JP2986354B2 - Annealed cast iron pipe with corrosion resistance - Google Patents
Annealed cast iron pipe with corrosion resistanceInfo
- Publication number
- JP2986354B2 JP2986354B2 JP6307926A JP30792694A JP2986354B2 JP 2986354 B2 JP2986354 B2 JP 2986354B2 JP 6307926 A JP6307926 A JP 6307926A JP 30792694 A JP30792694 A JP 30792694A JP 2986354 B2 JP2986354 B2 JP 2986354B2
- Authority
- JP
- Japan
- Prior art keywords
- cast iron
- pipe
- iron pipe
- layer
- corrosion resistance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Coating By Spraying Or Casting (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、耐食性を備えた焼鈍鋳
鉄管に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annealing casting having corrosion resistance.
Regarding iron pipe .
【０００２】[0002]
【従来の技術】鋳造された直後の鋳放し鋳鉄管は、通
常、均一組織の確保や、セメンタイトを分解して延性の
大きいフェライト組織を得るため、鋳造後に横転炉に装
入して９００〜１０００℃程度の高温で焼鈍される。こ
の焼鈍時に、鋳鉄管の表面に酸化鉄の被膜が形成され
る。この酸化鉄被膜は、耐食性が比較的良好であるた
め、除去されることなく、そのまま管の表面に残置され
ていたが、ポーラスであり、鋳鉄母材との密着性に劣
る。このため、特開平６−１０１０１３号公報に開示さ
れているように、焼鈍に先立ち、鋳放し鋳鉄管の外周面
にアルミニウム溶射層を形成し、これを焼鈍することに
より、耐食性Ｆｅ−Ａｌ合金層が被覆されるようになっ
た。2. Description of the Related Art An as-cast cast iron pipe immediately after being cast is usually charged into a roll-over furnace after casting in order to secure a uniform structure and to obtain a ferritic structure having high ductility by decomposing cementite. Annealed at a high temperature of about ° C. During this annealing, a coating of iron oxide is formed on the surface of the cast iron tube. This iron oxide coating was left on the surface of the pipe without being removed because it has relatively good corrosion resistance, but it is porous and has poor adhesion to the cast iron base material. Therefore, as disclosed in Japanese Patent Application Laid-Open No. Hei 6-101013, prior to annealing, an aluminum sprayed layer is formed on the outer peripheral surface of an as-cast cast iron pipe, and this is annealed to form a corrosion-resistant Fe-Al alloy layer. Became coated.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、アルミ
ニウム溶射層には気孔が残留し易く、該気孔を通して焼
鈍中に溶射層内に酸素が侵入し、溶射層内に酸化物が生
成する傾向がある。このため、焼鈍後のＦｅ−Ａｌ合金
層中に酸化スケールが残存する場合があり、材質的にあ
るいは層厚の均一な耐食性Ｆｅ−Ａｌ合金層が得にく
く、品質にバラツキが生じ易い傾向があり、そのため、
耐食性において問題があった。 本発明は係る問題に鑑み
てなされたもので、鋳鉄管表面に均一な高品質のＦｅ −
Ａｌ合金層を密着被覆すると共に、更に前記Ｆｅ−Ａｌ
合金層の表面を酸化Ｍｇ層で密着状に被覆させることに
より、耐食性を備えた焼鈍鋳鉄管を提供することを目的
とする。 However, pores are apt to remain in the aluminum sprayed layer, and oxygen tends to enter the sprayed layer during annealing through the pores to form oxides in the sprayed layer. For this reason, an oxide scale may remain in the Fe-Al alloy layer after annealing, and it is difficult to obtain a corrosion-resistant Fe-Al alloy layer having a uniform material or thickness, and the quality tends to vary. Therefore,
There was a problem in corrosion resistance. The present invention has been made in view of such a problem.
It was made Te, uniform high quality cast iron pipe surface Fe -
An Al alloy layer is adhered and coated, and the Fe-Al
Coating the surface of the alloy layer with an Mg oxide layer in close contact
The purpose is to provide an annealed cast iron tube with more corrosion resistance
And
【０００４】[0004]
【課題を解決するための手段】本発明の耐食性を備えた
焼鈍鋳鉄管は、母管である鋳鉄管表面にＦｅ−Ａｌ合金
層が密着被覆されており、更に前記Ｆｅ−Ａｌ合金層の
表面に酸化Ｍｇ層が密着被覆形成させたものである。係
る本発明の焼鈍鋳鉄管は、下記の方法により製造され
る。 即ち、鋳放し鋳鉄管の要部表面に耐食性金属の溶射
層を形成した後、該鋳鉄管を焼鈍する焼鈍鋳鉄管の耐食
合金被覆方法において、前記耐食性金属として、Ａｌを
主成分とし、Ｍｇを０．１wt％以上、好ましくは１．０
〜１５wt％含有するＡｌＭｇ合金を用いる。According to the present invention, an annealed cast iron pipe having corrosion resistance is provided on a surface of a cast iron pipe as a base pipe by using an Fe-Al alloy.
Layer is tightly coated and further comprises a Fe-Al alloy layer.
An Mg oxide layer is formed on the surface in close contact coating . Person in charge
The annealed cast iron pipe of the present invention is manufactured by the following method.
You. That is , in a method for coating a corrosion-resistant alloy on an annealed cast iron pipe in which a sprayed layer of a corrosion-resistant metal is formed on a surface of a main part of an as-cast cast iron pipe and then annealed, the cast iron pipe includes Al as a main component as the corrosion-resistant metal, and Mg as an alloy. 0.1 wt% or more, preferably 1.0 wt%
An AlMg alloy containing １５15 wt% is used.
【０００５】このようにして溶射層を形成する耐食性金
属としてＡｌＭｇ合金を使用すると、融点が純Ａｌより
も低くなるため、溶射層の母材側、即ち、鋳鉄管表面の
粒子間結合力すなわち密着性が向上すると共に緻密な溶
射層が形成され、焼鈍中に溶射層の内部が酸化しにく
い。また、ＭｇはＡｌに比して酸化され易いため、Ａｌ
が酸化され難くなり、前記内部酸化の防止と相まって均
一なＦｅ−Ａｌ合金層が生成される。この際、Ｍｇの酸
化により酸化マグネシウムが生成するが、これはＦｅ−
Ａｌ合金層の上に層状に密着形成され、耐食性の向上に
寄与する。この際、Ｍｇ含有量が０．１wt％未満では前
記作用が不足し、所期の効果が得難くなる。このため、
０．１wt％以上、好ましくは１wt％以上の含有がよい。
一方、Ｍｇ含有量の上限については、５０wt％程度まで
は所期の耐食性Ｆｅ−Ａｌ合金層が形成されるが、好ま
しくは１５wt％以下に止めるのがよい。１５wt％を越え
るとＭｇの固溶限を越え、金属間化合物が生成するよう
になり、均一性が損なわれる傾向が生じるからである。[0005] Using the AlMg alloy as corrosion-resistant metal forming the sprayed layer in this manner result, the melting point is lower than that of pure Al, the base material side of the sprayed layer, i.e., the interparticle binding force or adhesion of cast iron pipe surface As a result, a dense sprayed layer is formed, and the inside of the sprayed layer is hardly oxidized during annealing. Further, Mg is more easily oxidized than Al,
Is hardly oxidized, and a uniform Fe—Al alloy layer is generated in combination with the prevention of the internal oxidation. At this time , magnesium oxide is generated by oxidation of Mg, which is caused by Fe-
It is formed in a layered manner on the Al alloy layer and contributes to the improvement of corrosion resistance. At this time, if the Mg content is less than 0.1% by weight, the above effect is insufficient, and the desired effect is hardly obtained. For this reason,
0.1 wt% or more, preferably 1 wt% or more is good.
On the other hand, as for the upper limit of the Mg content, a desired corrosion-resistant Fe—Al alloy layer is formed up to about 50 wt%, but it is better to keep it to 15 wt% or less. If it exceeds 15 wt%, the solid solubility limit of Mg will be exceeded, and an intermetallic compound will be formed, which tends to impair the uniformity.
【０００６】次に本発明の実施態様を更に詳説する。ま
ず、焼鈍前の鋳放し鋳鉄管１の外周全面あるいは直管端
部等の要部表面に所定Ｍｇ含有量のＡｌＭｇ合金の溶射
層を形成する。前記ＡｌＭｇ合金溶射層の厚さは３０〜
２００μm 程度でよい。かかるＡｌＭｇ合金溶射層が積
層形成された鋳鉄管を横転炉で、９００〜１０００℃程
度で数十分間〜数時間保持するフェライト化焼鈍を行う
と、図１に示すように、鋳鉄管１の外表面にＦｅ−Ａｌ
合金層２が形成され、さらにその上に酸化マグネシウム
層３が密着形成された本発明の耐食性を備えた焼鈍鋳鉄
管が得られる。 Next, embodiments of the present invention will be described in more detail. First, a sprayed layer of an AlMg alloy having a predetermined Mg content is formed on the entire outer peripheral surface of the as-cast cast iron pipe 1 before annealing or on a surface of a main part such as an end of a straight pipe. The thickness of the AlMg alloy sprayed layer is 30 to
It may be about 200 μm. When the cast iron tube on which the AlMg alloy sprayed layer is formed is subjected to ferrite annealing in a roll-over furnace at about 900 to 1000 ° C. for several tens of minutes to several hours, as shown in FIG. Fe-Al on outer surface
An annealed cast iron with corrosion resistance according to the present invention in which an alloy layer 2 is formed and a magnesium oxide layer 3 is further formed thereon.
A tube is obtained.
【０００７】本発明の適用対象となる母管鋳鉄管は、受
口部を有する直管や、異形管のいずれでもよい。また、
ＡｌＭｇ溶射層は、直管や異形管における、例えば配管
接合部である直管端部に形成されるが、管外周面の全面
に形成してもよいことは勿論である。配管時、管は必要
な長さに切断して使用されることがあるが、直管部の全
面に被覆被膜が形成されておれば、いずれの位置で管を
切断しても、接合部での酸化被膜の剥離を防止すること
ができ、また管外周面全体の耐食性を向上させることが
でき好適である。また、溶射が可能な限り、管の内面に
も本発明を適用することができる。The mother pipe cast iron pipe to which the present invention is applied may be either a straight pipe having a socket or a deformed pipe. Also,
The AlMg sprayed layer is formed, for example, at the end of a straight pipe or a deformed pipe, for example, at the end of a straight pipe which is a pipe joint, but may be formed on the entire outer peripheral surface of the pipe. At the time of piping, the pipe may be cut to the required length and used.However, if a coating film is formed on the entire surface of the straight pipe, even if the pipe is cut at any position, This is preferable because the oxide film can be prevented from peeling off, and the corrosion resistance of the entire outer peripheral surface of the tube can be improved. In addition, the present invention can be applied to the inner surface of a tube as long as thermal spraying is possible.
【０００８】[0008]
【実施例】 次に、具体的な実施例を掲げる。呼び径φ７
５×４ｍ、Ａ型の鋳放し鋳鉄管の外周全面にＡｌ−５wt
％Ｍｇ合金を約１２０μm の厚さで溶射した。この鋳鉄
管を横転炉で９８０℃、１．５ｈｒの条件で焼鈍した。
焼鈍後、鋳鉄管の横断面を顕微鏡観察したところ、母管
外周面に約１３０μmの厚さのＦｅ−Ａｌ合金層を介し
て約１５μm の酸化マグネシウム層が形成されていた。 [Example] Next, set forth the specific examples. Nominal diameter φ7
5x4m, A-5wt A-type as-cast iron pipe
% Mg alloy was sprayed at a thickness of about 120 μm. The cast iron tube was annealed in a roll-over furnace at 980 ° C. for 1.5 hours.
After annealing, the cross section of the cast iron tube was observed with a microscope. As a result, a magnesium oxide layer having a thickness of about 15 μm was formed on the outer peripheral surface of the mother pipe via a Fe—Al alloy layer having a thickness of about 130 μm.
【０００９】また、以上のようにして製造された耐食合
金被覆鋳鉄管を用いて、耐食性試験を行った。比較のた
め、Ａｌ溶射層を形成する他、同条件で製造した耐食合
金被覆鋳鉄管（従来例）についても同試験を実施した。
試験要領は、耐食合金被覆層の外表面に塩水（濃度３．
０％）を噴霧し、目視により管表面を観察し、赤錆が認
められるまでの日数を求めた。その結果、実施例では１
００日経過しても赤錆の発生は皆無であったが、従来例
では１５日目頃から錆が認められるようになった。Further, a corrosion resistance test was performed using the corrosion-resistant alloy-coated cast iron pipe manufactured as described above. For comparison, the same test was performed on a corrosion-resistant alloy-coated cast iron pipe (conventional example) manufactured under the same conditions, in addition to forming an Al sprayed layer.
The test procedure was such that salt water (concentration of 3.
(0%), and the tube surface was visually observed to determine the number of days until red rust was observed. As a result, in the embodiment, 1
Although no red rust was generated even after the lapse of 00 days, rust began to be observed from about the 15th day in the conventional example.
【００１０】[0010]
【発明の効果】以上説明した通り、本発明の耐食性を備
えた焼鈍鋳鉄管は、母管である鋳鉄管表面にＦｅ−Ａｌ
合金層が密着被覆されており、更に前記Ｆｅ−Ａｌ合金
層の表面に酸化Ｍｇ層が密着被覆形成されてなるので、
鋳鉄管、Ｆｅ−Ａｌ合金層及び酸化Ｍｇ層の三者が密着
形成され、この際、表面層のＭｇがＡｌに比べ酸化され
易いため、中間層のＦｅ−Ａｌ合金層の密着性が向上し
全体として耐食性に優れた焼鈍鋳鉄管が得られる。 As described above, the corrosion resistance of the present invention is provided.
The obtained annealed cast iron pipe is made of Fe-Al on the surface of the base cast iron pipe.
The alloy layer is tightly coated, and the Fe-Al alloy
Since the Mg oxide layer is formed in close contact with the surface of the layer,
Adhesion of cast iron tube, Fe-Al alloy layer and Mg oxide layer
At this time, Mg in the surface layer is oxidized compared to Al
Easy to improve the adhesion of the intermediate Fe-Al alloy layer
As a whole, an annealed cast iron pipe having excellent corrosion resistance can be obtained.
【図１】本発明に係る耐食性を備えた焼鈍鋳鉄管の要部
縦断面図である。FIG. 1 is a longitudinal sectional view of a main part of an annealed cast iron pipe having corrosion resistance according to the present invention.
１ 鋳鉄管（母管） ２ Ｆｅ−Ａｌ合金層 ３ 酸化マグネシウム層 Reference Signs List 1 cast iron pipe (base pipe) 2 Fe-Al alloy layer 3 magnesium oxide layer
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭60−9867（ＪＰ，Ａ) 特開 平５−84591（ＪＰ，Ａ) 特開 平６−219855（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) C23C 4/08 C23C 4/18 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-9867 (JP, A) JP-A-5-84591 (JP, A) JP-A-6-219855 (JP, A) (58) Investigation Field (Int.Cl. 6 , DB name) C23C 4/08 C23C 4/18
Claims (1)
層が密着被覆されており、更に前記Ｆｅ−Ａｌ合金層の
表面に酸化Ｍｇ層が密着被覆形成されてなることを特徴
とする耐食性を備えた焼鈍鋳鉄管。 An Fe-Al alloy is provided on a surface of a cast iron pipe as a mother pipe.
Layer is tightly coated and further comprises a Fe-Al alloy layer.
The feature is that the surface is coated with Mg oxide layer
Annealed cast iron pipe with corrosion resistance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6307926A JP2986354B2 (en) | 1994-12-12 | 1994-12-12 | Annealed cast iron pipe with corrosion resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6307926A JP2986354B2 (en) | 1994-12-12 | 1994-12-12 | Annealed cast iron pipe with corrosion resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08165552A JPH08165552A (en) | 1996-06-25 |
| JP2986354B2 true JP2986354B2 (en) | 1999-12-06 |
Family
ID=17974838
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6307926A Expired - Fee Related JP2986354B2 (en) | 1994-12-12 | 1994-12-12 | Annealed cast iron pipe with corrosion resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2986354B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6500136B2 (en) * | 2018-02-09 | 2019-04-10 | 吉川工業株式会社 | Corrosion-resistant thermal spray coating, method for forming the same, and thermal spraying apparatus for forming the same |
-
1994
- 1994-12-12 JP JP6307926A patent/JP2986354B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08165552A (en) | 1996-06-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |