Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore
doi:10.3850/978-981-18-6021-8_OR-01-0144
Additive Manufacturing of Spatially Configurable Heterostructured Materials
Singapore Institute of Manufacturing Technology, A*STAR, 73 Nanyang Drive, 637662, Singapore
ABSTRACT
Laser additive manufacturing (LAM) enables the processing of heterogeneous materials with customised architectures to combine the merits of constitutive materials for attaining better mechanical property and functionality. To fully leverage the material-complexity capability of LAM, this study explored LAM of non-laminar spatially heterostructured materials (SHM) with configurable architectures to combine superior properties from the constitutive AISI 420 stainless steel and C300 maraging steel to enhance the overall properties. It is proven that the hatch spacing (h) has a significant effect on the microstructural evolutions and mechanical properties of the SHMs as it affects the layer thickness and inter-dilution regions. The mechanical properties of the SHMs were evaluated at multi-scales. The sample with h of 1.5 mm possesses a high tensile strength of about 1.6 GPa along with a reasonable break elongation of 8.1%, showing a good strength-ductility combination. Micropillar compression tests were conducted to measure localised mechanical properties, which is critical to understand the strengthening mechanism. Additionally, the SHM substantiates a much higher strength than many lamellar and linear functionally graded materials reported in the literature. This can be explained by the rule-of-mixture effect and hetero-deformation induced strengthening (HDIS). Furthermore, in-situ deformation observation reveals multiple deformation bands in SHM, which delays necking and contributed to ductility in tandem with the transformation induced plasticity (TRIP) effect. The findings demonstrated a novel approach to circumvent material property tradeoffs.
Keywords: Heterostructured materials, Voxelized architecture, High-strength steel, Strength-ductility synergy, Deformation behaviour.
Singapore Institute of Manufacturing Technology, A*STAR, 73 Nanyang Drive, 637662, Singapore
ABSTRACT
Laser additive manufacturing (LAM) enables the processing of heterogeneous materials with customised architectures to combine the merits of constitutive materials for attaining better mechanical property and functionality. To fully leverage the material-complexity capability of LAM, this study explored LAM of non-laminar spatially heterostructured materials (SHM) with configurable architectures to combine superior properties from the constitutive AISI 420 stainless steel and C300 maraging steel to enhance the overall properties. It is proven that the hatch spacing (h) has a significant effect on the microstructural evolutions and mechanical properties of the SHMs as it affects the layer thickness and inter-dilution regions. The mechanical properties of the SHMs were evaluated at multi-scales. The sample with h of 1.5 mm possesses a high tensile strength of about 1.6 GPa along with a reasonable break elongation of 8.1%, showing a good strength-ductility combination. Micropillar compression tests were conducted to measure localised mechanical properties, which is critical to understand the strengthening mechanism. Additionally, the SHM substantiates a much higher strength than many lamellar and linear functionally graded materials reported in the literature. This can be explained by the rule-of-mixture effect and hetero-deformation induced strengthening (HDIS). Furthermore, in-situ deformation observation reveals multiple deformation bands in SHM, which delays necking and contributed to ductility in tandem with the transformation induced plasticity (TRIP) effect. The findings demonstrated a novel approach to circumvent material property tradeoffs.
Keywords: Heterostructured materials, Voxelized architecture, High-strength steel, Strength-ductility synergy, Deformation behaviour.