Fractography and X-ray photoelectron spectroscopy of free-machining steels

AbstractA fractographic study was carried out on machining chips from re-sulphurized steels in which it was observed that the chips broken at low temperatures (−196°C) failed predominantly by intergranular fracture. The occurrence of intergranular failure was found to be dependent on the sulphur content of the steels. Chemical analysis of the intergranular facets by X-ray photoelectron spectroscopy revealed sulphur. The reduction in grain boundary cohesion due to a small amount of sulphur at the grain boundaries is discussed in relation to the free-machining properties of re-sulphurized steels.