Products Description
Testing the mechanical properties of S280GD+AZ steel coils relies on three core standard tests - tensile test, salt spray test, and hardness test - to verify yield strength compliance, aluzinc AZ coating corrosion lifespan, and higher structural-grade hardness compared with regular forming steel grades.
S280GD+AZ is a high-strength structural aluzinc steel widely used in solar mounting systems, high-rise roofing, and coastal infrastructure. To guarantee project safety and a 25-year service life, every batch of S280GD+AZ steel coils must undergo strict performance inspection. Standard mechanical and corrosion testing can confirm whether the substrate meets EN 10346 strength requirements and whether the AZ aluzinc coating provides qualified anti-corrosion protection. Below is a detailed introduction to the complete testing process and standards.
1. Tensile Test: Verify Yield Strength & Mechanical Performance
The tensile test is the most critical inspection for S280GD+AZ, used to confirm its minimum yield strength reaches ≥280MPa and meets structural load-bearing design standards.
The tensile test follows EN ISO 6892-1 standard. Standard sample strips are cut from the head, middle, and tail of S280GD+AZ steel coils to ensure batch consistency.
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Key Testing Purposes
Confirm minimum yield strength ≥280MPa to distinguish structural grade from ordinary forming grades like DX51D.
Detect tensile strength range: 330–450MPa.
Control elongation to ensure sufficient formability for roll forming and bending processing.
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Practical Significance
Only qualified tensile test data can ensure S280GD+AZ withstands long-term wind pressure, snow load, and static weight in solar brackets and high-rise roofing, avoiding structural deformation or collapse.
2. Salt Spray Test: Prove AZ Coating Corrosion Resistance Lifespan
The salt spray test simulates high-salt fog coastal environments, verifying that the 55% Al-Zn AZ coating of S280GD+AZ delivers stable corrosion resistance and supports a 25-year service life.
The test complies with ASTM B117 neutral salt spray standard, the mainstream inspection method for aluzinc steel coatings worldwide.
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Testing Process & Standard
Place S280GD+AZ sample in continuous salt spray atmosphere with 5% sodium chloride solution.
Observe surface rust, white rust, and coating peeling at fixed time intervals.
Qualified S280GD+AZ with standard AZ100–AZ150 coating can maintain no red rust for over 720 hours in salt spray testing.
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Practical Value
This test effectively proves that the AZ aluzinc coating of S280GD+AZ performs far better than ordinary galvanized steel in coastal and humid industrial areas, ensuring long-term durability for photovoltaic support and exterior building structures.
3. Hardness Test: Distinguish Structural Grade from Ordinary Forming Grade
Hardness testing verifies that S280GD+AZ structural steel has higher hardness than regular stamping grades, reflecting its stronger internal structural rigidity and load-bearing capacity.
The test adopts Rockwell HRB or Vickers HV hardness testing methods, commonly used for coated thin steel coils.
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Core Characteristics
S280GD+AZ structural aluzinc steel shows higher hardness value than DX51D and other commercial drawing grades.
Higher hardness means better rigidity, anti-pressure ability, and resistance to bending deformation under external load.
Hardness data matches yield strength results, forming dual verification of structural performance.
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Application Meaning
Hardness testing helps buyers and processors quickly identify genuine S280GD+AZ structural grade steel, avoiding substitution with low-hardness ordinary forming steel for load-bearing projects.
4. Standard Full Inspection Flow for S280GD+AZ Steel Coils
Complete qualification inspection of S280GD+AZ must combine tensile test + salt spray test + hardness test to ensure mechanical properties, coating performance, and structural rigidity all meet EN 10346 requirements.
Cut standard samples from different positions of steel coils.
Conduct tensile test to check yield strength, tensile strength and elongation.
Perform hardness test to confirm structural-grade rigidity.
Carry out salt spray test to verify AZ coating anti-corrosion ability.
Record all data and issue official mill test certificate (MTC).
Frequently Asked Questions (FAQ)
1. Why is the tensile test essential for S280GD+AZ?
It ensures the steel coil meets the minimum 280MPa yield strength standard, which is the core mechanical index for structural load-bearing applications such as solar mounting and roofing.
2. What standard is used for the S280GD+AZ salt spray test?
It follows ASTM B117 neutral salt spray test standard, the global universal standard for evaluating aluzinc AZ coating corrosion resistance.
3. How many hours of salt spray testing can qualified S280GD+AZ pass?
With regular AZ100–AZ150 coating weight, qualified S280GD+AZ can remain free of red rust for more than 720 hours, supporting a 25-year service life in high salt spray environments.
4. What is the difference in hardness between S280GD+AZ and DX51D?
S280GD+AZ structural grade has higher hardness and rigidity; DX51D stamping grade is lower in hardness with better ductility for complex bending rather than load bearing.
5. Can hardness testing alone confirm S280GD+AZ grade?
No. Hardness can be used as auxiliary identification; tensile test yield strength data is the final authoritative basis.
6. Are the test samples taken only from the coil surface?
No. Samples are taken from the head, middle and tail of S280GD+AZ steel coils to ensure the whole batch has stable and consistent mechanical properties.
7. Do all S280GD+AZ batches need salt spray testing?
Key batches for coastal solar and high-rise projects require mandatory salt spray testing; conventional projects can adopt random sampling inspection.
8. Will test results be provided as official documents?
Yes. All qualified S280GD+AZ steel coils can be supplied with Mill Test Certificate (MTC) including tensile, hardness and salt spray test data.
