Study on Solidification Process for Ingots on Moulds with Insulating Plates

摘要

The article describes that by means of the radioactive isotopic tracer atom, the tests of solidification for low and medium carbon killed steel ingots on big-end-down moulds (FX 7.1) with insulating plates are carried on. The solidification curves after pouring for 20, 40, 60, 70, 80, and 100 minutes are measured. The results indicate that the solidification speed of the molten steel in hot top is slower than in ingot body at initial and middle solidification stages, the filling role of molten steel from the hot top to the ingots body can be played. At the end of solidification (after pouring the medium carbon steel for 100 minutes), the metallic bridge appears obviously on the lower part of ingot shoulder, and the filling is prevented. Therefore secondary pipe is formed in the lower center axis of the ingot. Secondary pipe can not be eliminated whenever the heat insulation effects are improved on the head of the ingots. On the basis of the solidification curves of ingots, the solidification mechanism of the ingots with insulating plates is described.