When exposed, the fracture faces are usually shiny or “rubbed” (unless oxidation has occurred) and are typically described as being, multi-faceted, saw toothed, “crumbly”, cratered or even “ice cream scooped” in appearance. Close examination will reveal that fracture appears to initiate at multiple areas all over the fracture face. Fracture can be seen to flow in almost every direction from multiple points below the surface toward the surface resulting in the typical cratered or “crumbly” appearance.
The affected area can vary in size from small individual spalls to very large areas of the roll barrel. The fracturing can be contained in localized areas or be present in bands extending around the full roll circumference.
Ribbon fatigue spalling can also initiate at areas of contact stress cracking and spalling (see section III.A) which will result in a larger and deeper spall. In these cases, when the fatigue ribbon is traced back to the initiation site, it will be found to initiate just below the surface at an area exhibiting the characteristics of contact stress spalling.