EXPERIMENTAL AND THEORETICAL STUDY OF THE BENDING BEHAVIOUR OF SINTERED ALLOYS WITH DIFFERENT MICROSTRUCTURE

摘要

The bending behaviour of PM iron, AISI316L and DistaloyAE-0.5%C at two density levels was investigated by means of three point bending tests. The results of the tests are compared with a finite element model which, using experimental curves obtained by tensile and compressive tests, describes the load-deflection bending behaviour of the materials and gives useful information on the stress and strain distributions on the specimen during plastic deformation until fracture. The materials show a clear asymmetry in the tensile and compressive behaviour: the elastic modulus, yield strength and strain hardening rate are higher under compression than under tension. This gives rise to a shift of the neutral axis towards the compressive side of the bend specimen and strongly influences the bending load-deflection responses of the materials. All the results are discussed with reference the collaboration factor concept, which is defined as the ratio between the transverse rupture strength and the ultimate tensile strength. It is representative of the ductility of the materials and can be used as a suitable parameter for the comparison between sintered steels and wrought steels. The effect of density and matrix microstructure is then highlighted.