Abstract
Additive manufacturing (AM) techniques including laser powder bed fusion have been widely used to produce metallic components with microstructures and mechanical properties distinctly different from the conventionally manufactured counterparts. Understanding how AM parameters affect the evolution of microstructure, including texture, of these AM metallic components is critical for appropriate manipulation of their processing and therefore their mechanical properties. Here we conducted a systematic investigation of texture evolution of a face-centred cubic CrMnFeCoNi high-entropy alloy cuboid fabricated using laser powder bed fusion. Our results showed that the texture evolutions along the build direction were different between the corner and central parts of the sample. Detailed analysis suggested that the texture evolution is closely related to local thermal gradient, which is a property that can be manipulated through changing AM parameters. The different textures lead to the significant variations of mechanical properties within the sample.
Highlights
Additive manufacturing (AM) is an advanced technology for rapid production of components with complex geometries
It is generally recognised that the development of crystallographic texture in AM components is a consequence of the cooperated effects of the direction of thermal gradient[14, 15, 17, 18, 22, 27, 31] and the decreased nucleation energy enabled by epitaxial growth [15, 32, 33], the cooling rate [16, 17, 28], and the scan strategy [19–21, 24–26]
The texture evolution exhibited dissimilar behaviours at different locations within a single as-fabricated product. Such different texture developments produced by identical AM processing parameters are attributed to the disparity of local thermal histories between the central and corner parts
Summary
Additive manufacturing (AM) is an advanced technology for rapid production of components with complex geometries. Opposed to the conventional subtractive manufacturing approaches where unwanted materials are removed from an overdimensioned bulk piece, AM is an incremental process based on layer-by-layer deposition of materials from a feedstock of wires or powders that is often selectively melted by a high power focused laser or electron beam [1–4]. As a near-net or net shape fabrication technology, AM significantly reduces the materials cost by only consuming the required amount of feedstock materials and is ideal for producing components made from expensive materials like many high-entropy alloys (HEAs) [5]. During the LPBF process, metallic powders are melted by a high power focused laser beam to fabricate net-shaped or near-net-shaped products [4]. The processing parameters such as scanning speed and laser power are controlled by computer programs [3]. The layer-by-layer materials deposition and traverse scanning path during the LPBF process significantly influence the solidification texture owing to the local thermal gradients and preferred grain growth direction [14–18], which is \ 001 [ for face-centred cubic (FCC) alloys [19–22]
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