Is 0.15c mild carbon steel FCC structure or BCC?

0.15c mild carbon steel primarily has a body-centered cubic (BCC) structure at room temperature. While carbon can influence the microstructure, in low carbon steels like 0.15c, the predominant phase is BCC ferrite. At elevated temperatures, it may transform to a face-centered cubic (FCC) structure, but under normal conditions, it remains BCC.