Heat-treating and nano-reinforcing improvements on fretting fatigue properties and fracture behaviors of cylinder head aluminum alloys

Abstract

The presence of cyclic loading alongside the wear increases the probability of fretting fatigue phenomenon in the cylinder head of automobiles. In the current study, the nano-reinforcing and the T6 heat-treating impact on the fretting fatigue behavior of the cylinder head aluminum alloy were studied. Fretting fatigue tests were performed in the high-cycle fatigue regime, under 15 N contact load and four different stress levels (75, 100, 125, and 150 MPa). According to the test results, the fretting fatigue lifetime of heat-treated nano-composites under the lowest stress level increased by about 621%. Furthermore, the fracture surface of the studied aluminum alloys, the worn surface of the cast-iron ring used as fretting pads, and the derbies obtained during the fretting test were investigated with the help of field emission scanning electron microscopy. The failure behavior of the cylinder head materials concerning the presence of the quasi-cleavage and cleavage marks were brittle in all cases. In addition, as it is observed the wear mechanism of fretting pads was adhesive.