The peritectic phase transition of steel during the initial stages of solidification in the mold
Driven by the diversification of steel products, the demand for production of steels close to the peritectic composition range especially in the case of HSLA (High Strength Low Alloy) and AHSS (Advanced High Strength Steel) has been increasing. The ever increasing demands on the mechanical properties of steel products and cost reduction in alloy designs, for example in the automotive industry to reduce the mass of motor vehicles, are the main reasons why these steels are designed close to the peritectic composition range. However, steels falling within the peritectic composition range are notoriously difficult to cast by continuous casting techniques and Figure 1 shows an example of shell-thinning in a continuously-cast steel of peritectic composition, the breakout occurring ostensibly as a result of the occurrence of the peritectic phase transition. The casting problems of these steels are exacerbated at high casting speeds and new high-speed casting technologies, aimed at achieving high production rates to attain economics of production, are specifically prone to casting difficulties.