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Things You Need to Know about Galvalume Steel Coils


Galvalume steel coil is an alloy-coated steel coil widely used in building materials, home appliances, automobiles, environment, machinery, ships and many other fields.There are things below you need to know about galvalume steel coil.

Hot-dip galvanized steel has been widely used in various industries such as construction and home appliances since its inception. Due to the continuous expansion of the scope of use, the product's formability and various properties of the steel coil continue to improve, resulting in a galvalume steel coil that is superior to the hot-dip galvanized steel coil in some properties. The galvalume steel coil is a cold-rolled hard steel coil with various strength and thickness specifications as the base material, and the AL-Zn alloy galvanized coated steel coil is obtained by hot dip plating. The galvalume steel coil is covered with aluminum-zinc alloy on the surface of the steel coil.

What is galvalume steel coil?

The galvalume steel coil is composed of an aluminum-zinc alloy structure, which is composed of 55% aluminum, 43.4% zinc and 1.6% silicon solidified at a high temperature of 600 ° C. The entire structure is composed of aluminum-iron-silicon-zinc, forming a dense quaternary an alloy-coated steel coil that is crystalline.

Development history of galvalume steel coil.

In 1965, Bethlehem (BIEC International Inc) developed and registered the patent;

1972 Bethlehem Steel, USA: Applicable Standards for Initial Commercial Production: ASTMA792/M; JISG3321; BSEN10215-1995; GB/T14978-2008

What are the advantages of galvalume steel coil?

The surface of the galvalume steel coil has a characteristic smooth, flat and gorgeous star flower, and the base color is silver white. The special coating structure makes it have excellent corrosion resistance. The normal service life of the galvalume steel coil can reach 25a, the heat resistance is very good, and it can be used in a high temperature environment of 315 ° C; the adhesion between the coating and the paint film is good, and it has good processing performance, which can be punched, sheared, welded, etc.; Good surface conductivity.

The advantages are as follows:

1. Corrosion resistance

galvalume steel coil has strong corrosion resistance, and its normal service life can reach 25 years, which is 3-6 times longer than that of galvanized steel coil and almost the same with stainless steel. The corrosion resistance of galvalume steel coil comes from the barrier protection function of aluminum and the dedicated protection function of zinc. While zinc is dedicated to maintenance on trims, scratches, and coating scratches, aluminum forms an insoluble oxide layer (alumina) that prevents corrosion-resistant substances from further corroding the interior. Aluminum-zinc alloy steel coils have been exposed to outdoor exposure tests for more than 20 years in various atmospheric environments, and it has been proved that the trimming protection function of 55% aluminum-zinc alloy steel coils is better than that of galvanized steel coils and 5% aluminum-plated steel coils. Zinc steel coil is preferred.

2. Heat reflectivity

The thermal reflectivity of galvalume steel coil is very high, which is twice that of galvanized steel coil.

3. Heat resistance

The aluminum-zinc alloy steel coil itself has excellent heat resistance and can be used in a high temperature environment up to 315 degrees. Similar to high temperature oxidation resistance of aluminized steel coil, it is often used in chimney pipes, ovens, luminaires and fluorescent lampshades.

4. Recoatability (paint film adhesion)

The aluminum-zinc-coated steel coil can maintain excellent adhesion with the paint film, and it can be directly painted or powdered without special pretreatment.

5. Corrosion resistance after coating

After the galvalume steel coil itself is partially coated and baked, the corrosion resistance of the non-sprayed steel coil will decrease very little. The function is much better than electroplating color galvanized and electrogalvanized steel coil and hot-dip galvanized steel coil.

6. Machinability (shearing, stamping, spot welding, seam welding)

Galvalume steel coil has excellent processing function, can be punched, sheared, welded, etc., and the coating has good adhesion and impact resistance.

7. Electrical conductivity

The surface of the galvalume steel coil can meet the needs of electromagnetic shielding through special waxing treatment.

8. Economical

Because the density of 55%AL-Zn is smaller than that of Zn, under the same weight and the same thickness of the gold-plated layer, the area of the galvalume steel coil is more than 3% larger than that of the galvanized steel coil.

9. Easy to paint

The galvalume steel coil has excellent adhesion to the paint and can be painted without pretreatment and weathering.

Disadvantages of galvalume steel coil?

1. Welding performance

Due to the increase in mechanical properties of Al-Zn coating, the surface coating density of the inner substrate is better, and the manganese content is relatively high. Therefore, Al-Zn coating cannot be welded under ordinary welding conditions, and can only be connected by other parties such as rivets. In terms of welding, hot-dip galvanized steel coil performs better, and there is no welding problem.

2. Applicability of Tide-Temperature Concrete

The aluminum-zinc coating contains aluminum, and the aluminum composition is prone to chemical reactions in direct contact with acidic wet concrete. Therefore, it is not very suitable for floor slabs.

3. Coating thickness and steel coil thickness limit

Most of the domestic galvalume production units are restructured from hot-dip galvanized units, and there are certain restrictions on the thickness of galvalume steel coils. Coil thickness is limited to only 0.27 to 2.5. In terms of coating, it can only achieve a minimum of 30 grams per square and a maximum of 220 grams per square.

The difference between galvalume steel coil and galvanized steel coil

The galvalume steel coil with 55% Al-Zn alloy coating has superior corrosion resistance compared with the same thickness of galvanized steel coil when exposed to the same environment on both sides. The galvalume steel coil with 55% aluminum-zinc alloy coating not only has good corrosion resistance, but also the color-coated products have excellent adhesion and flexibility.

The difference between galvalume steel coil and galvanized steel coil mainly lies in the difference of coating. The surface of galvalume steel coil is evenly distributed with a layer of zinc material, which plays an anodic protection role for the base metal, that is to say, the replacement of zinc material Sexual corrosion protects the use of the base metal, and only when the zinc is completely corroded can the base metal inside be damaged.

The surface coating of the galvalume steel coil is composed of 55% aluminum, 43.5% zinc and a small amount of other elements. The surface of the galvanized coating is a honeycomb structure at the microscopic level, and the "honeycomb" composed of aluminum contains zinc. , In this case, although the aluminum-zinc coating also plays the role of anodic protection, on the one hand, due to the reduction of zinc content, on the other hand, because the zinc material is wrapped by aluminum and is not easy to be electrolyzed, the role of anodic protection is greatly reduced, so once plated The aluminum-zinc steel coil is cut, and it will rust quickly when the cut edge basically loses its protection. Therefore, the aluminum-zinc steel coil should be cut as little as possible. Once cut, the edge should be protected by anti-rust paint or zinc-rich paint. In order to prolong the service life of the steel coil.

Aluminized steel coils are generally used in:

1. Automobile, motorcycle muffler, exhaust pipe, fuel tank.

2. Combustion furnace, heat exchanger, dryer, air conditioner, etc.

3. Household water heaters, gas stoves, bread boxes, chimneys, microwave ovens, food processing machinery, electric ovens, cooking utensils.

It can also be used for building covers, walls, ceilings and other thermal insulation components.

Galvanized steel coils are generally used in:

Construction industry: light steel keel, corrugated board, ventilation duct, floor bearing board, movable room, factory roof and body, municipal engineering enclosure.

Used as a substrate for downstream products--

Home appliance industry: shells and bottom plates of home appliances such as air conditioners, refrigerators, washing machines, microwave ovens, water heaters, and computer cases.

Automotive industry: car body, outer panel, inner panel, bottom plate, door, etc.

Other industries: storage and transportation, packaging, granaries, chimneys, buckets, ship bulkheads, etc.

Galvalume steel coils are generally used in:

Construction: roofs, walls, garages, soundproof walls, pipes and modular houses, etc.

Automobile: muffler, exhaust pipe, wiper accessories, fuel tank, truck box, etc.

Home appliances: refrigerator back panels, gas stoves, air conditioners, electronic microwave ovens, LCD frames, CRT explosion-proof belts, LED backlights, electrical cabinets, etc. Agricultural: pig houses, chicken houses, granaries, greenhouse pipes, etc.

Others: thermal insulation cover, heat exchanger, dryer, water heater, etc.

Precautions for the use of galvanized steel coils

Storage: It should be stored indoors such as warehouses, kept dry and ventilated, and should not be stored for a long time in an acidic climate. When storing outdoors, it is necessary to prevent rain and avoid condensation caused by oxidation stains.

Transportation: To avoid external impact, SKID should be used to support the steel coil on the transportation tool to reduce stacking and take rain-proof measures.

Processing: When COILCENTER is shearing, the same lubricating oil as the aluminum plate should be used. When drilling or cutting galvanized steel sheets, it is necessary to remove scattered iron filings in time.

What is the price of galvalume steel coil?

Similar to many other materials, the price of galvalume steel coil has been tepid, and investors and producers have not had much confidence in such products. Both fundamentally and technically, the rise of the aluminum and zinc price has not driven the price of the galvalume steel coil. It is also reasonable that the price of the galvalume steel coil is difficult to rise.

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