Juan Daniel Trejos, Luis Arturo Reyes, Carlos Garza, Patricia Zambrano and Omar Lopez-Botello
An experimental and numerical study of thermal profiles of 316 L stainless steel during selective laser melting (SLM) was developed. This study aims to present a novel approach to…
Abstract
Purpose
An experimental and numerical study of thermal profiles of 316 L stainless steel during selective laser melting (SLM) was developed. This study aims to present a novel approach to determine the significance and contribution of thermal numerical modeling enhancement factors of SLM.
Design/methodology/approach
Surface and volumetric heat models were proposed to compare the laser interaction with the powder bed and substrate, considering the powder size, absorptance and propagation of the laser energy through the effective depth of the metal layer. The approach consists in evaluating the contribution of the thermal conductivity anisotropic enhancement factors to establish the factors that minimized the error of the predicted results vs the experimental data.
Findings
The level of confidence of the carried-out analysis is of 97.8% for the width of the melt pool and of 99.8% for the depth of the melt pool. The enhancement factors of the y and z spatial coordinates influence the most in the predicted melt pool geometry.
Research limitations/implications
Nevertheless, the methodology presented in this study is not limited to 316 L stainless steel and can be applied to any metallic material used for SLM processes.
Practical implications
This study is focused on 316 L stainless steel, which is commonly used in SLM and is considered a durable material for high-temperature, high-corrosion and high-stress situations.
Social implications
The additive manufacturing (AM) technology is a relatively new technology becoming global. The AM technology may have health benefits when compared to the conventional industrial processes, as the workers avoid extended periods of exposure present in conventional manufacturing.
Originality/value
This study presents a novel approach to determine the significance and contribution of thermal numerical modeling enhancement factors of SLM. It was found that the volumetric heat model and anisotropic enhancement thermal approaches used in the present research, had a good agreement with experimental results.
Details
Keywords
Sultan AlRedha, Anton Shterenlikht, Mahmoud Mostafavi, Derreck Van Gelderen, Omar Eduardo Lopez-Botello, Luis Arturo Reyes, Patricia Zambrano and Carlos Garza
A key challenge found in additive manufacturing is the difficulty to produce components with replicable microstructure and mechanical performance in distinct orientations. This…
Abstract
Purpose
A key challenge found in additive manufacturing is the difficulty to produce components with replicable microstructure and mechanical performance in distinct orientations. This study aims to investigate the influence of build orientation on the fracture toughness of additively manufactured AlSi10Mg specimens.
Design/methodology/approach
The AlSi10Mg specimens were manufactured using the selective laser melting (SLM) technology. The fracture toughness was experimentally determined (under ASTM E399-09) using C(T) specimens manufactured in different orientations. The microstructure of the specimens was examined using metallography to determine the effects of grain orientation on fracture toughness.
Findings
The fracture toughness magnitude of manufactured specimens ranged between 36 and 50 MPam, which closely matched conventional bulk material and literature values regarding AlSi10Mg components. The C(T) specimens printed in the T-L orientation yielded the highest fracture toughness. The grain orientation and fracture toughness values confirm the anisotropic nature of SLM parts where the T-L-oriented specimen obtained the highest KIC value. A clear interaction between the melt pool boundaries and micro-slipping during the loading application was observed.
Originality/value
The novelty of this paper consists in elucidating the relationship between grain orientation and fracture toughness of additively manufactured AlSi10Mg specimens because of the anisotropy generated by the different melting pool boundaries and orientations in SLM. The findings show that melt pool boundaries can behave as easier pathways for cracks to propagate and subsequently reduce the fracture toughness of specimens with cracks perpendicular to the build direction.
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Germán Omar Barrionuevo, Jorge Andrés Ramos-Grez, Magdalena Walczak, Xavier Sánchez-Sánchez, Carolina Guerra, Alexis Debut and Edison Haro
The effect of processing parameters on the microstructure of steel produced by laser-based powder bed fusion (LPBF) is a recognized opportunity for property design through…
Abstract
Purpose
The effect of processing parameters on the microstructure of steel produced by laser-based powder bed fusion (LPBF) is a recognized opportunity for property design through microstructure control. Because the LPBF generates a textured microstructure associated with high anisotropy, it is of interest to determine the fabrication plane that would generate the desired property distribution within a component.
Design/methodology/approach
The microstructure of 316 L produced by LPBF was characterized experimentally (optical, scanning electron microscopy, glow discharge emission spectrometry and X-ray diffraction), and a finite element method was used to study the microstructure features of grain diameter, grain orientation and thermal parameters of cooling rate, thermal gradient and molten pool dimensions.
Findings
The computational tool of Ansys Additive was found efficient in reproducing the experimental effect of varying laser power, scanning speed and hatch spacing on the microstructure. In particular, the conditions for obtaining maximum densification and minimum fusion defects were consistent with the experiment, and the features of higher microhardness near the component’s surface and distribution of surface roughness were also reproduced.
Originality/value
To the best of the author’s knowledge, this paper is believed to be the first systematic attempt to use Ansys Additive to investigate the anisotropy of the 316 L SS produced by LPBF.