The continually increasing demand for high-quality corrosion-resistant steels and alloys, coupled with the accumulation of steel scrap contaminated by harmful impurities, is making it more and more important to be able to treat steel outside the steelmaking furnace. Such treatment should include the removal of phosphorus and sulfur and efficient deoxidation of the steel.The technology most commonly employed for the oxidative refining of ordinary grades of steel cannot be used for high-chromium steels because chromium has a higher affinity for oxygen than does phosphorus at Cr concentrations greater than 2 percent and P concentrations less than 0.050 percent. Thus, it is essential to dephosphorize high-chromium steels under reducing conditions with the use of metallic calcium. In the range of temperatures normally used for steelmaking, the dephosphorizatuion of high-alloy steels by metallic calcium is described by the equation 3Ca_l + 2P_l = 3Ca_3P_(2s). This reaction is unlikely to occur in the given temperature range due to the high partial pressure of the calcium vapor and the low solubility of calcium in such melts at normal pressure. Proceeding on this basis, we studied the behavior of compounds and alloys of calcium and the feasibility of increasing its concentration in the slag phase.
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