Galvalume Steel Coil (GL Coil)

Overview of Galvalume Steel Coil (GL Coil)

Galvalume steel coil, also known as Aluzinc steel coil (GL coil), is a carbon steel strip hot-dip coated with a unique 55% aluminum-zinc alloy. This advanced coating, consisting of approximately 55% aluminum, 43.4% zinc, and 1.6% silicon, provides superior long-term corrosion resistance compared to traditional galvanized steel, especially in severe atmospheric and marine environments. Specified under standards such as ASTM A792 / EN 10346 / JIS G3321, Galvalume steel coil combines the barrier protection of aluminum with the sacrificial protection of zinc, creating a highly durable and cost-effective material.

The coil is manufactured on a continuous hot-dip coating line where a cold rolled steel coil is cleaned, annealed, and immersed in a molten bath of the Al-Zn alloy before being recoiled. The resulting coating offers 2 to 4 times the service life of galvanized steel with an equivalent coating thickness. The Al-Zn alloy coating weight is designated by ‘AZ’, with common specifications including AZ100 (100 g/m²), AZ150 (150 g/m²), and AZ185 (185 g/m²). Galvalume steel coil is the primary raw material for high-performance metal roofing, architectural wall cladding, and as the premium substrate for Prepainted Galvalume (PPGL) steel.

Key Features and Coating Performance

Galvalume steel coil offers exceptional corrosion resistance through a combination of barrier and sacrificial protection. The high aluminum content in the coating forms a durable, inert aluminum oxide barrier layer that isolates the steel from the environment. The zinc component provides sacrificial cathodic protection at cut edges, scratches, and perforations. This dual mechanism results in a service life that can exceed 50 years, particularly for AZ150 coatings.

The coil is supplied in a thickness range from 0.12mm to 3.0mm with widths from 600mm to 1500mm, typically in weights of 3-8 tons. Substrate grades include DX51D+AZ (general forming), DX52D+AZ (deep drawing), up to DX54D+AZ (extra deep drawing), and high-strength structural grades like S280GD+AZ and S350GD+AZ. Galvalume steel has a characteristic small, silvery, and aesthetically pleasing spangle. Common surface treatments include clear Anti-Fingerprint (AFP) coating (acrylic passivation), which prevents staining and improves roll-forming performance, and oiling.

Main Applications of Galvalume Steel Coil

As a primary raw material, Galvalume steel coil is processed by roll-formers and manufacturers to produce a wide range of products. It is the preferred choice for creating architectural and residential metal roofing systems, including standing seam roofs, corrugated panels, and roof tiles. It is slit and formed into wall cladding, building facades, industrial siding, and components for pre-engineered metal buildings where long-term durability and low maintenance are critical.

The agricultural sector uses GL coil to manufacture grain silos, barns, and livestock confinements. In the automotive industry, its excellent heat resistance (up to 315°C) makes it ideal for producing mufflers, exhaust pipes, and heat shields. Appliance manufacturers form Galvalume coil into components for air conditioners, ovens, and water heaters. Most importantly, it is the primary substrate for producing Prepainted Galvalume (PPGL) coils, which are then used in a vast array of colored architectural and decorative applications.

Why Choose Us for Galvalume Steel Coil

Shandong Tanglu Metal Material Co., Ltd. supplies premium Galvalume steel coil (Aluzinc) from leading Chinese mills with internationally recognized production lines certified to ISO 9001 and ISO 14001 standards. Every coil is subject to stringent quality control, including chemical composition analysis, mechanical property testing (tensile, yield, elongation), and Al-Zn coating weight verification according to ASTM A792 / EN 10346. We also perform salt spray corrosion testing (ASTM B117) to confirm the coating’s superior performance.

We provide a full range of specifications, including thickness from 0.12mm to 3.0mm, width 600-1500mm, and Al-Zn coating weights from AZ50 to AZ200. We stock various substrate grades (DX51D+AZ to S350GD+AZ) with surface treatments like Anti-Fingerprint (AFP) coating. With extensive experience exporting to roofing manufacturers, PPGL producers, and construction contractors in over 80 countries, we can fulfill both project-based and bulk container orders efficiently. Each shipment is accompanied by an original mill test certificate (MTC) to EN 10204 3.1, with options for EN 10204 3.2 and third-party inspections (SGS, BV) to meet your project’s quality assurance requirements.