In accordance with the national standard GB/T 1591-2018, as of February 1, 2019, the Q345B specification has been cancelled and replaced with Q355B, aligning with the EU's S355 standard.
Q355 is a type of steel. It is a low-alloy high-strength structural steel, widely used in bridges, vehicles, ships, buildings, pressure vessels, and special equipment. The "Q" signifies yield strength, with 355 indicating the yield strength of this steel is 355 MPa, which decreases with the increase in material thickness.
Chemical Composition