Joining of iron base powder metal parts by sintering

Joining processes are very important to produce complex shape parts in powder metallurgy. Joining with sintering is a low cost process in comparison to other joining processes such as welding and brazing. In this study, joining with sintering of three part (flake-plug-body) assembly was examined. Powder samples with the composition Fe-0.6P (flake), Fe-0.6P-3Cu-0.4C (plug) and Fe-0.6P-2Cu (body) were pressed under a pressure of 600 MPa, sintered at 1120°C for 45 minutes under a reducing (%90N2+%10H2) gas mixture and endogas atmosphere, and their mechanical properties were measured. Original 3 part assemblies in the green state and in pre-sintered condition were sintered under the same conditions, and the bonding strength between flake-plug and body-plug was measured. In order to determine the effect of mechanical fit clearence on bonding strength flake-plug and body-plug parts, ring-pellet green samples were prepared and sintered under the same conditions. The interface of ring-pellet samples was examined with optical and scanning electron microscopy. The study show that green parts joined with sintering give sufficient bonding strength in a mechanical fit clerance range of +10 microns and -25 microns and the sintering process can be used in joining of flake-plug-body parts.