New Model And Adjustment Protocol For The Viscoplastic Stage Of Densification During Load Assisted Sintering : Application To Hot Isostatic Pressing Of A 316L Steel Powder
Résumé
Due to lacks of final shape prediction after HIP by the Abouaf-Chenot model used in previous collaborative projects, we implement a new model initially developed for stage III creep (with reversed stress). The so-called LPS model (viscoplastic) meets the Gurson model (plastic) when the Norton exponent tends to infinity and provides the exact solution for a hollow sphere. The complex mathematical definition of the gauge surface was first numerically approached to simplify the numerical implementation of the model. The creep law of the bulk material is determined by Hot Uniaxial Pressing tests using a SPS device. The model is then fitted on the densification curve obtained by a simple diameter measurement of a spherical container after interrupted HIP tests. The model is finally implemented in a finite element simulation and confronted to the 3D reconstruction of the external shape of a large 316L steel part elaborated by HIP.