Session: 03-07 Metals: Laser Processing

Paper Number: 93986

93986 - Effect of Build Geometry, Orientation and Heat Treatments on the Microstructure and Mechanical Properties of Laser Powder Bed Fusion Cucrzr Alloy 

The precipitation hardenable CuCrZr alloy offers high thermal and electrical conductivity along with excellent mechanical properties. Therefore, it is used in a wide range of applications such as in aerospace and nuclear industries. The conventional processing of CuCrZr has several challenges such as coarsening of Cr precipitates, heterogeneous microstructure, and difficulties in obtaining the complex shapes. Additive manufacturing (AM) using laser powder bed fusion (LPBF) process can produce complex geometries of metals with high accuracy. The present work investigates the dependence of the build geometry and build orientation on the porosity, microstructure, and mechanical properties in as-printed and heat treated conditions of the LPBF CuCrZr. The lack of fusion porosities were observed which showed a strong dependence on the build geometry. The as-printed, solution and aged, and direct aged samples were characterized for the precipitation behavior. The as-printed microstructure comprised a cellular substructure inside the grains along with nano-scale precipitates at the grain interiors. Direct aging facilitated the formation of finer sized precipitates. Detailed characterization using transmission electron microscopy was carried out to understand the morphology of secondary phases in the copper matrix. Direct aged specimens are expected to exhibit better mechanical properties as compared to the solutionized and aged specimens due to the presence of nano size precipitates in the copper matrix. The build geometry and orientation had a profound effect on the microhardness and tensile strength. Fracture surface of the tensile samples exhibited both micro-voids and cleavage facets indicating a quasi-cleavage mode of fracture. Heat treatment optimization was able to illustrate the structural stability of the LPBF CuCrZr alloy.

Presenting Author: Anup Kulkarni Pratt and Whitney R&D Center

Presenting Author Biography: Dr. Anup Kulkarni is a Senior Engineer at Pratt and Whitney R&D Center, Bangalore, India. He has a Ph.D. in the specialization of Welding Engineering from Indian Institute of Technology Roorkee. Prior to that he completed his masters in Manufacturing Technology from National Institute of Technology Tiruchirappalli. His research interests are welding engineering, additive manufacturing, materials characterization, and modelling and simulations, etc.

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