Phosphorus is second only to sulfur in the continuous casting billet of A131 Grade AH36 steel plate with high segregation degree. Moreover, the diffusion rate of phosphorus in the iron solid solution is very small, so the segregation of phosphorus is difficult to eliminate, which seriously affects the performance of A131 Grade AH36 steel plate.
Phosphorus is dissolved in ferrite in the form of solid solution, which is very brittle. The phosphorus-rich zone formed promotes A131 Grade AH36 steel plate to become brittle, and reduces the plasticity, toughness and solderability of A131 Grade AH36 steel plate.
It is easy to crack A131 Grade AH36 steel plate during hot working, and it is easy to crack during welding.
Phosphorus is an element that reduces the surface tension of A131 Grade AH36 steel plate. With the increase of phosphorus content, the surface tension of molten steel decreases significantly, thus reducing the crack resistance of steel.
Therefore, A131 Grade AH36 steel plate has strict requirements for the content of sulfur and phosphorus, among which the content of sulfur is strictly controlled.
