High-Temperature Simulation Study of Cracking Mechanism During the Strip Casting Process of P-Containing Weathering Steel

The growth of the transportation industry has sharply increased the demand for high-strength weathering steel plates. However, cracks easily occur in the strip casting process of these alloys. This paper studied the cracking mechanism of P-containing weathering steel during the strip casting process by simulating the high-temperature exposure. It was revealed that P segregates and enriches in the interdendritic region (corresponding to the prior austenite grain boundary after solidification), leading to significant alterations in the chemical composition of the molten steel in that area. The two-phase region is further enlarged, thereby delaying the complete solidification of the P-segregated regions. Consequently, the melt adjacent to the prior austenite grain boundary may not be entirely solidified once the as-cast strip is taken off the casting roll. Also, cracking initiates in these softer regions during the straightening stage due to stress. Enhancing the secondary cooling to encourage complete solidification while minimizing the strip’s bending degree after exiting the strip caster is recommended to reduce cracking.