Reinforcing Inconel 718 Superalloy by Nano-TiC Particles in Selective Laser Melting

Author(s):  
Yachao Wang ◽  
Jing Shi ◽  
Yun Wang

Metal components produced by additive manufacturing processes usually have inferior properties and performances as compared with the counterparts by the traditional forming and machining processes. To close the gap, the metal matrix can be strengthened by adding reinforcement particles in additive manufacturing processes. This research presents the fabrication of nano-TiC reinforced Inconel 718 composites using selective laser melting (SLM). Tensile and wear performance tests are conducted to evaluate the mechanical properties of the formed composites. It is discovered that the composites exhibit improved mechanical properties in terms of ultimate tensile strength and yield stress. Compared with the pure Inconel 718 specimens by SLM, the ultimate tensile strength and yield stress of the reinforced Inconel 718 increase by 207 MPa and 204 MPa, respectively, with 0.5 wt.% addition of nano-TiC particle. Smaller increases are observed with 0.25 wt.% and 1.0 wt.% nano-TiC additions. On the other hand, the addition of nano-TiC particles decreases the ductility of Inconel 718. To investigate the strengthening mechanism of nano reinforcement particles in SLM, the microstructures with different levels of nano-TiC particles are observed. The results indicate that the microstructure of Inconel 718 is remarkably refined by the TiC particles, and the reinforcement particle significantly impede the growth of columnar grain in the solidification process.

Author(s):  
Xiaoqing Wang ◽  
Xibing Gong ◽  
Kevin Chou

This study presents a thorough literature review on the powder-bed laser additive manufacturing processes such as selective laser melting (SLM) of Inconel 718 parts. The paper first introduces the general aspects of powder-bed laser additive manufacturing and then discusses the unique characteristics and advantages of SLM. Moreover, the bulk of this study includes extensive discussions of microstructures and mechanical properties, together with the application ranges, of Inconel 718 parts fabricated by SLM.


Author(s):  
Xiaoqing Wang ◽  
Xibing Gong ◽  
Kevin Chou

This study presents a thorough literature review on the powder-bed laser additive manufacturing processes such as selective laser melting of Inconel 718 parts. This article first introduces the general aspects of powder-bed laser additive manufacturing and then discusses the unique characteristics and advantages of selective laser melting. The bulk of this study includes extensive discussions of microstructures and mechanical properties, together with the application ranges of Inconel 718 parts fabricated by selective laser melting.


Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3603
Author(s):  
Tim Pasang ◽  
Benny Tavlovich ◽  
Omry Yannay ◽  
Ben Jakson ◽  
Mike Fry ◽  
...  

An investigation of mechanical properties of Ti6Al4V produced by additive manufacturing (AM) in the as-printed condition have been conducted and compared with wrought alloys. The AM samples were built by Selective Laser Melting (SLM) and Electron Beam Melting (EBM) in 0°, 45° and 90°—relative to horizontal direction. Similarly, the wrought samples were also cut and tested in the same directions relative to the plate rolling direction. The microstructures of the samples were significantly different on all samples. α′ martensite was observed on the SLM, acicular α on EBM and combination of both on the wrought alloy. EBM samples had higher surface roughness (Ra) compared with both SLM and wrought alloy. SLM samples were comparatively harder than wrought alloy and EBM. Tensile strength of the wrought alloy was higher in all directions except for 45°, where SLM samples showed higher strength than both EBM and wrought alloy on that direction. The ductility of the wrought alloy was consistently higher than both SLM and EBM indicated by clear necking feature on the wrought alloy samples. Dimples were observed on all fracture surfaces.


Author(s):  
Yachao Wang ◽  
Jing Shi ◽  
Xiaoyang Deng ◽  
Shiqiang Lu

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 filler material for various composites. On the other hand, the development MMNCs (metal matrix nanocomposites) through additive manufacturing (AM) processes has become a major innovation in the field of advanced structural materials, owing to shorter production lead time, less material waste, high production flexibility. It is of great innovativeness to have the attractive features combined to produce GNPs reinforced MMNCs using AM techniques. In addition, metal components produced by laser assisted additive manufacturing (LAAM) methods usually have inferior mechanical properties, as compared to the counterparts by the traditional metal forming processes. To achieve optimized mechanical properties, the obtained MMNCs are subjected to various post treatment routines and the effect of post heat treatment on material properties is investigated. In this study, pure Inconel 718 and GNPs reinforced IN718 with 1.1 vol.% and 4.4 vol.% filler material are fabricated by selective laser melting (SLM). Room temperature tensile tests are conducted to evaluate the tensile properties. Scanning electron microscopy (SEM) observations are conducted to analyze the microstructure 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 composites possess dense microstructure and enhanced tensile strength. The strengthening effect and mechanisms involved in the composites are discussed. Solution treatments at three levels of temperature (940, 980, and 1020°C) for 1 hour period are carried out to evaluate the effect of the heat treatment on the material microstructure and therefore the resulted mechanical properties of the composite material. The results of samples with and without heat treatment are also compared. The experiments results indicate that that addition of GNPs into Inconel 718 results in significant strength improvement. Moreover, at any volume content of reinforcement, higher solution treatment leads to lower strength, mainly due to coarsened microstructure. The addition of GNPs effectively inhibits the grain growth during the post heat process and the average grain size is significantly refined compared to unreinforced samples. Moreover, through the investigation of various strengthening mechanisms, it is found that Orowan strengthening effect is small and can be neglected for both as-built and heat treated conditions. Load transfer effect is the dominating strengthening effect among all contributors and solution treatment significantly reduces thermal mismatch strengthening.


Author(s):  
Akihiro Hirayama ◽  
Koichi Kaizu ◽  
Masaaki Kimura ◽  
Masahiro Kusaka

Abstract In this study, the microstructure and mechanical properties of AlSi12CuNi alloy fabricated by Selective Laser Melting (SLM) were investigated. Wide range of laser irradiation conditions were selected to optimize the process in terms of optimum volume density. As a result, fabricated objects with a relative density of 99% or higher and no crack could be obtained. The as-fabricated alloy exhibited significantly good mechanical properties; an ultimate tensile strength, a breaking elongation, and micro-hardness in comparison with the conventional die casting AlSi12CuNi alloy. The fine microstructures composed of the α-Al phase and nano-sized eutectic Al-Si network could be observed. The dimensions of the microstructures were smaller than that of the conventional die casting AlSi12CuNi alloy. The superior mechanical properties were attributed to the microstructure associated with the rapid solidification of the SLM process. The influence of building direction of mechanical properties on fabricated objects was evaluated. The ultimate tensile strength and breaking elongation were significantly affected by the building direction, which was higher in the case of a parallel direction to the roller moving direction. AlSi12CuNi alloy with good characteristics can be successfully fabricated by the SLM process.


2019 ◽  
Vol 25 (25) ◽  
pp. 60-65
Author(s):  
Radomila Konečná ◽  
Denisa Medvecká ◽  
Gianni Nicoletto

Abstract Additive manufacturing has recently expanded its potential with the development of selective laser melting (SLM) of metallic powders. This study investigates the relation between the mechanical properties and the microstructure of Ti6Al4V alloy produced by SLM followed by a hot isostatic pressing (HIP) treatment. HIP treatment minimizes the detrimental influence of material defects. Tensile specimens produced with reference to specific building axes were prepared using a Renishaw A250 system. It has been found that the tensile strength and elongation depend on specimen building direction. Microstructural and textural characterizations were carried out to identify the source of differences.


Author(s):  
Yachao Wang ◽  
Jing Shi ◽  
Shiqiang Lu ◽  
Yun Wang

Fabricating metal matrix composites (MMCs) through laser assisted additive manufacturing (LAAM) has attracted much attention in recent years. This is because the traditional metal components produced by LAAM are usually inferior to the counterparts produced by conventional manufacturing processes, reflected by porosity, lower density, and thus poorer mechanical properties and service performance. Adding reinforcements to metal matrix in LAAM process can alleviate the challenge. Also, for components produced by LAAM processes, post treatment is often required to further strengthen the material, reduce residual stress, or clean off surface for dimensional accuracy. However, research regarding how post treatment affects the microstructure and mechanical properties of LAAM-produced MMCs is still very rare in literature. In this study, a nano-TiC reinforced Inconel 718 composite is prepared using selective laser melting (SLM) technique. Various post heat treatment processes have been adopted to investigate their effect on final product properties. The motivation is that Inconel 718 is a Ni-based superalloy, whose full potential is explored in heat treatment after manufacturing processes. A composite with 0.5 wt.% nano-TiC addition is prepared. Three levels of solution temperatures at 940, 980, and 1020 °C (for 1 hr) or one level of annealing temperature at 1100 °C (for 1 hr) are adopted for the treatment, combined with the standard two-step aging (720 °C, 8 h, furnace cooling + 620 °C, 8 h, air cooling) on both the MMC and unreinforced Inconel 718 materials. Scanning electron microscopy (SEM) observation is conducted to analyze the microstructure of the composite and understand the reinforcing mechanism. Tensile tests are conducted to evaluate the tensile properties. It is discovered that compared with the pure Inconel 718 by SLM, the Inconel 718-TiC MMC exhibits improved ultimate tensile strength for both as-built and solution/annealing treated conditions. Microscopy observation shows that the dendritic structures of Inconel 718 is remarkably refined by the TiC particles in as-built samples, and grain coarsening is largely inhibited by the TiC particles for solution/annealing treated samples. For both reinforced and unreinforced Inconel 718, dissolving of Laves phase and precipitation of δ phase is observed, but annealing at 1100 °C is not favorable for the formation of δ phase. Aging treatment significantly increases the UTS values for both type of material. Moreover, the strengthening effect of added nano particles becomes less significant in the aged condition, due to the precipitation of γ′ and γ″. Future work includes the process parameter optimization, and further evaluation of other mechanical properties.


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