Abstract
Owing to its high specific strength and low density, Al–Cu alloys have been extensively used in aerospace for lightweight components. Additive manufacturing techniques such as selective laser melting, which offers geometric freedom, is suitable for topology-optimized designs. In this study, the effect of processing parameters on the densification, microstructure, and mechanical properties of additively manufactured Al–Cu alloy 2124 by selective laser melting was investigated. Parameters such as laser power, scanning speed, hatch spacing, and use of a support were studied. The results revealed that a grille support with a hollow structure played a resistant role in the transfer of heat to the base plate, thus reducing the temperature gradient and lessening cracks in the building part. Smaller hatch spacing was beneficial for the achievement of a higher relative density and strength due to track re-melting and liquid phase backflow, which could fill cracks and pores during the building process. An ultimate tensile strength as high as 300 MPa of the vertically built sample was obtained at optimized processing parameters, while the elongation was relatively limited. Moreover, columnar grains were found to be responsible for the anisotropy of the mechanical properties of the as-printed 2124 alloy.
Highlights
Additive manufacturing (AM) is an advanced technique characterized by a layer-by-layer fabrication process that produces parts with a complex geometry [1]
The aforementioned results indicated that neither a high laser power nor fast scanning speed was suitable for selective laser melting (SLM) in the present condition
This work investigated the microstructure and mechanical properties of Al alloy 2124 samples printed by SLM at various laser power, scanning speed, and hatch spacing parameters
Summary
Additive manufacturing (AM) is an advanced technique characterized by a layer-by-layer fabrication process that produces parts with a complex geometry [1]. Due to the inherently high laser reflectivity and high thermal conductivity of Al alloy powders, it is generally difficult to produce Al alloy parts with a high performance by SLM. It means that producing Al alloy parts needs a higher energy density, which is easy to cause pores, cracks, inclusions and other defects in parts because of metal splashing and greater residual stress during printing. These defects will reduce the performance of parts
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