Open Hearth Steel Castings

c and open-hearth processes will be presented in this series of articles which cover: First?The selection and representative composition of melting stocks, alloys, refractories, fuels, melting materials and fluxes. Second?Furnace construction and the melting and manipulation of heats. Third?The conditions of melting as effecting the physical properties of products. Fourth?The analyses and physical tests of different grades of products. Fifth?The effect of the constituent materials and metalloids usually present in open-hearth steel castings. Sixth?Heat treatment or annealing, with notes on microscopic examinations. Seventh?Discussion of the causes of blow holes and shrinkage cracks. Eighth?The repair of defects by thermit welding. Ninth?Approximate cost of open-hearth installations.and soda) ; an excess of any tends to lower the fusion point of the sand, destroying its required sintering or refractoriness. Usually a silica sand with less than 95 per cent silica will not answer for a refractory. It is a question of local conditions as to whether the fuel may be natural gas, oil, tar, or producer gas. Natural gas is by far the most satisfactory, owing to its high calorific value and its non-contamination of the bath or molten charge. It is fed directly into the working body of the furnace without any preheating or a passing through the regenerator chambers. Oil, next in efficiency, may be crude petroleum or a grade known as residuum; a ...