Fig.8 EDX spectrums of wear debris in slip and stick region under SP,
(j) slip region;(k) stick region.
The EDX spectrum shows that there is a huge difference in the oxygen
content of the wear debris between the slip region and the stick region.
Obviously, the oxygen content in the slip region is higher than that of
in the stick region. The oxygen of wear debris in slip region is thought
to come from the oxidation of the steel which is caused by a huge amount
of heat out of the fretting and friction between the sample and the pad
in the contact stress condition. The wear debris is considered to be a
mixture of sample material and its oxide in the slip region. The oxygen
content of the stick region is very low, which indicates that there is
little oxidation of the sample in the stick region. The wear debris is
basically composed of the sample material in the stick region. Since the
slip region is located at the edge of the fretting zone and the relative
displacement occurs between the sample and the fretting pad, the
oxidation becomes very easy with sufficient oxygen; The stick region is
located in the middle of the fretting zone, and its relative
displacement is quite small, which would cause an insufficient oxygen
environment, so the degree of oxidation is extremely low. A number of
researchers had focused on the oxidation of wear debris during fretting
fatigue. Wang et al.1 had reported the chemical
composition of fretting debris of AlSi9Cu2Mg Alloy. Peng et
al.15 had analyzed the oxidation degree of the
sample’s loading side, center position and fixed side respectively, and
found that the oxidation was uneven.
- Fretting fatigue fracture analysis
- Macro Fracture Analysis
Due to the effects of diverse factors, the fracture morphology shows
unique features. The combination of contact stress and cyclic stress may
change the crack initiation position and propagation path. The macro
fracture morphology of the equivalent stress of 400 MPa under SP and DP
are shown in the Fig.9;