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Pressing and sintering in powder technology

: Riedel, H.

Rappaz, M.; Kedro, M. ; European Cooperation in the Field of Scientific and Technical Research -COST-:
Modelling in Materials Science and Processing
Luxembourg: Office for Official Publications of the European Communities, 1996
ISBN: 92-827-7661-1
General Workshop on Modelling in Materials Science and Processing (MMSP) <1996, Davos>
Conference Paper
Fraunhofer IWM ()
die compaction; Matrizenpressung; powder metallurgy; Pulvermetallurgie; simulation; sintering; Sintern

Two of the major problems in powder technology are cracking of the parts during die pressing and shape distortions during sintering, the latter being more severe the more the material shrinks. Limitations to the geometrical accuracy of the parts arise also from the (anisotropic) spring-back during unloading and ejection after pressing. These problems are addressed by finite element modelling. First, phenomenological and micromechanical models for powder compaction during die pressing are described including one with evolving anisotropy. Second, crack formation during pressing and ejection is modelled as a strain localization process in the finite element simulation. Third, a model for liquid phase sintering is described, which includes particle rearrangement, contact flattening by the solution/precipitation mechanism and grain coarsening. Finally the feasibility of the whole approach is demonstrated by simulating the pressing and sintering of a hard metal cutting tool and comparing pre dicted distortions with measured values.