Abstract: The fracture of oxide scale on the hotrolled low carbon steel strip in cold rolling without pickling was investigated. It is found that microcracks were formed in the oxide scale near the entry to the roll bite due to the elastic deformation of the steel strip near the gap of the rolls， running perpendicular to the rolling direction. Density of cracks increased with the distance closer to the bite entry. The oxide scale was cracked only with the reduction of single pass lower than 16%， while the reduction of single pass was higher than 16%， the oxide scale began to spall. When the interface shear stress was beyond the adhesive strength between the oxide scale and the steel surface， spalling and powdering of the oxide scale from the surface of the steel strips will occur. Under the same total reduction condition， the multipass rolling is favor to protect the integrality of the oxide scale.

Key words: oxide scale, without pickling, cold rolling, fracture behavior, low carbon steels