| Grade System | Typical Grades | Execution Standard | Surface Condition | Common Size (mm) | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Main Application Fields |
| GB (China) | Q355B/C/D/E | GB/T 1591-2018 | Hot rolled black skin, pickled, painted, galvanized | Plate: 6–200 | ≥355 (≤16mm) | 470–630 | ≥21 | Building steel structure, bridge, engineering machinery, pressure vessel, vehicle |
| Strip: 2.0–25.0 | ||||||||
| Q345R | GB/T 713-2023 | Hot rolled, normalized, ultrasonic tested | 6–150 | ≥345 | 470–630 | ≥21 | Pressure vessel, boiler drum, storage tank, chemical equipment | |
| EN (Europe) | S355JR/J0/J2 | EN 10025-2 | Hot rolled, pickled, coated | 3–250 | ≥355 (≤16mm) | 470–630 | ≥21 | Steel structure, bridge, machinery manufacturing, ship, pipeline |
| 16Mo3 | EN 10028 | Hot rolled, normalized | 3–80 | ≥260 | 440–590 | ≥22 | Boiler, heat exchanger, medium & high temperature pressure vessel | |
| JIS (Japan) | SM400C | JIS G3106 | Hot rolled, pickled | 6–250 | ≥245 | 400–510 | ≥23 | Ship, bridge, engineering machinery, automobile chassis |
| SPFH540 | JIS G3134 | Hot rolled & pickled | 2.0–16.0 | ≥355 | 540 | ≥21 | Automotive structural parts, high-strength stamping parts, engineering machinery | |
| ASTM (USA) | A572 Gr.50 | ASTM A572 | Hot rolled, coated | 6–150 | ≥345 | 450–600 | ≥18 | Building, bridge, transmission tower, heavy machinery |
| A516 Gr.70 | ASTM A516 | Hot rolled, normalized | 6–200 | ≥260 | 485–620 | ≥21 | Low-temperature pressure vessel, storage tank, chemical equipment |
II. Key Information Specifications
1. Surface Condition
Hot Rolled Black: Original rolled surface with oxide scale coating. Low cost, suitable for structural components where appearance and corrosion resistance are not required.
Pickled: Oxide scale removed, resulting in a smooth surface conducive to welding, painting, and stamping. Examples include automotive-grade SPFH540.
Zinc/ZF Coating: Corrosion-resistant coating for outdoor or humid environments, e.g., highway guardrails, structural steel components.
Painted/Coated: Secondary corrosion protection for enhanced weather resistance.
2. Dimension Range
Plate: Thickness 3–250 mm, width 1000–2500 mm, length 2000–12000 mm.
Coil: Thickness 2.0–25.0 mm, width 700–1830 mm, inner diameter 508/610 mm.
Sections: H-beams, I-beams, angles, channels for steel structural frameworks.
3. Key Performance Characteristics
Yield Strength: Slightly decreases with increasing thickness (e.g., Q355 with thickness >16 mm follows standard gradient reduction).
Impact Toughness: Quality grades (B/C/D/E, JR/J0/J2) correspond to different temperature impact requirements (e.g., Q355E meets -40°C impact).
Weldability: Designed for low-carbon, low-alloy steel with good weld heat-affected zone toughness, suitable for various welding processes.
III. Grade Selection Guide
General Structures: Prioritize Q355 (Chinese standard) or S355 (European standard) for high cost-effectiveness and broad applicability.
Pressure Vessels: Select Q345R (Chinese standard), 16Mo3 (European standard), or A516 Gr.70 (American standard) for enhanced high/low-temperature toughness and pressure stability.
Automotive / Lightweight Applications: Select SPFH540 (Japanese Standard) for pickled surfaces, high strength, and excellent formability.
Shipbuilding / Offshore: Select SM400C (Japanese Standard) for superior low-temperature toughness, suitable for ice zones and marine environments.
