Chemical element composition of Q345R (R-HIC) plate

Smelting analysis of chemical element composition of Q345R (R-HIC) plate:
C≤0.20; Si: 0.20-0.55; Si: 0.20-0.60; Mn: 1.20-1.36; Al≥0.020; Ca: 0.0015-0.0030; O≤0.004; CE≤0.45; P≤0.015; S≤0.003.

Note: (1) The Ca value is for reference only, not as acceptance conditions. The content of Ca and O can be replaced by the analysis value of the finished product instead of the analysis value of the smelting;

(2) The calculation formula of carbon equivalent (CE) is as follows: CE=C+Mn/6+(Cu+Ni)/15+(Cr+Mo+V)/5

(3) In order to improve the properties of the Q345R (R-HIC) plate, some microalloying elements can be added.

Phosphorus (P): In general, phosphorus is a harmful element in steel, which increases the cold brittleness of steel, deteriorates welding performance, reduces plasticity, and deteriorates cold bending performance. Therefore, the phosphorus content in steel is usually required to be less than 0.045%, and the requirements for high-quality steel are lower.

Sulfur (S): Sulfur is also a harmful element in general. It makes the steel hot brittle, reduces the ductility and toughness of the steel, and causes cracks during forging and rolling. Sulfur is also detrimental to weldability, reducing corrosion resistance. Therefore, the sulfur content is usually required to be less than 0.055%, and the high-quality steel is required to be less than 0.040%. Adding 0.08-0.20% sulfur to steel can improve machinability, usually called free-cutting steel.