Hot Rolled Coil Price Chart

HRC prices vary from country to country.

Chinese HRC prices:

URL https://finance.sina.com.cn/futures/quotes/HC0.shtml

The website is in Chinese, 3532 means that the price of hot-rolled coil per ton is 3532 yuan, and the currency is RMB.

U.S. HRC prices:

URL https://www.investing.com/commodities/us-steel-coil-futures-historical-data

The price of hot rolled coil in the United States is US$1,099 per ton.

Factors Influencing the Price of Hot Rolled Coil

1 supply and demand

The demand side includes engineering infrastructure, manufacturing and processing, etc. When the global demand for hot-rolled coils is strong, the price will increase. Hot-rolled coils are the raw material for galvanized roofing. For example, when earthquakes occur in some countries, metal roofing is required to build a large number of temporary houses.

The production capacity and operating rate of factories including hot-rolled coils on the supply side.

2 raw material cost

Iron ore, steel scrap, coal, and natural gas are raw materials for producing hot-rolled coils, and their price changes will affect the price of hot-rolled coils

4 stock

Including changes in global social inventory and steel mill inventory data

5 Macro policies

The Chinese government’s steel mills implement environmental protection policies to limit production capacity, and the US government imposed a 25% tariff on hot-rolled coils in 2018, which will affect prices.

What is Zincalume Steel?

Zincalume steel is a type of steel that has a coating made of a combination of aluminum, zinc, and silicon. This coating is applied to the steel in a continuous hot-dip process, which results in a highly corrosion-resistant and durable material.

Zincalume steel coil is commonly used in construction for roofing, walling, and fencing applications. It is highly valued for its superior corrosion resistance as well as its ability to withstand extreme weather conditions.

Additionally, zinc-plated steel is lightweight, easy to handle and install, and has a long lifespan. Overall, zinc is a popular and versatile material that is used in a wide range of industries for its strength, durability, and resistance to corrosion.

The development of Zincalume began in 1976 to serve the building needs of customers in Australia. After 20 years, it has leveled up by introducing Zincalume® steel with Activate® technology.

It underwent several tests at BlueScope’s production facilities in New South Wales, Australia. The technology adheres to the AS/NZS 1365:1996 (R2016) and AS 1397:2021 Australian Standards. The BlueScope warranties ensure that the steel can last for years with less maintenance.

AM vs. AZ

Zincalume® aluminum/zinc/magnesium alloy coated steel, also known as AM, uses patented Activate® technology.

AM offers good performance due to the changes in composition as well as its coating structure to withstand harsh environments. It is composed of 55 percent aluminum, 2 percent magnesium, 1.5 percent silicon, and a balance of zinc.

AM is more resilient and long-lasting compared to Zincalume® aluminum/zinc alloy coated steel (AZ). AZ was developed by BlueScope in 1976 by coating the steel with 55 percent aluminum, 1.5 percent silicon, and a balance of zinc.

Source: https://cdn.dcs.bluescope.com.au/download/ctb-06

Coating Structure

To give you a clear picture of the coating structure of Zincalume steel, take a look at the two figures below. Figure 1a shows the AZ coating microstructure consisting of dendrites and interdendritic regions. It is in the interdendritic region where the zinc coating lies, while the aluminum coating lies in the dendrites.

The silicon, which resembles needle particles, lies in the interdendritic region. A formation of Zn, Al, Si, and Fe at the interface of the steel acts as a bond between the coating and the base steel.

An image showing the cross-section of the typical microstructures of AM and AZ coatings

Fig. 1A: An image showing ZINCALUME® steel AZ150 (superseded)

Fig. 1b: An image showing the next generation ZINCALUME® steel AM125

Take a look at figure 1b. You will see the AM alloy coating microstructure consisting of a zinc-rich matrix where the aluminum lies. You will find fine particles of magnesium silicide (Mg2Si) and magnesium zinc (MgZn2).

Most of the magnesium silicide is going towards the coating layer’s bottom part. The magnesium-zinc goes in the direction of the coating layer’s top part. Both positions of the MgZn2 and Mg2Si reinforce the AM coating’s resistance to corrosion.

https://cdn.dcs.bluescope.com.au/download/ctb-06

Corrosion Protection Mechanisms

The coating of aluminum/zinc alloy-coated steel guards the steel against corrosion. (figure1c)

Figure 1d shows the protective mechanism of the aluminum/zinc/magnesium alloy-coated steel. The metallic coating guards the steel against corrosion. The MgZn2 that lies on top of the coating offers sacrificial protection at the start of the weathering of the steel.

Figure 1e shows how the aluminum-rich dendrites act as a barrier against corrosion while the zinc area starts corroding. Over the years of use, the aluminum-rich areas slowly corrode when the zinc-rich region becomes exhausted, giving a limited sacrificial protection to the steel base.

When the weathering of the coating is at its peak, Mg2Si begins to activate the aluminum-rich areas. The sacrificial protection on the steel base is not limited compared to the MgZn2. It prevents the development of red rust even in harsh environmental conditions over the years. See Figure 1f.

Source: https://cdn.dcs.bluescope.com.au/download/ctb-06

Cut Edges

The zinc-rich interdendritic region where there is atmospheric exposure results in corrosion at the cut edges and scratches. It is in these areas where the corrosion acts as a sacrificial protection, blocking off extreme corrosion after filling up the coating’s cavities.

AM offers resilient and long-lasting anti-corrosion properties at cut edges and scratches. The magnesium silicide particles provide extraordinary protective barriers to slow down corrosion. It blocks the corrosion gateways to the substrate.

Source: https://cdn.dcs.bluescope.com.au/download/tb-10

Bends

Both Colorbond® and Zincalume® steels are manufactured as flat sheets before passing through pressing or roll forming.

The paint and coating in Colorbond steel stretch the paint and coating, which leads to cracking. AM coatings are less ductile as they are harder compared to AZ coatings. It leads to cracking in the steel’s tight bends.

Image showing the 90-degree bend of unpainted steel exposed in marine area.

https://cdn.dcs.bluescope.com.au/download/tb-10

Conclusion

AM coatings are more resilient and long-lasting than AZ coatings. But it all depends on the application of the steel. Zincalume’s Al-Zn-Mg coatings offer barrier protection to the steel base even after several years of use.

What is ZAM steel?

ZAM steel is a brand of steel made by Nippon Steel Corporation. This hot-dip coated steel sheet boasts of its ability to fight corrosion over many years of use. The coating layer consists of 6 percent aluminum, 3 percent magnesium, and the rest is zinc. ZAM is an acronym for zinc, aluminum, and magnesium.

ZAM steel has a wide market due to its unique composition and long-lasting performance compared to hot-dip galvanized coatings. The technological advancement of ZAM makes it a sought-after brand worldwide that complies with the AS1397:2011 standards.

The blend of aluminum and magnesium makes the steel resistant to corrosion and scratches. The aluminum content is the secret to its high formability, which makes ZAM versatile in various applications.

ZAM’s superior anti-corrosion properties make it an excellent material for structures that are exposed to harsh environments. Its applications include boat and marina sheds, horticultural and agricultural sheds, refineries, spa and pool areas, and outdoor composite slabs.

Corrosion resistance mechanism of ZAM steel

ZAM’s corrosion resistance mechanism is due to its coating layer of aluminum and magnesium. The blend of Mg and Al creates an enduring protective film on its zinc base, giving protection against corrosion.

Compared to hot-dip galvanized coating layers, ZAM offers a finer and tighter adhesive property on the substrate. ZAM’s coating surfaces block the corrosive action over a long period of exposure to harsh environments.

In a salt spray test that lasted for four hours on both ZAM and hot-dip galvanized steel, ZAM formed a protective film on the coating surface. Take a glimpse at the figure below:

The cut-edge parts of the ZAM steel have superior corrosion resistance. The ends are covered with a fine base that contains a protective film comprising aluminum and magnesium leaching on its coating layer.

The corrosion resistance on the cut edge was based on a test on the steel substrate. The initial exposure period took several weeks, during which there was an initial rust on the exposed cut edge. The rust formed due to oxidation from condensation and rain.

The intermediate exposure period took several weeks to years. During this period, the cut edge resists corrosion due to the fine zinc-based protective film, which has a leaching of zinc, aluminum, and magnesium coating layers. The substrate turns darker to gray-black over the years of exposure to the elements.

Weldability

The coating layer of ZAM steel affects its weldability performance due to its zinc base. Zinc has a low melting point, which is not ideal for arc welding. This application leads to weak joints and deformation compared to cold- and hot-rolled steel sheets.

ZAM is prone to splashing, hole formation, and cracking. ZAM performs better if you weld it into joints, provided the structure has adequate strength and is under proper conditions.

Experts recommend conducting tests when welding ZAM steel to achieve greater strength and maximum welding parameters. The weld quality depends on the type of welding machine and shape of the joints.

Defective joints are avoidable if you follow the right conditions when welding ZAM steel. The joints should have enough weld strength and adequate internal sectional structure before welding the steel.

Applications

ZAM is a versatile steel brand that is useful in various applications. ZAM is popular choice in the building and construction sector. It is used for making refrigerant ducts, ceiling crosspieces, indoor baseball fields, sound barrier louvers, heavy-duty shutters, and house frames.

In road and civil engineering, its uses include bridge reinforcing plate, soundproof wall (ZPG treatment), wind barrier panel, sound barrier, sound barrier member, snow fence, guardrail, bridge railing, pipe for joining bolts of concrete block, rock bolt, windbreak screen, drain reinforcement pipe, handrail in tunnel, steel pipe pile, and fireproof protection for optical fiber.

ZAM is ideal for making automobile parts such as wiper linkage, filter case, radiator fan motor cover, starter motor yoke, hood lock, horn, pulley, splash guard, window regulator motor yoke, tank heat protector, constant velocity joint cover, and lower sash.

ZAM steel is also used in making electric power and electric equipment, farming structures, railroads, housing, and construction.

Conclusion

ZAM steel is a high-performing brand that can withstand corrosion even after many years of use. The color may fade, but its resistance to corrosion is unmatched compared to galvanized sheets.

References:

https://www.nipponsteel.com/product/catalog_download/pdf/U110en.pdf

ZAM Case Study. Nipponsteel

What is aluminum zinc alloy coated steel?

Aluminum-zinc alloy-coated steel is also known as galvalume. It is a type of metallic-coated steel product with a layer of aluminum, zinc, and silicon coated onto a steel sheet or coil. This coating provides both corrosion resistance and heat reflectivity to the steel, making it suitable for a wide range of applications.

The process of making galvalume involves coating the steel sheet with a layer of molten aluminum-zinc alloy. The aluminum provides a barrier to corrosion. The zinc provides extra layer of protection for the steel. The silicon is added to the alloy to improve the adhesion of the coating to the steel substrate.

Galvalume is often used in construction applications, such as roofing and siding. Automotive and appliance industries use it in making parts and components. It is known for its durability, resistance to corrosion, and low maintenance requirements.

The zinc, aluminum, and silicon coatings provide protection for the base metal, which is similar to galvanization.

Aluminum Zinc Alloy vs. Galvanized Coatings

Galvanized coatings are made by applying a layer of zinc to a steel substrate. This can be done through either hot-dip galvanizing or electroplating. The zinc provides sacrificial protection to the steel, meaning that it will corrode before the steel does.

Galvanized coatings are often used in applications where the steel will be exposed to corrosive environments, such as outdoor structures or equipment.

Aluminum, zinc, and silicon comprise the steel substrate of aluminum-zinc alloy coatings. The aluminum provides a barrier to corrosion, while the zinc provides sacrificial protection.

The silicon is added to improve the adhesion of the coating to the steel substrate. Aluminum-zinc alloy coatings are known for their superior corrosion resistance compared to galvanized coatings, especially in harsh environments.

Galvanized coatings have a characteristic bright and shiny finish. Aluminum-zinc alloy coatings have a duller, matte appearance.

Aluminum Zinc Alloy Coated Steel Life

Aluminum-zinc alloy-coated steel can last for several decades of use. A comparative study of roofing was conducted in Northern America, which is subject to industrial and acid rains.

There was a deterioration in galvanized roofing compared to 55 percent aluminum-zinc sheets. The 55% Al-Zn sheet looks like new, even if the surface has lost its sheen due to dirt and exposure to the elements.

Since 1994, there has been little change in the aluminum-zinc coatings over galvanized sheets. Experts concluded that the life expectancy of 55 percent aluminum-zinc coated steel is twice that of steel that undergoes the hot dip galvanization process.

The long-term evaluations in Indianapolis in 1994 proved that steel sheets with 55 percent Al-Zn can last for thirty to forty years. For marine applications, the lifespan could be twice that of galvanized sheets.

The durability of Al-Zn coatings can save money on repairs and maintenance of the roofing sheet even if the surface cosmetic value has diminished over the years.

https://www.steelroofing.com/assets/doc/40yearsoflife.pdf

Conclusion

There is no doubt that the 55% aluminum-zinc alloy coated steel performs better than galvanized sheets. The test results showed its versatility and long-lasting performance, which is cost-saving

What is Pre-Painted Steel Coil?

Pre-painted steel coil, also known as pre-coated steel coil or color-coated steel coil, is a product made of hot-dip galvanized steel sheet, hot-dip galvalume steel sheet, electro-galvanized steel sheet, etc. that has been coated with one or more layers of organic paint or other protective coatings.

The pre-painting process protects the metal substrate from corrosion. It improves its durability and aesthetic appearance and provides a wide range of color choices.

According to the EN-10169-1 standard, an organic coating material is applied to the rolled metal strip to protect it from corrosion. Cleaning and pre-treatment of chemicals are applied to one or both sides of the metal surface with a single or multiple coats of paint or powder.

Pre-painted steel coils are widely used in various applications, such as:

• indoor and outdoor applications in building and construction (roofing, wall cladding, garage doors)
• domestic appliances (refrigerators, washing machines, bakeware)
• cabinets and office furniture
• transport and automotive sectors
• lighting fittings

Pre-painted steel coils come in a variety of color coatings, surface textures, and gloss levels. The paint coatings have high chemical resistance, flexibility, and non-stick properties.

The coated coils are available in different cuts. Customers may request coils with narrow widths, profiled, deep drawn, and different lengths and shapes. There are a variety of pre-painted steel coils as manufacturers continue to develop modern designs and coatings.

Substrate of Pre-Painted Steel Coil

The substrate of a pre-painted steel coil refers to the base metal, where the organic coating takes place. The substrate of pre-painted steel coil include the following:

Hot Dipping Galvanized Steel Coil

Hot-dip galvanized steel coil is a substrate made by immersing steel in a bath of molten zinc to create a layer of zinc coating that protects the steel from corrosion. This method adopts galvanizing production as a continuous process. The cold-rolled coils stay in the dissolved zinc bath to continue their galvanizing process.

Hot Dipping Galvalume Steel Coil (55% aluminum/zinc)

Hot-dip galvalume steel is a popular choice for cladding and construction uses. This substrate offers corrosion resistance to the steel when exposed to harsh environments. The zinc coating provides galvanic protection when the steel surface suffers from scratches over many years of use, keeping the steel functional and intact.

Zinc-magnesium-coated steel

Zinc-magnesium-coated steel replaces steel and has a coating of 1 to 3.5 percent magnesium and 0.5 to 3.5 percent aluminum. It achieves metastable eutectic structure by fast cooling after a molten zinc bath.

The steel has a better performance against corrosion compared to hot-dipped galvanized steel, which has a pure zinc coating. Zinc, magnesium, and aluminum form an oxide protection layer on the steel, which means it can stand against corrosion at the exposed edges and boundary layer.

Product Life of Pre-Painted Steel Coil

Pre-painted steel coils can last for several years because the paint offers an extra layer of protection to the steel. Paints contain corrosion-inhibiting agents that can thwart moisture, heat, oxygen, and corrosion-inducing agents from causing damage to the steel.

Although paints fade over time and become dull due to heat, they can minimize the damage to the steel even if moisture penetrates the paint. Paint manufacturers have developed paint coatings with advanced features by adding corrosion-inhibiting agents.

These inhibiting agents lie at the interface between the metal and the paint coating. They minimize rusting and corrosion to the steel. The inhibiting agents protect the metal from losing its adhesion to the paint when there are blisters and scratches at the exposed areas.

The agents also protect the paint from undercutting corrosion, so the metal does corrode even if there are scratches and cut edges. Paints help improve the product life of steel sheets and coils depending on several factors.

These factors include the paint coating thickness, resistance to harsh environmental conditions, primer coating, and paint pre-treatment that contains corrosion-inhibiting agents.

Choose a paint that has a lower moisture permeability. This type of paint protects the steel from flaking and blistering due to water absorption. Optimizing the product life of pre-painted steel coils depends on the choice of paint and treatment technology.

Choose a paint that contains corrosion-inhibiting agents. Ensure that you apply the right primer coating, metallic coating type, and pre-treatment to make the steel last for years.

Source:

https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote-4-1.pdf

Paint System Durability

Although pre-painted steel coil greatly extends the service life of the product, when the life reaches the limit. They may fail in some aspects, like fading and chalking, that affect the aesthetic value of the product.

Paints are prone to blistering and flaking over time. It occurs when the paint separates along the pretreatment or metallic coating bond line, the primer or pre-treatment bond line, and the primer/paint bond line.

There are factors that influence the durability of the paint system. Such factors are in relation to the combination of the pre-treatment, primer, and paint coating to the elements and environmental conditions. Paints may lose their adhesion if there is corrosion of the steel substrate.

Latitudinally undercutting corrosion is the most common form of paint failure. It is due to a scratch at the exposed edge or in the paint. Chemical reactions, moisture, and heat exposure can also cause bulk corrosion and degradation of the adhesion bond, which leads to paint damage.

Advantages of Pre-Painted Steel Coil

Prepainted steel coils have an organic coating layer that offers resistance to corrosion and guarantees longevity. Here are the advantages of pre-painted steel:

Advantages in Design

Prepainted steel products are aesthetically appealing due to their design, texture, and color variations. The surface finish comes in printed films that look like woodgrain, matte, high gloss, embossed, orange-peel, or smooth. They are available in various aluminum alloys and grades that are easy to bend and adjust during application.

Manufacturers are producing sustainable and recyclable prepainted steel. This steel has a superior performance against corrosion despite its thinner organic coatings, which are common in post-applied films and powder. The organic coatings are less costly as they do not need regular repainting and maintenance.

Sustainable in Life Span

Prepainted metals undergo a coil coating process that offers long-lasting service without costing much. Since they are organic paint coatings, they are less costly but offer a sustainable, effective, and reliable design solution for various applications.

Manufacturers take close supervision during the coating operations, ensuring that the prepainted metals yield a premium, recyclable, and sustainable design that can last for up to forty years in the harshest environments.

Coil Coated Metal Joining and Forming

Prepainted metals have a high formability, which means they are easy to bend, blank, form, draw, and rewind. Driving mechanical fasteners like rivets, screws, bolts, and Tog-L locks does not require extra force. They are easy to bind using an adhesive bond or lock seam.

They are weldable and formable into different shapes due to their aluminum content. The surface is free of dirt and imperfections as the aluminum and steel undergo cleaning, priming, painting, and curing. They offer superior performance to their post-painted counterparts.

Prepainted Metal and Cut-Edge

Prepainted steel coils boast of their prepainted cut-edge that offers superior performance for several years. The reason is that cut edges are less susceptible to corrosion compared to post-painted metals without exposed edges.

Source:

https://prepaintedmetal.eu/874/889

https://prepaintedmetal.eu/875/benefits

https://www.coilcoating.org/media-resources/prepainted-metal-can-provide-cost-and-quality-benefits-to-manufacturers

Types of Top Coating

Pre-painted steel coils offer a long-lasting solution to building and construction needs. They boast of an organic coating layer that guarantees high resistance to corrosion, making them last for years compared to galvanized steel sheets. Their base metals consist of HDG electrogalvanized, hot-dip zinc-aluminum-magnesium, and cold-rolled.

Here are the top coatings on prepainted steel sheets and coils:

Polyester (PE)

Polyester coatings offer solidarity and flexibility to the metal sheets due to the monomer reactants used during the formulation of the polyester resin. These reactants have the ability to regulate the polyester’s performance during application. They consist of physical properties that enable them to resist weathering and degradation to the metal over many years of use.

High Durable Polyester (HDP)

High-durability polyester resin refers to a coating consisting of a high-molecular-weight polyester resin with a lesser amount of branched polymer. The polyester resin can be hydroxyl or carboxyl functional, which offers superior resistance to ultra violet compared to an ordinary polyester resin. These high-molecular-weight resins contain a high amount of isophthalic acid and can withstand aggressive environments.

Silicone Modified Polyester (SMP)

SMP is an improved version of commercial coil coatings due to its solvent-based chemistry. Comparing with PVDF coatings, SMP’s polyester can stand against weathering, while its silicon content offers gloss coating retention. The downside of SMP is that it is less flexible because the polymers have a branched structure and high crosslinks.

Polyvinylidene Fluoride (PVDF)

PVDF is a solvent-based architectural paint system that has superior weathering properties compared to other coating types. Its vinylidene fluoride monomer undergoes homopolymerization. This method allows the production of materials with an unobtrusive molecular weight and size suitable for a specific application.

The melamine-acrylic composition of PVDF is 70 percent PVDF and 30 percent acrylic for superior weathering performance and properties. Its downside is that it is costly and less flexible.

Source: https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote-4-1.pdf

Process of Pre-Painted Steel Coil

The fabrication of prepainted steel coils and sheets begins with the delivery of the substrate in coil form directly from the rolling mills. There are three sections involved in the coil coating line: entry, processing, and exit.

Each step ensures that the finished prepainted metal products are durable, high-performing, and aesthetically appealing. The machines in the production line work simultaneously to paint 2,000 to 4,000 square feet of metal strips per 4 minutes.

Here are steps at the coating line:

Step 1: Cleaning the Metal Strip

Cleaning up the oil, dirt, and impurities of the cold-rolled coil involves brushing, an alkaline dip, a water bath, or brushing.

Step 2: Application of Zinc and Alloy

The application of aluminum and zinc depends on the application and customer requirements. Some products consist of 100 percent zinc, while others contain magnesium alloy.

Step 3: Treatment of the Surface

This step is vital to ensuring that the paint and primer bond well with the metal strip. Due to some chemical restrictions, the surface is treated with chemicals, such as alkaline oxidation, depending on the supplier and country of origin.

Step 4: Metal Rinsing and Drying

Rinsing the metal strip helps ensure that it has no chemical residue before applying primer. Drying the metal is a must to ensure that the subsequent layers bond well.

Step 5: Application of Primer

A coating of primer can be on one or both sides of the metal strip. Primer application hastens the adhesion of the finished paint layer.

Step 6: Curing and Cooling the Strip

Curing takes 15 to 16 seconds. This method allows the primer to harden, dry, and reach the desired temperature before applying the next coating.

Step 7: Front and Back Coating

This step is the final painting stage, wherein two-coat paint systems are applied.

Step 8: Drying, Curing, and Cooling

The product undergoes this step to ensure that the steel product is ready for rewinding, rerolling, and shipping to end users.

Step 9: Packaging

Image showing a coil coating line schematic.

Source: https://www.coilcoating.org/process

Conclusion

The choice of steel substrate depends on the specific requirements of the application. Users must consider the level of corrosion resistance, aesthetics, and cost when choosing a steel product.

What is Galvanized Steel Coil?

Galvanized steel coil is a type of steel coil that has been coated with a layer of zinc to protect it from rust and corrosion. The process of galvanization involves immersing the steel coil in a bath of molten zinc, which creates a metallurgical bond between the zinc and the steel. It results in rust and corrosion resistance.

Galvanized steel coil is commonly used in a variety of industrial applications, such as the construction of buildings, bridges, and other infrastructure projects, as well as in the manufacturing of automotive parts, electrical equipment, and household appliances. It is also frequently used in the production of metal roofing and siding for residential and commercial buildings.

Galvanized steel is typically made from low-carbon steel, which is a type of steel that contains less than 0.2% carbon. This type of steel is used because it is easy to work with and has good welding and forming properties.

Steels Grade of Galvanized Steel Coil

Commercial Steel (CS)

This steel consists of carbon with a level range of 0.04 percent to 0.10 percent and manganese with a level range of 0.2 to 0.6 percent. CS has a cold-rolled substrate with a fifty- to eighty-percent reduction before it undergoes galvanizing line processing. Commercial steel has three types of chemical compositions, such as CS Type A, CS Type B, and CS Type C.

Forming Steel (FS)

This steel has about 0.25 percent manganese and 0.04 to 0.06 percent carbon. FS is not as hard compared to CS due to its 60 to 80 percent cold reduction during processing, which makes it formable during application.

Structural Steel (SS)

SS has a carbon level range of 0.04 to 0.20 percent and a manganese level range of 0.4 to 1.6 percent. The steel sheet undergoes cold rolling for a fifty- to seventy-percent reduction. Structural steel has a yield strength of 33–80 ksi and passes the standard requirements for mechanical properties.

Hot-Dip Galvanized Steel Coil Process

Hot-dip galvanized steel coil undergoes several steps. It passes a continuing process by using an entry-end welder to connect the coil’s end to the next coil. Dirt, oils, and surface contaminants on the sheet surface are eliminated in an alkaline cleaning section.

The steel passes through a heating process in an annealing furnace at the highest temperatures to apply the desired mechanical properties, such as formability and strength. The steel sheet undergoes a molten zinc bath at a certain coating level, depending on the application.

An application of gas knives takes place to clean up excess metal coating and reach the desired coating weight. The steel sheet goes to a cooling section to cool off and allow the coating to solidify after being removed from the bath. It passes through a temper mill to obtain the steel’s desired finish on its surface before flattening it using a tension leveler.

After meeting the end-user requirements, the steel sheet passes through a treatment section to protect it from storage stains on its coating surface. A forming oil is applied in the oiling section to prevent the sheet from rusting before it goes to a recoiler for rewinding.

resource: https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_2_1.pdf

Useful Galvanized coil Metrics

Theoretical Weight (Mass) per Unit Area

Hot-dip galvanized steel coil has a lower density compared to steel. Compared to an uncoated steel with the same thickness, hot-dip galvanized steel has a lesser weight per unit area. The theoretical weight per unit area is essential when manufacturing large volumes of coated steel.

The coating type, coating thickness, and steel substrate influence the weight adjustment in zinc alloys. The coating factor (CF) represents the weight (mass) adjustment per unit area. It is the weight difference between the steel of the same thickness and the coating metal. To calculate the theoretical weight per unit area of the coated sheet, you have to subtract the CF from the weight of the uncoated steel sheet with the same thickness.

resource: https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_1_10.pdf

What Portion of a Galvanized Coil is Zinc?

A standard galvanized coil has about 99.7 percent zinc coating. But it all depends on the steel sheet’s coil thickness. For example, a steel coil with 0.012″ thick G90 sheet has 12.5% zinc, while 0.050″ thick G90 has 3 percent zinc.

Thinner gauges contain a higher zinc content. The cost of zinc impacts the thickness of zinc coatings on galvanized sheets. The galvanizing thicknesses are represented by G numbers. For example, G60 has a zinc coating of 0.60 oz/ft2 on both sides. The zinc coating for each side is 0.5 mil (1 mil is equivalent to 0.001 inch).

resource: https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_1_10.pdf

Selecting Coating Thickness (Weight or Mass) for Galvanized Steel Coil

Effect of Atmospheric Conditions

Atmospheric conditions impact the corrosion rate of galvanized steel coils. Different regions of the world have different influences on their outdoor applications, like the southwestern part of the United States. This region experiences long, foggy seasons and high annual rainfall that contribute to corrosion.

Other factors affecting the corrosion rate include pollutants and impurities in the air, such as acid, nitrates, chlorides, sulfates, and smoke emissions. The oxygen content of the electrolyte, extreme temperatures, moisture, and humidity all contribute to the product life of galvanized steel coils.

Product Life Considerations

The coating weight (mass) in hot-dip galvanized steel depends on its performance requirements in the desired application. Outdoor applications like a metal building roof require a thicker zinc coating to prevent red rust formation.

Over the years, the roof has slowly started showing some red rust, which experts call the time for failure. This occurrence could have been avoided if the roof had a thick zinc coating. Considering the product life of the galvanized steel for a given application can reduce the perforation and corrosion rate.

Identifying the ideal thickness of steel and the ideal thickness of zinc coating for the specific outdoor applications can prevent failure. It is vital to match the information on the product life and corrosion rate by determining the zinc coating weight.

It can be seen in the picture. The greater the weight of the zinc coating, the longer the service life. 

A G60 coating weight will exhibit approximately twice the life of a G30 coating weight.

A G90 coating weight will exhibit about 50% longer life than a G60 coating weight.

resource: https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_1_6.pdf

Galvanized Coil vs. Galvannealed

Galvanized steel coil and galvannealed steel coil are two types of steel that have been coated with zinc to provide protection against corrosion. However, there are some key differences between these two types of steel:

Coating process: Galvanized steel coil is coated with a layer of zinc by immersing the steel coil in a bath of molten zinc. Galvannealed steel coil, on the other hand, is first coated with a layer of zinc and then subjected to a heat treatment process that alloyed the zinc and the steel, resulting in a zinc-iron alloy coating.

Coating appearance: Galvanized steel coil has a shiny, spangled appearance, while galvannealed steel coil has a matte gray finish.

Weldability: Galvanized steel coil is easier to weld than galvannealed steel coil, because the zinc coating on galvanized steel melts at a lower temperature than the zinc-iron alloy coating on galvannealed steel.

Paint adhesion: Galvannealed steel coil has better paint adhesion than galvanized steel coil, because the matte surface of galvannealed steel provides a better surface for paint to adhere to.

Hot-Dip Galvanized Steel Sheet  Spangle

Spangles on galvanized steel sheets come in different sizes and shapes. The sparkles look like snowflakes or stars that glitter when there is light reflection. Producers of hot-dip galvanized steel have developed technology to reduce the size of spangles as customers prefer smooth and lead-free coatings.

Here are the different sizes of spangles.

• Regular spangle: This is a visible spangle that develops when the molten zinc that clings to the steel cools uncontrollably below the zinc’s melting point. It results in multifaceted zinc crystals.
• Minimized spangle: The spangle looks visible, yet it contains smaller and fewer patterns compared to the regular spangle. The development of zinc crystal growth is inhibited using a special production technique or a combined technique of molten zinc bathing and cooling.
• Spangle-free: The galvanized sheet is smooth with the absence of surface irregularities. The uniform finish is a product of coating batch chemistry, cooling technique, or a combination of both.

Figure A shows large spangles≥ 15 mm across and Figure B shows medium spangles up to 10 mm across

Figure C has small spangles up to 5 mm across, Figure D is spangle-free ≤ 0.5 mm across.

resource: https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_2_6.pdf

Buyer’s Guide

Material Grade

When purchasing galvanized steel coils, the appropriate material grade should be selected according to the application. For roofing applications, the DX51D material of the en 10346 standard (equivalent to the Commercial steel of the ASTM A653 standard) should be selected. The light steel frame application will choose the astm a653 standard structural steel material, but it is necessary to purchase a suitable yield strength.

Coating Mass

The coating mass of the en 10346 standard is usually Z100, Z140, Z200, Z225, and Z275, which means both surfaces grams per square meter under the triple spot test method.

The coating mass of the ASTM A653 standard is commonly G30, G40, G60, and G90, which means both sides oz/square foot under the triple spot test method.

Tip: G90 = Z275

In the highly corrosive environment such as the seaside, you should choose the Z275 weight, and its price is relatively high.

Surface treatment

The purchase of galvanized coils should indicate the surface treatment, including Chemical passivation, Oiling, Phosphating, which play a role in preventing corrosion during transportation.

Conclusion

Choosing galvanized steel coil for outdoor application is a good decision. The product life depends on the thickness of the coating and the steel sheet.

What is Galvalume Steel Coil?

Galvalume steel coil is a type of steel coil that has a coating of aluminum-zinc alloy, which is applied to it through a continuous hot-dip process. The coating provides corrosion resistance to the steel. It is ideal for use in outdoor environments and in applications where moisture and humidity are present.

Galvalume steel coils are commonly used in roofing, siding, and other construction applications. They offer a combination of durability, corrosion resistance, and heat resistance that makes them a popular choice in extreme environmental conditions.

The name “Galvalume” is a combination of “galvanized” and “aluminum,” reflecting the fact that the coating is made up of both materials. The coating consists of aluminum (55%), silicone (1.6%), and zinc (43.4%).

The aluminum coating offers malleability, while the zinc offers galvanic protection for the steel from corrosion. This coating gives the steel a plain and smooth finish while ensuring long-lasting performance and aesthetic appeal for the finished project.

Galvalume Life Expectancy

Galvalume steel coils are resistant to corrosion and rusting, which means they can last for several decades even in harsh environments. According to research, galvalume has proven its outstanding performance in North America, which is prone to extreme conditions such as winter and acid rain.

The outdoor exposure tests on actual building installations prove that Galvalume steel sheets and coils are more resilient and have better corrosion resistance than zinc-coated sheets with the same coating thickness under the same harsh conditions. The steel’s service life expectancy can reach an average of up to 35 years without regular maintenance.

Source: https://sadofascoprod.blob.core.windows.net/media/clhmvpyk/amd-0621-galvalume-brochure-update-en.pdf

The test also revealed that the service life of Galvalume could reach 40 to 60 years in both rural and industrial environments. The study consists of atmospheric tests in which researchers used flat coupon samples over a span of 17 years in Canada and over 36 years in the United States.

Superior Cut Edge Protection

Galvalume steel coils have superior cutting-edge protection due to their aluminum-zinc alloy coating. The coating on the steel substrate offers long-lasting protection against the elements that contribute to corrosion, especially on the exposed edges of the steel.

The protective zinc coating offers galvanic protection to the steel. It means that the zinc does not produce corrosion within the encapsulated steel. This technology extends the life of galvalume steel by preventing the degradation of the underlying metal over time.

The aluminum component of Galvalume offers a long-term barrier against corrosion. It gives protection to the exposed edges under harsh environmental conditions. The cutting-edge protection of Galvalume makes it advantageous compared to galvanized steel and aluminum-coated steel.

Although galvanized steel has less corrosion, it can produce red rust at the bare edges, while aluminized steel performs only in marine environments. Galvalume provides a longer-lasting barrier to degradation than other types of steel products.

Manufacture

Galvalume has an alloy coating of 55 percent aluminum, 43.5 percent zinc, and 1.5 percent silicon during the hot-dip process. Silicon acts as a barrier against the development of a breakable intermetallic layer. This layer develops during the hot-dip processing while the zinc coating takes place.

The molten coating and steel sheet interact during the manufacturing, affecting the coating’s adhesion during applications. The hard and brittle intermetallic alloy layer must remain thin during processing by adding silicon to the 55 percent aluminum-zinc bath. Silicon helps control the expansion of the alloy layer, making it formable during application.

Silicon does not have a role in preventing corrosion. Some applications of aluminum-zinc-silicon alloy-coated steel were not effective in deep drawing. Instead of using steel coils or sheets with a 55 percent aluminum-zinc-silicon alloy, customers prefer galvanized sheets.

Recent coating technology uses clear resin coatings known as 55 percent Al-Zn Plus, which are effective in some applications of deep drawing.

Source: https://sadofascoprod.blob.core.windows.net/media/clhmvpyk/amd-0621-galvalume-brochure-update-en.pdf

Coating Microstructure

The 55% Al-Zn coating microstructure of galvalume consists of two phases. The first phase is known as the aluminum-rich dendritic phase, which develops during the solidification process. At this phase, the dendrite growth is due to the swift movement of the solid or liquid interface in the direction of the undercooled melt.

The second phase is known as the interdendritic zinc-rich region. It develops when the solidifying liquid’s zinc concentration is at its highest peak. The microstructure phases are vital to reaching the ideal corrosion resistance.

Apart from the two primary microstructural phases, there are other phases involved in the process, such as the intermetallic layer at the steel-coating interface and the discrete needles of the elemental silicon.

Note: See the figure below to find the interdendritic zinc-rich, aluminum-rich region, and the silicon needle.  The figure describes the microstructure of a 55 percent aluminum-zinc coating.

Source: https://www.galvinfo.com/wp-content/uploads/sites/8/2017/05/GalvInfoNote_1_4.pdf

Corrosion Resistance

Galvalume steel coils have superior performance compared to galvanized coatings in rural, industrial, and marine environments. The aluminum-zinc alloy coating has a unique dendritic structure that protects the steel from corrosion.

The zinc-rich areas are the first to corrode under harsh conditions. The corrosion rate decreases in the interdendritic areas of the coating because the corrosive products penetrate the interdendritic interstices. This development results in the flattening of the corrosion rate curve in various environments.

The 55 percent aluminum zinc coating corrosion behavior works differently with a galvanized coating, which has a uniform thinning process. The aluminum-rich dendrites act as a protective coating, while the zinc-rich regions offer galvanic protection to prevent rusting on the sheared and exposed parts of the steel.

Standard

Galvalume steel coil is manufactured according to different standards. It depends on the country or region where it is produced and used. Here are some examples of standards that are commonly used for galvalume steel coil:

• ASTM A792: This is the standard specification for steel sheets coated with a 55% aluminum-zinc alloy by the hot-dip process. This standard covers galvalume steel coil for use in architectural, building, and construction applications.
• JIS G 3321: This is the Japanese Industrial Standard for hot-dip, 55% aluminum-zinc alloy-coated steel sheet and strip. It covers galvalume steel coil for use in industrial and civil engineering applications.
• EN 10346: This standard refers to the European standard for hot-dip coated steel flat products for cold forming. This standard covers galvalume steel coils and sheets for use in construction applications.
• AS 1397: This is the Australian standard for steel sheet and strip, hot-dipped zinc-coated or aluminum zinc-coated. It covers galvalume steel coil and sheet for use in building and construction applications.

These standards specify the requirements for the different characteristics of galvalume steel coils. It includes the chemical composition, mechanical properties, dimensions, and surface quality of the products. The international standard-setting bodies ensure that the galvalume steel coil produced in different countries meets certain quality and performance standards.

Galvalume Steel Coil Process

Decoiling – Cleaning – Annealing – Zinc pot – Cooling – Air knife – Straightening – Post-treatment – Coiling

Detailed steps of the galvalume steel sheet processing

Step 1:

Pre-treatment: After the cold-rolled coil arrives in the galvalume workshop, after passing through the uncoiler,  through the degreasing section, and the reduction furnace, the steel coil is cleaned and its components are reduced to the extent that it can be galvanized.

Step 2:

Central section: The most critical technology is this step. After passing through the zinc pot, a layer of zinc layer is plated on the surface of the steel plate. After coming out of the zinc pot, it is cooled and shaped by the cooling tower.

Step 3:

Post-processing: The steel plate finally comes to the post-processing stage after various processes. After finishing, straightening and passivation, and finally coiling

Galvalume Sheet vs. Galvanized Sheet

Galvalume sheet and galvanized sheet are types of coated steel sheets for various applications. Here are some differences between galvalume sheet and galvanized sheet:

• Corrosion Resistance: Galvalume sheet offers better corrosion resistance compared to galvanized sheet because of the aluminum and silicon in its coating. Galvalume sheet has been shown to provide up to two to four times longer service life compared to galvanized sheet in some applications. Galvanized sheet is prone to corrosion because it does not have silicon and aluminum coating.  
• Composition: Galvalume sheet is made of a combination of zinc, aluminum, and silicon, while galvanized sheet is coated with pure zinc.
• Surface Appearance: Galvalume sheet has a shiny, spangled surface, while galvanized sheet has a matte surface.
• Formability: Galvalume sheet is more formable than galvanized sheet. This is due to its lower coating weight and higher ductility. This makes it easier to work with and bend into different shapes.
• Cost: Galvanized sheet is generally cheaper than galvalume sheet due to its simpler coating composition.
• Popularity: Galvalume is a popular choice in metal roofing in the agricultural, commercial, residential, and industrial sectors. In the late 90s and early 2000, over 90 percent of the industry had transformed from galvanized substrate to galvalume substrate.

Sources:

Conclusion

Galvalume steel coil offers better corrosion resistance and formability than galvanized steel coil. The choice between the two depends on the specific application and the required performance characteristics.

GI Coil Price in India

• Manu Metal 2mm Galvanized Iron GP Coil for the automobile industry costs ₹ 85 / kilogram. This rustproof hot rolled GI coil has a thickness of 2 mm and a width of two feet.
• Winsteel Empire GI Galvanized Iron Coil is available at ₹ 70 / Kilogram. This hot-rolled GI coil has a thickness range of 0.3 – 3 mm and coil widths of 1 to 3 feet. The coil length is available up to 1200 meters.
• Limited Company Galvanized GI Coils for industrial uses are available at ₹ 48,000/ metric ton. This coil is a 100 percent product of India. It has a thickness of   0.30 – 3.00 mm and tensile strength of 240 – 550 Mpa. 
• Super Steel Enterprises GI Coil is available at ₹ 48/ Kilogram. This hot-rolled galvanized iron coil has a width of 600 to 1200mm, and its thickness is 0.5 to 2mm. 
• Maheshkumar & Co. Galvanized Iron Coil (mild steel) for construction costs ₹ 65 per kilogram. This hot-rolled GI coil is corrosion-resistant. The minimum order quantity is 3000 kilograms. 
• ITC Polished Galvanized Iron Coil for industrial purposes is available at ₹ 70 per kilogram. This rectangular GI coil has a thickness of 3.5 mm and a width of four feet. The minimum order quantity (MOQ) is 100 kilograms. 
• Jindal Stainless Steel Galvanized Coil for construction costs ₹ 49 per kilogram. It has a thickness of 0.5 to 6mm and a weight of 2 to 3 tons. It is available in various standard grades, such as EN, BDS, DIN, JIS, ASTM A, and GOST. 
• Indian & Imported Galvanized Iron Coil at ₹ 60 per kilogram. It is available in various packagings, such as pallet packing, export quality packing, and plastic & Hessian cloth packing. This coil comes in hard, semi-hard, and soft hard materials. It has a thickness of 0.05mm to 4.00mm and widths of 4.5mm to 2000mm. 
• Sim Enterprises Galvanized Iron Coil price is ₹ 55 per kilogram. This corrosion-resistant GI coil has a thickness of 0.30mm and a width of five feet. It comes in roll packaging. 
• ESSAR/JINDAL/POSCO 90gsm/120gsm GI Coils are available at ₹ 55/ Kilogram. These coils have a surface finish of 90gsm/120gsm and dimensions of 1000 and 1220. 1250, and 1500. They come in thicknesses of 0.5mm to 120mm and lengths of one meter and above. The minimum order quantity is 5000 per kilogram.

Conclusion

Have you found the lowest price of GI coil in India? Get it from Super Steel Enterprises. It offers the lowest price at ₹ 48/ Kilogram.

PPGI Coil Price in India

• Dana Steel Prepainted Galvanized PPGI Steel Coil has a thickness of 0.12mm to 1.0mm, and surface treatment is Polyester – RMP/SMP/HDP or PVDF ( Poly Vinyl Di Fluoride). The inner diameter coil is 508mm, and the accuracy of +/- 0.02mm. The zinc coating ranges from 40gsm – 350 gsm. This PPGI coil weighs 3 to 6 metric tons with a tensile strength of 280-550 Mpa. The coil price is 60 Rupees per kilo. 
• Shree Balaj PPGI Sheet Coils cost ₹ 86 / Kg to 100/Kg. The coils have a thickness of 0.3 mm to 0.7 mm and weigh 1220 to 1450mm. The surface has a paint coating.
• Swagat Steel PPGI Sheets for ₹ 74 / Kilogram. It comes in any color and brand, and its thickness is 0.40mm to 0.60mm. MOQ is 1000 kilograms
• Vishal Agro Steel Color Coated PPGI Color Coil at ₹ 95,000 /ton. This product is available in 1220mm, with 1440 mm widths and thicknesses of 0.35- .80 mm. The minimum Order Quantity is five tons.
• Jain Iron & Steel PPGI Coil at ₹ 68 / kilogram. PPGI’s thickness is 1mm to 6mm, with widths from 20 to 200mm. MOQ is 10000/kilogram.
• Prabhat Color-Coated Construction PPGI Coil at ₹ 77 / Kg. 

This coil has a thickness of 0.15 – 1.00mm with a width of 760- 600mm. Its input coil weight is up to  15 MT and its output coil weight of 4-6 MT. The tensile strength is up to 550 Mpa, while the yield strength is up to 450 Mpa. The coating thickness is up to 45 microns.

• Tata Blue 0.5mm PPGI color-coated coil at ₹ 63 / Kg. It has a thickness of 0.5mm with roll packaging.
• Morvi Nandan Steels, Red PPGI Coil at ₹ 88 / Kg. This color-coated coil has a thickness of 1mm with a glossy finish. MOQ is 200 kilograms. 
• Balaji Industries Color Coated PPGI COIL for ₹ 89 / Kg. This coil is available in all colors and dimensions. The minimum order quantity is 4000 kilograms.
• A. K. Roofing, Blue PPGI Color Coated Galvanized Coils at 

₹ 99 / Kg. This Indian-made product has a thickness of 0.40 mm. MOQ is five kilograms.

• Deep Chand Traders Coated White PPGI Coil at ₹ 95 / Kg. The thickness of this coil for construction is 2mm. The minimum order quantity is 200 kilograms.

Conclusion

Have you found the lowest price of PPGI in India? Dana Steel Prepainted Galvanized PPGI Steel Coil is the cheapest at 60 Rupees per kilo. 

The thickness of the substrate affects the price. The thicker the substrate, the lower the price.

The thickness of the aluzinc layer of the galvalume sheet, the minimum of our company’s aluzinc layer is 30g, the highest can be 180g, the higher the aluzinc layer, the higher the price

Galvalume steel coils are divided into anti-fingerprint-resistant and ordinary anti-fingerprint-resistant. The anti-fingerprint galvalume coil is coated with a layer of colorless and transparent resin on the basis of the galvalume coil, which can protect the surface of the coil from being scratched and prolong its service life. The price of a fingerprint-resistant aluzinc coil is 10-20 US dollars per ton higher than that of an ordinary fingerprint-resistant aluzinc coil of the same thickness. Now most customers purchase fingerprint-resistant galvalume coils.

This is the reference price of FOB Qingdao, Japan