Abstract: A method is provided for influencing the properties of cast iron by adding magnesium to the cast iron melt and measuring the oxygen content of the cast iron melt. Magnesium is added to the cast iron melt until the oxygen content of the cast iron melt is approximately 0.005 to 0.2 ppm at a temperature of approximately 1,420° C. A sensor for measuring the oxygen content in cast iron melts contains an electrochemical measuring cell containing a solid electrolyte tube.

Abstract: A magnesium treatment process is proposed for the production of a treated iron melt containing less than 100 grams per ton non-metallic inclusions. The treatment reaction is so arranged that the magnesium is introduced into the melt from a chamber at a depth of at least 200 mm below the surface of the melt. Thus, the quantity of vaporized magnesium produces a mixing energy of at least 1,000 W/m.sup.3, which ensures the necessary elimination of non-metallic inclusions. The surface of the molten mass is covered by a non-oxidizing, preferably a reducing atmosphere.

Abstract: Conventionally, heat treatment was necessary in the final stage of producing nodular cast iron products to give the nodular cast iron with desired mechanical properties. This was necessary because of the loss of graphitization capability of the molten metal when it is being formed into nodular cast iron during the process of spheroidization, and the heat treatment is therefore required to decompose cementite formation and thereby promote graphitization. The process of producing nodular cast iron according to the present invention can achieve the promotion of graphitization and the increase in the number of graphite nodules, which are both important for the production of high-quality thin-shell cast iron products, through the synergetic effect of processing the molten metal with a graphitization agent such as SiC or CaC.sub.2 and of adding a graphite atomization agent such as Bi.

Abstract: A process for removing impurities from molten metal by propelling a bullet toward and into the molten metal at a velocity sufficient for the bullet to penetrate, vaporize, and react with the impurities. The bullet contains a reactive substance, is heavier than the molten metal, and is formed of a metal or metals which are to remain with the molten metal when it is solidified.