Evaluation of Vermicularity of Compacted Graphite Iron Based on Multiple Characteristic Points of Thermal Analysis

Abstract

The vermiculation effects of compacted graphite cast iron are seriously affected by the metallurgical and technological factors. The change of characteristic points on the cooling curve is attributed to the interaction of these factors, so it is difficult to establish the evaluation relationship between the vermicularity and the characteristic points of thermal analysis curve. Based on the idea of statistics, a method was studied to evaluate the vermicularity of molten iron by comparing with an established characteristic points representation model of hypothetical ideal metallurgical quality state under the production condition. The results showed that the method can meet the requirements of evaluating the vermicularity of molten iron by multiple characteristic points on the cooling curve. As the matching process among cooling curves was omitted, the calculation and evaluation efficiency can be improved. In addition, it is expected to achieve on-line classification and regulation of vermiculation effect in front of furnace by expanding the sample capacity for establishing the characterization model.

Fig. 1 Illustration of 10 critical characteristic points of vermicularity evaluation of CGI: 7 temperature points of the cooling curve and 3 first order differential points on corresponding cooling rate curve.