What is the Q345R (R-HIC) steel composition?

Q345R (R-HIC) steel is a hydrogen resistant steel plate for boilers and pressure vessels.
Q345R (R-HIC) delivery status: normalizing

Q345R (R-HIC) steel composition(%)
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.

In order to improve the performance of Q345R steel 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 generally required to be less than 0.045%, and the requirement for high-quality steel is lower.
Sulfur (S): Sulfur is also a harmful element under normal circumstances. Make steel hot brittle, reduce steel ductility and toughness, and cause cracks during forging and rolling. Sulfur is also detrimental to welding performance, reducing corrosion resistance. Therefore, the sulfur content is generally 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 the machinability, usually called free-cutting steel.