Behaviour of oxide scales in hot steel strip rolling

The behaviour of oxide scales in the finishing Hot Strip Mill is simulated by the hot Plane Strain Compression Test (PSCT). Compared with the ideal case of homogeneous plastic co-deformation of the oxide layer and the underlying metal, different types of defects are described: delamination at the interface or within the oxide layer; interfacial plastic instability due to the jump of the mechanical properties; perpendicular, through-thickness cracks where the axial strain parallel to the interface dominates, followed by micro-extrusion of metal between the fragments; oblique cracks followed by sliding along the lips, where shear dominates. The Finite Element Method (FEM) is used to bring elements of interpretation, as to which conditions determine each mechanism. Conclusions for the behaviour in hot rolling are sketched.