Failure analysis of GCr15SiMn steel bearing sleeve

This paper presents a failure analysis of a bearing sleeve made from GCr15 steel. The bearing sleeve fractured, when being interference fitted. The fracture surfaces were observed by visual and SEM. The crack initiated from the top end of the bearing sleeve and propagated towards the bottom. Intergranular brittle fracture is the main failure mechanism. Detailed investigation of the microstructure indicates needle-like bainite, with lamellar troostite occuring at grain boundaries as a discontinuous network. A banded structure was observed on the bearing sleeve material, but Charpy impact tests of samples taken from different orientations of the failed sleeve show that the failure of the bearing sleeve has nothing to do with the banded structure. The discontinuous network structure lowers the strength of the grain boundary. Insufficient quenching rate and low quenching temperature are responsible for the formation of the discontinuous grain boundary network.