Abstract

The study is devoted to the processes accompanying introduction of bismuth to molten steel. Two variants of such introduction were used, viz. bismuth granules and bismuth contained in a steel tube. The time of tube melting, the behaviour of granules and droplets of bismuth and of the gas bubbles formed at their surfaces in the steel melt are discussed. Experiments were carried out with the 0.4 C – 1 %Cr steel melt at 1550–1580 º? by means of the X-ray – TV observation. Based on image analysis the volumes of droplets and bubbles were estimated as a function of time. Arguments are provided to support the supposition that the bubbles of bismuth vapour in steel melt are enveloped by liquid metal. Estimates of the horizontal constituent of velocity of bismuth droplets in inhomogeneously heated steel presumably permitted to observe the thermocapillary effect previously found in some other systems. Simultaneous evaluation of the volume of bismuth droplets and forming bubbles and of the contact area of the phases permitted to estimate the specific rate of evaporation of bismuth to the bubble of its own vapour at 1580 °C. It was found to be several orders of magnitude lower than that of evaporation of bismuth into vacuum.

 

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