DX51D+AZ Vs. S350GD+AZ: How To Choose The Right Strength For Your Project

DX51D+AZ is a commercial forming-grade galvalume steel for general bending and non-load-bearing usage, while S350GD+AZ is a high-strength structural galvalume grade designed for load-bearing, wind resistance and structural engineering applications; the two differ fundamentally in yield strength, forming performance and applicable scenarios.

 

DX51D+AZ is a standard low-strength commercial galvalume steel grade under EN 10346 and GB/T 2518, optimized for excellent cold forming, bending and profiling without strict structural load requirements.

 

Standard yield strength: ≤260 MPa

Tensile strength: 360–510 MPa

Elongation rate: ≥22%, excellent bending and roll-forming ability

Coating range: AZ40–AZ275 g/m² fully available

Market share: Occupies over 65% of global galvalume roofing and cladding material consumption (2025 industry statistical data)

Best for: Simple profiling, roof sheets, wall panels, common civil building enclosure materials, home appliance shell parts

 

S350GD+AZ is a high-strength structural galvalume steel grade formulated for load-bearing structural components, featuring minimum 350 MPa yield strength and outstanding wind and pressure resistance.

 

Standard minimum yield strength: ≥350 MPa

Tensile strength: 420–560 MPa

Elongation rate: ≥16%, limited deep forming performance compared with DX51D+AZ

Coating compatibility: Supports full AZ coating weight from AZ80 to AZ275 g/m²

Structural advantage: Can reduce steel usage by 15–20% in purlin and steel truss projects due to high strength

Best for: Steel purlins, structural frames, warehouse buildings, high-rise enclosure, coastal wind-resistant structures, automotive structural parts

 

The biggest gap between the two grades lies in yield strength and ductility; DX51D+AZ wins in formability, S350GD+AZ dominates in structural bearing capacity.

 

Parameter	DX51D+AZ	S350GD+AZ	Practical Impact
Yield Strength	≤260 MPa	≥350 MPa	S350GD+AZ bears higher wind and structural load
Elongation	≥22%	≥16%	DX51D+AZ suits complex bending and deep profiling
Forming Ability	Excellent	Moderate	DX51D+AZ for customized curved profiles
Structural Load	Not recommended	Fully applicable	S350GD+AZ for load-bearing structural parts
Price Level	Base price	5–7% higher	S350GD+AZ has slight premium but saves material quantity

 

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Choose DX51D+AZ for non-structural decorative and enclosure materials; choose S350GD+AZ once the project involves load bearing, wind resistance and structural stress.

• Choose DX51D+AZ If Your Project Is:

Metal roof panels and wall cladding without structural load

Simple corrugated sheets, flat sheets and light profiling

Household electrical equipment shells, ventilation ducts

Low-rise temporary buildings with no strict wind resistance requirements

Projects requiring complex bending, rolling and deep drawing processing

 

• Choose S350GD+AZ If Your Project Is:

Steel purlins, C/Z section steel, roof truss structures

Large warehouse, factory building, logistics park main steel enclosure

Coastal high wind pressure areas, rainy and harsh climate zones

High-rise building exterior wall structural supporting parts

Projects pursuing lightweight design to reduce overall steel consumption

 

Both DX51D+AZ and S350GD+AZ support the full AZ coating weight range and have identical corrosion resistance under the same coating mass; strength grade does not affect anti-rust performance.

 

Same coating standard: 55% Al, 43.4% Zn, 1.6% Si alloy composition

Salt spray test data: Both grades with AZ150 coating reach over 5000 hours neutral salt spray resistance

Coastal / industrial environment: Both can use AZ180–AZ220 heavy coating for extended service life

No difference in surface quality, spangle type and passivation treatment between the two grades

 

Although S350GD+AZ has a unit price 5–7% higher than DX51D+AZ, it can cut overall project steel consumption by 15–20%, resulting in comprehensive cost reduction for structural projects.

 

For regular roofing projects: DX51D+AZ is more cost-effective with sufficient performance

For large steel structure factories: S350GD+AZ lowers total material and installation cost

Long-term service life: Both grades achieve 25–50 years outdoor service with standard AZ coating

 

Q1: Can DX51D+AZ replace S350GD+AZ for structural purlins?

A1: No. DX51D+AZ lacks sufficient yield strength to bear wind load and structural stress; using it instead will bring hidden safety risks and fail engineering design standards.

 

Q2: Can S350GD+AZ be used for common roof sheets?

A2: It is technically usable but not recommended. S350GD+AZ has poorer ductility, is harder to profile, and has a higher unit cost, causing unnecessary waste for ordinary roof projects.

 

Q3: Do DX51D+AZ and S350GD+AZ differ in corrosion resistance?

A3: No. Corrosion performance depends only on AZ coating weight and production process. With the same coating mass, both grades have exactly the same anti-rust and heat reflection performance.

 

Q4: What is the most commonly used coating for these two grades?

A4: AZ150 is the mainstream choice for global construction accounts for over 70% of orders; AZ100 for indoor use and AZ180–AZ220 for coastal and industrial polluted areas.

 

Q5: Are both grades compliant with international standards?

A5: Yes. Both fully comply with EN 10346, GB/T 2518, and match international technical parameters, suitable for export to Europe, Southeast Asia, Africa and other markets.

 

Q6: Can GNEE STEEL supply customized thickness and coating for both grades?

A6: Yes. GNEE STEEL provides DX51D+AZ and S350GD+AZ in full thickness range 0.2–3.0mm, customizable spangle, passivation and oiling treatment, supporting one-stop project matching supply.