Development and property identification of 316L stainless steel feedstock for PIM and µPIM

Micro Powder Injection Moulding (µPIM) is one of the key technologies for manufacturing 3D near net shape micro-components. In this paper we examine the properties and behaviour of sinter feedstocks using very fine powders with different binder systems. A feedstock made from mixtures of a 16 µm particle size powder and two different binder systems are compared with the same particle size commercial feedstock. For the evaluation of the influence of the particle size of the powder on viscous behaviour of feedstock, a 5 µm feedstock mixed by our research group has been compared with 16 µm commercial feedstock. The 5 µm feedstock has been used for Micro PIM experiment, including injection, debinding and sintering stages. The mechanical properties and shrinkage of final sintered parts made with different sintering cycles have been determined. Another part of the paper is the real-time test of the shrinkage rate of a cylindrical specimen in a dilatometer during the sintering stage. And the identification of a thermo-elasto-viscoplastic constitutive law for sintering model. This allows the prediction of the shrinkage, the relative density, the final residual stress and deformation of micro-components.