How to Choose Cold Rolled & Galvanized & Galvalume Steel Coils

14 March 18

When it comes to selecting steel coils, you cannot afford to second-guess. You must be satisfied that your pick is appropriate for your particular project since making the wrong choice can lead to disappointing results. However, this is usually easier said than done especially because different types of steel materials differ significantly in terms of functionality. The manufacturing process informs the functionality of the various types of rolled steel coils. Depending on the manufacturing process, there are several distinct types of steel coils in the market: cold rolled steel, hot dipped galvanized steel coil, and Galvalume steel coil among others. Below is a discussion of what these varieties are, their strengths, and their applications.

1. Cold Rolled Steel Coil

Cold rolled steel is a type of flat steel coil manufactured when hot rolled steel which has been pickled is subjected to a cold thickness reduction process. Basically, the cold rolled steel is manufactured through the same process as the hot rolled steel only that the cold rolled variety is subjected to further manipulation to give it its desired and distinctive characteristics. The additional process usually happens at room temperature. Since the cold reduction of thickness is done below the recrystallization temperature, the final alloy has greater strength.

After the cold rolling process, the steel coil can then be taken through the process of annealing. This has to do with heating the alloy above the recrystallization temperature and cooling it back to room temperature. This process is important because it relieves the internal stress that develops during the cold rolling. Annealing also resettles the steel’s microstructure and enhances its mechanical properties. Annealing makes it easy to customize steel coils to meet the particular project specification.

After annealing, the cold rolled steel coils are then put through the tampering process. Tampering simply involves putting the steel coils under light pressure to flatten them and give them a premium finish.

One of the most beneficial properties of the cold rolled steel is its high strength. The manufacturing process it undergoes increases its strength by up to 20 percent. This material also has high resistance to denting. Cold rolled steel also has high formability. It can also be easily enameled and painted. If it is coated with a protective paint, its resistance to corrosion is enhanced, and its useful life is extended.

The properties of cold rolled steel make it a versatile material with a wide range of application. For instance, it is a great choice for home appliances and automobile manufacturing. It is among the best materials used for home and office furniture and water heaters. It is suitable for both unexposed and exposed parts.

Cold Rolled Automotive Strips​​

2. Hot Dipped Galvanized Steel Coil

As the name suggests, hot dipped galvanized steel coils are simply steel coils that have been treated in a process called galvanization. Galvanization can simply be understood as the process of coating one metal with another type of metal. In this case, steel is coated with zinc. The coating is usually done to prevent rusting and other forms of corrosion on steel. Galvanizing is done by dipping steel in molten zinc heated to about 4600C.This process, also known as electrolysis, ensures that zinc is deposited firmly on steel.

One of the greatest strengths of hot dipped galvanized steel coil is that it is rust resistant. Besides, it much affordable compared to stainless steel. Furthermore, its thickness can be customized to meet specific customer’s needs. Usually, the thickness range from 0.24 mm and 0.3 mm. Zinc coating normally ranges in size from 30- 450g/M2 for single coating, and 60- 900g/M2 for double coating. Thus, hot dipped galvanized steel is not only strong but also adequately protected from elements that encourage rusting. Consequently, Hot dipped galvanized steel coil is a versatile material that can be applied in many different areas.

Hot dipped galvanized steel has found favor with Industrial perfectionists that need affordable rust-resistant steel. Thus, hot dipped galvanized steel is used industries such as construction and automotive. These steel coils can be found in products such as drum containers, HVAC systems, Refrigerators, washing machines, car parts, decking, ductwork, flushing and much more. In a nutshell, hot dipped galvanized steel coils have numerous commercial, industrial and residential applications.

Galvanized Coils​​

3. Galvalume Steel Coil

Galvalume steel coil is made in the same process the cold rolled steel and then coated with an alloy mainly consisting of zinc and aluminum. Usually, the alloy used in coating is 45 percent zinc and 55 percent aluminum. Thus, it is different from the galvanized variety which is only coated with zinc. Galvalume is highly resistant to corrosion since zinc and aluminum have been proven to work well together to provide a strong barrier protection on steel coils. Besides, it can be color coated to enhance its resistance to corrosion. In fact, color coated Galvalume steel coils last up to four times longer than other steel coil varieties.

Galvalume steel coils have a number of advantages above other rolled steel coil varieties. For instance, the Galvalume steel coils have a smoother and a more fluent surface compared to the hot dipped galvanized variety. Besides, its corrosion resistance property is superior to that of the galvanized variety. Galvalume steel coils are also known for their strong ability to withstand high temperatures. For instance, Galvalume can stand a temperature of up to 3150 without tarnishing. Besides, it can normally be applied for a long period at a temperature of 5000C.

The special properties of Galvalume steel coils make them ideal for a number of applications. For instance, its high resistance to corrosion makes it a material of choice industries such as petrochemical industries, construction industry, paper industry, and mechanical engineering. It is also be used to build structures in areas where corrosion is likely to happen such as in the sea. Since it is highly resistant to rust, it can be used for roofing. Automobile manufacturers apply it in heat shields, vent pipes, mobile mufflers, and bottom accessories. Galvalume steel coil is also used in home appliances such as HVAC systems, refrigerators, explosion proof steel strip, and ovens.

Galvalume Steel Coils​​

The Takeaway

Overall, it is apparent that rolled steel coils have a many industrial, domestic, and commercial applications. However, different varieties of steel coils differ significantly in terms of strength and resistance to rust and other forms of corrosion. Thus, if you have projects that require a steel coil, you must define the parameters of your project and pick the right steel coil based on those parameters. For instance, if you are building a bridge on salty water, the rate of corrosion is going to be high, and therefore, it would be prudent to go for the Galvalume variety due to its stronger resistance to corrosion compared to other steel coil varieties.

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