Xina Huang, Lihui Lang, Shuili Gong and Mali Zhao
The purpose of this paper is to investigate the post-treatment processes on lattice structures of selective laser melting. Moreover, the effect of pressure during hot isostatic…
Abstract
Purpose
The purpose of this paper is to investigate the post-treatment processes on lattice structures of selective laser melting. Moreover, the effect of pressure during hot isostatic pressing (HIP) is determined.
Design/methodology/approach
Three post-treatment processes, annealing at 650°C, 920°C and HIP were adopted. The microstructure evolution and mechanical properties of selective lasering melted Ti6Al4V lattice structures after post-treatment were systematically investigated by optical microscope, scanning electron microscope, electron backscattered diffraction, differential scanning calorimetry and quasi-static mechanics tests.
Findings
The main findings in this paper are as below: first, the pores existing in the samples as-fabricated, annealed at 650°C and 920°C are disappeared after HIP. Second, the microstructure and compressive properties after HIP are similar to that after pure annealing at the same temperature. However, the HIPed sample had the highest number of cycles to failure. Third, the fracture mechanism of as-fabricated samples changes from mixed fracture to the micro-voids accumulation fracture after post-treatment processes.
Originality/value
HIP post-treatment can be replaced by annealing at the same temperature when the requirement for porosity and fatigue life is not very high.
Details
Keywords
Xina Huang, Shoubin Ding, Lihui Lang and Shuili Gong
The purpose of this paper is to investigate the effect of strut size on the compressive response for selective laser-melted lattice structure with a body-centered cubic (BCC) unit…
Abstract
Purpose
The purpose of this paper is to investigate the effect of strut size on the compressive response for selective laser-melted lattice structure with a body-centered cubic (BCC) unit cell.
Design/methodology/approach
Theoretical analysis and numerical simulation were used to predict the compressive stiffness and strength of the lattice structures with different struts, and compression testing was conducted to validate the predicted results. The effect of strut size on actual porosity was determined with the dry weighting method. Scanning electron microscopy was used to observe the fracture morphologies.
Findings
The actual porosities in all the specimens turned out to be a little lower than the values expected from design. The maximum deviation appears at the strut size of 1.25 mm. The theoretical analysis reveals that the junctions of BCC unit cells are the most loaded points, and the maximum compression resistance load is proportional to the strut size. The stress–strain curves and collapse modes predicted by numerical simulation are in good agreement with the theoretical calculation and experimental results. The compression stress increases monotonously in strut size of 0.50–2.00 mm. The fracture morphologies reflect a transition from a mixed to ductile fracture mechanism. The lattice structure shows a stable plastic deformation without a destructive fracture for the strut size of 2.00 mm.
Originality/value
The findings of this study can provide theoretical and experimental support for the choice of strut size under different stress conditions. In addition, they are conductive to in-depth study of the compressive properties for lattice structures with different geometrical dimensions fabricated by selective laser melting.
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Walter R. Allen is Allan Murray Cartter Professor in Higher Education, Graduate School of Education and Information Studies at the University of California, Los Angeles. He is…
Abstract
Walter R. Allen is Allan Murray Cartter Professor in Higher Education, Graduate School of Education and Information Studies at the University of California, Los Angeles. He is also distinguished professor of sociology and director of CHOICES, a longitudinal study of college attendance among African Americans and Latinos in California. Allen's research interests include higher education, race and ethnicity, family patterns, and social inequality. He has been a consultant to courts, communities, business, and government. Allen's more than 100 publications include: Towards a Brighter Tomorrow: College Barriers, Hopes and Plans of Black, Latino/a and Asian American Students in California (2009); Till Victory is Won: The African American Struggle for Higher Education in California (2009); Everyday Discrimination in a National Sample of Incoming Law Students (2008); Higher Education in a Global Society: Achieving Diversity, Equity and Excellence (2006); Enacting Diverse Learning Environments: Improving the Climate for Racial/Ethnic Diversity in Higher Education (1999); College in Black and White: African American Students in Predominantly White and Historically Black Public Universities (1991); and The Colorline and the Quality of Life in America (1989).