DX51D Z275 Galvanized Steel Coil Specifications: Full Technical Guide

When sourcing high-strength, corrosion-resistant flat steel for industrial manufacturing, understanding DX51D Z275 galvanized steel coil specifications is critical. This material, defined by EN 10346, combines a cold-forming steel substrate (DX51D) with a heavy zinc coating of 275 g/m² (Z275). As a leading galvanized steel supplier with 15+ years of export experience, ChinaCNU Steel produces these coils at our ISO-certified Qingdao factory, offering FOB pricing and a standard MOQ of 25 tons. In this guide, we break down the exact mechanical properties, coating tolerances, and dimensional data you need to specify DX51D+Z275 for your next project. Whether you are a procurement manager for a roofing manufacturer or a structural engineer, this page provides the technical depth that beats competitors like Hengze Steel, SteelPRO Group, and Wanzhi Group.

Understanding DX51D Z275: Material Designation and Coating

The designation DX51D+Z275 follows the European standard EN 10346. “DX51D” indicates a steel grade intended for cold forming, with a maximum yield strength of 280 MPa. The “Z275” suffix means the hot dip galvanized coil carries a total zinc coating mass of 275 g/m² (both sides combined). This is a heavy-duty coating, significantly thicker than common Z60 or Z120 grades, providing superior corrosion resistance in aggressive environments. Many buyers confuse Z275 with coating thickness; in practice, Z275 equates to approximately 19-20 microns per side. Our Qingdao factory uses a continuous hot-dip process, ensuring a uniform spangle and excellent adhesion. For comparison, a GI coil with Z60 coating is ideal for indoor applications, while Z275 is specified for outdoor structures, agricultural buildings, and solar mounting systems. This specification is also commonly referenced alongside DX51D+AZ150 (Aluzinc), but the Z275 offers better cathodic protection at a lower cost. When you order from ChinaCNU Steel, each coil is tested for coating weight per ASTM A90 or EN 10346 annex.

Mechanical Properties and Dimensional Tolerances

Yield Strength and Tensile Data

The DX51D grade is a low-carbon steel optimized for bending and profiling. The guaranteed DX51D Z275 galvanized steel coil specifications include a minimum yield strength of 140 MPa and a maximum of 280 MPa in the as-delivered condition. Tensile strength ranges from 270 to 500 MPa, with elongation (A80) of at least 22%. These values ensure the material can be roll-formed into trapezoidal sheets, corrugated panels, or purlins without cracking the zinc layer. Our production line at the Qingdao factory consistently delivers yield strengths in the 180-240 MPa range, which is ideal for most construction applications. If you require higher strength, we also offer S350GD+Z275, but DX51D remains the most cost-effective choice for cold forming.

Thickness, Width, and Flatness Tolerances

Standard thickness for DX51D Z275 coils ranges from 0.30 mm to 3.00 mm. Widths are available from 600 mm to 1500 mm. Tolerances follow EN 10143 Class A (normal) or Class B (tight). For example, a 1.2 mm thick coil has a tolerance of ±0.06 mm (Class A). Width tolerances are ±5 mm for slit edges. Flatness is controlled to a maximum wave height of 3 mm per 1000 mm length. These tolerances are critical for automated stamping and roll-forming lines. We recommend specifying Class B tolerances for exposed architectural panels. All coils are edge-trimmed and oiled to prevent white rust during transit. For a quick reference, see the comparison table below.

Data Comparison: DX51D Z275 vs. Z60 vs. Z120 vs. AZ150

This table clearly shows that Z275 offers the best balance of corrosion resistance and economy for most structural steel applications. While AZ150 provides longer life in salt-spray tests, the Z275 coating is more ductile and easier to weld. Our hot dip galvanized coil with Z275 is the most popular export grade from our Qingdao factory, accounting for 60% of our monthly production.

Quality Certifications and Export Standards

Every coil of DX51D Z275 delivered by ChinaCNU Steel is ISO certified under ISO 9001:2015 and complies with EN 10346:2015. We also meet ASTM A653/A653M for the US market, where the equivalent designation is CS Type B with G90 coating (Z275 roughly equals G90). Our factory in Qingdao has exported to over 50 countries, including the USA, Canada, Australia, UAE, and all EU nations. Each shipment includes mill test certificates (MTC) with chemical composition, mechanical properties, and coating weight analysis. We use third-party inspection agencies like SGS or BV for large orders at no extra cost. This transparency beats competitors who often omit detailed test data. For buyers requiring specific surface treatments—such as chromate passivation, oiling, or anti-fingerprint coating—we offer these as standard options with a 2-week lead time.

Pricing, MOQ, and Logistics from Qingdao

We offer competitive FOB pricing from Tianjin Xingang port. For DX51D Z275 galvanized steel coil, the current FOB price ranges from $680 to $720 per metric ton (depending on thickness and width). Our MOQ is 25 tons per size, which allows us to maintain efficient production runs and pass the savings to you. For a standard 20-foot container, you can fit approximately 25-28 tons of coil (width 1000-1250 mm). We also offer CIF, CNF, and DDP terms for regular clients. Lead time is 15-20 days after confirmation of proforma invoice. All coils are packed for sea freight: three layers of waterproof paper, steel side caps, and steel skids with export-grade strapping. This packaging ensures zero damage even on long voyages to South America or Africa. As a galvanized steel supplier with a Qingdao factory, we control the entire supply chain—from hot-dip line to loading—which is why we can offer reliable delivery dates.

Frequently Asked Questions (FAQ)

1. What is the difference between DX51D Z275 and DX51D Z120?

The primary difference is the zinc coating mass. Z275 has 275 g/m² total coating, while Z120 has only 120 g/m². This makes Z275 approximately 2.3 times more corrosion-resistant in salt-spray tests. Z120 is suitable for indoor or short-life applications, while Z275 is specified for outdoor structures requiring 10-20 year durability.

2. Can DX51D Z275 be welded without damaging the coating?

Yes, but zinc fumes are toxic, so proper ventilation is required. For spot welding or seam welding, the Z275 coating may be partially burned off near the weld zone. We recommend using a zinc-rich primer on welded areas for continued corrosion protection. For structural welds, grinding the coating off first is common practice.

3. What is the minimum order quantity (MOQ) for DX51D Z275 coils?

Our standard MOQ is 25 metric tons per size/specification. For trial orders, we can accommodate 15-20 tons at a slight premium. Contact our sales team for custom requirements. We also accept mixed containers (multiple sizes) for larger commitments.

4. How does the FOB price from Qingdao compare to other Chinese ports?

Tianjin Xingang port offers competitive ocean freight rates to North America, Europe, and Southeast Asia. Our FOB prices are typically 2-3% lower than those from Tianjin or Shanghai due to lower inland logistics costs. We also have faster vessel schedules to the US West Coast (18 days) and Rotterdam (25 days).

5. Does the Z275 coating meet the ASTM G90 standard?

Yes, Z275 (275 g/m²) is approximately equivalent to G90 (90 g/ft²) under ASTM A653. The exact conversion: 1 g/ft² = 10.76 g/m², so G90 = 968.4 g/m²? This is a common misconception. Actually, G90 refers to the coating weight in ounces per square foot. G90 = 0.90 oz/ft² = 275 g/m². So Z275 is the direct metric equivalent of ASTM G90. Both standards specify the same coating mass.