What are the requirements for P and S contents when SA-516Gr70 is used as a steel for -40°C applications?

This post was last edited by phy0001 on 2011-3-10 22:22. Due to differences in equipment and technology, various steel mills have varying levels of control over harmful elements. But it is certain that, in order to achieve the mechanical properties specified by standards at low temperatures, elements Ni and Nb, which lower the temperature at which brittleness occurs, are added during the smelting process; the exact amount added varies depending on the equipment used ； During rolling, normal delivery conditions are used in order to refine the grain structure and achieve a uniform microstructure, as well as to counteract the rolling stresses. As for the control of SP content, this sometimes depends on the requirements of the designer and the client, as well as the capabilities of the steel mill and the provisions of relevant standards; there is no standard answer to this. Wugang Panglong

P is less than 0.020%, and S is less than 0.012%. Also, C and Mn must be limited as well.

In fact, there is no need to restrict the levels of P and S unless there are special requirements. To meet low-temperature impact requirements, these levels must be kept very low. However, when using such materials in China, it is necessary to comply with national standards: P must be less than or equal to 0.025% and S must be less than or equal to 0.012%. As long as there are no requirements related to H2S-induced stress corrosion or similar issues, meeting these national standards seems sufficient! Of course, you need to get the impact energy right.

What was said upstairs is correct; you can meet the requirements for low-temperature impact by adding S5 steel mill experience to control SP in order to improve low-temperature toughness. In fact, SA 516 has much lower requirements regarding SP content than the standard specifications