Effect of Microstructure on the Mechanical Reliability of P/M Steels

The statistical analysis, carried out by means of the Weibull statistics, on the distribution of rupture strengths, can provide suitable data about the mechanical reliability of sintered materials. In the present work this method is applied to the study of the mechanical characteristics of P/M steels produced using diffusion-bonded Distaloy-type powders. These materials are widely used and are characterized by a composite heterogeneous microstructure. The study shows that these materials possess a good mechanical reliability in the as-sintered and in the as-quenched and tempered states, whereas they are unreliable in the as-quenched state. A linear relationship exists between Weibull modulus and elongation. This relationship however, is different to that manifested by Fe-C-P alloys, studied in a previous work. This was interpreted on the basis of the different mechanisms of deformation and fracture which are linked to the different characteristics of the microstructures.