S355JR is a low-alloy high-strength structural steel compliant with the European standard EN 10025-2. The "S" stands for structural steel, "355" indicates its minimum yield strength of 355 MPa, and "JR" signifies that the material has good ductility and impact properties.

S355JR Yield Standards

• Yield Strength: The minimum yield strength of S355JR is 355 MPa, which is the stress level at which the material begins to undergo permanent deformation during tension.
• Tensile Strength: Typically ranges between 470 to 630 MPa, representing the maximum stress the material can withstand.
• Elongation: In tensile tests, the elongation of S355JR is generally not less than 21%, indicating good plastic deformation capability.
• Impact Absorbed Energy: At room temperature, the minimum Charpy V-notch impact absorbed energy is usually required to be no less than 34J.

National Standard Yield Standards

In Chinese national standards, the equivalent material to S355JR is the Q345 series steel, as detailed below:

• Q345B: Yield strength of 345 MPa, tensile strength between 470 to 630 MPa, elongation not less than 21%, and impact absorbed energy no less than 34J at 0°C.
• Q345C: Yield strength of 345 MPa, tensile strength between 470 to 630 MPa, elongation not less than 19%, and impact absorbed energy no less than 34J at 0°C.
• Q345D: Yield strength of 345 MPa, tensile strength between 470 to 630 MPa, elongation not less than 18%, and impact absorbed energy no less than 27J at -20°C.
• Q345E: Yield strength of 345 MPa, tensile strength between 470 to 630 MPa, elongation not less than 17%, and impact absorbed energy no less than 27J at -40°C.

Comparative Analysis

Compared to the national standard Q345 series steel, the main differences for S355JR lie in the requirements for yield strength and impact absorbed energy. S355JR has a slightly higher yield strength than the Q345 series' 345 MPa, while in terms of impact absorbed energy, S355JR typically only requires testing at room temperature, whereas the Q345 series, depending on the grade, may require impact testing at temperatures as low as -40°C.