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Ti6Al4V scaffolds fabricated by laser powder bed fusion with hybrid volumetric energy density

Bhanupratap Gaur (Mechanical Engineering Department, Biomedical Engineering and Technology Innovation Centre (BETIC) Lab, Indian Institute of Technology Bombay, Mumbai, India)
Deepak Soman (Mechanical Engineering Department, Microstructural Mechanics and Micro-forming Laboratory (MMMF Lab), Indian Institute of Technology Bombay, Mumbai, India)
Rupesh Ghyar (Mechanical Engineering Department, Biomedical Engineering and Technology Innovation Centre (BETIC) Lab, Indian Institute of Technology Bombay, Mumbai, India)
Ravi Bhallamudi (Mechanical Engineering Department, Biomedical Engineering and Technology Innovation Centre (BETIC) Lab, Indian Institute of Technology Bombay, Mumbai, India)

Rapid Prototyping Journal

ISSN: 1355-2546

Article publication date: 1 July 2022

Issue publication date: 2 January 2023

122

Abstract

Purpose

Additive manufacturing of metallic scaffolds using laser powder bed fusion is challenging because of the accumulation of extra material below overhanging and horizontal surfaces. It reduces porosity and pore size and increases the effective strut size. These challenges are normally overcome by using volumetric energy density (VED) values lower than the optimum values, which, however, results in poor physio-mechanical properties. The purpose of this study is to assist scaffold manufacturers with a novel approach to fabricate stronger yet accurate scaffolds.

Design/methodology/approach

This paper presents a strategy for laser exposure that enables fabricating titanium-6–aluminum-4–vanedium (Ti6Al4V) alloy scaffolds with the required properties without compromising the geometric features. The process starts from computer-aided design models sliced into layers; dividing them into core (upper) and downskin (lower) layers; and fabrication using hybrid VED (low values for downskin layers and high values for core layers).

Findings

While exposing the core layers, laser remelted the downskin layers, resulting in better physio-mechanical properties (surface roughness, microhardness and density) for the whole strut without affecting its dimensional accuracy. A regression equation was developed to select the downskin thickness for a given combination of strut thickness and core VED to achieve the desired range of properties. The proposed approach was validated using microstructure analysis and compression testing.

Practical implications

This paper is expected to be valuable for the manufacturers of Ti6Al4V scaffolds, in achieving the desired properties.

Originality/value

This is probably the first time the hybrid VED approach has been applied for obtaining scaffolds with the desirable physio-mechanical and geometrical properties.

Keywords

Acknowledgements

The investigation involved preparing the samples and conducting the experiments using medical device development and medical metal printing facilities at Biomedical Engineering and Technology Innovation Centre, IIT Bombay, established with funding support from RG Science & Technology Commission, Mumbai, and the Department of Science & Technology, New Delhi. The authors acknowledge the support of Professor Sushil Mishra for providing access to the Microstructural Mechanics and Microforming Lab and Advanced Mechanical Testing Facility, IIT Bombay, for microstructural study and compression tests.

Declaration of competing interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Ethical standard statement: All institutional and national guidelines for the care and use of laboratory animals were followed.

Data sharing: Test data related to the experiments can be found using the link: https://osf.io/y98kh/?view_only=3655c8cc5644405cb5eba36ddafe6b8b

Citation

Gaur, B., Soman, D., Ghyar, R. and Bhallamudi, R. (2023), "Ti6Al4V scaffolds fabricated by laser powder bed fusion with hybrid volumetric energy density", Rapid Prototyping Journal, Vol. 29 No. 1, pp. 67-79. https://doi.org/10.1108/RPJ-01-2022-0036

Publisher

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Emerald Publishing Limited

Copyright © 2022, Emerald Publishing Limited

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