Využití termické analýzy pro predikci mikrostruktury a vlastností litin

Abstract

The thesis is focused on the iron melting in laboratory and production and its thermal analysis. In the first chapter we do the thermal analysis and compare different types of charges in the laboratory. There is the specific thermal regime for the iron melting based on the preserving of the overheating temperature applied for the comparison. The metallurgical quality parameter is obtained from the first derivation of the cooling curve. The classification of different types of iron is based on the results of the chill test (white or gray type of solidification), comparison of metallographical structures, number of eutectic cells and the measurement of concentric shrinkage in the proposed test cast. The thermal curve of cooling helps to calculate volume changes in the crystallization stage. The metallurgical preparation of the iron for the working layer of the rolls in the production of ironworks specialized on spun cast rolls for hot strip mill is based on the thermal analysis. There is a new methodology for metallurgical preparation of iron and new classification of cooling curve based on first derivation applied in the production. The results of thermal analysis are applied and there are metallurgical changes of melting before the tapping by addition of graphite or carbide elements. Then the thermal analysis is applied again. The probe from casting of the rolls serves for analysis of graphite amount and the hardness in the level of working layer. We consider this type of thermal analysis as a suitable tool for the classification of metallurgical quality of iron. We should also apply this method for the prediction of metalographical, mechanical and foundries attributes of cast iron, but it is necessary to establish suitable parameters of evaluation.