Papers by Author: Patrice Peyre

Abstract: A Ti-47Al-2Cr-2Nb (at.%) material was fabricated using two laser-based methods, “Selective Laser Melting” (SLM) and “Direct Metal Deposition” (DMD), for potential uses in aircraft jet engines. Experiments were conducted under controlled atmosphere by changing the processing parameters. Optimal parameters were searched for this relatively low ductility material to prevent cracking due to built-up residual stresses during fast cooling. It was observed that these non-equilibrium cooling conditions were fast enough to generate ultra fine and metastable structures exhibiting high microhardness values. Post heat-treatments were successfully used to restore homogeneous lamellar or duplex microstructures and to relieve the residual stresses. A comparison of these two methods is provided in terms of powder requirements and of process parameters to achieve noncracked structures and fully dense materials.

Abstract: Laser shock processing (LSP) is a new and competitive technology in comparison with classical mechanical surface treatments for alloys strengthening. The compressive residual stress could be induced by LSP, which further significantly affects materials surface properties. Aluminum based alloy 6056 is used for aeronautic components and their surface strengthening is very important to increase components’ durability. The main factors of LSP, which affect the surface properties of alloys, such as surface roughness and residual stress gradient, are studied and analyzed in present study. The sin2* method with pseudo-grazing incidence X-ray diffraction (GIXRD) is used to determine the residual stress gradient after LSP treatment. In addition, the FEM simulation of residual stress distribution induced by LSP is also carried out and the results are compared with experimental data.