Analysis of crack development, both growth and closure, in steel oxide scale under hot compression

Numerical analysis based on the finite element method allowed evaluation of conditions for crack development in oxide scale during compression in hot metal forming, particularly in the hot rolling of steel. In addition to cracks formed ahead of contact with the roll, through-thickness cracks can also occur under roll pressure within the roll gap. The modeling has revealed that sometimes cracking that started at the uppermost oxide scale layer was stopped at the thin oxide scale layer nearest to the stock surface. Alternatively, crack closure within the roll gap was possible at high temperature in places where both viscous sliding and ductile behavior of the scale were more pronounced. Many aspects of the modeling are supported by experimental observations.