Microstructure and anisotropic mechanical properties of selective laser melted Ti6Al4V alloy under different scanning strategies

Zheng, Zhongpeng; Jin, Xin; Bai, Yuchao; Yang, Yun; Ni, Chenbing; Lu, Wen Feng; Wang, Hao

doi:10.1016/j.msea.2021.142236

Cited by 63 publications

(17 citation statements)

References 41 publications

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“…Esmaily et al also applied a different scan strategy, rotating 90 °between the layers, as opposed to the 67 °rotation used in this study. The difference in scanning rotation has resulted in a difference in grain growth in other metals processed by PBF-LB, such as in Ti alloys (Zheng et al, 2022) and in Ni alloys (Carter et al, 2014). However, no major difference was observed in the morphology of the larger grains in this study and the article by Esmaily et al However, there is a large number of the smaller equiaxed grains present in this study.…”

Section: Compositional and Microstructural Characterizationcontrasting

confidence: 60%

Microstructural Origins of the Corrosion Resistance of a Mg-Y-Nd-Zr Alloy Processed by Powder Bed Fusion – Laser Beam

Åhman

D’Elia

Mellin

et al. 2022

Front. Bioeng. Biotechnol.

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Magnesium alloys are biocompatible, biodegradable and have the ability to promote bone ingrowth, making them ideal candidate materials for replacing auto- and allografts in future treatments of large bone defects. Powder bed fusion–laser beam (PBF-LB) additive manufacturing of these alloys would further allow for the production of complex structures, optimized for bone grafting. However, the corrosion rates of structures processed by PBF-LB remain too high. An improved understanding of the influence of the microstructure generated during PBF-LB on the corrosion properties is considered key to their future implementation in implants. In this study, the effect of PBF-LB processing and subsequent hot isostatic pressing (HIP) on the microstructure and texture in different sample directions was studied and related to the corrosion behavior of a Mg-Y-Nd-Zr alloy. The results were compared with an extruded Mg-Y-Nd-Zr alloy. A higher amount of secondary phases resulted in a higher rate of localized corrosion for the PBF-LB processed material compared to that for the extruded one. Due to growth of the secondary phases, the corrosion rate was further increased after HIP. Moreover, a strong texture was observed in the PBF-LB material, and it was also enhanced in the HIP material. While this affected the electrochemical activity as measured by potentiodynamic polarization tests, any texture effect appeared to be masked by the contribution of the secondary phases in the longer-term mass change and hydrogen evolution tests. Future work should look further into the influence of individual process parameters on the microstructure and the resulting corrosion behavior of the material, to further clarify its interdependence.

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Section: Compositional and Microstructural Characterizationcontrasting

confidence: 60%

Microstructural Origins of the Corrosion Resistance of a Mg-Y-Nd-Zr Alloy Processed by Powder Bed Fusion – Laser Beam

Åhman

D’Elia

Mellin

et al. 2022

Front. Bioeng. Biotechnol.

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“…Figure 9 presents the anisotropy of the microhardness in the x and y-directions, as well as between the transverse and sagittal planes of as-fabricated specimens. The anisotropy of the microhardness in the as-fabricated L-PBF NiTa specimens correlates to the directional anisotropy of mechanical properties in L-PBF parts reported by researchers [32][33][34][35]. The variation in microhardness value along the x and y-direction of as-fabricated specimens is the result of the orientation of grain structure caused by the zig-zag scanning strategy [32,33].…”

Section: Residual Stress and Microhardnesssupporting

confidence: 59%

Effect of Vacuum Heat Treatment on the Microstructure of a Laser Powder-Bed Fusion-Fabricated NiTa Alloy

Bussmann

Chattopadhyay

2022

Metals

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The semiconductor industry uses a physical vapor-deposition process, with a nickel-tantalum (NiTa) alloy-sputtering target, to apply an amorphous NiTa thin film layer between the magnetic soft underlayer and substrate of a heat-assisted magnetic-recording hard disk drive. Currently, the alloy-sputtering target is produced through a hot-pressing (HP) process followed by a hot isostatic pressing (HIP). In this study, we demonstrate a better process for producing the sputtering targets, using laser powder-bed fusion (L-PBF) followed by vacuum heat treatment (VHT), to produce alloy targets with superior microstructural characteristics that will produce better-quality thin films. We compare as-fabricated (just L-PBF) specimens with specimens produced by L-PBF and then annealed at different conditions. Where the as-fabricated specimens are characterized by columnar dendrites, annealing at 1275 °C for 4 h produces a uniform equiaxed grain microstructure and a uniformly dispersed fcc Ta precipitate. In addition, the average microhardness value is reduced from 725 ± 40 to 594 ± 26 HV0.2 and the maximum compressive residual stress is reduced from 180 ± 50 MPa to 20 ± 10 MPa as the result of dislocation elimination during the recovery and recrystallization process. Finally, due to microstructure recrystallization, the VHT-treated L-PBF NiTa specimens exhibit a smaller grain size (2.1 ± 0.2 µm) than the traditional HIP-treated HP specimens (6.0 ± 0.6 µm).

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“…On the other hand, the top surface has irregular polygon-shaped prior-β grains (Fig. 4 (a)) [ 44 ]. The as-built microstructure is affected by the processing parameters.…”

Section: Solidification Microstructure Evolution Within Pbf-lbmentioning

confidence: 99%

“…For example, larger prior-β grain width and smaller α’ martensite size can be obtained when using higher laser energy density [ 32 ]. Recently, Zheng et al [ 45 ] reported the effects of different scanning strategies on the microstructure and mechanical properties of Ti6Al4V alloy produced by L-PBF. According to their study, the acicular martensite α’ (Fig.…”

Section: Solidification Microstructure Evolution Within Pbf-lbmentioning

confidence: 99%

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Digitisation of metal AM for part microstructure and property control

et al. 2022

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Metal additive manufacturing, which uses a layer-by-layer approach to fabricate parts, has many potential advantages over conventional techniques, including the ability to produced complex geometries, fast new design part production, personalised production, have lower cost and produce less material waste. While these advantages make AM an attractive option for industry, determining process parameters which result in specific properties, such as the level of porosity and tensile strength, can be a long and costly endeavour. In this review, the state-of-the-art in the control of part properties in AM is examined, including the effect of microstructure on part properties. The simulation of microstructure formation via numerical simulation and machine learning is examined which can provide process quality control and has the potential to aid in rapid process optimisation via closed loop control. In-situ monitoring of the AM process, is also discussed as a route to enable first time right production in the AM process, along with the hybrid approach of AM fabrication with post-processing steps such as shock peening, heat treatment and rolling. At the end of the paper, an outlook is presented with a view towards potential avenues for further research required in the field of metal AM.

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Microstructure and anisotropic mechanical properties of selective laser melted Ti6Al4V alloy under different scanning strategies

Cited by 63 publications

References 41 publications

Microstructural Origins of the Corrosion Resistance of a Mg-Y-Nd-Zr Alloy Processed by Powder Bed Fusion – Laser Beam

Microstructural Origins of the Corrosion Resistance of a Mg-Y-Nd-Zr Alloy Processed by Powder Bed Fusion – Laser Beam

Effect of Vacuum Heat Treatment on the Microstructure of a Laser Powder-Bed Fusion-Fabricated NiTa Alloy

Digitisation of metal AM for part microstructure and property control

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