scholarly journals Texture and Microstructural Features at Different Length Scales in Inconel 718 Produced by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1293 ◽  
Author(s):  
Michele Calandri ◽  
Shuo Yin ◽  
Barry Aldwell ◽  
Flaviana Calignano ◽  
Rocco Lupoi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Selective Laser Melting ◽  
Crystallographic Texture ◽  
Inconel 718 ◽  
Electron Backscatter Diffraction ◽  
Deep Understanding ◽  
Grain Morphology ◽  
Laser Melting ◽  
Length Scales ◽  
Post Process

Nickel-based Inconel 718 is a very good candidate for selective laser melting (SLM). During the SLM process, Inconel 718 develops a complex and heterogeneous microstructure. A deep understanding of the microstructural features of the as-built SLM material is essential for the design of a proper post-process heat treatment. In this study, the microstructure of as-built SLM Inconel 718 was investigated at different length scales using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Electron backscatter diffraction (EBSD) was also used to analyze the grain morphology and crystallographic texture. Grains elongated in the build direction and crossing several deposited layers were observed. The grains are not constrained by the laser tracks or by the melt pools, which indicates epitaxial growth controls the solidification. Each grain is composed of fine columnar dendrites that develop along one of their <100> axes oriented in the direction of the local thermal gradient. Consequently, prominent <100> crystallographic texture was observed and the dendrites tend to grow to the build direction or with occasional change of 90° at the edge of the melt pools. At the dendrite length scale, the microsegregation of the alloying elements, interdendritic precipitates, and dislocations was also detected.

scholarly journals Formability, Microstructure and Properties of Inconel 718 Superalloy Fabricated by Selective Laser Melting Additive Manufacture Technology

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 991
Author(s):  
Xiaoping Liu ◽  
Kuaishe Wang ◽  
Ping Hu ◽  
Xiaomei He ◽  
Baicheng Yan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Laser Scanning ◽  
Laser Energy ◽  
High Surface ◽  
Additive Manufacture ◽  
Internal Cavity ◽  
Laser Melting ◽  
Manufacture Technology

Many urgently needed inconel superalloy parts with complex internal cavity geometry and high surface precision are difficult to prepare by traditional subtractive manufacturing methods because of its poor machinability. The additive manufacturing technology that has emerged in recent years became a research hotspot in the manufacture of refractory and difficult-to-process metals. In the present study, selective laser melting (SLM), a typical additive manufacture technology, was used to prepare Inconel 718 samples. The influences of input laser energy density ((E, J/mm3) on densification behavior, phases composition, microstructures, microhardness, and wear performance of the SLM as-built Inconel 718 samples were explored in detail. X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to examine the phase composition and microstructure evolutions. The results show that the formablity, microstructures and mechanical properties of the printed samples were all improved with the increase of E within the parameter setting range of this study. At a lower E, the poor surface morphology and balling effect occurred, the density, hardness, and wear resistance were all at a relatively lower level. When an E value of 190 J/mm was properly set, the surface open-pores and balling effect disappeared, the laser scanning tracks became smooth and continuous, the near-full dense (99.15%) and specimens with good metallurgical bonding and no critical defect were obtained, in which the average microhardness value reached 348 HV0.2 and wear rate was 5.67 × 10−4 mm3/N·m. The homogeneity of the superalloy Inconel 718 was also explored.

Characterization of Microstructure and Mechanical Property of Inconel 718 From Selective Laser Melting

2015 ◽  
Author(s):  
Xibing Gong ◽  
Xiaoqing Wang ◽  
Vernon Cole ◽  
Zachary Jones ◽  
Kenneth Cooper ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Electron Backscatter Diffraction ◽  
Texture Evolution ◽  
Side Surface ◽  
Laves Phase ◽  
Laser Melting ◽  
Backscatter Diffraction ◽  
Equiaxed Grains

In this study, the microstructures and mechanical properties of Inconel 718 fabricated from selective laser melting (SLM) process were experimentally investigated. Specimens with different build heights were prepared for microstructural observations by optical microscopy and scanning electron microscope. The texture evolution was also examined using electron backscatter diffraction (EBSD). In general, columnar γ dendrites are found along the build direction from the X-plane (side surface), while the microstructure of Z-plane (scanning surface) is characterized by equiaxed grains. The microstructures vary along the build height: the top layers present coarse columnar dendrites while the bottom layers show much narrower columnar dendrites owing to a higher cooling rate. The top layers also present the combination of a γ matrix and a higher percentage of the Laves phase, while the bottom layers show a much less Laves phase due to, again, a higher cooling rate. Random textures are shown for the SLM Inconel 718 samples. Nanoindentation tests identify the Young’s modulus and hardness of about 200 GPa and 7 GPa, respectivley.

Tailored microstructure and robust joint of Inconel 718/316L bimetallic multi-material fabricated by selective laser melting

2020 ◽  
Author(s):  
Shifeng Wen ◽  
Keyu Chen ◽  
Yusi Che ◽  
Yang Liu ◽  
Jie Gan ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Inconel 718 ◽  
Electron Backscatter Diffraction ◽  
Strengthening Mechanism ◽  
Nickel Steel ◽  
Laser Melting ◽  
Processing Technologies ◽  
Microstructural Morphology ◽  
Traditional Processing ◽  
Backscatter Diffraction

Abstract In this study, selective laser melting (SLM) technology was used to fabricate Inconel 718/316L bimetallic multi-material with robust bonding strength, and a deep insight into the microstructural morphology, mechanical property and its strengthening mechanism of the joint was taken. The transition region with a wide of approximately 150 μm was defined and showed a dominating columnar region which was embedded in dispersed Laves phase occupied the molten of Inconel 718 closed to the joint. X-ray diffraction (XRD) pattern detected the strong peaks of γ', γ'' and a weaker peak of d phase precipitates. Electron backscatter diffraction (EBSD) analysis showed that a distinct grain coarsened region existing and Inconel 718 region had a strong fabric texture with a <001>// Z (BD) orientation. The shear strength of the as-built joint was calculated to be 449.5 MPa, which was comparable to the nickel/steel multi-materials formed by other traditional processing technologies.

Effect of Post Heat Treatment on the Microstructure and Tensile Properties of Nano TiC Particulate Reinforced Inconel 718 by Selective Laser Melting

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Yachao Wang ◽  
Jing Shi
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Solution Treatment ◽  
Nano Particles ◽  
Solution Temperature ◽  
Laser Melting ◽  
Post Heat Treatment ◽  
Particulate Reinforced

Abstract To strengthen the metal components by selective laser melting (SLM), adding reinforcement particles and applying post treatments are generally regarded as the two effective means. However, how post heat treatment affects the properties of nano particulate reinforced metal composites obtained by laser additive manufacturing (AM) processes has rarely been studied. In this study, Inconel 718 matrix composite reinforced by 0.5 wt% nano TiC particles was prepared using SLM. To evaluate the effect of the heat treatment routines on the performance of the SLM-produced composite, two levels of solution temperature (980 and 1100 °C) were designed, and the solution treatment was followed by a standard two-step aging (720 °C for 8 h and 620 °C for 8 h). Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) observations were performed to examine the microstructure, and transmission electron microscopy (TEM) observation was conducted to characterize the morphologies of incorporated nano particles and precipitated phases. Tensile tests were conducted to evaluate the mechanical properties of the formed composites. It was found that nano particles can effectively strengthen the metal matrix under both as-built and heat-treated conditions, and the material undergoes static recrystallization during the post heat treatment. Also, it was discovered that nano TiC particles play an important role in refining the microstructure of Inconel 718 composite below 980 °C. The maximum tensile strength of 1370 MPa was observed under 980 °C + aging condition, representing a 16% increase as compared with the unreinforced Inconel 718.

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.

scholarly journals On the Use of EBSD and Microhardness to Study the Microstructure Properties of Tungsten Samples Prepared by Selective Laser Melting

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1215
Author(s):  
Mirza Atif Abbas ◽  
Yan Anru ◽  
Zhi Yong Wang
Keyword(s):  
Selective Laser Melting ◽  
Electron Backscatter Diffraction ◽  
Fusion Reactors ◽  
Laser Melting ◽  
Kikuchi Pattern ◽  
Plasma Facing Components ◽  
Electron Backscatter ◽  
Ebsd Technique ◽  
Temperature Exposure ◽  
Backscatter Diffraction

Additively manufactured tungsten and its alloys have been widely used for plasma facing components (PFCs) in future nuclear fusion reactors. Under the fusion process, PFCs experience a high-temperature exposure, which will ultimately affect the microstructural features, keeping in mind the importance of microstructures. In this study, microhardness and electron backscatter diffraction (EBSD) techniques were used to study the specimens. Vickers hardness method was used to study tungsten under different parameters. EBSD technique was used to study the microstructure and Kikuchi pattern of samples under different orientations. We mainly focused on selective laser melting (SLM) parameters and the effects of these parameters on the results of different techniques used to study the behavior of samples.

Sign in / Sign up

Export Citation Format

Share Document