Products Description
SPA-H Atmospheric Corrosion Resistant Structural Steel Sheet is a high-strength weathering structural steel specifically designed for applications requiring superior atmospheric corrosion resistance without protective coatings.
This advanced steel grade forms a stable protective oxide layer that significantly reduces corrosion rates, making it ideal for exposed structural applications in harsh environmental conditions.
Chemical Composition
| Element (Symbol and Name) | Percentage Range (%) |
|---|---|
| C (Carbon) | 0.12 - 0.20 |
| Mn (Manganese) | 0.50 - 1.50 |
| P (Phosphorus) | ≤ 0.04 |
| S (Sulfur) | ≤ 0.03 |
| Cu (Copper) | 0.25 - 0.55 |
| Cr (Chromium) | 0.20 - 0.50 |
| Ni (Nickel) | 0.30 - 0.50 |
The primary role of key alloying elements in SPA H Steel includes:
- Copper: Enhances corrosion resistance by promoting the formation of a protective patina.
- Chromium: Increases hardness and strength while improving resistance to oxidation.
- Nickel: Enhances toughness and ductility, particularly at lower temperatures.
Mechanical Properties
| Property | Condition/Temper | Test Temperature | Typical Value/Range (Metric) | Typical Value/Range (Imperial) | Reference Standard for Test Method |
|---|---|---|---|---|---|
| Tensile Strength | As Rolled | Room Temp | 490 - 620 MPa | 71 - 90 ksi | ASTM E8 |
| Yield Strength (0.2% offset) | As Rolled | Room Temp | 355 - 450 MPa | 51 - 65 ksi | ASTM E8 |
| Elongation | As Rolled | Room Temp | 20 - 25% | 20 - 25% | ASTM E8 |
| Hardness (Brinell) | As Rolled | Room Temp | 150 - 200 HB | 150 - 200 HB | ASTM E10 |
| Impact Strength (Charpy) | -40°C | -40°C | 27 J | 20 ft-lbf | ASTM E23 |
The combination of these mechanical properties allows SPA H Steel to withstand significant mechanical loads while maintaining structural integrity, making it suitable for applications such as bridges and buildings.
Processing Characteristics
SPA-H weathering steel plates have high strength and hardness, with a yield strength of 325–420 MPa and a tensile strength of 470–600 MPa, though their plasticity is slightly lower than general structural steel.
During processing, SPA-H plates need to be preheated to reduce the risk of cold cracking. The typical preheating temperature is 150–200°C, adjusted according to plate thickness (usually 4–25 mm) and process requirements.
For cold forming, care should be taken to ensure the bending radius is at least 3–5 times the plate thickness to avoid cracking or surface wrinkling.
For large-scale bending or complex shape processing, experimental verification is recommended beforehand to ensure stresses and deformations remain within safe limits.
Welding Characteristics
SPA-H steel plates can be welded using manual arc welding, submerged arc welding, gas-shielded welding, and other common methods.
Before welding, the steel surface must be thoroughly cleaned to remove oil, oxides, and other impurities to ensure weld quality.
During welding, SPA-H plates generally require preheating, typically controlled at 100–150°C, with specific parameters selected according to plate thickness and welding method.
Cooling rates of the weld should be controlled within 15–25°C/min to reduce the risk of cracking.
After welding, slag removal and thermal shock treatment should be performed in time. The weld joint typically achieves strength comparable to the base metal, meeting general structural requirements.
