Fe is the basis.
According to TU 14-1-991-74, the chemical composition is given for steel grade 33X3SNMVFA-VD (SP33-VD, EP613-VD). It is allowed to increase the content of sulfur and phosphorus by about 0010% with a total content of sulfur and phosphorus not more than 0.020%. Deviations in chemical composition are allowed: carbon ± 0.010%, manganese + 0.050 / -0.20%, silicon, chromium, nickel and tungsten ± 0.050% each, molybdenum ± 0.030%, vanadium +0.020%. Partial or complete replacement of tungsten with molybdenum is allowed, based on: 2.2 parts by weight of tungsten are replaced by one part by weight of molybdenum. When the tungsten is completely replaced, the molybdenum content should be in the range 0.75-0.95%.
According to TU 14-1-4461-88, the chemical composition of the steel must comply with the standards indicated in Table 2 (Appendix 1), sent on request by the Central Research Institute of Chemical Technology named after Bardin. The sulfur content of sulfur is not more than 0.011%, phosphorus is not more than 0.015%, while the total content of sulfur and phosphorus should not be more than 0.022%. The residual copper content should not be more than 0.15%. With the consent of the consumer, it is allowed - up to 0.20%. In the finished sheets the following deviations in chemical composition from the norms indicated in Table 2 are allowed: carbon + 0.02 / -0.010%; tungsten ± 0.10%; manganese, silicon, chromium and nickel ± 0.050%; molybdenum ± 0.030%; vanadium +0.020%. Partial or complete replacement of tungsten by molybdenum from the calculation of 2.5 mass fraction of tungsten is allowed with one mass fraction of molybdenum.