S355J2 is a European standard low-alloy high-strength structural steel with excellent low-temperature impact properties. "S" stands for structural steel, "355" indicates its minimum yield strength of 355 MPa, and "J2" signifies that the material has good impact toughness at low temperatures of -20°C.

S355J2 Low-Temperature Impact Properties

• Standard: S355J2 complies with the European standard EN 10025-2:2004.
• Chemical Composition: Carbon (C) content not exceeding 0.22%, silicon (Si) content not exceeding 0.55%, manganese (Mn) content not exceeding 1.60%, phosphorus (P) content not exceeding 0.025%, sulfur (S) content not exceeding 0.025%.
• Yield Strength: Depending on plate thickness, the yield strength is ≥355 MPa for thicknesses below 16mm, ≥345 MPa for 16-40mm, ≥335 MPa for 40-63mm, and so on, decreasing as plate thickness increases.
• Tensile Strength: Typically between 450-680 MPa.
• Impact Absorbed Energy: At low temperatures of -20°C, the impact absorbed energy is ≥27J.

Comparison with National Standard Low-Temperature Impact Properties

In Chinese national standards, the equivalent steels to S355J2 are Q345D or Q345E, with specific comparisons as follows:

• Q345D: Yield strength of 345 MPa, tensile strength of 470-630 MPa, elongation not less than 18%, and impact absorbed energy ≥27J at low temperatures of -20°C.
• Q345E: Yield strength of 345 MPa, tensile strength of 470-630 MPa, elongation not less than 17%, and impact absorbed energy ≥27J at low temperatures of -40°C.

Comparative Analysis

Compared to Q345D, S355J2 has a slightly higher yield strength, while Q345D's impact test temperature is -20°C, and Q345E's impact test temperature is even lower at -40°C. This indicates that Q345E maintains good impact toughness at even lower temperatures.

Applications

S355J2 is widely used in building structures, bridges, ships, vehicle structural components, and the manufacturing of various tools, cutting tools, molds, and measuring instruments. Q345D and Q345E are also widely used in similar fields, especially within China.

Summary

S355J2, along with Q345D and Q345E from Chinese national standards, are all high-strength structural steels with excellent low-temperature impact properties. S355J2 has a slightly higher yield strength, while Q345E undergoes impact testing at even lower temperatures. These steels are selected based on specific engineering requirements and environmental conditions to ensure structural safety and reliability.