The Ultimate Guide To Galvalume Steel Grades: China Vs. International Standards

 

Galvalume steel refers to hot-dip aluminum-zinc alloy coated steel (55% Al, 43.4% Zn, 1.6% Si), with China's GB/T standards aligning closely with global norms while maintaining localized grade designations for cost-efficiency and regional adaptability.

 

Galvalume steel is a cold-rolled or hot-rolled steel substrate coated with a 55% aluminum-zinc alloy via continuous hot-dip process, delivering 2–4 times longer corrosion resistance than traditional hot-dip galvanized steel (HDG) and excellent heat reflectivity (up to 80% for infrared radiation).

 

• Key Performance Metrics (2025 Industry Data)

Coating Composition: 55% Al, 43.4% Zn, 1.6% Si (fixed global standard)

Coating Weight Range: AZ30–AZ275 g/m² (China: AZ40–AZ220 g/m²; International: AZ30–AZ275 g/m²)

Service Life: 15–25 years (indoor), 25–50 years (outdoor, non-coastal)

Yield Strength: 220–550 MPa (covers commercial, drawing, and structural grades)

 

China's Galvalume steel standards are primarily GB/T 2518-2019 (general purpose) and GB/T 3274 (structural use), while international mainstream standards include ASTM A792M (US), EN 10346/10327 (Europe), and JIS G 3321 (Japan). All standards follow the same coating composition but differ in grade naming rules and tolerance ranges.

 

• Standard Core Differences

 

Standard	Grade Naming Logic	Key Features
China GB/T	DC51D+AZ / S250GD+AZ (substrate strength + coating type)	Emphasizes cold-forming performance; tight thickness tolerance (±0.03mm)
ASTM A792M	CS-B / SS230 (commercial/structural + yield strength ksi)	Simplified grade system; focuses on tensile strength for North American construction
EN 10346	DX51D+AZ / S220GD+AZ (same as China's structural grades)	Global universal grades; strict coating uniformity requirements
JIS G 3321	SGLCC / SGLC400 (Steel Galvalume Commercial + strength)	Divided into general (SGLCC) and structural (SGLC) series; popular in Asia

 

 

3.1 Commercial & Drawing Grades

Commercial Galvalume steel grades are designed for non-structural applications (roofing, wall panels, appliances), with China's DC series fully equivalent to global mainstream grades.

 

China GB/T	EN 10346	ASTM A792M	JIS G 3321	Key Application
DC51D+AZ	DX51D+AZ	CS-B / CS-C	SGLCC	General roofing, wall cladding
DC52D+AZ	DX52D+AZ	DS	SGLCD	Deep drawing parts (appliance shells)
DC53D+AZ	DX53D+AZ	DDS	SGLCDD	Extra-deep drawing (complex stamped parts)
DC54D+AZ	DX54D+AZ	-	-	Ultra-deep drawing (high-precision components)

 

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3.2 Structural Grades (Load-Bearing Applications)

Structural Galvalume steel grades have yield strength ≥250 MPa, used for steel structures, purlins, and automotive parts. China's S series aligns with EN and ASTM structural grades.

 

China GB/T	EN 10346	ASTM A792M	JIS G 3321	Yield Strength (MPa)
S250GD+AZ	S250GD+AZ	SS255	-	≥250
S280GD+AZ	S280GD+AZ	SS275	SGLC400	≥280
S350GD+AZ	S350GD+AZ	SS340	SGLC440	≥350
S550GD+AZ	S550GD+AZ	SS550	SGLC570	≥550

 

Galvalume coating weight (AZ value) directly determines corrosion resistance, with China's standard range (AZ40–AZ220 g/m²) covering 90% of global application scenarios. International standards offer a wider range (AZ30–AZ275 g/m²) for extreme environments.

 

• Coating Weight Classification & Application

 

Coating Type	Weight Range (g/m²)	China Standard	International Standard	Typical Use
Light Coating	AZ30–AZ80	AZ40–AZ80	AZ30–AZ80	Indoor appliances, dry areas
Medium Coating	AZ100–AZ150	AZ100–AZ150	AZ100–AZ150	General construction, roofing
Heavy Coating	AZ180–AZ275	AZ180–AZ220	AZ180–AZ275	Coastal areas, industrial zones

 

• Key Performance Difference (2025 Test Data)

 

Corrosion Resistance: China's AZ150 = ASTM AZ150 = EN AZ150 (5000+ hours salt spray resistance)

Thickness Tolerance: China ±0.03mm vs. International ±0.04mm (China has stricter precision)

Price Advantage: China's Galvalume steel is 8–12% lower than European/American equivalents (due to localized production and scale)

 

Selecting Galvalume steel grades depends on application scenario, required strength, corrosion environment, and budget-China's GB/T grades offer the best balance of performance and cost for global projects.

• Step-by-Step Selection

Non-structural (roofing/wall panels): Choose DC51D+AZ (China) / DX51D+AZ (EN) / SGLCC (JIS) with AZ100–AZ150 coating

Deep drawing (appliances): Choose DC52D+AZ / DX52D+AZ / SGLCD

Structural (purlins/steel frames): Choose S350GD+AZ (China) / S350GD+AZ (EN) / SGLC440 (JIS)

Coastal/industrial areas: Upgrade to AZ180+ coating weight for 30% longer service life

 

Q1: Is China's Galvalume steel equivalent to international standards?

A1: Yes. China's GB/T 2518-2019 and GB/T 3274 standards are fully aligned with EN 10346, ASTM A792M, and JIS G 3321 in coating composition, mechanical properties, and grade equivalence.

 

Q2: What is the most popular Galvalume steel grade in China for export?

A2: DC51D+AZ (commercial grade) and S350GD+AZ (structural grade) are the top choices, accounting for 70% of China's Galvalume steel exports (2025 customs data).

 

Q3: Does Galvalume steel require additional painting?

A3: No. Galvalume steel has inherent corrosion resistance. Painting is optional for aesthetic purposes or extreme environments (e.g., chemical plants).

 

Q4: What is the maximum thickness of Galvalume steel available?

A4: China's standard thickness range is 0.2–3.0mm; international standards offer 0.3–2.25mm. Custom thicknesses up to 4.0mm are available for special projects.

 

Q5: How does Galvalume steel compare to HDG in cost and performance?

A5: Galvalume steel costs 5–8% more than HDG but delivers 2–4 times longer corrosion resistance, reducing maintenance costs by 40% over 10 years.

 

Q6: Can GNEE STEEL provide customized Galvalume steel grades?

A6: Yes. GNEE STEEL offers customized grades (e.g., DC51D+AZ with AZ200 coating, S280GD+AZ for automotive parts) and complies with GB/T, EN, ASTM, and JIS standards.