Product Code: ICAL07_106

Heat Flow and Structural Development during Direct Metal Deposition of Waspaloy Wire using a High Power Diode Laser
Authors:
D Graham McCartney, School of Mechanical, Materials and Manufacturing Engineering; Nottingham Great Britain
Ian R Pashby, School of Mechanical, Materials and Manufacturing Engineering, The University of Nottingham; Nottingham Great Britain
Joel Segal, School of Mechanical, Materials and Manufacturing Engineering; Nottingham Great Britain
Nur Hussein, School of Mechanical, Materials and Manufacturing Engineering, The University of Manchester; Nottingham Great Britain
Presented at ICALEO 2007

Direct metal deposition using a wire fed high power diode laser is a feasible process to form multiple layers of Waspaloy deposit at excellent deposition rates. In conjunction with a manipulation system, a complex three-dimensional structure could be fabricated offering promising applications for repair, feature addition and new component manufacture. Understanding the microstructure and mechanical properties of the material, especially one such as Waspaloy which is used in aerospace engines, is crucial to ensure its performance. The building of parts, layer-by-layer, causes dynamic changes in the underlying substrate and the previously deposited layer geometry due to the thermal cycling experienced. The heating and cooling rates during the deposition process affect the microstructure of the alloy which has an important impact on the mechanical properties of the material. The aim of the study is to understand the mechanisms of deposition involving both melting and resolidification stages. A further objective is to evaluate the microstructural evolution during deposition and the changes in microhardness when multiple layers are deposited. The main findings include: an analysis of the melt pool shape and depth of melting during deposition; the grain and dendrite orientations arising from solidification; the effect of the heating and cooling cycles on secondary phase formation and coarsening; and changes in layer by layer hardness in as deposited material. These results will be presented, related to measured thermal cycles and discussed in detail in this paper.