JP2002180286A - Stainless steel sheet for roof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheet material for roof having designing properties which has excellent durability, and naturally has a brick-like color tone with time after construction. SOLUTION: The stainless steel sheet for roof consists of a base steel sheet made of stainless steel and a Zn-Fe alloy layer formed on at least one side of the base steel sheet. The Zn-Fe alloy layer compositionally contains Fe of 0.5 to 10 g/m2, and is structurally consisting of one or more selected from a ζphase, a η phase, a δ1 phase and a Γ1 phase. After being constructed as a roof, Fe in the Ze-Fe alloy phase is slowly oxidized, and the color of iron oxides is utilized to impart a brick-like color tone thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stainless steel sheet for roofs which exhibits a brick-like color tone over time after construction and is excellent in durability, workability and design.

[0002]

2. Description of the Related Art Conventionally, stainless steel sheets, various hot-dip coated steel sheets, and coated steel sheets thereof have been mainly used as roof steel sheets. Stainless steel sheets, hot-dip aluminum-coated steel sheets, and hot-dip 55% aluminum-zinc-coated steel sheets have excellent corrosion resistance and weather resistance. Therefore, when their metallic luster is preferred, they may be used as roofing materials. However, since the gloss often does not match the natural environment, a surface treatment such as a coloring treatment by painting is often performed. The hot-dip galvanized steel sheet is mainly painted and used as a roof steel sheet. When a color tone having a design property is imparted to these steel sheets, they are often mainly painted. However, the coating deteriorates over time, and gradually becomes inferior in appearance.

[0003] As a method of giving a maintenance-free and designable color tone regardless of coating, there is a case where a corrosion product of a metal is used. According to this method, not only the color tone is simply imparted, but also a feeling of weight and luxury that cannot be obtained by painting can be obtained. Copper produces a patina, a basic corrosion product, in the atmosphere, and its color tone has long been used in shrines and temples as a roofing material for copper sheets to make it even more interesting to buildings. In recent years, a copper-plated steel sheet may be used in addition to an old copper sheet, and the surface is often subjected to a patina treatment in advance.

[0004] Further, since zinc produces a black-grey corrosion product in the atmosphere, a steel sheet which has been colored to this color by a phosphate treatment in advance has been developed.
No. 3 and the like. As described above, a sheet material having a color tone of a corrosion product generated by the metal in the atmosphere is preferred. In addition to copper and zinc, a sheet material having a different color tone and a high-quality design and excellent in design is required. Had been. In general, conventional roofing materials are often designed so that their appearance, color tone, etc. do not change as much as possible. However, in the present invention, the fact that the color tone, etc. of the surface gradually changes over time as a roofing material is used in reverse. To improve the design and prevent the deterioration of the material even when maintenance-free.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been devised to solve such a problem, and is excellent in durability and workability. It is an object of the present invention to provide a high-quality design steel plate for a roof, which has a high tone.

[0006]

In order to achieve the object, a stainless steel sheet for a roof of the present invention comprises a base steel sheet made of stainless steel and a Zn-Fe alloy layer formed on at least one surface of the base steel sheet. The Zn—Fe alloy layer contains 0.5 to 10 g / m ² of Fe in composition, and one or more phases of ζ phase, η phase, δ1 phase, and Γ1 phase are systematically formed. It consists of.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the roof steel sheet of the present invention, a stainless steel sheet is first used as a base steel sheet in order to secure corrosion resistance. The most important property required for a roof steel plate is that no holes are formed and rain does not leak. In the case of the present invention, the Zn—Fe alloy layer on the surface of the steel sheet is not intended for corrosion resistance. Although Zn in the alloy layer has a temporary anticorrosion property, a long-term anticorrosion property such as hot-dip galvanized plating usually used for building materials cannot be expected. Further, even if the Zn-Fe alloy layer of the present invention is formed on the surface of a normal steel sheet, the base material is immediately corroded, so that the color tone becomes too dark and the durability of the base material is deteriorated. Stainless steel has traditionally been used in fields where corrosion resistance is required, such as roofing and exterior materials, as well as food and beverage handling materials, by utilizing the fact that the passivation film formed on the surface exhibits excellent corrosion resistance. Have been. Also in the present invention, it is necessary to use a stainless steel plate as the base steel plate in order to secure the original function of the roof that protects the house from the weather.

Next, in order to obtain a brick-like color tone, the surface of the base stainless steel sheet is made of Zn-Fe containing Fe which is easily oxidized.
An alloy layer is formed. The method for forming the Zn—Fe alloy layer is not particularly limited. Zn-Fe by electroplating
Alloy plating may be performed, or alloying may be performed by heating at 240 to 400 ° C. after performing electric Zn plating. Since stainless steel is used for the base steel sheet, Zn
After plating and alloying by heating, F
At the same time as e, Cr is also diffused, and an alloy layer in which Cr is dissolved is formed. The roofing material having the Cr solid solution alloy layer has an effect of being generally more excellent in corrosion resistance than the roofing material having a Zn—Fe alloy layer formed simply by electroplating. Cr acts as an alloy element for improving the corrosion resistance of Zn, and it is presumed that the corrosion resistance was improved because Cr suppressed the corrosion of Zn.

[0009] In the present invention, F in the Zn-Fe alloy layer
The color is obtained by the rust layer formed when e is corroded,
This color tone changes depending on the amount of Fe in the alloy. That is, the smaller the amount of Fe, the lighter the color and the brighter the color.
The greater the amount of e, the deeper the color and the darker the tone. And
When the amount of Fe in the alloy is less than 0.5 g / m ^{2, the} effect of imparting a color tone by the iron rust layer is small, that is, the color is thin,
A high-quality brick tone cannot be obtained. Also, Fe
When the amount exceeds 10 g / m ² , the color tone gradually becomes darker,
The color tone is similar to that of a normal cold-rolled steel plate. Since the design is a matter of preference, there is no particular upper limit on the amount of Fe in the alloy layer when the dark brown cold-rolled steel sheet prefers a rusty color. However, in the case of electroplating, the greater the basis weight, the more disadvantageous in cost. Therefore, in the present invention, the upper limit of the amount of Fe in the alloy is set to 10 g / m ² . In addition,
The Fe amount is calculated as follows from the average Fe content and the amount of adhesion in the Zn—Fe alloy layer. Fe content (g / m ² ) = average Fe content in alloy layer (%)
× adhesion amount (g / m ² ) / 100

The structure of the alloy layer is as follows: ζ phase, η phase, δ1 phase, Γ phase
It is necessary to use one phase of one phase or a mixed phase of two or more phases. According to the study of the present inventors, when the Γ phase is formed in the Zn-Fe alloy layer shown in the binary system equilibrium diagram, the adhesion of the alloy layer in the case of roll forming or bending as a roof material is considered. It was confirmed that the property was reduced. Therefore, in the present invention, the Zn-Fe alloy layer excludes the Γ phase,
One phase of ζ phase, η phase, δ1 phase, and Γ1 phase or a mixed phase of two or more phases.

Since the η phase is a Zn phase in which Fe is dissolved, it cannot be called an alloy phase in a strict sense. However, a layer plated with pure Zn by electroplating is not called an η-phase, and a Zn-plated layer in which Zn is dissolved as a solid solution is usually called an η-phase. If the Zn-Fe layer in which Fe is dissolved is formed on the surface, the intended purpose can be achieved by oxidizing the Fe. Therefore, in the present invention, a solid solution of the η phase is also referred to as an alloy phase.

The alloy layers having various structures as described above are:
A stainless steel sheet with a Zn layer formed on the surface
-It can be formed by heat treatment for a long time.
Conditions for heat treatment of stainless steel sheet with Zn layer
Is determined by the amount of Zn deposited, temperature, and time
However, for example, SUS430 has a Zn adhesion amount of 20 g / m2. ^TwoPlace
Alloy at 260 ° C x 12 hours and 300 ° C x 5 hours
As a result, ζ phase, δ1 phase and Γ1 phase appeared. Ma
The Γ phase was produced at 550 ° C or higher from the Zn-Fe equilibrium diagram.
In order to prevent the appearance of the Γ phase,
It is necessary to alloy at a temperature of preferably 400 ° C. or lower.

In the present invention, the material spontaneously corrodes and is colored when installed on the roof. For this reason, it is not necessary to perform a process that causes an increase in cost, such as giving a color tone by performing a process that causes chemical corrosion in advance, and an inexpensive product can be provided. The present invention can be used without a clear coating, but a general clear coating may be applied to prevent scratches during processing and construction. However, the thicker the coating film, the greater the effect as a protective film against corrosion of the plating layer, and the longer the time until the color tone changes. Therefore, acrylic-based, urethane-based,
It is desirable to select a paint such as a polyethylene-based or polyolefin-based paint having as poor weather resistance as possible, and not to make the film thickness too large.

[0014]

Example 1 Using SUS430 having a thickness of 0.4 mm as a base steel plate, Zn plating of 20 g / m ² was applied by an electroplating line, and thereafter, the alloy was formed by heating at 300 ° C. for 10 hours by batch processing. As a result, a Zn—Fe alloy layer of 22 g / m ² was formed, and the alloy layer contained 2.6 g of Fe per unit area.
Phase, δ1 phase and Δ1 phase. Using the stainless steel sheet having this alloy layer as a test piece, the workability and the color tone one year after the atmospheric exposure test were investigated. For evaluation of workability, cellotape (registered trademark) was peeled off after the 2t bending test, and the presence or absence of peeling of the alloy layer was investigated. As a result, there was no peeling, the workability was sufficient, the color tone after one year was reddish brown, and the design was good.

[0015]

Embodiment 2 As in Embodiment 1, SUS having a plate thickness of 0.4 mm is used.
Using 430 as a base steel sheet, a sample was prepared in which the Fe content and the crystal structure of the alloy layer were changed by electro-Zn plating and heat alloying under various conditions. The later color tone was investigated. The result is
The results are shown in Table 1 together with the results of Example 1 (Example 1 of the present invention). The results of the peeling test were evaluated as follows depending on the presence or absence of peeling of the alloy, and are shown in the table. ：: no peeling, Δ: small amount of peeling, ×: many peeling.

The steel sheet having the composition and structure specified in the present invention has a sufficient workability, and after one year, a brick-like color tone with excellent design properties has been obtained. On the other hand, Comparative Example 1 in which the amount of Fe in the alloy layer was small had a light color tone, and Comparative Example 3 in which the Fe amount was too large was too dark to satisfy the design. Further, Comparative Example 2, in which the Δ phase was formed, had a large amount of peeling during processing and was not practically usable.

[0017]

[0018]

As described above, according to the present invention,
The stainless steel sheet used as the base steel sheet has excellent durability and excellent workability by specifying the phase structure.
It is possible to provide a roof steel plate having a high-class feeling and a design property, which exhibits a brick-like color tone over time after construction using rust.

Claims (1)

[Claims] 1. A base steel sheet made of stainless steel, and a Zn—Fe alloy layer formed on at least one surface of the base steel sheet, wherein the Zn—Fe alloy layer has a composition of 0.5 to 10 g.
/ M ² of Fe, and 組織 phase, η phase, δ 1
A stainless steel sheet for a roof, comprising at least one of two or more phases.