Laser powder bed fusion processing of AD730® alloy

The Additive Manufacturing (AM) ability of AD730® alloy by laser powder bed fusion (PBF-LB) is investigated for comparison with the cast & wrought AD730® alloy developed by Aubert & Duval for gas turbine applications. Several designs of experiments were needed to identify stable manufacturing conditions and build-up strategy in terms of low defect rate and microstructure soundness. In particular, the laser power, the scan speed, the layers' thickness, the hatching distance, and the scanning strategy were determined to successfully produce crack-free samples. The PBF-LB AD730® alloy exhibits columnar grains along the build direction. The resultant texture is close to a singlecrystalline-like cube texture. Upon annealing (solution annealing + single aging treatment), such a strong texture is preserved despite the formation of a network of fine transgranular secondary g' precipitates. Room temperature tensile properties are encouraging with yield stress lying between the coarse and fine grain microstructures of cast & wrought AD730®, for both orientations. An anisotropic mechanical behavior is obtained with higher properties for specimens printed along X and Y orientations than along Z. Finally, no evidence of premature failure due to micro-cracks has been detected in the overall test specimens.