Metal AMS
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61 - Influence of the layer thickness and contours on mechanical properties of 17-4PH obtained by metal extrusion additive manufacturing


Additive manufacturing (AM) is present in different industrial domains. This is the results of the advantages of AM like freedom of design, reduction of waste materials and one step fabrication. The metallic parts obtained with AM are up to now mainly produced by laser powder bed fusion (LPBF). Although the good mechanical properties of the parts are adapted for sensitive applications, their price is still high and limits their applications. More recently, Metal Extrusion Additive Manufacturing (MEAM) has emerged as a promising method for producing metal parts with drastic reductions in cost, manufacturing time and the ability to produce large parts. However, the mechanical performance of MEAM parts is inferior to that of LPBF parts due to the defect population inherent in the process (i.e. the layer-by-layer deposition of bound extruded powder followed by debinding and sintering steps, and the anisotropic mechanical properties). The challenge is how to take advantage of design flexibility and low-cost production of MEAM process in the presence of fabrication defects. The aim of this study is to analyze the effect of layer thickness and the presence of contours on the mechanical behavior, deformation mechanisms and crack propagation. An experimental approach allowing information to be accessed at the microscale was coupled with digital image correlation to analyze mechanical parameters extracted from kinematic fields. The results show that the layer thickness is an important printing parameter for such process since it greatly affects crack propagation. The macroscopic behavior of samples fabricated with two different layer thickness highlights a gap in elasticity and plastic evolutions. This gap is around 100 MPa in stress. Conversely, the notch opening displacement is comparable for all investigated samples. Then, difference in layer thickness results in difference in defects population in the material bulk, in mechanisms of deformations and fractures. The presence of the contours greatly modified the deformation mechanisms and the crack propagation. The deformations are accumulated in the contours and the fracture occurred by delamination. For the samples without the contours, the failure occurred suddenly.


EPF Ecole d'ingénieurs, Cachan, France / Laboratoire de Mécanique de Paris-Saclay, Gif-sur-Yvette, France

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61 - Influence of the layer thickness and contours on mechanical properties of 17-4PH obtained by metal extrusion additive manufacturing



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