I found more of the Portuguese bearings....

In both shell and low friction bearing materials its manganese inclusions that are frowned upon and max figures of number of inclusions on the surface are in the specs of the steel. That is the reason that when SKF etc first set up a bearing factory in a new country they import the steel for some years until the local steel makers understand these requirements. Even the best steel maker can have an off day and I have seen bins full of bearings with the inclusions showing where the shell is first formed and the bending operation opens the inclusion up.