Following the progress of sintering in steel powder compacts through original experiments

Abstract

In order to evaluate the progress of sintering in powder steel compacts, two experiments were performed. First, the electrical resistivity of a die pressed compact was continuously measured during a sintering cycle up to 1130°C inside an adapted dilatometer. The main changes occur at intermediate temperatures, since the resistivity falls by a factor of about 100 between room temperature and 800°C and is almost constant afterwards. In the second set of experiments, partially sintered specimens are submitted to a tensile test until failure and their fracture surfaces are analysed in terms of welded area fraction of interparticle contacts. The yield and ultimate strengths, significantly increase between 600 and 1000°C. These results prove that interparticle joining operates early in the sintering cycle, above 1000°C. They also show that the strengthening of the material is not closely correlated with electrical resistivity changes during heating; interparticle contacts are able to conduct electricity before they are strong enough to support tensile stresses.