been developed in recent years, does not have sufficient corrosion resistance, and there is a strong demand for longer life of wire products. The present invention has been made to solve the above problem, and an object of the present invention is to provide a steel wire having high corrosion resistance. Means for Solving the Problems The present invention relates to a steel wire, wherein the plating structure is such that the upper layer is a mixture of a Zn solid solution and an Al solid solution, and the lower layer is substantially a Fe-Zn-Al ternary metal. For zinc-aluminum alloy-plated steel wire, which is a compound,
Apply hot-dip Zn plating at 440-460 ° C, immersion time 5-10 seconds,
Subsequently, the thickness of the lower layer formed by applying a molten Zn—Al-based alloy plating at a plating temperature of 420 to 450 ° C. and an immersion time of 5 to 30 seconds is 2 to 10 μm. The present inventors have paid attention to the high corrosion resistance of Zn-Al-based alloy plating, and have studied its application to wires and the like. In this process Zn-A
Salt spray test of l-based alloy plated wires (hereinafter SST
), It was found that the rate of corrosion loss of the lower plating layer was lower than that of the upper plating layer. In order to investigate the cause, the analysis of the plating layer was advanced, and it was confirmed that an intermetallic compound layer containing Fe-Zn-Al as a main component was formed in the lower layer portion of the plating having high corrosion resistance. In addition, corrosion test samples of “intermetallic compound containing Fe-Zn-Al as the main component” as the lower layer of the plating and “Zn solid solution-Al solid solution mixed phase alloy” as the upper layer of the plating were manufactured.
When SST was performed, it was recognized that the former corrosion weight loss rate was less than 1/2 of the latter. The present invention is based on the above findings, and aims to obtain a long-life wire product by positively utilizing the high corrosion resistance of an intermetallic compound containing Fe-Zn-Al as a main component. -Zn-Al alloys utilizing the corrosion resistance of Al solid solution mixed phase alloys, for example, Zn-5% Al-0.03% La-0.025% Ce alloy, Zn-5
% Al-0.1% Mg alloy is different from one-layer plated product. In the present invention, the thickness of the intermetallic compound layer is 2 to 10 μm
The reason for this is that if the thickness is less than 2 μm, the effect of improving corrosion resistance by the two-layer plating is reduced, and if there is an intermetallic compound layer exceeding 10 μm, cracks are likely to occur during bending of the wire, and the torsion characteristics of the wire are reduced. That's why. The above-described two-layer structure plating can be realized by performing hot-dip Zn plating on a wire and then hot-dip a Zn-Al-based alloy, as shown in Examples described later. In addition, the surface of the wire of the present invention or its twisted body is 3
As a layer, resin coating, chemical treatment of chromic acid, tannic acid, or the like, or other metal, for example, lead, aluminum, or the like can be applied, so that corrosion resistance and fatigue resistance can be enhanced. EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples. In addition,% in each example means weight%. Example 1 A hard steel wire having a diameter of 2.3 mm was first subjected to pure Zn plating, and then an Al concentration of 4.2% was formed thereon, and the remaining Z was composed mainly of Zn.
n-Al alloy plating was applied. First, pure Zn plating is applied to a 2.3 mm diameter wire made of hard steel wire JIS G 3506 SWRH62A as a raw material at a bath temperature of 440 to 460 ° C. and an immersion time of 5 to 10 seconds. %,
The remainder is a Zn-Al based alloy plating whose main component is Zn.
The application was performed at 450 ° C. for a dipping time of 5 to 30 seconds. By this process, a 6 μm thick intermetallic compound layer mainly composed of Fe-Zn-Al
A plated wire having a two-layer plating structure of a Zn solid solution-Al solid solution mixed layer having a thickness of 37 μm was obtained thereon. Table 1 shows the corrosion resistance and mechanical properties of the two-layer plated wire or the stranded wire obtained by twisting seven wires, and the Zn-Al-based alloy one-layer plated wire or seven twisted wires. This is the result of comparison with. Table 2 shows the results of a practical comparison test with a rope that was formed by laying three more twisted ropes of seven layers of two-layer plating and laying them on a coastal road for one year and applying normal Zn plating. is there. As is evident from these results, the wire of the present invention or the stranded body composed of the same has higher corrosion resistance and mechanical properties than Zn-Al single-layer alloy-plated or Zn-plated products. There is no color. In addition, Zn-5% Al-0.5% misch metal alloy, Zn-5%
As a result of performing a comparative test similar to the above example using an Al-0.5% Mg alloy, the effect of improving corrosion resistance by the two-layer structure was recognized. Further, as a result of the bending fatigue resistance test, the lower layer thickness was 9
When the thickness is less than 1 μm, the wire does not break even after 1 million bendings, but when the underlayer thickness is more than 15 μm, the wire breaks even after bending about 100,000 times. As described above, when the two-layer plated wire according to the present invention or the stranded body composed of the same is used in a corrosive environment, a longer life is expected as compared with conventional products.
In coastal areas and hot spring areas, if used for cable suspension lines, power pole branch lines, overhead ground lines, wire mesh, guard ropes, baskets, oyster cultivation wires, etc., economy can be achieved. Long life can be expected especially for cable suspension lines that are repeatedly bent and deformed by wind pressure. It is also very effective for wires used in severe corrosive environments such as grape shelf wires.

───────────────────────────────────────────────────── フロントページの続き (72)発明者高沢寿佳武蔵野市緑町３丁目９番11号日本電信電話株式会社電子機構技術研究所内 (72)発明者松平雄三武蔵野市緑町３丁目９番11号日本電信電話株式会社電子機構技術研究所内 (72)発明者松田重治茨城県新治郡出島村大字宍倉5707番地東京製綱株式会社研究所内 (72)発明者汐谷益雄茨城県新治郡出島村大字宍倉5707番地東京製綱株式会社研究所内 (72)発明者山木和久茨城県新治郡出島村大字宍倉5707番地東京製綱株式会社研究所内 (56)参考文献特開昭56−112452（ＪＰ，Ａ) 特表昭57−500475（ＪＰ，Ａ) 特公昭54−33223（ＪＰ，Ｂ２) 「鉛と亜鉛」第120号ｐ21−38（昭59 −７−15) ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hisaka Takazawa 3-9-11 Midoricho, Musashino City Nippon Telegraph and Telephone Telephone Co., Ltd. (72) Inventor Yuzo Matsudaira 3-9-11 Midoricho, Musashino City Nippon Telegraph and Telephone Telephone Co., Ltd. (72) Inventor Shigeharu Matsuda 5707 Shishikura, Dejima Village, Niigata-gun, Ibaraki Prefecture In Tokyo Research Laboratory (72) Inventor Masuo Shiotani 5707 Shishikura, Dejima Village, Niigata-gun, Ibaraki Prefecture In Tokyo Research Laboratory (72) Inventor Kazuhisa Yamaki 5707 Shishikura, Dejima Village, Niigata-gun, Ibaraki Prefecture In Tokyo Research Laboratory (56) References JP-A-56-112452 (JP, A) Special table 1979-500475 (JP, A) Japanese Patent Publication No. 54-33223 (JP, B2) "Lead and zinc" No. 120, p21-38 (Showa 59 -7-15)

Claims

(57) [Claims] The plating structure is such that the upper layer is a mixture of Zn solid solution and Al solid solution, and the lower layer is a zinc-aluminum alloy-plated steel wire in which the lower layer is substantially Fe-Zn-Al ternary intermetallic compound. Melted Zn with immersion time 5-10 seconds
High corrosion resistance characterized in that the thickness of the lower layer formed by applying a molten Zn-Al-based alloy plating at a plating temperature of 420 to 450 ° C. and an immersion time of 5 to 30 seconds is 2 to 10 μm. Zinc-aluminum alloy plated steel wire.