Didier Guichard

Production of Net-Shape Static Parts by Direct HIPing of Nickel Base Superalloy Prealloyed Powders

In order to reduce costs and increase the operating temperatures in aero-turboengines and space propulsion systems, net-shape or near net-shape production processes have been developed for static parts through HIPing (Hot Isostatic Pressing) of nickel base superalloys prealloyed powders. The presented results hereafter are related to the manufacturing processes and the mechanical properties (tensile, creep and LCF) characterisation. The effects of net shape surfaces and of surface conditioning have been investigated too. Examples of actual parts (CFM56 turbine casing and Vulcain rocket engine gas generator) illustrate the presentation. This study has confirmed the interest of this production route and future potential for development.

Damage Mechanisms and Rupture Criterion of PM Ti-6Al-4V at 20K

A two parameters rupture criterion for Ti-6Al-4V is proposed, based on cryogenic rupture tests. microstructural observations and FEM analysis,. The damage mechanisms including the cavities nucleation process are analyzed. Moreover, the final steps of rupture are discussed with the help of the thermo-mechanical coupling mechanisms that are expected to operate at low temperatures.