Abstract
Microscopic crack initiation and crack propagation processes have been studied in a sintered Fe-Ni-Cu-Mo alloyed steel during tensile testing. As-sintered and heat-treated specimens with density of ~7.15 g.cm^-3 were pressed from Fe-4%Ni-1.5%Cu-0.5%Mo diffusion alloyed powder (Distaloy AE) with addition of 0.7 % graphite. The microstructure of both as-sintered and heat-treated materials was characterised. Static tensile tests were carried out on the specimens with polished and etched surface under a gradually increased loading. The microcrack initiation and propagation processes in as-sintered and heat-treated microstructure were analysed by light and scanning electron microscopy. The observations showed that failure mechanisms are strongly dependent on matrix microstructure and pores localisation.

Key words
failure, Fe-Ni-Cu-Mo sintered steel, microstructure, tensile testing, microcrack initiation and propagation

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