The phase transformation of pearlite heat‐resistant steel during solidification is observed using high‐temperature confocal scanning laser microscopy. The precipitation of the δ‐ferrite (δ) phase proceeds in a cellular manner at cooling rates of 5 and 15 °C min−1, whereas precipitation occurs in a dendritic manner at a cooling rate of 100 °C min−1. Furthermore, a change in the solidification path is observed at high cooling rates. When the experimental steel is cooled at a low cooling rate of 5 °C min−1, the sequence of continuous solidification is L → L + δ → L + δ + γ → δ + γ, which is consistent with that of equilibrium. However, when the cooling rate increases to 15 and 100 °C min−1, the sequence of continuous solidification is L → L + δ → L + δ + γ → L + γ→γ. Furthermore, at various cooling rates, the interface of the peritectic transformation of δ → γ presents three different modes: planar and cellular modes controlled by solute diffusion and massive transformation controlled by the processes that occur at the transformation interfaces. The different δ → γ transformation modes and the associated different degrees of volume shrinkage are hypothesized to lead to uneven strand shell growth during continuous casting.