Features of the Formation of a Shrink Shell in the Conditions of Casting Steel on SCCM

Processy litʹâ, 2019, Tom 138, №6, p.30-37

Abstract

Received 16.10.2019

UDK 621.746.047

In the conditions of a metallurgical micro-mill, as a rule, there are no tasks of serial casting, and in the production of products of high quality steels and alloys a method of semi-continuous casting is quite effective. One of the main problems of this method of casting is the yield of a suitable value, which is smaller than the technology of continuous casting and depends on the shrinkage processes in the main part of the workpiece, which receive significant development at the final stage of crystallization. In turn, the magnitude and depth of distribution of the shrinkage shell largely depends on the conditions of heat dissipation in the mold, as well as the possibility of feeding the shrinkage cavity with new portions of the melt. The article presents the results of physical modeling, which led to a qualitative and quantitative assessment of the processes of forming a shrink shell of continuous casting, as well as to study the theoretical possibility of managing them. The substantiation of the choice of the modeling substance and the description of the laboratory installation and the methods of conducting the experiments are given. It is established that the intensity of cooling significantly influences the process of forming the shrinkage shell of a semi-continuous billet and has a curvilinear dependence. The shrinkage sink has the lowest depth at a flow rate of 2.25 l/min for cooling the mold and increases linearly with the coolant flow rate of 4.1 l/min. Further change in the depth of the shrinkage sink at water flow rates of 4.1 to 14 l/min has a complex curvilinear nature, which is associated with the formation of a gas gap between the crust of the modeling substance and the wall of the shell of the mold of the laboratory unit. The formation of such a gas gap reduces the heat flow from the workpiece to the sleeve, as evidenced by the decrease in the depth of the shrinkage sink in the flow rate of cooling water from 2.25 to 4.1 l/min.