After a review on tribologically transformed structures (TTSs), TTS nu
cleation during fretting wear tests is discussed for different experim
ental conditions. A ball-on-flat contact was used for testing. Through
metallographical examinations, parameters were proposed to predict th
e zones where TTS nucleation is favoured, and to understand better the
initiation mechanisms. (C) 1997 Published by Elsevier Science S.A.