Finite Element Analysis of Impression Creep on P91

Abstract

Impression creep is a versatile technique that is used nowadays for studying the creep deformation of different materials and there is no tertiary stage in this method; it's a non-destructive process. The present work deals with finite element analysis of plastic deformation corresponding to the impression creep deformation of P91 steel. In the FE model, a 3D deformable body is used as a specimen along with a rigid hollow cylindrical indenter with a 0.07 fillet. The effect of sizes of the specimen and indenter was studied, the diameter of the specimen was changed from 10mm,15mm, and 20mm whereas the indenter diameter was changed from 1mm,1.5mm, and 2mm respectively. Moreover, it was found that when punch diameter is increased the induced stress is reduced. It is observed that there is no effect on the diameter of the specimen, however, when the diameter of the indenter is increased from 1mm to 1.5mm and 1.5mm to 2mm, induced stress is reduced by approximately 10% and 20%, respectively. The simulation was run for 100 hours. Furthermore, the optimum distance between two impressions in P91 steel was studied and the distance between two indenters was altered from 10mm,8mm,6mm and 4mm respectively with the same loading and boundary conditions, and the same mesh size. It was observed that for P91 there is no contact between two deformations at 4mm.For P91 steel we can perform two impression creep tests from 4mm apart.