Q390B steel plate is a high-strength low-alloy structural steel produced according to the Chinese national standard GB/T 1591-2018. "Q" represents the first letter of the Chinese word for yield strength (屈), "390" indicates a minimum yield strength of 390 MPa, and "B" denotes the quality grade of the material.

Performance Characteristics of Q390B

• Chemical Composition: The chemical composition of Q390B mainly includes a carbon (C) content not exceeding 0.20%, manganese (Mn) content between 1.00-1.60%, silicon (Si) content not exceeding 0.55%, phosphorus (P) and sulfur (S) content not exceeding 0.035% and 0.035% respectively, and may also contain alloying elements such as niobium (Nb), vanadium (V), and titanium (Ti).
• Mechanical Properties: It has high strength and good plasticity, with a yield strength not less than 390 MPa, tensile strength between 470-630 MPa, and elongation typically above 18%.
• Impact Toughness: It exhibits good impact toughness, maintaining stable impact absorption energy at different temperatures.

Comparison with European Standards

The European standard steel equivalent to Q390B is the S355 series, with specific comparisons as follows:

• S355J2: S355J2 steel plate according to European standard EN 10025-2 has a minimum yield strength of 355 MPa, tensile strength between 450-680 MPa, and impact absorption energy not less than 27J at -20°C.
• S355J0: Similar to S355J2 but with better low-temperature impact performance, with impact absorption energy not less than 27J at 0°C.

Comparative Analysis

• Yield Strength: The minimum yield strength of Q390B is slightly higher than that of S355J2, indicating that Q390B can withstand higher loads under the same conditions.
• Impact Toughness: The impact toughness requirement of Q390B at +20°C is higher than the -20°C impact requirement of S355J2, but S355J2 is specifically designed for low-temperature environments, offering better low-temperature toughness.
• Application Fields: Although both are widely used in construction, machinery manufacturing, shipbuilding, and other fields, Q390B may be more suitable for applications requiring higher yield strength.

Summary

Both Q390B steel plate and the European standard S355 series steel plates are high-strength structural steels with good weldability and processability. Q390B has a slightly higher yield strength, while S355J2 has an advantage in low-temperature impact performance. Users should select the appropriate material grade based on specific engineering requirements and environmental conditions.