MATERIALS TESTING, cilt.55, ss.840-844, 2013 (SCI İndekslerine Giren Dergi)
In this study, fracture analysis of a eutectoid steel used as material for a Clamping head and which failed in service was carried out to investigate the effect of heat treatment and also the micro structural features on the failure. The fracture surface was initially examined by scanning electron microscopy to determine the fracture type and possible paths for crack propagation. In the next step, the cross section of the steel was prepared by metallographical techniques and the matrix phases were determined using light microscope in etched condition. The steel surface exhibited a mixed fracture consisting of typical intergranular and quasi-cleavage fracture. The matrix showed segregation regions as band structure and included retained austenite in addition to martensite. Furthermore, several internal cracks were observed in the matrix due to the quenching effect, and the martensitic regions were very effective on the formation of intergranular fracture. Retained austenite possibly plays an important role in forming quasi-cleavage fracture during service loading.