Abstract: The paper deals with the effect of ion nitriding and
carbonitriding on fatigue strength of steel parts under the fretting
conditions. Instrumented fatigue tests were carried out on surface
treated flat bars from EA1N and EA4T steels with different strength.
The chosen surfacing decrease importantly an unfavorable fretting
effect. Nitridation suppressed the unfavorable effect of fretting
almost entirely, while the influence of carbonitridation was less
striking. The results were compared with those ones obtained on bars
without surfacing. The causes of favorable influence of surfacing are
discussed.