The effect of laser remelting on the surface chemistry of Ti6al4V components fabricated by selective laser melting

Vaithilingam, Jayasheelan; Goodridge, Ruth; Hague, Richard; Christie, S.; Edmondson, Stephen

doi:10.1016/j.jmatprotec.2016.01.022

Cited by 176 publications

(58 citation statements)

References 20 publications

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“…Laser polishing, chemical polishing, electrochemical polishing, and abrasive flow polishing have shown great potential for the treatment of the surfaces of AM parts. Laser polishing is efficient and can directly use the laser source of laser melting deposition equipment, but this technique is prone to causing thermal damage [8] and is more difficult to irradiate with uniform intensity on complex surfaces, which leads to deviations from the designed geometry [9]. Chemical polishing and electrochemical polishing can effectively treat all kinds of freeform surfaces, lattices and porous structural parts [10,11], but do not solve the environment, health and safety problems.…”

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confidence: 99%

Material Removal in Ultrasonic Abrasive Polishing of Additive Manufactured Components

2019

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Featured Application: The study of the material removal mechanisms in ultrasonic abrasive polishing provides technical support for the surface modification of metal-based additive manufactured components which have poor surface quality. In addition, the technology can be further applied to smoothing various complex shapes and the internal features of both metal and non-metal parts, due to the use of loose abrasive particles and the possibility of uniform material removal process.Abstract: Powder-based layered Additive Manufacturing (AM) techniques lead to high surface roughness, due to the balling and partial melting of powders, which cannot satisfy the requirements of design and practical use. Consequently, until there is a significant step-change in the resolution of AM technology, finishing processes will be a necessary step in the additive manufacturing process. In this work, ultrasonic abrasive polishing experiments are conducted with the aim of improving the surface quality of additive manufactured components. The roles of cavitation bubbles and abrasive particles in material removal are discussed. The impact action of abrasive particles is simulated using the Smoothed Particle Hydrodynamics (SPH) method. The effects of ultrasonic output power and the concentration of abrasive suspension on machining characteristics are also examined. It is found that the cavitation bubble collapse in ultrasonic polishing can remove the partially melted structures efficiently, and further roughness improvement could be obtained using the micro-cut and impact of abrasive particles in the slurry. An increase in the ultrasonic output power and abrasive concentration within a certain range lead to a more desirable polishing effect.Additive Manufacturing (AM) technology has developed rapidly over the past two decades. Metal-based AM techniques represented by Powder Bed Fusion (PBF) have advantages, including the production of fine features with great geometrical accuracy and high-strength-to-weight ratios. However, its forming mechanism, based on the melting of metal powders, induces the agglomeration of partially melted powders and a balling phenomenon in the process [1]. Therefore, the average roughness (Ra) of metal-based AM parts is generally higher than 10 µm [2], which not only affects the appearance, but also greatly influences several functional properties, including fatigue resistance, friction performance and heat transfer [3][4][5]. Accordingly, post-process finishing is required to improve the surface quality of AM parts [6,7]. AM parts always have complex shapes and features, which makes the finishing process difficult. Several surface modification processes for AM parts have been reported in the literature. However, each process has limitations and complexities. Implementing hand polishing as one of the main finishing processes for AM parts would increase the labor cost and time, and the surface quality would be poor. Laser polishing, chemical polishing, electrochemical polishing, and abrasive flow polishing have s...

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confidence: 99%

Material Removal in Ultrasonic Abrasive Polishing of Additive Manufactured Components

2019

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“…Microstructure morphologies of the as-received Ti6Al4V and AA6060 are shown in Figure 1. For Ti6Al4V, the α-Ti phase is shown in dark and in the form of equiaxed grains and the β-Ti phase is represented by the bright regions [22,23]. The microstructure contains a volume fraction of 93.9% of the α-Ti phase and 6.1% of the β-Ti phase.…”

Section: Base Materialsmentioning

confidence: 99%

Interfacial Characteristics of Dissimilar Ti6Al4V/AA6060 Lap Joint by Pulsed Nd:YAG Laser Welding

Xue

Péreira

Vincze

et al. 2019

Metals

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This paper focuses on the interfacial characteristics of dissimilar Ti6Al4V/AA6060 lap joint produced by pulsed Nd:YAG laser beam welding. The process-sensitivity analysis of welding-induced interface joining quality was performed by using the orthogonal design method. Microstructural tests such as scanning electron microscopy and energy dispersive X-ray spectroscopy were used to observe the interfacial characteristics. The mechanism of interfacial crack initiation, which is an important indicator of joint property and performance, was assessed and analyzed. The preferred propagation paths of welding cracks along the interfaces of different intermetallic layers with high dislocation density were analyzed and discussed in-depth. The results indicate that discontinuous potential phases in the micro-crack tip would mitigate the mechanical resistance or performance of the welded joint, while the continuous intermetallic layer can lead to a sound jointing performance under pulsed Nd:YAG laser welding process.

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Section: Introductionmentioning

confidence: 99%

“…It is commonly employed as a post-process treatment for enhancing the homogeneity in microstructure and reducing the porosity in the surface layer [31][32][33][34]. Examples of successful applications to bio-metallic materials include AISI 316L stainless steel [31] and Ti6Al4V [34]. Unlike the more popular technique, namely laser ablation (or laser surface texturing), which is based on the removal of material to create the surface patterns, laser remelting modifies the surface based on the reallocation of material while in its molten state (i.e., no material is removed when the surface is irradiated by a laser beam) [29].…”

Section: Introductionmentioning

confidence: 99%

A Preliminary Study to Enhance the Tribological Performance of CoCrMo Alloy by Fibre Laser Remelting for Articular Joint Implant Applications

2018

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Abstract:CoCrMo alloy has long been used as a pairing femoral head material for articular joint implant applications because of its biocompatibility and reliable tribological performance. However, friction and wear issues are still present for CoCrMo (metal)/CoCrMo (metal) or CoCrMo (metal)/ultrahigh molecular weight polyethylene (UHMWPE) (plastic) pairs in clinical observations. The particulate wear debris generated from the worn surfaces of CoCrMo or UHMWPE can pose a severe threat to human tissues, eventually resulting in the failure of implants and the need for revision surgeries. As a result, a further improvement in tribological properties of this alloy is still needed, and it is of great interest to both the implant manufacturers and clinical surgeons. In this study, the surface of CoCrMo alloy was laser-treated by a fibre laser system in an open-air condition (i.e., no gas chamber required). The CoCrMo surfaces before and after laser remelting were analysed and characterised by a range of mechanical tests (i.e., surface roughness measurement and Vickers micro-hardness test) and microstructural analysis (i.e., XRD phase detection). The tribological properties were assessed by pin-on-disk tribometry and dynamic light scattering (DLS). Our results indicate that the laser-treated surfaces demonstrated a friction-reducing effect for all the tribopairs (i.e., CoCrMo against CoCrMo and CoCrMo against UHHMWPE) and enhanced wear resistance for the CoCrMo/CoCrMo pair. Such beneficial effects are chiefly attributable to the presence of the laser-formed hard coating on the surface. Laser remelting possesses several competitive advantages of being a clean, non-contact, fast, highly accurate and automated process compared to other surface coating methods. The promising results of this study point to the possibility that laser remelting can be a practical and effective surface modification technique to further improve the tribological performance of CoCr-based orthopaedic implants.

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The effect of laser remelting on the surface chemistry of Ti6al4V components fabricated by selective laser melting

Cited by 176 publications

References 20 publications

Material Removal in Ultrasonic Abrasive Polishing of Additive Manufactured Components

Material Removal in Ultrasonic Abrasive Polishing of Additive Manufactured Components

Interfacial Characteristics of Dissimilar Ti6Al4V/AA6060 Lap Joint by Pulsed Nd:YAG Laser Welding

A Preliminary Study to Enhance the Tribological Performance of CoCrMo Alloy by Fibre Laser Remelting for Articular Joint Implant Applications

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