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.
  1. Fretting fatigue fracture analysis
  2. 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;