The Effect of P on the Microstructure and Melting Temperature of Fe2SiO4 in Silicon-Containing Steels Investigated by In Situ Observation

In this study, two silicon-containing steels with different P contents were used, and reheating tests were conducted in an industrial furnace in a hot strip plant. The effect of P on the microstructure and melting temperature of Fe2SiO4 in silicon-containing steels was investigated using a backscattered electron (BSE) detector and energy-dispersive spectroscopy (EDS). The melting process of Fe2SiO4 was also observed in situ for the two steels with different P contents. The results show that the addition of P could lower the melting point of the eutectic compound Fe2SiO4/FeO, which is helpful for descaling the oxide scale. The melting point decreases with the increasing P content, and the melting point of Fe2SiO4/FeO can reduce up to 954.2 ◦C when the content of P reaches 0.115 wt %. Furthermore, P-compounds form in the dispersive particles located in the iron matrix near the interface between the matrix and inner oxide scale when the P content is relatively high. In addition, a method of in situ observation was proposed to study the effect of P on the melting point of Fe2SiO4/FeO in silicon-containing steel. The results are of more practical significance for the descaling of oxide scale in silicon-containing steel.