Microstructure and Tensile Performance of Graphene-Reinforced Inconel 718 Alloy Via Selective Laser Melting and Post-Treatments

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Yachao Wang ◽  
Jing Shi
Keyword(s):  
Selective Laser Melting ◽  
Inconel 718 ◽  
Metal Matrix ◽  
Load Transfer ◽  
High Strength ◽  
Solution Temperature ◽  
Strengthening Effect ◽  
Laser Melting ◽  
Inconel 718 Alloy ◽  
Dense Microstructure

Abstract Graphene is an ideal reinforcement material for metal matrix composites (MMCs) owing to its high strength, high ductility, light weight, as well as good bonding with metal matrix. In this study, graphene nanoplatelets (GNPs) reinforced Inconel 718 composites are fabricated by selective laser melting (SLM) technique and processed under various postheat treatment schemes. It is found that the fabrication of GNPs-reinforced MMC using the SLM technique is a viable approach. The obtained composite possesses dense microstructure and enhanced tensile strength. Postheat treatments at two levels of solution temperature (980 and 1220 °C) for 1 h followed by two-step aging are carried out. The experimental results indicate that the addition of GNPs into Inconel 718 matrix results in significant strength improvement. Under the as-built condition, the ultimate tensile strengths (UTSs) of SLM Inconel 718 materials are 997 and 1447 MPa, respectively, at 0 and 4.4 vol % GNP content. The strengthening effect of GNPs is most prominent under the as-built condition, and the strength of as-built GNPs-reinforced Inconel 718 is higher than that of unreinforced Inconel 718 under any processing conditions. The formation of γ′ and γ″ precipitates is suppressed in the GNPs-reinforced composite under the aging condition due to the formation of metallic carbide (MC) carbide and the depletion of Nb. GNPs effectively inhibits grain growth during postheat treatment. Quantitative investigation of the various strengthening effects demonstrates that load transfer effect is dominating among all contributors.

Microstructure and Tensile Properties of SLM Graphene Reinforced Inconel 718 Alloy After Post Heat Treatment

2018 ◽  
Author(s):  
Yachao Wang ◽  
Jing Shi
Keyword(s):  
Heat Treatment ◽  
Inconel 718 ◽  
Metal Matrix ◽  
High Strength ◽  
Solution Temperature ◽  
Strengthening Effect ◽  
Post Heat Treatment ◽  
Inconel 718 Alloy ◽  
Dense Microstructure ◽  
High Flexibility

Graphene is an ideal reinforcement material for metal matrix composites (MMC) owing to its high strength, high ductility, light weight, as well as good bonding with metal matrix. Additive manufacturing such as selective laser melting (SLM) brings the advantages of low material waste, high flexibility, and short production lead cycle. In this study, graphene nano-platelets (GNPs) reinforced Inconel 718 composites are fabricated by SLM technique and processed under various post heat treatment schemes. It is found that fabrication of GNPs reinforced MMC using SLM technique is a viable approach. The obtained composite possesses dense microstructure and enhanced tensile strength. Post heat treatments at two levels of solution temperature (980 and 1220°C) for 1 hour followed by two-step aging are carried out. The experiment results indicate that addition of GNPs into Inconel 718 matrix results in significant strength improvement. At as-built condition, the ultimate tensile strengths are 997 and 1447 MPa, respectively at 0 and 4.4vol.% GNP content. Moreover, under as-built and solution treated condition, high content of GNPs results in overall higher UTS value and the strengthening effect is most significant at as-built condition. Meanwhile, γ′ and γ″ precipitation hardening is suppressed in the GNPs reinforced composite under aged condition due to the formation of MC carbide and depletion of Nb. Incorporating GNPs in Inconel 718 effectively inhibits the grain growth during post heat treatment.

Selective Laser Melting of Graphene Reinforced Inconel 718 Superalloy: Evaluation of Microstructure and Tensile Performance

2016 ◽  
Author(s):  
Yachao Wang ◽  
Jing Shi ◽  
Shiqiang Lu ◽  
Yun Wang
Keyword(s):  
High Temperature ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Metal Matrix ◽  
Mechanical Performance ◽  
Dynamic Properties ◽  
Matrix Material ◽  
Strengthening Effect ◽  
Laser Melting ◽  
Wide Range

Graphene nanoplatelets (GNPs) have many outstanding properties, such as high mechanical strengths, light weight, and high electric conductivity. These unique properties make it an ideal reinforcement used for metal matrix composite (MMCs). In the past few years, many studies have been performed to incorporate GNPs into metal matrix and investigate the properties of obtained metal matrix composites. Meanwhile, fabrication of MMCs through laser assisted additive manufacturing (LAAM) has attracted much attention in recent years due to the advantages of low waste, high precision, short production lead time, and high workpiece complexity capability. In this study, the two attractive features are combined to produce GNPs reinforced MMC using selective laser melting (SLM) process, one of the LAAM processes. The target metal matrix material is Inconel 718, a nickel-based Ni-Cr-Fe austenitic superalloy that possesses excellent workability and mechanical performance and has wide applications in industries. Inconel 718 holds outstanding mechanical performance, corrosion, oxidation, and wear performance over a wide range of temperatures, making it an attractive superalloy used for high temperature service components. In the experiment, pure Inconel 718 and GNPs reinforced Inconel 718 composites with two levels of GNPs content (i.e., 0.25 and 1 wt.%) are obtained by SLM. Note that the SLM process, a novel powder mixture procedure is adopted to ensure the even dispersion of GNPs in the Inconel 718 powders. Room temperature tensile tests are conducted to evaluate the tensile properties. Scanning electron microscopy (SEM) observations are conducted to analyze the fracture surface of materials and to understand the reinforcing mechanism. It is found that fabrication of GNPs reinforced MMC using SLM is a viable approach. The obtained composite possesses dense microstructure and significantly enhanced tensile strength. The ultimate tensile strengths (UTS) are 997.8, 1296.3 and 1511.6 MPa, and the Young’s moduli are 475, 536, and 675 GPa, for 0 wt.% (pure Inconel 718), 0.25 wt.%, and 1 wt.% GNP additions, respectively. The bonding between GNPs and matrix material appears to be strong, and GNPs are well retained during the SLM process. The strengthening effect and mechanisms involved in the composites are discussed. Load transfer, thermal expansion coefficient mismatch, and dislocation hindering are believed to be the three main reinforcing mechanisms involved. It should be noted that more work needs to be conducted in the future to obtain more comprehensive information regarding other static and dynamic properties, and the high temperature performances of the GNP reinforced MMCs produced by SLM. Process parameter optimization should also be investigated.

Selective Laser Melting of Graphene-Reinforced Inconel 718 Superalloy: Evaluation of Microstructure and Tensile Performance

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Yachao Wang ◽  
Jing Shi ◽  
Shiqiang Lu ◽  
Yun Wang
Keyword(s):  
Metal Matrix Composites ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Metal Matrix ◽  
Mechanical Performance ◽  
Dynamic Properties ◽  
Matrix Material ◽  
Strengthening Effect ◽  
Matrix Composites ◽  
Laser Melting

Graphene nanoplatelets (GNPs) have many outstanding properties, such as high mechanical strengths, light weight, and high electric conductivity. These unique properties make it an ideal reinforcement used for metal matrix composites (MMCs). In the past few years, many studies have been performed to incorporate GNPs into metal matrix and investigate the properties of obtained metal matrix composites. Meanwhile, fabrication of MMCs through laser-assisted additive manufacturing (LAAM) has attracted much attention in recent years due to the advantages of low waste, high precision, short production lead time, and high workpiece complexity capability. In this study, the two attractive features are combined to produce GNPs reinforced MMC using selective laser melting (SLM) process, one of the LAAM processes. The target metal matrix material is Inconel 718, a nickel-based Ni–Cr–Fe austenitic superalloy that possesses excellent workability and mechanical performance, and has wide applications in industries. In the experiment, pure Inconel 718 and GNPs reinforced Inconel 718 composites with two levels of GNPs content (i.e., 0.25 and 1 wt. %) are obtained by SLM. Note that before the SLM process, a novel powder mixture procedure is employed to ensure the even dispersion of GNPs in the Inconel 718 powders. Room temperature tensile tests are conducted to evaluate the tensile properties. Scanning electron microscopy (SEM) observations are conducted to analyze the fracture surface of materials and to understand the reinforcing mechanism. It is found that fabrication of GNPs reinforced MMC using SLM is a viable approach. The obtained composite possesses dense microstructure and significantly enhanced tensile strength. The ultimate tensile strengths (UTSs) are 997.8, 1296.3, and 1511.6 MPa, and the Young's moduli are 475, 536, and 675 GPa, for 0 wt. % (pure Inconel 718), 0.25 wt. %, and 1 wt. % GNP additions, respectively. The bonding between GNPs and matrix material appears to be strong, and GNPs could be retained during the SLM process. The strengthening effect and mechanisms involved in the composites are discussed. Load transfer, thermal expansion coefficient mismatch, and dislocation hindering are believed to be the three main reinforcing mechanisms involved. It should be noted that more work needs to be conducted in the future to obtain more comprehensive information regarding other static and dynamic properties and the high-temperature performances of the GNP-reinforced MMCs produced by SLM. Process parameter optimization should also be investigated.

scholarly journals Very-High-Cycle Fatigue Behavior of Inconel 718 Alloy Fabricated by Selective Laser Melting at Elevated Temperature

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1001
Author(s):  
Zongxian Song ◽  
Wenbin Gao ◽  
Dongpo Wang ◽  
Zhisheng Wu ◽  
Meifang Yan ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Selective Laser Melting ◽  
Fatigue Resistance ◽  
Inconel 718 ◽  
High Cycle Fatigue ◽  
Cycle Fatigue ◽  
Laser Melting ◽  
Inconel 718 Alloy ◽  
Very High Cycle Fatigue ◽  
Very High

This study investigates the very-high-cycle fatigue (VHCF) behavior at elevated temperature (650 °C) of the Inconel 718 alloy fabricated by selective laser melting (SLM). The results are compared with those of the wrought alloy. Large columnar grain with a cellular structure in the grain interior and Laves/δ phases precipitated along the grain boundaries were exhibited in the SLM alloy, while fine equiaxed grains were present in the wrought alloy. The elevated temperature had a minor effect on the fatigue resistance in the regime below 108 cycles for the SLM alloy but significantly reduced the fatigue strength in the VHCF regime above 108 cycles. Both the SLM and wrought specimens exhibited similar fatigue resistance in the fatigue life regime of fewer than 107–108 cycles at elevated temperature, and the surface initiation mechanism was dominant in both alloys. In a VHCF regime above 107–108 cycles at elevated temperature, the wrought material exhibited slightly better fatigue resistance than the SLM alloy. All fatigue cracks are initiated from the internal defects or the microstructure discontinuities. The precipitation of Laves and δ phases is examined after fatigue tests at high temperatures, and the effect of microstructure on the formation and the propagation of the microstructural small cracks is also discussed.

Properties of aluminum metal matrix composites manufactured by selective laser melting

2021 ◽  
Vol 112 (7) ◽  
pp. 552-564
Author(s):  
Christian Felber ◽  
Florian Rödl ◽  
Ferdinand Haider
Keyword(s):  
Additive Manufacturing ◽  
Aluminum Alloys ◽  
Selective Laser Melting ◽  
Metal Matrix ◽  
High Hardness ◽  
High Strength ◽  
Laser Melting ◽  
Scanning Calorimetry ◽  
Particle Reinforcement ◽  
The Matrix

Abstract The most promising metal processing additive manufacturing technique in industry is selective laser melting, but only a few alloys are commercially available, limiting the potential of this technique. In particular high strength aluminum alloys, which are of great importance in the automotive industry, are missing. An aluminum 2024 alloy, reinforced by Ti-6Al-4V and B4C particles, could be used as a high strength alternative for aluminum alloys. Heat treating can be used to improve the mechanical properties of the metal matrix composite. Dynamic scanning calorimetry shows the formation of Al2Cu precipitates in the matrix instead of the expected Al2CuMg phases due to the loss of magnesium during printing, and precipitation processes are accelerated due to particle reinforcement and additive manufacturing. Strong reactions between aluminum and Ti-6Al-4V are observed in the microstructure, while B4C shows no reaction with the matrix or the titanium. The material shows high hardness, high stiffness, and low ductility through precipitation and particle reinforcement.

Friction and wear behaviour of Inconel 718 alloy fabricated by selective laser melting after heat treatments

2018 ◽  
Vol 98 (12) ◽  
pp. 547-555 ◽  
Author(s):  
Zhanyong Zhao ◽  
Hongqiao Qu ◽  
Peikang Bai ◽  
Jing Li ◽  
Liyun Wu ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Inconel 718 ◽  
Friction And Wear ◽  
Heat Treatments ◽  
Wear Behaviour ◽  
Laser Melting ◽  
Inconel 718 Alloy
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