Effect of Boron on the Interfacial Heat Transfer, Contact Behavior, and Microstructure in the Simulation of Strip Casting of 3.5 Wt Pct Si Non-oriented Silicon Steel

This study used the droplet solidification test and fast dip test to investigate the effects of boron on the interfacial heat transfer, contact behavior, naturally deposited film, and microstructure of 3.5 wt pct Si non-oriented silicon steel during sub-rapid solidification. The results showed that boron altered the surface tension of the molten steel, enhancing the interfacial wettability and heat transfer behavior between the steel and substrate. As the boron content increased from 0 to 97 ppm, the final contact angle decreased from 125 to 96 deg, while the maximum heat flux increased from 6.89 to 10.29 MW/m2, ultimately enhancing the surface quality of the cast strip. During the solidification of boron-containing silicon steel, boron volatilizes and combines with oxygen to form B2O3 on the substrate surface. It reduced the proportion of high melting point silicon oxides in the deposited film, decreasing its melting point. Furthermore, due to boron segregation and improved interfacial heat transfer, the average grain size of the cast strip decreased from 256 to 216 mu m, accompanied by a more complex grain orientation.