Author(s)

S. Pommier, J.M. Rongvaux, C. Prioul & D. Frangois

Abstract

Creep fatigue short crack propagation in a stress gradient S. Pommier," J.M. Rongvaux,* C. Prioul," D. Frangois" " Laboratoire MSS-Mat. URA 850 ECP, 92295 Chdtenay Malabry, France * Laboratoire Materiaux et Procedes, SNECMA (Corbeil), 91003 Evry Cedex, France ABSTRACT Double notched specimens of nickel base superalloy N18 have been subjected to creep fatigue loading at 650°C. Finite element analysis using the elastoviscoplastic constitutive equation of N18, exhibited a strong stress relaxation at the notch root. By introducing the computed viscoplastic stress gradient into the calculation of the stress intensity factor (SIF), crack growth rates measured on notched specimens are much closer to those measured on smooth specimens. INTRODUCTION With the need of improvement of aircraft gas turbine performances, security components, such as turbine and compressor discs, should be subjected to increasing stresses and temperatures. They now tend to be fabricated with powder me

Keywords