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15 pages, 10567 KiB

Open AccessArticle

Effect of Co-Coated Al₂O₃ Composite Powders on LPBF-Manufactured CoCrMo Alloy

by Lehui Zhang, Wei Liu, Yu Cao, Haoxin Sun, Qiusheng Xie, Junyun Lai and Peikang Bai

Metals 2023, 13(2), 310; https://doi.org/10.3390/met13020310 - 03 Feb 2023

Viewed by 1148

Abstract

In this study, we systematically examined the influence mechanisms of introduced cobalt coated alumina (Co-coated Al₂O₃) particles on the microstructure and properties of cobalt-chromium-molybdenum (CoCrMo) alloy printed by Laser Powder Bed Fusion (LPBF). The Co-coated Al₂O₃ [...] Read more.

In this study, we systematically examined the influence mechanisms of introduced cobalt coated alumina (Co-coated Al₂O₃) particles on the microstructure and properties of cobalt-chromium-molybdenum (CoCrMo) alloy printed by Laser Powder Bed Fusion (LPBF). The Co-coated Al₂O₃ composite powders with different density of cobalt coating were prepared by varying Al₂O₃ load from 1 g/150 mL to 2 g/150 mL during the electroless plating process. Then they were mixed with CoCrMo powders in the proportion of 1 wt.% and formed standard samples by LPBF technology. The results showed that the addition of Co-coated Al₂O₃ particles improved the friction performance of CoCrMo alloys significantly. The wear depth of CCM@2Al₂O₃ was only 2.18 μm and the wear volume of it was about 10% of pure CoCrMo alloy. The CoCrMo alloy introduced the Co-coated Al₂O₃ particles with a 1 g/150 mL Al₂O₃ load formed metal-ceramic bonding interface, which solved the problem of poor wettability between Al₂O₃ and matrix in LPBF process. Such CoCrMo alloy exhibited excellent tensile properties and the mean microhardness of it reached 379.9 ± 3.5 HV_0.5. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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12 pages, 4477 KiB

Open AccessArticle

Microstructure and High Temperature-Mechanical Properties of TiC/Graphene/Ti6Al4V Composite Formed by Laser Powder Bed Fusion

by Shijie Chang, Wenbo Du, Zhanyong Zhao and Peikang Bai

Metals 2023, 13(1), 163; https://doi.org/10.3390/met13010163 - 12 Jan 2023

Cited by 4 | Viewed by 1890

Abstract

TiC/graphene/Ti6Al4V composites were prepared by laser powder bed fusion using graphene and Ti6Al4V powder. The differences in microstructure and high-temperature mechanical properties between the Ti6Al4V alloy and the TiC/graphene/Ti6Al4V composite were studied. The tensile and microhardness of the two materials were tested at [...] Read more.

TiC/graphene/Ti6Al4V composites were prepared by laser powder bed fusion using graphene and Ti6Al4V powder. The differences in microstructure and high-temperature mechanical properties between the Ti6Al4V alloy and the TiC/graphene/Ti6Al4V composite were studied. The tensile and microhardness of the two materials were tested at 400 °C, 500 °C, and 600 °C; the results of the TiC/graphene/Ti6Al4V composite were 126 MPa, 162 MPa, and 76 MPa and 70 HV, 59 HV, and 61HV, respectively, higher than those of the Ti6Al4V alloy. These results happened because graphene reacted with Ti to form TiC particles, which were homogeneously distributed amongst α’ acicular martensite. The addition of graphene refined the size of the acicular α’ martensite. At the same time, the graphene and TiC particles showed a dispersion-strengthening effect. The mechanical properties of the TiC/graphene/Ti6Al4V composite were improved by the combination of fine-grain strengthening and dispersion strengthening mechanisms. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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15 pages, 5708 KiB

Open AccessArticle

The Processing Map of Laser Powder Bed Fusion In-Situ Alloying for Controlling the Composition Inhomogeneity of AlCu Alloy

by Yang Zhou, Xiaohan Chen, Fan Zhou, Xinggang Li, Yuhe Huang and Qiang Zhu

Metals 2023, 13(1), 97; https://doi.org/10.3390/met13010097 - 02 Jan 2023

Viewed by 1527

Abstract

In-situ alloying is a facile method for exploring high-performance metallic materials for additive manufacturing. However, composition inhomogeneity is inevitable, and it is a double-edged sword for the properties of in-situ alloyed parts. Appropriately controlling the composition inhomogeneity benefits the applications of in-situ alloying [...] Read more.

In-situ alloying is a facile method for exploring high-performance metallic materials for additive manufacturing. However, composition inhomogeneity is inevitable, and it is a double-edged sword for the properties of in-situ alloyed parts. Appropriately controlling the composition inhomogeneity benefits the applications of in-situ alloying in specific microstructural and properties design. In this work, the Al20Cu alloy was selected as the benchmark alloy to investigate the tailoring of composition inhomogeneity. The morphology and area percentage of composition inhomogeneity in the as-built samples were firstly analyzed. These results provided evidence for the formation of composition inhomogeneity and indicate that its content is tightly dependent on processing parameters. The characteristics of the molten pool under various processing parameters were investigated by modeling the laser remelting process. Based on these, a processing map was established to guide the tailoring of composition inhomogeneity. This study expands the understanding of the formation mechanism of composition inhomogeneity in in-situ alloyed parts and sheds light on employing laser powder bed fusion in-situ alloying for new materials development. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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9 pages, 2879 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Selective Laser Melted Reduced Activation Ferritic/Martensitic Steel

by Zihao Yuan, Chenyu Xiao, Hao Liu, Xuejing Sun, Guangyi Zhao, Hongbin Liao, Wei Qian, Jingkun Yuan, Changshi Lao and Huajie Wang

Metals 2022, 12(12), 2044; https://doi.org/10.3390/met12122044 - 28 Nov 2022

Cited by 1 | Viewed by 1141

Abstract

Cube and tensile samples of reduced activation ferritic/martensitic steel were formed at different laser powers and scanning velocities using a selective laser melting process; the microstructural characteristics and tensile properties of the cube and tensile samples were investigated in this study. The experimental [...] Read more.

Cube and tensile samples of reduced activation ferritic/martensitic steel were formed at different laser powers and scanning velocities using a selective laser melting process; the microstructural characteristics and tensile properties of the cube and tensile samples were investigated in this study. The experimental results showed that the SLMed CLF-1 samples that formed with selected laser melting were near-fully dense, and the relative density of the SLMed CLF-1 samples exceeded 99%. Meanwhile, there were numerous nano-sized spherical and needle-like precipitate dispersions distributed in the grains and boundary of the grains, and the precipitates were mainly composed of M23C6 carbide and MX carbide. The microstructure was composed of columnar grains and equiaxed grains arranged in a sequence, and the smallest average size of the grains was 15 ± 2.1 µm when measured at 320 W of power and 800 mm/s scanning velocity. In addition, the sample at 320 W of power and 800 mm/s scanning velocity exhibited higher yield strength (875 ± 6.0 MPa) and higher elongation (25.6 ± 0.8%) than that of the sample at 200 W of power, 800 mm/s scanning velocity, yield strength of 715 ± 1.5 MPa, and elongation of 22.6 ± 1.2%. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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20 pages, 7868 KiB

Open AccessArticle

Influence of Relative Humidity and Oxygen Concentration on Corrosion Behaviour of Copper in H₂S-Containing Liquid Petroleum Gas

by Xianqiang Li, Yuan Lu, Qiang Wei, Hu Wang and Juan Xie

Metals 2022, 12(12), 2015; https://doi.org/10.3390/met12122015 - 24 Nov 2022

Cited by 1 | Viewed by 1707

Abstract

In this paper, the influences of relative humidity (RH) and concentration of O₂ on copper corrosion in H₂S-containing LPG (liquid petroleum gas) were studied. The corrosion products obtained in different environments were also analysed by scanning electron microscopy [...] Read more.

In this paper, the influences of relative humidity (RH) and concentration of O₂ on copper corrosion in H₂S-containing LPG (liquid petroleum gas) were studied. The corrosion products obtained in different environments were also analysed by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). In H₂S-containing LPG, RH has pronounced influence on the corrosion grade of copper. The variation in the critical point (CP) with the RH of LPG is a linear relationship. The presence of O₂ in dry H₂S has limited influence on the corrosion of copper. In the presence of different RHs, the CP always follows a negative exponential function with O₂ concentration. The analysis of different corrosion products implies different corrosion behaviours and mechanisms, which are dependent on the presence or absence of water vapour. The corrosion mechanisms obtained in four different environments were also proposed. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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20 pages, 37489 KiB

Open AccessArticle

Numerical Investigation on the Effect of Residual Stresses on the Effective Mechanical Properties of 3D-Printed TPMS Lattices

by Nissar Ahmed, Imad Barsoum and Rashid K. Abu Al-Rub

Metals 2022, 12(8), 1344; https://doi.org/10.3390/met12081344 - 12 Aug 2022

Cited by 14 | Viewed by 2860

Abstract

The layer-by-layer process of additive manufacturing (AM) is known to give rise to high thermal gradients in the built body resulting in the accumulation of high residual stresses. In the current study, a numerical investigation is conducted on the effect of residual stresses [...] Read more.

The layer-by-layer process of additive manufacturing (AM) is known to give rise to high thermal gradients in the built body resulting in the accumulation of high residual stresses. In the current study, a numerical investigation is conducted on the effect of residual stresses on the mechanical properties of IN718 triply periodic minimal surface (TPMS) lattices fabricated using the selective laser melting (SLM) process for different relative densities. The AM simulation of four different sheet- and ligament-based TPMS topologies, namely, Schwarz Primitive, Schoen Gyroid, Schoen IWP-S, and IWP-L, are performed using a sequentially coupled thermomechanical finite element model to evaluate the thermal histories and residual stress evolution throughout the SLM process. The finite element results are utilized to obtain the effective mechanical properties, such as elastic modulus, yield strength, and specific energy absorption (SEA), of the TPMS lattices while accounting for the residual stress field arising from the SLM process. The mechanical properties are correlated to relative density using the Gibson–Ashby power laws and reveal that the effect of the residual stresses on the elastic modulus of the as-built TPMS samples can be significant, especially for the Schwarz Primitive and Schoen-IWP-L TPMS topologies, when compared to the results without accounting for residual stresses. However, the effect of the residual stresses is less significant on yield strength and SEA of the TPMS samples. The work demonstrates a methodology for numerical simulations of the SLM process to quantify the influence of inherited residual stresses on the effective mechanical properties of complex TPMS topologies. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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18 pages, 7670 KiB

Open AccessArticle

Influence of Powder Characteristics on the Microstructure and Mechanical Behaviour of GH4099 Superalloy Fabricated by Electron Beam Melting

by Shixing Wang, Shen Tao and Hui Peng

Metals 2022, 12(8), 1301; https://doi.org/10.3390/met12081301 - 03 Aug 2022

Cited by 4 | Viewed by 1938

Abstract

A Chinese superalloy, GH4099 (~20 vol.% γ′ phase), which can operate for long periods of time at temperatures of 1173–1273 K, was fabricated by electron beam melting (EBM). Argon gas atomized (GA) and plasma rotation electrode process (PREP) powders with similar composition and [...] Read more.

A Chinese superalloy, GH4099 (~20 vol.% γ′ phase), which can operate for long periods of time at temperatures of 1173–1273 K, was fabricated by electron beam melting (EBM). Argon gas atomized (GA) and plasma rotation electrode process (PREP) powders with similar composition and size distribution were used as raw materials for comparison. The microstructure and mechanical properties of both the as-EBMed and post-treated alloy samples were investigated. The results show that the different powder characteristics result in different build temperatures for GA and PREP samples, which are 1253 K and 1373 K, respectively. By increasing the building temperature, the EBM processing window shifts towards a higher scanning speed direction. Microstructure analysis reveals that both as-EBM samples show a similar grain width (measured to be ~200 μm), while the size of γ′ precipitated in the PREP sample (~90 nm) is larger than that of the GA sample (~130 nm) due to the higher build temperature. Fine spherical γ′ phase precipitates uniformly after heat treatment (HT). Furthermore, intergranular cracking was observed for the as-fabricated PREP sample as a result of local enrichment of Si at grain boundaries. The cracks were completely eliminated by hot isostatic pressing (HIP) and did not re-open during subsequent heat treatment (HT) of solution treatment and aging. The tensile strength of the PREP sample after HIP and HT is ~920 MPa in the building direction and ~850 MPa in the horizontal direction, comparable with that of the wrought alloy. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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13 pages, 3505 KiB

Open AccessArticle

Effects of Process Parameters on the Relative Density and Properties of CuCrZr Alloy Produced by Selective Laser Melting

by Jiaxin Li, Zezhou Kuai, Zhonghua Li, Bin Liu, Yanlei Chen, Shengyu Lu, Yunfei Nie and Zhicheng Yang

Metals 2022, 12(5), 701; https://doi.org/10.3390/met12050701 - 19 Apr 2022

Cited by 8 | Viewed by 2394

Abstract

CuCrZr alloy has the advantages of good electrical conductivity, thermal conductivity, high hardness, crack resistance and high softening temperature. It is extensively used in important fields such as rail transit, aerospace, thermonuclear fusion and electronic information. Due to its high melting point, reflectivity, [...] Read more.

CuCrZr alloy has the advantages of good electrical conductivity, thermal conductivity, high hardness, crack resistance and high softening temperature. It is extensively used in important fields such as rail transit, aerospace, thermonuclear fusion and electronic information. Due to its high melting point, reflectivity, thermal conductivity, etc., it is more difficult to manufacture by selective laser melting (SLM). In this work, the effect of SLM process parameters on the characteristics of CuCrZr samples, such as relative density, hardness and tensile properties, has been investigated using orthogonal experiment method. The experimental results show that laser power is the main factor affecting the properties of the alloy. The tensile strength of the alloy increases with an increase in laser power; it first increases and then decreases with an increase in scanning speed. The optimal combination of process parameters in this paper is as follows: laser power is 240 W, scanning speed is 750 mm/s and scanning spacing is 0.07 mm. The relative density, ultimate tensile strength and hardness of the alloy fabricated by best SLM process parameters was 98.79%, 347 MPa, 133.9 HV, respectively. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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13 pages, 3956 KiB

Open AccessArticle

Effect of Solution Temperature on the Microstructure and Properties of 17-4PH High-Strength Steel Samples Formed by Selective Laser Melting

by Zhanyong Zhao, Hailin Wang, Pengcheng Huo, Peikang Bai, Wenbo Du, Xiaofeng Li, Jianmin Li and Wei Zhang

Metals 2022, 12(3), 425; https://doi.org/10.3390/met12030425 - 28 Feb 2022

Cited by 7 | Viewed by 2913

Abstract

Samples of 17-4PH high-strength steel were processed by selective laser melting (SLM) and solution-processed. The effects of the solution temperature on the microstructure and mechanical properties of the samples were studied. The 17-4PH high-strength steel is primarily composed of martensite, with a small [...] Read more.

Samples of 17-4PH high-strength steel were processed by selective laser melting (SLM) and solution-processed. The effects of the solution temperature on the microstructure and mechanical properties of the samples were studied. The 17-4PH high-strength steel is primarily composed of martensite, with a small number of austenite phases, and contains many dislocations. After the solution treatment, the grain size gradually increased, yielding typical martensite. The samples were subjected to an aging treatment after the solution treatment. Precipitates formed in the samples, conducive to improving their strength and hardness. The Vickers hardening and wear properties of the 17-4PH high-strength steel samples first increased and then decreased with increasing solution temperature. After the solution treatment at 1040 °C for 2 h and aging at 480 °C for 4 h, the Vickers hardening of the 17-4PH high-strength steel increased to 392 HV0.5, and the friction coefficient was approximately 0.6. These values were, respectively, 7% and 5% higher than those for the untreated samples. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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Review

Jump to: Research

22 pages, 2352 KiB

Open AccessReview

Current Status and Challenges of Powder Bed Fusion-Based Metal Additive Manufacturing: Literature Review

by Naol Dessalegn Dejene and Hirpa G. Lemu

Metals 2023, 13(2), 424; https://doi.org/10.3390/met13020424 - 18 Feb 2023

Cited by 18 | Viewed by 6605

Abstract

Powder bed fusion (PBF) is recognized as one of the most common additive manufacturing technologies because of its attractive capability of fabricating complex geometries using many possible materials. However, the quality and reliability of parts produced by this technology are observed to be [...] Read more.

Powder bed fusion (PBF) is recognized as one of the most common additive manufacturing technologies because of its attractive capability of fabricating complex geometries using many possible materials. However, the quality and reliability of parts produced by this technology are observed to be crucial aspects. In addition, the challenges of PBF-produced parts are hot issues among stakeholders because parts are still insufficient to meet the strict requirements of high-tech industries. This paper discusses the present state of the art in PBF and technological challenges, with a focus on selective laser melting (SLM). The review work focuses mainly on articles that emphasize the status and challenges of PBF metal-based AM, and the study is primarily limited to open-access sources, with special attention given to the process parameters and flaws as a determining factor for printed part quality and reliability. Moreover, the common defects due to an unstrained process parameter of SLM and those needed to monitor and sustain the quality and reliability of components are encompassed. From this review work, it has been observed that there are several factors, such as laser parameters, powder characteristics, material properties of powder and the printing chamber environments, that affect the SLM printing process and the mechanical properties of printed parts. It is also concluded that the SLM process is not only expensive and slow compared with conventional manufacturing processes, but it also suffers from key drawbacks, such as its reliability and quality in terms of dimensional accuracy, mechanical strength and surface roughness. Full article

(This article belongs to the Special Issue 3D Printing of Metal)

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