This study presents our fundamental study to understand the crystal formation in rapid cooling of... more This study presents our fundamental study to understand the crystal formation in rapid cooling of cubic crystalline alloys (namely, 316L steel and NiCoCrFeMn) and how crystal microstructure evolves during the repeated deposition of material in powder-bed laser melting. The rapid cooling results in extremely fine rod-like cells. Cells in a fresh meltpool epitaxially grow from existing grains in the substrate (or existing cells in previously solidified meltpools). It is found that the orientation of existing crystals and the thermal gradient are two governing variables for the evolution of cells in meltpools.
The rapid development of cold spraying technology for additive manufacturing of engineering compo... more The rapid development of cold spraying technology for additive manufacturing of engineering components has made it a viable option for developing thick deposits from high-entropy alloys (HEAs). The microstructure of cold-sprayed CoCrFeNiMn deposit was investigated in this study using electron backscattered diffraction, scanning electron microscopy, and finite element analysis (FEA). The limited studies on the impact deformation behavior of the HEA during cold spraying, limiting our understanding of impact phenomena, and interactions between the HEA particles under ultra-high strain rate deformation motivated this study. From the microstructural characterization, heterogeneous microstructure appears to be formed in the cold-sprayed HEA deposit, comprising of equiaxed ultrafine grains at the particle–particle interfacial regions and coarse grains at the particle interiors. The FEA reveals large strain (> 250%) and temperature (> 90% of the alloy solidus temperature), mainly at t...
List of process paramaters and resulting properties of printed samples after laser powder bed fus... more List of process paramaters and resulting properties of printed samples after laser powder bed fusion. Process parameters include: manufacturer of LPBF equipment, equipment model and laser type of the printer, laser power (P), scan speed (v), nominal powder layer thickness (t), hatch spacing (h), laser beam diameter (spot size (d), focus offset distance of the laser beam, scanning strategy, rotation angle of scanning strategy between layers and the build plate temperature. Information about the post-processing of the alloys was collected as to whether the alloy was heat-treated, heat treatment type, temperature and duration of each heat treatment step. <br> Properties include consolidation, hardness, yield stress, elongation to failure, tensile strength <br> Dataset was collected from peer-reviewed publicaions. Sources of the original data are provided within the datasheet.
This study presents our fundamental study to understand the crystal formation in rapid cooling of... more This study presents our fundamental study to understand the crystal formation in rapid cooling of cubic crystalline alloys (namely, 316L steel and NiCoCrFeMn) and how crystal microstructure evolves during the repeated deposition of material in powder-bed laser melting. The rapid cooling results in extremely fine rod-like cells. Cells in a fresh meltpool epitaxially grow from existing grains in the substrate (or existing cells in previously solidified meltpools). It is found that the orientation of existing crystals and the thermal gradient are two governing variables for the evolution of cells in meltpools.
In-depth understanding of microstructure development is required to fabricate high quality produc... more In-depth understanding of microstructure development is required to fabricate high quality products by additive manufacturing (for example, 3D printing). Here we report the governing role of side-branching in the microstructure development of alloys by laser powder bed fusion. We show that perturbations on the sides of cells (or dendrites) facilitate crystals to change growth direction by side-branching along orthogonal directions in response to changes in local heat flux. While the continuous epitaxial growth is responsible for slender columnar grains confined to the centreline of melt pools, side-branching frequently happening on the sides of melt pools enables crystals to follow drastic changes in thermal gradient across adjacent melt pools, resulting in substantial broadening of grains. The variation of scan pattern can interrupt the vertical columnar microstructure, but promotes both in-layer and out-of-layer side-branching, in particular resulting in the helical growth of micr...
This study presents our fundamental study to understand the crystal formation in rapid cooling of... more This study presents our fundamental study to understand the crystal formation in rapid cooling of cubic crystalline alloys (namely, 316L steel and NiCoCrFeMn) and how crystal microstructure evolves during the repeated deposition of material in powder-bed laser melting. The rapid cooling results in extremely fine rod-like cells. Cells in a fresh meltpool epitaxially grow from existing grains in the substrate (or existing cells in previously solidified meltpools). It is found that the orientation of existing crystals and the thermal gradient are two governing variables for the evolution of cells in meltpools.
The rapid development of cold spraying technology for additive manufacturing of engineering compo... more The rapid development of cold spraying technology for additive manufacturing of engineering components has made it a viable option for developing thick deposits from high-entropy alloys (HEAs). The microstructure of cold-sprayed CoCrFeNiMn deposit was investigated in this study using electron backscattered diffraction, scanning electron microscopy, and finite element analysis (FEA). The limited studies on the impact deformation behavior of the HEA during cold spraying, limiting our understanding of impact phenomena, and interactions between the HEA particles under ultra-high strain rate deformation motivated this study. From the microstructural characterization, heterogeneous microstructure appears to be formed in the cold-sprayed HEA deposit, comprising of equiaxed ultrafine grains at the particle–particle interfacial regions and coarse grains at the particle interiors. The FEA reveals large strain (> 250%) and temperature (> 90% of the alloy solidus temperature), mainly at t...
List of process paramaters and resulting properties of printed samples after laser powder bed fus... more List of process paramaters and resulting properties of printed samples after laser powder bed fusion. Process parameters include: manufacturer of LPBF equipment, equipment model and laser type of the printer, laser power (P), scan speed (v), nominal powder layer thickness (t), hatch spacing (h), laser beam diameter (spot size (d), focus offset distance of the laser beam, scanning strategy, rotation angle of scanning strategy between layers and the build plate temperature. Information about the post-processing of the alloys was collected as to whether the alloy was heat-treated, heat treatment type, temperature and duration of each heat treatment step. <br> Properties include consolidation, hardness, yield stress, elongation to failure, tensile strength <br> Dataset was collected from peer-reviewed publicaions. Sources of the original data are provided within the datasheet.
This study presents our fundamental study to understand the crystal formation in rapid cooling of... more This study presents our fundamental study to understand the crystal formation in rapid cooling of cubic crystalline alloys (namely, 316L steel and NiCoCrFeMn) and how crystal microstructure evolves during the repeated deposition of material in powder-bed laser melting. The rapid cooling results in extremely fine rod-like cells. Cells in a fresh meltpool epitaxially grow from existing grains in the substrate (or existing cells in previously solidified meltpools). It is found that the orientation of existing crystals and the thermal gradient are two governing variables for the evolution of cells in meltpools.
In-depth understanding of microstructure development is required to fabricate high quality produc... more In-depth understanding of microstructure development is required to fabricate high quality products by additive manufacturing (for example, 3D printing). Here we report the governing role of side-branching in the microstructure development of alloys by laser powder bed fusion. We show that perturbations on the sides of cells (or dendrites) facilitate crystals to change growth direction by side-branching along orthogonal directions in response to changes in local heat flux. While the continuous epitaxial growth is responsible for slender columnar grains confined to the centreline of melt pools, side-branching frequently happening on the sides of melt pools enables crystals to follow drastic changes in thermal gradient across adjacent melt pools, resulting in substantial broadening of grains. The variation of scan pattern can interrupt the vertical columnar microstructure, but promotes both in-layer and out-of-layer side-branching, in particular resulting in the helical growth of micr...
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