Galvanized corrugated steel sheet

Galvanized corrugated steel plate is a commonly used building material, which is made of cold-rolled continuous hot-dip galvanized sheet steel and steel strip with a thickness of 0.25~2.5mm. Because of its excellent anti-corrosion properties and strength, this material has been widely used in many fields such as construction, packaging, railway vehicles, agricultural machinery manufacturing and daily necessities.

First, galvanized corrugated steel plate common problems

What is galvanized corrugated steel? Galvanized corrugated steel plate is a kind of metal sheet treated by cold rolling, corrugated pressing and continuous hot dip galvanizing. The zinc layer on its surface can effectively prevent steel corrosion and extend service life.

What are the uses of galvanized corrugated steel? Widely used in construction, packaging, railway vehicles, agricultural machinery manufacturing and daily necessities and other fields. Common applications such as granary roof, compartment board, container and so on.

Second, the price of galvanized corrugated steel plate

Calculation method: Taking DN32 type galvanized pipe as an example, its unit price is 5180 yuan/ton, and the weight per meter is 3.56kg.

Third, the density of galvanized corrugated steel plate

Hot-rolled steel plate density reference value: In general, the density of hot-rolled steel plate is about 7.9g/cm³. The specific density may vary slightly depending on the composition of the steel.

The effect of the composition of steel on density: Steel is an iron-carbon alloy with a carbon content between 0.04% and 2.3%. In order to ensure its toughness and plasticity, the carbon content is generally not more than 1.7%. The main elements include iron and carbon, while other elements such as manganese, silicon, phosphorus, and sulfur are also present in small amounts.

Fourth, arch corrugated steel roof method

1. Polyurethane spraying

Polyurethane spraying is one of the more common thermal insulation methods for arched corrugated steel roofs, which has the following characteristics:

Fast construction: The spraying process is simple, no additional supporting materials are required, and the construction speed is fast.

The effect is remarkable: hard foam polyurethane has good thermal insulation performance, and can quickly form a uniform thermal insulation layer after spraying.

Light weight: hard foam polyurethane itself light weight, will not increase the arched corrugated steel roof load, to ensure structural safety.

Widely used: At present, most of the domestic grain warehouses are using this kind of thermal insulation.

2. Glass wool

The method of using glass wool as insulation material is as follows:

Easy to lay: lay glass wool on the original roof, and then cover a layer of 0.8MM thin sheet.

Good insulation effect: glass wool has a good insulation effect, suitable for projects requiring efficient insulation.

Reasonable cost: the cost of glass wool is relatively low, and the construction process is mature, which is very suitable for the needs of the domestic market.

Advanced option: This method is considered an ideal thermal insulation option in the domestic market.

History of arched corrugated steel roof

Origin: The concept of arched corrugated steel roofs originated in the United States in the 1940s. At that time, some architects were inspired by the structural modeling of the skin texture of natural plants, and began to try to make large-span structures with extremely thin materials through corrugated stiffening.

Early application: They used thin steel plates as materials, established mechanical models, and analyzed reasonable structural forms in theory. In 1955, the United States used this roof for military purposes (such as combat hangars, barracks, etc.).

Technical development: Due to the low cost and efficient construction speed, this structure soon attracted more and more researchers and users. In particular, the introduction of computer numerical control technology makes the design and production of metal roofs more simple and rapid.

International monopoly: Due to various reasons (such as economic factors), the scientific research of this technology and the development and production of molding units have been monopolized by large companies in the United States, the United Kingdom and other countries for a long time, which limits its promotion in the world to a certain extent.

China's introduction: in the late 1980s, China sent staff to the United States for investigation, but it is very difficult to completely introduce foreign technology. First of all, the equipment cost is extremely expensive, and secondly, foreign technology does not take into account the comprehensive technical level of our country (such as materials, loads, etc.).

6. Domestic development trends

Early application: Since 1992, relying on American equipment and technology, China has built the first metal arch roof.

Rapid development: Because this structure has the advantages of light weight, material province, fast construction speed, low cost, high indoor headroom, large span capacity, etc., it is very suitable for our country's national conditions, in just ten years, this structure has firmly gained a foothold in our country's construction market.

Seven, coated steel plate galvanized steel plate overview

1. Introduction of galvanized steel plate

Definition: Galvanized steel plate is coated with a zinc layer on the surface of the steel plate to achieve the purpose of corrosion resistance.

Historical background: Galvanizing technology was first studied by the French Meloman in 1742, and was applied to industrial production in 1836. In 1837, the British Glauford obtained a patent for flux method hot dip galvanizing. In 1935, the American Senjimir proposed the method of continuous hot dip galvanizing with protective gas reduction, known as the "Senjimir method".

China's development: China began the production of hot galvanized sheet in Anshan in the 1940s, and built the first continuous hot galvanized strip line in Wuhan in 1979.

2. Introduction to hot plating method

Overview: Hot plating method is divided into flux method and protective gas reduction method. Suitable for parts requiring strong corrosion resistance.

Flux process. The annealed steel sheet is acid-washed to remove the surface oxides. It is then passed through a flux tank containing ZnCl₂ and NH₄Cl. It is then entered into a molten zinc tank for galvanizing.

Protective gas reduction method: widely used in continuous hot dip galvanizing of strip steel. The strip steel first passes through the flame heating furnace to burn off the residual oil on the surface, and at the same time, the iron oxide film is formed on the surface. Then enter the reduction annealing furnace containing H₂ and N₂ mixed gas to heat to 710~920℃, so that the iron oxide film is reduced to sponge iron. After the surface purification and activated strip steel is cooled to a temperature slightly higher than that of molten zinc, it is entered into a zinc pan at 450~460 ° C, and the zinc layer thickness is controlled by an air knife. Finally, it was passivated by chromate solution to improve the resistance to white rust.

3. Introduction of electroplating method

Overview: Electroplating method is suitable for unpainted parts or painted parts with low corrosion resistance requirements.

Alkaline method and acid method: The alkaline method pollutes the environment and has low production efficiency, and is actually not used. The acid process consists of plating solution ZnSO₄·7H₂O, NH₄Cl, and Al₂(SO₄)₃·18H₂O with pure zinc as anode and strip steel as cathode. Under the action of electric current, the zinc anode plate is dissolved into Zn² + into the plating solution while Zn² + is reduced into metallic zinc deposited on the strip surface at the cathode. The coating was treated with a mixture of phosphate and chromate to improve its finish. The surface of electric galvanized steel plate is bright and smooth, which has been mainly used in the automotive industry in the past, and has been expanded to the electrical industry and other aspects in recent years.