Microstructure and mechanical properties of Hastelloy X produced by HP-SLM (high power selective laser melting)

In order to increase the production rate during selective laser melting (SLM), a high power laser with a large beam diameter is used to build fully dense Hastelloy X parts. Compared to SLM with a low power and small diameter beam, the productivitywas increased from 6mm(3)/s to 16mm(3)/s, i.e. 2.6 times faster. Besides the productivity benefit, the influence of the use of a high power laser on the rapid solidification microstructure and concomitantmaterial properties is highlighted. The current paper compares themicrostructure and tensile properties of Hastelloy X built with low and high power lasers. The use of a high power laser results in wider and shallowermelt pools inducing an enhanced morphological and crystallographic texture along the building direction (BD). In addition, the increased heat input results in coarser sub-grains or high density dislocation walls for samples processed with a high power laser. Additionally, the influence of hot isostatic pressing (HIP) as a postprocessing technique was evaluated. After HIP, the tensile fracture strain increased as compared to the strain in the as-built state and helped in obtaining competitive mechanical properties as compared to conventionally processed Hastelloy X parts. (c) 2019 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.