Stress Concentration at Pores in Sintered Materials

Abstract

Statistical distributions for the stress concentration factor A _k at pores in three sintered iron based materials have been determined using the equivalent ellipse concept. Pore dimensions were obtained by metallographic examination of fracture surfaces produced by impact at liquid nitrogen temperatures. Most of the pores (80%) were characterised by A _k < 5; the vast majority of the remainder had values in the range 5–8 and the maximum observed value was 12. The means and standard deviations of the A _k distributions were found to vary only marginally with material composition and compaction pressure. On the basis of these distributions, conclusions are drawn concerning the local yielding, deformation, and fracture of porous ductile materials. PM/0691