What are the differences between Q345B material and Q345D steel

The main difference between Q345B material and Q345D steel lies in the chemical composition. The max. carbon content of Q345D steel is 0.18%, while the max. carbon content of Q345B material is 0.2%. Q345B material and Q345D steel have different S and P contents. Q345D steel has max. S and P contents of 0.03% and 0.03%, while Q345B material has max. S and P contents of 0.04% and 0.04%.

The difference in mechanical properties between Q345B material and Q345D steel is the elongation and impact energy. The elongation of Q345D steel is 22% min., and the elongation of Q345B material is 21% min.. The impact absorption energy of Q345D steel is 34% (-20℃), while the impact absorption energy of Q345B material is 34% (20℃).

Other mechanical properties of Q345B material and Q345D steel, such as yield strength and tensile strength, are not much different.