鋳鉄の黒鉛組織ならびに機械的性質におよぼす硫黄，マンガンおよびけい素の影響

抄録

  It has been confirmed by one of the authors that various properties of gray cast iron are improved by reducing sulphur content in the pig iron to the minimum, presumably due to the change of graphite and other structures by the decrease of sulphur content. Generally speaking, when sulphur is contained in the molten pig iron, it tends to decrease the interfacial energy between the molten pig and the austenite, making it easy to precipitate on the graphite piece through the austenite phase.
  It is said, therefore, that as the sulpher content increases, the distance between the graphite pieces becomes so much wider, and the graphite pieces become so much large or coarse. On the contrary, if the sulphur content is reduced to the minimum, the graphite pieces become smaller, thereby if the improving the mechanical proprties. It is also said that sulphur and manganese contained togetrher in the pig iron will form a stable sulphide such as MnS, and that, if their quantity is increased, graphite tends to become larger. The effect of sulphur content on the mechanical properties of the gray cast iron may vary depending upon the quantity of manganese simultaneously contained, and also may be influenced by the silicon content, which is an element that accelerates graphitization. After studying these relations, it has been verified that sulphur content being the main factor giving great influence to the mechanial properties, the lower the sulphur content, is the better the mechanical properties are.