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.

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 Selective Laser Melting Strategy for Fabrication of Thin Struts Usable in Lattice Structures

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1763 ◽  
Author(s):  
Radek Vrána ◽  
Daniel Koutný ◽  
David Paloušek ◽  
Libor Pantělejev ◽  
Jan Jaroš ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Selective Laser Melting ◽  
Laser Scanning ◽  
Laser Energy ◽  
Lattice Structure ◽  
Processing Parameters ◽  
Laser Melting ◽  
Contour Lines ◽  
Lower Porosity ◽  
Linear Laser

This paper deals with the selective laser melting (SLM) processing strategy for strut-lattice structure production which uses only contour lines and allows the porosity and roughness level to be managed based on combination of the input and linear energy parameters. To evaluate the influence of a laser scanning strategy on material properties and surface roughness a set of experiments was performed. The single welds test was used to find the appropriate processing parameters to achieve continuous welds with known width. Strut samples were used to find a suitable value of weld overlapping and to clarify the influence of input and linear laser energy on the strut porosity and surface roughness. The samples of inclined hollow struts were used to compare the wall thickness with single welds width; the results showed about 25% wider welds in the case of a hollow strut. Using the proposed SLM strategy it is possible to reach a significantly lower porosity and surface roughness of the struts. The best results for struts with an inclination of 35.26° were achieved with 25% track overlapping, input energy in the range from 9 J to 10.5 J and linear energy Elin from 0.25 to 0.4 J/mm; in particular, the relative density of 99.83% and the surface roughness on the side of the strut of Ra 14.6 μm in an as-built state was achieved.

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.

Selective Laser Melting of Mechanically Alloyed Metastable Al5Fe2 Powders

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Hugo Montiel ◽  
Ben Xu ◽  
Jianzhi Li
Keyword(s):  
Aluminum Alloys ◽  
Energy Density ◽  
Selective Laser Melting ◽  
Laser Power ◽  
Laser Scanning ◽  
Laser Energy ◽  
Scanning Speed ◽  
High Energy ◽  
Laser Energy Density ◽  
Laser Melting

Aluminum alloys, which are high-strength lightweight materials, were processed by selective laser melting (SLM) with high-energy consumption and poor finish due to quick heat dissipation. Previous investigations reported that SLM with 300 W laser power and 500 mm/s scanning speed can process the aluminum alloys, such as Al-Si12 and AlSi10Mg. This work aims to process the powders to alter their properties and to reduce the laser intensity required in the process, and it also reports that the SLM-processed Al–Fe alloys utilize the metastable alloy by mechanical alloying (MA). The elemental Al and Fe powders were first alloyed in a ball mill in a relative short time period (∼15 h) employing high milling intensities, high ball-to-powder ratio (≥20:1), and high milling velocities (≥400 rpm), which produced fine metastable Al–Fe powders, and these powders were processed later by the SLM. The optimum laser power, the scanning speed, hatch distance, and substrate temperature were investigated by a series of experiments. Experimental results indicated that decreasing the laser energy density while increasing the laser scanning speed can benefit for smoother laser hatch lines, and the metastable Al5Fe2 alloy powders can be processed and stabilized under a 200-W laser energy density and a scanning speed of 1000 mm/s. It is expected that the combination of pre-excited materials in a metastable phase will open a new window to optimize the SLM process for aluminum alloys and other metallic alloys.

scholarly journals Fabrication of Mesh Patterns Using a Selective Laser-Melting Process

2019 ◽  
Vol 9 (9) ◽  
pp. 1922 ◽  
Author(s):  
Tae Woo Hwang ◽  
Young Yun Woo ◽  
Sang Wook Han ◽  
Young Hoon Moon
Keyword(s):  
Selective Laser Melting ◽  
Laser Scanning ◽  
Dimensional Accuracy ◽  
Base Plate ◽  
Steel Powder ◽  
Melting Process ◽  
304 Stainless Steel ◽  
Process Conditions ◽  
Laser Melting ◽  
Metal Mesh

The selective laser-melting (SLM) process can be applied to the additive building of complex metal parts using melting metal powder with laser scanning. A metal mesh is a common type of metal screen consisting of parallel rows and intersecting columns. It is widely used in the agricultural, industrial, transportation, and machine protection sectors. This study investigated the fabrication of parts containing a mesh pattern from the SLM of AISI 304 stainless steel powder. The formation of a mesh pattern has a strong potential to increase the functionality and cost-effectiveness of the SLM process. To fabricate a single-layered thin mesh pattern, laser layering has been conducted on a copper base plate. The high thermal conductivity of copper allows heat to pass through it quickly, and prevents the adhesion of a thin laser-melted layer. The effects of the process conditions such as the laser scan speed and scanning path on the size and dimensional accuracy of the fabricated mesh patterns were characterized. As the analysis results indicate, a part with a mesh pattern was successfully obtained, and the application of the proposed method was shown to be feasible with a high degree of reliability.

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