EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

The thin solidifying shell in the meniscus region of continuous caster deforms due to severe contraction of steel during solidification for near peritectic composition of steel and there is potential risk of cracking and in the extreme cases, breakout of shell. The main purpose of the present study was to contribute an improved understanding of peritectic transformation through high temperature experimentation. Peritectic grades of steel are cast at slower speed due to these phenomena. So to increase the productivity of a caster, peritectic grades of steel should be accurately identified so that other grades can be cast at higher speed. There are several methods which are being used to identify peritectic grades. Most shop uses ferrite potential formulae to identify if a particular steel grade will behave as peritectic or not. In the present study a high temperature experimental technique was used to identify peritectic grades of steel. Differential scanning calorimetry (DSC) is a technique which was used to identify any type of reaction or phase transformation which is associated with enthalpy change. Using this novel technique, more than 80 steel samples of different chemistry were studied to identify peitectic grades. Peritectic grades will have an enthalpy change for both peritectic transformation and melting, whereas for low carbon only melting takes place. So a single peak close to melting temperature of steel is considered a low carbon grade whereas two peaks near melting temperature is considered as peritectic grade. The DSC measurement was further substantiated through calculated thermal variation coefficients (TVC) and the outcome of a new ferrite potential formula. It was observed that out of all steel chemistries 50% of steel chemistries which were being cast as peritectic were identified as low carbon and can be cast at higher speed.