Reasons Analysis on Defect of a GCr15SiMn Steel Bearing Ring

The surface crack defect appearing after processing of a GCr15SiMn steel bearing ring was analyzed by optical microscope and scanning electron microscope. The results show that there was no decarburization phenomenon around the defect. There were some oxide inclusions in the cracks, and they were mainly monox, chromium oxide and manganese oxide. Through analyzing the cause and mechanism of the high temperature oxide inclusions, it could be concluded that the defect was caused by forging crack which induced high-temperature oxidation of the surrounding matrix elements, and it was not raw material metallurgic defect.