On the effect of microstructural parameters on tensile properties of a high work-hardening Fe3Al-based alloy

The Fe3Al-based alloys have a potential application in some tribological circumstances, especially where oxidation or sulfidation is also a major concern. The work-hardening rate is one of the critical mechanical properties that affects the tribological properties. By the addition of Cr, Mo, Zr, Nb, C, a Fe3Al-based alloy with a high work-hardening rate and an acceptable ambient ductility has been obtained. The improvements of its yield stress and work-hardening rate are attributed to the formation of carbides and the solid solution of alloying element molybdenum. The investigations on the relationship between microstructure, surface preparation and tensile properties indicate that microstructural control plays a very important role in improving the intrinsic ductility. The test environment and surface preparation have no effect on the yield stress and work-hardening rate, but indeed on the ductility. The microstructure affects the intrinsic ductility by influencing crack propagation. Initial surface roughness and moisture environment greatly promote the environmental hydrogen embrittlement and lead to premature failure. The alloy investigated has a higher sensitivity to surface defects in air than that in vacuum, indicating that any surface preparation that changes surface roughness plays a very important role in controlling the ambient ductility when these materials are tested or serve in air.