The effect of HF-HNO3 chemical polishing on the surface roughness and fatigue life of laser powder bed fusion produced Ti6Al4V

Bezuidenhout, Martin; Haar, Gerrit Matthys Ter; Becker, Thorsten Hermann; Rudolph, S.; Damm, Oliver; Sacks, Natasha

doi:10.1016/j.mtcomm.2020.101396

Cited by 50 publications

(41 citation statements)

References 36 publications

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“…Therefore, it is important to reduce the surface roughness of the parts manufactured by PBF, especially for applications in need of long fatigue life. Generally, surface treatments such as chemical milling [ 16 , 17 ], CNC machining [ 18 , 19 ], and abrasive flow machining [ 20 , 21 ] are applied as a post-processing step, after the PBF process, to overcome this surface quality problem. However, the complexity of the PBF parts, which is one of the most important strengths of AM, generally inhibits uniform material removal throughout the whole process or leads to a line-of-sight problem at some features like internal cooling channels [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Contact-Free Support Structures for the Direct Metal Laser Melting Process

Çelik

Tekoğlu²,

Yasa

et al. 2022

Materials

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Although Direct Metal Laser Melting (DMLM), a powder bed fusion (PBF) Additive Manufacturing (AM) for metallic materials, provides many advantages over conventional manufacturing such as almost unlimited design freedom, one of its main limitations is the need for support structures beneath overhang surfaces. Support structures are generally in contact with overhang surfaces to physically prop them up; therefore, they need to be removed after manufacturing due to not constituting a part of the main component design. The removal of supports is a process sequence adding extra time and cost to the overall manufacturing process and could result in damaging the main component. In this study, to examine the feasibility of contact-free supports for overhang surfaces in the DMLM process, coupons with these novel types of supports were prepared from CoCrMo alloy powder. This study aims to understand the effect of two parameters: the gap distance between supports and overhang surfaces and the inclination angle of overhang surfaces, on the surface topography and microstructural properties of these surfaces. Visual inspection, roughness measurements, and optical microscopy were utilized as characterization methods The roughness parameters (Ra, Rq, and Rz) were obtained using the focus variation method, and optical microscope analysis was performed on the cross-sections of the overhang surfaces to investigate the sub-surface microstructure and surface topology. Results showed that contact-free supports have a positive effect on decreasing surface roughness at all build angles when the gap distance is correctly set to avoid sintering of the powder in between the overhang and supports or to avoid too large gaps eliminating the desired effect of the higher thermal conductivity.

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Section: Introductionmentioning

confidence: 99%

Contact-Free Support Structures for the Direct Metal Laser Melting Process

Çelik

Tekoğlu²,

Yasa

et al. 2022

Materials

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Section: Resultsmentioning

confidence: 99%

“…When the shape parameters are higher than 1.2, the diameter of microstruts is too small, the accuracy and manufacture quality is worse, more incompletely melted powder adhered on the surface of the microstruts, and so there are more surface defects and stress concentrations, which will decrease the mechanical property of the lattice structures. [12,13] When the shape parameter is 1.2, the elastic modulus reaches the maximum value. The plateau stress is the largest when the shape parameters are 0.4 and 0.6, and then the plateau stress decreases significantly with the increase in shape parameters.…”

Section: Influence Of Shape Parameters On Quasistatic Compression Per...mentioning

confidence: 99%

“…The reason may be that when the relative density and shape parameters are the same, the smaller the unit size, the more the number of struts, and smaller the struts diameter in the lattice structure. In this case, more incompletely melted powder adhered on the surface of the microstruts fabricated by SLM, so there are more surface defects and stress concentrations, [12,13] which may be the weak spots of destruction and decrease the mechanical property.…”

Section: Elastic Modulusmentioning

confidence: 99%

“…As a member of the AM, selective laser melting (SLM) has been successfully used to fabricate intricate lattice structures for various applications. [7][8][9][10][11][12][13] However, the lattice structure prepared by SLM usually has errors with the original design. Although the manufacturing error can be reduced by optimizing the processing parameters, the manufacturing error cannot be completely eliminated due to the inherent characteristics of SLM.…”

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confidence: 99%

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Study on the Quasistatic Compression Performance of Arch Microstrut Lattice Structure by Selective Laser Melting

Zhao

Ding

et al. 2021

Adv Eng Mater

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In recent years, lattice structures have been widely used in aerospace, automobile, biomedicine, and other fields. Lattice structures are porous structures composed of repeating cellular units. Because of their high-porosity spatial structure and low density, lattice structures have high specific strength, high specific stiffness, good energy absorption ability, excellent thermal and acoustic insulation properties, and so on. [1][2][3][4][5][6] The properties of the lattice structures are defined by the cell structure, cell size, base material properties, and relative densities of the cellular unit.Because of the highly complex spatial structure of lattice structures, it is difficult to manufacture the lattice structures with the traditional manufacturing process. Recently, the development of the additive manufacturing (AM) technologies has made the manufacturing of lattice structures easier. Based on ASTM standard, [3] AM is defined as a process of joining materials to make parts from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing and formative manufacturing methodologies. As a member of the AM, selective laser melting (SLM) has been successfully used to fabricate intricate lattice structures for various applications. [7][8][9][10][11][12][13] However, the lattice structure prepared by SLM usually has errors with the original design. Although the manufacturing error can be reduced by optimizing the processing parameters, the manufacturing error cannot be completely eliminated due to the inherent characteristics of SLM. SLM is a forming method based on multilayer accumulation. During manufacturing, the transition between layers is discontinuous, so it will produce step effect. At the same time, the thermal diffusion in the laser processing area will lead to incomplete melting of the powder in the adjacent area, and the incomplete melting metal powder will adhere to the struts' surface, which will affect the manufacturing accuracy and mechanical property of the lattice structure. Further development on the manufacturing technology of lattice structures and improving the machining accuracy and quality are also the focus of future research.At present, the most common lattice structures include microstrut lattice structure (composed of straight struts and nodes), triply periodic minimal surfaces' lattice structure (consists of several smooth surfaces), and the structure derived from them. The microstrut lattice structures include body-centered cubic (BCC), face-centered cubic (FCC), rhombic dodecahedron (RD), et al. and the triply periodic minimal surfaces' lattice structures include Gyroid cellular (GC), Schoen Gyroid (SG), et al. Because of its simple structure and convenient manufacture, BCC lattice structures been widely studied and applied. [7][8][9] SLM technique offers a viable method for manufacturing highperformance BCC lattice structures, which have good property in absorbing energy, and the Gibson-Ashby model could be adapted to predict BCC lattice mechanical properties fo...

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Surface Modification of Porous Titanium and Titanium Alloy Implants Manufactured by Selective Laser Melting: A Review

Liu,

Li,

Wang

et al. 2023

Adv Eng Mater

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Titanium (Ti) and its alloy implants with porous structure manufactured by selective laser melting (SLM) can match elastic modulus of human bone to reduce the stress‐shielding effect and satisfy the personalized requirement in orthopedic surgery. Compared with conventional casting and forging Ti and its alloy implants, SLM implants possess unique microstructural features and excellent comprehensive mechanical properties. However, the un‐melted powder particles inevitably adhere to the surfaces of SLM implants, which may result in excessive surface roughness and potential health risks. Moreover, there are significant issues encountered, such as bioactivity, toxicity, antibacterial activity, corrosion and wear resistance. Consequently, surface modification methods are essential to remove the un‐melted powder particles and improve biological and mechanical properties of SLM implants. Herein, the research efforts focus exclusively on chemical (acid treatment, alkali treatment, sol‐gel, chemical vapor deposition and atomic layer deposition) and electrochemical methods (anodization and microarc oxidation) for SLM Ti and its alloy implants, especially for porous structures. Particularly, the characteristics of these methods are summarized, and their commonly used pre‐ and post‐treatment methods are introduced. In addition, the development trends and challenges in surface modification of SLM Ti and its alloy implants are discussed.This article is protected by copyright. All rights reserved.

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The effect of HF-HNO3 chemical polishing on the surface roughness and fatigue life of laser powder bed fusion produced Ti6Al4V

Cited by 50 publications

References 36 publications

Contact-Free Support Structures for the Direct Metal Laser Melting Process

Contact-Free Support Structures for the Direct Metal Laser Melting Process

Study on the Quasistatic Compression Performance of Arch Microstrut Lattice Structure by Selective Laser Melting

Surface Modification of Porous Titanium and Titanium Alloy Implants Manufactured by Selective Laser Melting: A Review

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