JP2002356760A - Material for civil-engineering and member for civil- engineering having excellent corrosion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material for civil-engineering and a member for civil- engineering which have excellent corrosion resistance. SOLUTION: To the material for civil-engineering and the member for civil- engineering, hot dip Zn-Al-Mg based alloy plating having a composition containing, by weight, 1 to 4% Mg and 4 to 22% Al, and the balance Zn with inevitable impurities is applied. The hot dip Zn-Al-Mg based alloy plating contains 0.001 to 0.1% Ti and 0.0005 to 0.045% B, and, if required, at least one kind of easily oxidizable element selected from rare earth elements, Y, Zr and Si can be incorporated therein in 0.005 to 2.0%. The material and member are suitably used for a member for piping, a member for fences (floor boards), a member for reinforcing, a member for bridges.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a civil engineering material and a civil engineering member plated with a molten Zn--Al--Mg alloy excellent in corrosion resistance.
The present invention relates to a member for a fence (floor panel), a member for reinforcement, a member for a bridge, and the like.

[0002]

2. Description of the Related Art Conventionally, civil engineering materials and civil engineering members used for piping, fences (floor boards), reinforcements, bridges, etc. are made of ordinary steel and high-strength steel by continuous hot-dip galvanizing equipment. Hot-dip galvanized steel sheets, coated hot-dip galvanized steel sheets coated on steel sheets, coated steel sheets directly coated on various steel sheets, and the like are used and formed into various members. Electrogalvanized steel materials are also used in which various steel sheets are processed into use forms, electrogalvanized, and further subjected to a chemical conversion treatment.

[0003] In recent years, in addition to steel members, various members using stainless steel or aluminum alloy have been developed for the purpose of weight reduction and long life. However, these members are used from the viewpoint of cost, press formability and weldability. The sites to be performed are restricted.

[0004] On the other hand, many civil engineering members are manufactured by forming a normal steel plate, a high-strength steel plate, a stainless steel plate or the like into a predetermined shape and then immersing it in a hot-dip plating bath (hereinafter referred to as "post-plating method"). . The post-plating method is excellent in terms of corrosion resistance because the amount of plating can be increased, but
It is immersed in a high-heat plating bath after the forming process, so that it is easily affected by thermal distortion, and the surface of the plated surface is not uniform. Further, since the plating process is performed after the forming process, productivity is inferior to forming a plated steel sheet manufactured by a continuous plating process with high productivity into a civil engineering member.

[0005]

The materials for civil engineering and civil engineering are more durable against deterioration of the material due to wind and rain, deterioration of corrosion resistance due to contact with soil or dissimilar materials, deterioration of scratch resistance, and the like. There is a need for components. The present invention has excellent corrosion resistance compared to conventional hot-dip coated steel sheets and painted steel sheets, has corrosion resistance equal to or higher than that of galvanized steel materials manufactured by a post-plating method, and can be manufactured at lower cost than stainless steel and aluminum alloys. It is intended to provide materials and civil engineering members.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide:
4 wt%, Al: 4 to 22 wt%, can be achieved by a civil engineering material and a civil engineering member plated with a molten Zn—Al—Mg-based alloy, the balance being Zn and unavoidable impurities. Hot-dip Zn-Al-Mg based alloy plating is
i: 0.001 to 0.1% by weight, B: 0.0005 to
0.045% by weight, and if necessary, 0.005 to 2.0% by weight of at least one oxidizable element selected from rare earth elements, Y, Zr or Si. Can be.

The civil engineering members of the present invention include piping members such as corrugated pipes, flumes, gratings, rain shooters (waterways), and flexible pipes, and pipe fixing members such as joints, hanging tools, metal fittings, and nets for rock fall protection. And fences, reinforcing boards, scaffolding boards, temporary enclosure fences, expanded metal, punching metal, striped steel sheets, embossed steel sheets,
Fence (floor panel) members and fixing hardware such as checker plates, anchors, steel pipe inflatable lock bolts, concrete panel core material (lath material), concrete formwork, concrete formwork holding metal fittings, panel frame materials, steel pipe bundle members , Reinforcement members such as formwork made of basic steel for construction (comprising panels, spacers, holders, supports, separators, and fittings), fixtures for lifelines and drainage pipes, steel wires (cables), structural members, etc. Bridge members, washers, lightweight channel steel, H-section steel, C-section steel, round steel pipe, square steel pipe, deformed pipe, lighting poles, signage members, cargo handling and transportation members (casters, carrier boards)
Etc.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below. The material (member) for civil engineering of the present invention is preferably manufactured by a continuous hot-dip plating process from the viewpoint of productivity, but can also be manufactured by a conventional post-plating method or the like.

The civil engineering materials and civil engineering materials of the present invention contain Mg: 1 to 4% by weight, Al: 4 to 22% by weight, molten Zn-Al-M comprising the balance of Zn and unavoidable impurities.
g-based plating is applied.

Mg content in the plating layer: 1 to 4% by weight Mg contained in the plating layer causes a Zn-based corrosion product containing Mg to be formed on the outermost layer of the plating layer, and together with Al in the plating layer, the general atmosphere. This has the effect of reducing the corrosion rate of the plating layer under the environment. This effect is due to the fact that Zn-based corrosion products containing Mg are stably present on the plating layer for a long period of time, and the formation of zinc oxide that deteriorates corrosion resistance is suppressed. This effect is exerted even when dissimilar metal corrosion occurs, and the plating layer is corroded in the initial stage of dissimilar metal corrosion, but when a Zn-based corrosion product containing Mg is formed, the plating layer interface with the dissimilar metal is covered. Thus, the progress of corrosion is suppressed.

Furthermore, a part of the Zn-based corrosion products containing Mg flows into the cut end face generated by cutting or the like and the non-plated portion generated by welding, and has a remarkable effect of suppressing corrosion of iron on the end face. . Further, the addition of Mg makes the plating layer hard, so that it is difficult to damage and the occurrence of scratches that can be a starting point of rust is suppressed. This is because the intermetallic compound Zn ₂ Mg is uniformly and finely dispersed in the plating layer, and this Zn ₂ Mg is a component of the ternary eutectic solidification structure of Zn / Al / Zn ₂ Mg.

Al content in the plating layer: 4 to 22% by weight Zn and Mg in the plating layer form Zn-based corrosion products containing Mg, whereas Al in the plating layer has extremely strong adhesion. It forms Zn-Al based corrosion products and contributes to improvement of corrosion resistance. Further, when Al is contained in the plating layer, Zn / Al / Zn ₂ Mg ternary eutectic appears in the solidification structure of the plating layer. Since the ternary eutectic structure is finer than the Zn / Zn ₂ Mg binary eutectic structure, the ternary eutectic structure is more preferable from the viewpoint of corrosion resistance and plating layer hardness. However, even if Al is added in excess of 22% by weight, the above effect is saturated, and the melting point of the plating metal increases with an increase in the Al content, so that it is necessary to maintain the plating bath at a high temperature. become worse.

[0013] Suppose Zn- containing no Al in the plating layer.
In the case of the Mg-based alloy, when the Mg-containing Zn-based corrosion product flows out, the corrosion of the plating layer rapidly progresses because there is no Zn-Al-based corrosion product having strong adhesion to the base.

[0014] The hot-dip Zn-Al-Mg based alloy plating of the present invention may further contain at least one of Ti and B or an easily oxidizable element selected from rare earth elements, Y, Zr and Si, if necessary. Can be.

[0015] Ti content in the plating layer: 0.001 to
0.1 wt%, B content in the plating layer: 0.0005 to 0.045 wt% Z which impairs the surface appearance by adding Ti and B in combination.
Z that suppresses generation of n ₁₁ Mg ₂ phase and crystallizes in the plating layer
The n-Mg based intermetallic compound can be substantially only Zn ₂ Mg.

Specifically, when the content of Ti is 0.001% by weight or more, the formation of Zn ₁₁ Mg ₂ phase can be effectively suppressed. A Ti—Al-based precipitate grows on the surface of the plating layer, and irregularities are formed on the plating layer, thereby impairing the appearance. Also,
When B is contained in an amount of 0.0005% by weight or more, Zn
The formation of ₁₁ Mg ₂ phase can be suppressed,
If it exceeds 045% by weight, Ti-B-based, Al
-B-based precipitates grow, and irregularities (thumps) are formed on the plating layer, thereby impairing the appearance.

The oxidizable element (rare earth element,
Y, Zr, Si): at least one of 0.005 to 2.
0% by weight Al and Mg content of the molten Zn-A of the present invention is relatively high
The 1-Mg-based plated steel sheet (member) has an effect of suppressing the phenomenon of “deterioration of the surface gloss of the plating layer” which is unique to the present steel sheet. "Degradation of surface gloss of plating layer" is a phenomenon in which a plated surface having a beautiful metallic luster changes to a gray color as time passes immediately after production, and is not preferable in terms of surface appearance. Such a discoloration phenomenon is caused by adding at least one of rare earth elements, Y, Zr, and Si to 0.005.
It can be suppressed by adding more than weight%. However, the effect is saturated even if it is added in excess of 2.0% by weight, so it is preferable to add 0.005 to 2.0% by weight.

Further, the higher the Al content of the plating layer, the more locally the Fe-Al intermetallic compound is formed at the interface between the plating layer and the steel substrate. Although there is a concern that the layer may be peeled off, this problem can be avoided by including a small amount of Si in the plating layer.

The plated steel sheet (member) may be subjected to a chromate or non-chromium chemical conversion treatment to improve corrosion resistance and coating adhesion. Several μm
If a certain amount of organic resin coating is applied after the chemical conversion treatment, the corrosion resistance and the scratch resistance are further improved, and when a lubricating component is contained in the resin, molding into various members becomes easy. In addition, by coating the coated steel sheet (member) depending on the usage environment,
Corrosion resistance can be enhanced and a beautiful appearance can be obtained.

The hot-dip galvanized steel sheet (member) having the plating composition of the present invention has a feature that the plating layer is harder than a conventional hot-dip galvanized steel sheet. This is because the intermetallic compound Zn ₂ Mg is dispersed in the plating layer,
Since the plated layer is hard, it has the feature that it is hard to be damaged by flying or contacted objects during processing of plated steel sheet into various civil engineering members of the present invention, or during transportation, construction, so the starting point of rust Can be suppressed.

Depending on the use of the civil engineering member, it may be necessary to consider the antiglare property. In this case, the roughness of the plated steel sheet and the chemical conversion treatment conditions must be adjusted during the manufacturing process of the plated steel sheet (member). It is also possible to reduce the reflectance and gloss by making appropriate adjustments.

[0022]

As described above, civil engineering materials and civil engineering members having the plating composition of the present invention have better corrosion resistance than conventional hot-dip coated steel sheets (members), and thus reduce the amount of plating adhesion. It is also possible to omit the coating process on the coated steel sheet. Since the plating layer is hard and hard to be damaged, the progress of corrosion due to the generation of scratches and the progress of corrosion due to contact with dissimilar metals can be suppressed. Further, since it becomes possible to substitute civil engineering materials and civil engineering members manufactured by the conventional post-plating method and electrogalvanizing method, productivity can be improved and manufacturing costs can be reduced.

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Claims (7)

[Claims] (1) Mg: 1 to 4% by weight, Al: 4 to 22% by weight, molten Zn- containing the balance of Zn and unavoidable impurities.
A material for civil engineering with excellent corrosion resistance coated with an Al-Mg alloy. 2. The hot-dip Zn—Al—Mg alloy plating further comprises 0.001 to 0.1% by weight of Ti, and 0.000% of B.
The civil engineering material according to claim 1, which contains 5 to 0.045% by weight. 3. The hot-dip Zn—Al—Mg alloy plating further comprises 0.005 to 2.0% by weight of at least one oxidizable element selected from rare earth elements, Y, Zr or Si.
The civil engineering material having excellent corrosion resistance according to claim 1 or 2. 4. A molten Zn—containing Mg: 1 to 4% by weight, Al: 4 to 22% by weight, the balance being Zn and unavoidable impurities.
A civil engineering member with excellent corrosion resistance that has been plated with an Al-Mg alloy. 5. The hot-dip Zn—Al—Mg alloy plating further comprises 0.001 to 0.1% by weight of Ti and 0.000% of B.
The civil engineering member excellent in corrosion resistance according to claim 4, which contains 5 to 0.045% by weight. 6. The hot-dip Zn—Al—Mg alloy plating further comprises 0.005 to 2.0% by weight of at least one oxidizable element selected from rare earth elements, Y, Zr or Si.
The civil engineering member having excellent corrosion resistance according to claim 4. 7. The member for civil engineering is a member for piping, a member for fence (floor panel), a member for reinforcement, and a member for bridge.
6. The member for civil engineering having excellent corrosion resistance according to 6.