Optimal P content range should be controlled in production of DH36 steel ship plate

DH36 steel ship plate, as one of the steels with higher quality, is mainly used to build large ships, offshore oil and drilling platforms. Its components have such problems as harsh working environment, huge design loads, extremely high stress concentration, difficult maintenance and repair, and serious damage.

At present, with the gradual promotion of high purity purification, microalloying and controlled rolling and cooling technologies in iron and steel enterprises, the quality of DH36 steel ship plate has been greatly improved. Among them, P element in steel belongs to harmful element. In steel, P impurity mainly exists in the form of grain boundary segregation. The existence of phosphorus is very unfavorable especially to the toughness of steel plate. The harm of phosphorus lies in the large segregation, which causes the brittle transition temperature of DH36 steel ship plate to rise sharply, that is, to improve the cold brittleness of DH36 steel ship plate. At the same time, phosphorus is a kind of interfacial active element. Segregation of phosphorus at grain boundaries will lead to serious grain boundary embrittlement, which makes the finished DH36 steel ship plate extremely brittle. Such DH36 steel ship plate is not conducive to processing, and has a great impact on the performance of the product.

P has a beneficial effect on the mechanical properties of some special steels to a certain extent. For example, the stress durability and plasticity of In-conel 718 Alloy can be improved when P content is 2.00 x 10-4.

The fluctuation of P content has a certain effect on the mechanical properties of DH36 steel ship plate. Therefore, the optimal P content range should be controlled in industrial production of DH36 high strength ship plate steel.