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This study aims to optimize the process of minimum quantity lubrication (MQL) grinding for Inconel 625 (IN 625) while enhancing its comprehensibility. The research employed experimental methods based on the Box-Behnken design to investigate critical parameters, including tangential force, surface roughness, specific energy, and apparent coefficient of friction. Further, machine learning techniques, specifically Random forest regression and Gaussian process regression (GPR), have been employed to build predictive models. These models have been assessed using metrics like R2, mean absolute error, and root mean square error. The results demonstrate that GPR outperforms other techniques in predicting the data accurately. Additionally, this study utilized multi-criteria decision-making techniques, namely TOPSIS and VIKOR, in conjunction with the entropy method to determine the optimal conditions for MQL grinding of IN 625. The optimized parameters for achieving low tangential force, high surface roughness, low specific energy, and low apparent coefficient of friction have been identified as a wheel speed of 1800 m/min, table speed of 9000 mm/min, and a depth of cut of 0.01 mm. Furthermore, a higher value of Ra (surface roughness) indicates the superior effectiveness of MQL grinding compared to dry grinding, as applying the MQL technique helps retain the sharpness of grit for a longer period of time. SEM image and EDS analysis of the ground surfaces confirm that better surface morphology has been obtained at optimized parameters of MQL grinding. [ABSTRACT FROM AUTHOR]

The usage of molten salt in concentrated solar power plants leads to corrosion in energy storage container materials. However, the effect of temperature, duration and environmental conditions plays a major role in the hot corrosion mechanism of the components. The present research investigates the corrosion behavior of Inconel 600 (IN 600) and Hastelloy C-276 (HC-276) in a 55 wt.% Na2SO4 + 45 wt.% Diatomite molten salt environment. Hot corrosion studies were performed by immersion at 40, 80 and 120 h exposures. X-ray diffraction and scanning electron microscopy analysis examined the oxide phases and morphology formed on the corroded material. The mass loss observed at a maximum duration of 120 h is 0.002 g/cm2 for Inconel 600 and 0.8965 g/cm2 for Hastelloy C-276. The Inconel 600 shows less weight loss compared to Hastelloy C-276 due to the formation of a protective oxide layer of NiCr2O4. The materials exposed to molten salt show different surface morphology during the tested durations. [ABSTRACT FROM AUTHOR]

Laser-produced plasma is a promising compact light source applicable in a broad range of wavelengths. We performed a spectroscopic analysis and plasma characterization of the laser-produced plasma of Al, Fe, Cu, and Inconel alloy (Ni/Cr/Fe) to explore their potential applications in the far-ultraviolet (FUV) region where these methods are yet widely exploited. The emission spectrum from each target exhibited a characteristic spectral profile over the wavelength range from 120 to 250 nm. These results were well reproduced by spectral simulations, providing detailed information on the plasma. We also developed a dedicated parabolic mirror that successfully collimated the plasma radiation into beam with an intensity enhanced by a factor of ∼ 35. Our study demonstrated the generation of collimated FUV radiation with an intensity of a 10 7 photons/pulse/1% bandwidth as a potent laboratory-size light source for various applications. [ABSTRACT FROM AUTHOR]

A stepwise multi-temperature thermogravimetric analysis (SMT-TGA) method is a rapid and time- and material-efficient measurement procedure for oxidation kinetics over a wide range of temperatures. It is suitable for alloy design and material selection procedures. It involves subjecting a sample to a series of steps at increasing temperatures, followed by steps at decreasing temperatures to identify possible effects on the evolution of oxide layer microstructures on oxidation kinetics. This method has been tested for a wide range of metallic alloys in the present work, allowing for the mapping of possible ranges of parabolic oxidation kinetics of industrial alloys between 600 and 1300°C. Two examples of effects of thermal history have also been described in this publication. [ABSTRACT FROM AUTHOR]

This study uses vacuum stir casting to manufacture magnesium alloy hybrid nanocomposites of silicon carbide nanoparticles (50 nm) and chopped basalt fibre. The different weight percentages (0 wt%, 3 wt%, 6 wt% and 9 wt%) of chopped basalt fibres with a constant weight percentage of 7.5 wt.% silicon carbide nanoparticles were added into molten AZ91E magnesium alloy at 600 rpm constant stirring speed. During the final casting process, 0.1 MPa vacuum pressure was applied to all the composites to reduce the casting defects. The prepared hybrid composite was characterised by physical, mechanical, microstructural and wear properties. The Quanta FEG model SEM apparatus was used to examine the distribution of silicon carbide nanoparticles and basalt fibre. The mechanical characteristics, such as ultimate tensile strength (UTS), yield strength and impact strength, were obtained for 7.5 wt% SiCnp/9 wt% basalt fibre reinforced AZ91E magnesium alloy matrix hybrid nanocomposite. Adding chopped basalt fibre enhanced the wear properties of conventional AZ91E magnesium alloy. [ABSTRACT FROM AUTHOR]

This study investigates the fretting wear resistance of Inconel 718 fabricated by laser-powder bed fusion (L-PBF) based additive manufacturing (AM) process. A set of the L-PBF processed coupons were subjected to homogenization followed by double aging heat treatment cycles to achieve hardness comparable to wrought material. Material characterization using optical microscopy, scanning electron microscopy (SEM) and x-ray diffraction techniques revealed a fine grained and textured microstructure in AM as-built samples. Point contact (ball-on-flat) fretting wear tests conducted under ambient conditions showed that AM as-built samples had the least wear resistance with a wear coefficient of 15.64 × 10−9 MPa−1 and a higher average coefficient of friction (COF) of 0.75. The wear resistance of the AM samples was found to be improved after heat treatment with the reduced wear coefficient of 10.35 × 10−9 MPa−1 and COF ranged between 0.60 and 0.70. The fretting loops, COF plots and SEM analysis on worn surfaces show that when the applied normal load is low (1N), the operating regime is gross slip regime and the corresponding wear damage is abrasion for all samples. When the load increases to high level (3N), a combined wear mechanism of delamination, adhesion and abrasive wear operating under partial slip regime is predominant with a considerable amount of subsurface cracking. The effect of heat treatment is seen as beneficial in terms of reduction in wear, COF and sub-surface crack which is attributed to improved hardness. [ABSTRACT FROM AUTHOR]

Inconel-625 is a high-performance nickel-based superalloy which offers exceptional properties such as extensive resistance to corrosion, high strength-to-weight ratio, hardness, and impressive heat tolerance. Machining precise holes with required dimensional accuracy is challenging in Inconel-625 using conventional drilling processes. The investigation aims to improve the quality characteristics of hole machined on Inconel-625 by using the abrasive aqua jet drilling (AAJD) process. The influence of jet pressure ( J P ), table feed ( T F ), mass flow rate ( M FR ) and gap distance ( G D ) on the erosion rate ( E R ), surface roughness ( R a ), circularity error (CIerror) and striation zone ( S Z N ) are investigated. The weighted principal component analysis (WPCA)-based response surface methodology (WPC-RSM) is employed to analyze and optimize process parameters. The optimal parameter settings ( J P -300 MPa, G D -1.5 mm, T F -64 mm/min, M FR -0.55 kg/min) are observed to produce substantial improvement in response. Comparing initial and optimal conditions, the surface roughness ( R a ) is decreased by 10.15% from 3.25 μ m to 2.92 μ m. The CIerror and S Z N are also reduced by 38.02% and 12.74%, respectively. The erosion rate ( E R ) is improved by 8.79% with the optimal settings. J P is found to be the most influential parameter, followed by M FR . Scanning electron microscopy (SEM) pictures and 3D roughness plots are used in the surface topography analysis. [ABSTRACT FROM AUTHOR]

In this work, three cooling strategies were proposed to increase the cooling rate and avoid extensive exposure to higher temperatures during the manufacturing of components in Inconel 625 using wire arc additive manufacturing (WAAM): forced cooling with compressed dry air jet, interpass idle time and the combination of both strategies. These strategies were compared for two welding technologies within gas metal arc welding (GMAW) process: pulsed and cold metal transfer (CMT). The results show that deposition using the GMAW-CMT welding mode showed better quality and uniformity than the GMAW-pulsed mode. The tested interpass idle time did not cause a significant effect on the mechanical properties, while the forced cooling using an air jet slightly improved the properties and may be used to increase productivity, especially for larger components. [ABSTRACT FROM AUTHOR]

Low-plasticity burnishing (LPB) is usually used for finishing of material to enhance service performance by improving the roughness and inducing compressive residual stress to surface and underneath layers. However, processing of nickel-based superalloys by burnishing is usually challenging because of resistance of material against plastic deformation. Therefore, the material should be burnished following multiple pass that results increase of production time. In the present work, a plausible solution, namely electric-current-assisted burnishing (ECAB), is introduced to be used as post-treatment for Inconel 718 material produced by laser powder bed fusion process. The surface integrity aspects, i.e., roughness, hardness, residual stress, microstructure change and fatigue life after LPB and ECAB under different pass number, were compared by as-built material to identify the efficiency of the introduced methodology. The results indicated that for conventionally burnished sample, after second pass, no more improvement in fatigue life of the sample is observed and even it decreases at third pass. On the other hand, it was found that for the ECABed samples, after only a single pass, the fatigue life and surface integrity aspects reach maximum values of conventionally burnished sample implying ECAB causes reduction of production time to one third. Moreover, it was found that in contrast to conventional burnishing process, in ECAB process, due to electroplasticity effect, contribution of pass number in improvement of fatigue life and surface integrity will be more substantial where continuous enhancement is seen up to three pass. Current is applied to the process, the pass number is more influential fatigue life and surface integrity aspects are. [ABSTRACT FROM AUTHOR]

In the current research work, in-house developed and fabricated multi-axis near-dry Electrical Discharge Machine (near-dry EDM) has been used having different tool positions, i.e. tool electrodes in horizontal position (Case-I) and vertical positions (Case-II) as a novel machining techniques in hard-to-reach places and also to improve the process performance. Design of Experiment tool has been used with three process parameters: voltage, discharge current, and pulse-on-time for experimentation purposes. In order to maximize Material Removal Rate (MRR), it was necessary to compare and enhance these parameters in both cases, i.e. Case-I, and Case-II. The machining process is significantly influenced by the vertical tool positions, as indicated by the largest percentage contribution in the Analysis of Variance results. The voltage has the least influence, while the pulse-on time is relatively less. In contrast, for the horizontal tool position, the voltage proved the most prominent factor in terms of influence, while the current ranked second in significance. Conversely, the pulse-on time exhibited the least impact among the three factors. The highest MRR 2.45 mm3/min was achieved in the vertical tool position while in horizontal machining, the highest MRR 0.144 mm3/min was observed. These findings provide valuable insights into the multi-axis near-dry EDM with proposed methodology. [ABSTRACT FROM AUTHOR]

Melt track width can vary in a wire-arc-directed energy-deposited material (DED) using a constant set of process parameters, leading to a lower-quality build. In this work, a novel framework is proposed that uses the data from the process parameter development stage to create optimized process parameters for a target layer width at different interpass temperatures without hot cracking. Inconel 718 is used as the model material since it is known to suffer from hot cracking during DED processing. In the proposed framework, a process window containing a few sets of process parameters (torch travel speed and wire feed rate) is established for crack-free deposition of Inconel 718, and these parameters are used to create a small database. A linear regression model is then employed to generate interpass-temperature-specific optimized process parameters for a target melt track width. The results demonstrate that the proposed approach can reduce the melt track width variation in the deposited walls from 12% to 3% error on average under different printing conditions. It also demonstrates that interpass temperature (IPT) can be used as a controlled variable and the optimized process parameters as initial values when applying control techniques to the process. [ABSTRACT FROM AUTHOR]

This study investigated the impact of temperature, time, and homogenisation on the transient liquid phase bonding of Inconel 617 to stainless steel 310, employing AWS BNI2 foil as an interlayer. Nine test series were conducted at temperatures of 1050 °C and 1100 °C, with bonding durations ranging from 10 to 60 min. The homogenisation process was carried out on specimens that underwent full isothermal solidification at a temperature of 1170 °C for 180 min. The microscopic analysis indicated that extending the time and raising the bonding temperature resulted in the extension of the isothermal solidified zone, accompanied by a reduction in the quantity of eutectic phases. Complete isothermal solidification was seen exclusively in samples bonded at temperatures of 1050 °C for 60 min and 1100 °C for a duration of 50 min. The size of the diffusion-affected zone expanded as the bonding temperature and duration rose, but the presence of brittle intermetallic phases diminished. The microstructure of the homogenised sample indicated that the diffusion-affected zone had been almost completely eliminated. Hardness variations indicated heightened hardness in the diffusion-affected zone (DAZ) and athermal solidified zone (ASZ). Shear strength is maximised in homogenised specimens with minimised ASZ. [ABSTRACT FROM AUTHOR]

Present work evaluates coarsening kinetics of γ′ precipitates in γ–γ′-based microstructure of a high Fe-containing low-density low-cost Ni-29.8Fe-11.1Cr-3.7Al (wt pct) medium entropy alloy. The experimentally estimated mean size of the γ′ precipitates, during isothermal ageing of the alloy at 600 °C for varying duration, agrees well with the theoretical prediction by considering interfacial energy of 10 mJ/m2. This investigation suggests the sluggish coarsening kinetics with diffusion of Cr across γ–γ′ interface as the rate controlling factor. [ABSTRACT FROM AUTHOR]

In this work, wire arc additive manufactured (WAAM-ed) Inconel 617- and 625-wmo grade alloys are characterized in detail for the type and distribution of precipitates in as-built and heat-treated conditions. The analyses are carried out near (~1 mm) and away (~10 mm) from the substrate along the build direction to investigate the effect of the substrate on the nature of precipitate formation. For each analysis location, morphological and chemical information of at least 400 precipitate features was identified and classified using stoichiometric analysis of SEM-EDS data combined with feature analytics. Carbides and carbonitrides are present in both Inconel 600 series alloys but Laves phase precipitates are identified only in the case of Inconel 625 wmo alloy. It is observed that the nature of precipitates size distribution is not altered significantly when compared between the two analysed locations for a particular grade. Furthermore, Laves phase precipitates closer to the substrate (1 mm) are richer in iron because of the effect of mild steel substrate on precipitation characteristics in Inconel 625 alloy. Our novel characterization approach will pave the way for comparing the microstructures of additively manufactured samples printed using different process parameters and variations. [ABSTRACT FROM AUTHOR]

Featured Application: Assessment of the mechanical properties of the weld lines between wrought and laser-based directed energy deposition overlays. The combination of wrought materials and laser-based directed energy deposition (DED-LB) is being increasingly used for manufacturing new and repairing old or damaged components in several industries. Aerospace components made of Inconel 718 featuring small-thickness DED-LB buildups are a remarkable example of such a combination due to the high added value it brings. Despite that these are usually critical components, the miniature testing methods to assess the local mechanical properties in the buildup area are not fully developed. This work contributes to this miniature testing development with an improvement of the small punch testing (SPT) technique for measuring the mechanical properties of the weld line between the DED-LB and the wrought substrate. A new criterion for weld line positioning in the SPT specimens is proposed and applied on samples of hybrid wrought/DED-LB Inconel 718. The results of positioning the weld line at the necking site of the SPT specimen show that the proposed approach is valid for assessing the properties of the transition zone between the wrought and additive states. For the specific conditions tested and taking the wrought material as a reference, the strength of the Inconel 718 drops 10% in the weld line and 20% in the buildup. [ABSTRACT FROM AUTHOR]

This study investigates the shrinkage characteristics of various materials in metal 3D printing using Material Extrusion (ME) technology. The materials examined include 17-4PH Stainless Steel V1 and V2, Inconel 625, H13 Tool Steel V1, and A2 Tool Steel. Experiments reveal that shrinkage rates vary significantly among these materials, with 17-4PH Stainless Steel V1 exhibiting the lowest average shrinkage rate of 16.2%, while Inconel 625 shows the highest average shrinkage rate of 24.5%. These findings are critical for improving dimensional accuracy in metal 3D printing. Additionally, results demonstrate that print orientation affects shrinkage. The analysis of product accuracy reveals inconsistencies between printed dimensions and design specifications, likely influenced by printing parameters. The conclusion underscores the importance of selecting appropriate printing materials and optimizing parameters to ensure dimensional accuracy in 3D printed products. [ABSTRACT FROM AUTHOR]

The surface roughness and surface residual stresses are affected by the coating thickness of physical vapor deposition (PVD) TiAlN tools, which could alter the service performance of machined components. However, the relationships among the tool coating thickness, the machined surface roughness, the surface residual stress, and the fatigue life are still not sufficiently illustrated. In this research, PVD TiAlN coatings with several thicknesses of 1.6 μm, 2 μm, 2.5 μm, and 3 μm were deposited on carbide tools. Turning experiments using Inconel 718 were conducted with uncoated and various TiAlN tools under flood cooling conditions. The surface roughness could be improved with the selection of thin PVD TiAlN coating thicknesses of 1.6 μm and 2 μm compared to that of uncoated tools. The tensile residual stresses at the machined surface in the directions of cutting speed and feed rate linearly decreased by 148.67% and exponentially decreased by 92.24% when the TiAlN coating thickness was increased from 0 μm to 3 μm. The values of the low-cycle fatigue life of machined Inconel 718 linearly increased by 15.60% with the increase in TiAlN coating thickness from 0 μm to 3 μm, which was mainly due to the improvement of surface residual stresses. The results could provide guidance for the selection of suitable TiAlN coating thicknesses for wet machining Inconel 718 based on the part service conditions. [ABSTRACT FROM AUTHOR]

Tailor-made materials used for advanced applications are nowadays of great research interest in various industrial and technological fields, ranging from aerospace and automotive applications to consumer goods and biomedical components. In the present research, Inconel 718 superalloy specimens were fabricated by the selective laser melting (SLM) technique. Structural characterization of the 3D-printed samples showed that they consisted of γ solid solution along with spherical carbide particles. To explore the applicability of these materials in abrasive tribological applications, reciprocating sliding tests were performed under dry conditions versus an Al2O3 counter-body. A 3D representation (triboscopy) of the tangential force during each sliding cycle was carried out in order to obtain better insight on the evolution of friction and to visualize localized tribological phenomena. Quantification of wear was performed with confocal microscopy and the wear mechanisms were analyzed with SEM and EDS techniques. Furthermore, the effect of surface finishing (as-printed and polished) on friction and wear were also investigated, and a comparison with other industrial materials is also included to evaluate the applicability of these alloys. The results indicated that surface finishing had an effect on friction during the run-in stage, whereas in steady-state conditions, no significant differences were observed between the as-printed and polished specimens. In all cases, the main wear mechanisms observed were a mixture of two-body and three-body abrasion, along with oxidative wear (indicated by the formation of an oxide-based tribo-layer). [ABSTRACT FROM AUTHOR]

The study aims to investigate the modal properties of a 60 × 70 × 80 mm gyroid structure made of Inconel 718 with 67.5% porosity. The geometry model for sample production was created using the software PTC Creo, whereas the geometry model for numerical analysis was created using the Python application ScaffoldStructures. FE analysis was performed using ANSYS 2024 R1 software. Free boundary conditions were used in experimental modal analysis to ensure feasibility. The analysis identified the first four natural frequencies ranging from 10 to 16 kHz. The results revealed that the first natural frequency corresponds to the first torsional frequency about the Z axis, the second to the first flexural mode in the XZ plane, the third to the first bending mode in the YZ plane, and the fourth to the first torsional mode about the X axis. Small differences between the results of numerical and experimental modal analysis can be attributed to geometric errors in the manufactured sample, careless removal from the platform, and due to reduction in the complexity of the numerical FE model. Employing modal analysis of a component, the stiffness of a lightweight component can be revealed. In the case of the sample with the cellular structure of gyroid type, relatively high stiffness regarding the material savings was identified, which can be advantageously used in many applications. [ABSTRACT FROM AUTHOR]

The flexibility of additive manufacturing techniques that produce parts from powders layer-by-layer directly from a digital model enabled the fabrication of complex lightweight lattice structures with precisely engineered mechanical properties. Herein, an investigation of the quasi-static and dynamic behavior of additively manufactured (AM) triply periodic minimal surface (TPMS) lattice structures before and after a novel post-process heat treatment step is conducted. The specimens were fabricated out of Inconel 718, a nickel–chromium-based superalloy, using a selective laser melting technique with three different topologies, namely, gyroid, primitive, and I-WP. The quasi-static tests were conducted at a strain rate of 0.002 s−1 and dynamic experiments were conducted using a split Hopkinson pressure bar at three different strain rates, 600 s−1, 800 s−1, and 1000 s−1. It was shown that while the strain rate does not significantly affect the mechanical responses of the lattice structures, the heat treatment step dramatically changes their behavior. Results demonstrated that after the heat treatment, the yield strength of the I-WP specimens increased by 65.2% under a quasi-static load. Also, flow stress after yielding in the dynamic tests was shown to increase around 9.6% for I-WP specimens and up to 12.8% for gyroid specimens. The specific energy absorption values were 10.5, 19.1, and 10.7 for I-WP, gyroid, and primitive, respectively, before the heat treatment, and changed to 19.6, 19.8, and 15.4 after the heat treatment. The results confirm that by precisely designing the architecture of a lattice structure and implementing a modified heat treatment process, it is possible to optimize the weight, strength, and energy absorption capability of this type of metamaterial. [ABSTRACT FROM AUTHOR]

In aeroengines, the fir-tree slot or tenon is a key component that connects the turbine disc and blades. Accordingly, it requires a high surface quality and highly precise contour machining. Wire electrical discharge machining (WEDM) offers highly precise machining, favorable surface quality, and vital machining flexibility, which are fundamentally advantageous for low-cost manufacturing of turbine disc tenon-slot structures. In this study, single-factor experiments and response surface methodology were employed to analyze the relationships between surface roughness (Rz), kerf width (K), pulse width, pulse interval, peak current, and voltage. In addition, predictive mathematical models describing how the surface roughness and kerf width are related to the discharge parameters were established. The maximum relative errors of the model predictions for the surface roughness and kerf width were only 4.55% and 7.03%, respectively, and they were distributed randomly. Combined with the prediction model, the offset of each time of multiple cuts was predicted and corrected. A 40-mm-thick superalloy Inconel 718 workpiece was used to machine a fir-tree slot structure with a surface roughness Ra of 0.432 μm, maximum recast layer thickness of 3.1 μm, and internal and external deviations of − 0.0089 mm and 0.009 mm, respectively. [ABSTRACT FROM AUTHOR]

Here, we present a superhydrophobic surface with enhanced corrosion protection prepared using a spin coating method on an IN617 substrate. It comprises a micro-nanostructured polydimethylsiloxane/octyltrimethoxysilane modified silicon dioxide coating. The composite coating exhibits excellent water repellency (WCA 152° ± 1.2°), mechanical robustness, thermal resistance (50–200 °C), chemical stability (pH 1–9), and improved anti-corrosion. [ABSTRACT FROM AUTHOR]

In order to improve the wear resistance of hot‑rolled high speed steel work rolls, Inconel 625 alloy coatings with 0%, 10%, 20%, and 30% (Ti, W) C content were prepared on ductile iron substrate by laser cladding technology. The effect of (Ti, W) C particles on the microstructure, hardness and wear resistance of the coatings was investigated. The (Ti, W) C particles are uniformly distributed in the coating, and have a good combination with the Inconel 625. The hardness of the coating increases from HV0.2280 to HV0. 2424 with the increase of the (Ti, W) C particle content. In the process of friction and wear, the (Ti, W) C particles, as hard phases, inhibit the local plastic deformation of the material during wear. The wear amount of Inconel 625 alloy coating containing 30% (Ti, W) C particles is only 0. 015 m³, and the average friction coefficient is 0. 061 6. It has been proved that the hardness and wear resistance of Inconel 625 alloy coating are significantly improved and the friction coefficient is reduced by adding a reasonable amount of (Ti, W) C particles. [ABSTRACT FROM AUTHOR]

An arc is used as a heat source in the manufacturing process known as wire arc additive manufacturing (WAAM), which uses layer-by-layer cladding to fuse wire. in the current work, wire arc additive manufacturing (WAAM)-fabricated inconel 625 alloy has been examined. The research was done on the microstructure, mechanical characteristics, and impact of the solidification rate on the characteristics of the manufactured specimens for the inconel 625 alloy. Microstructural analysis has shown that the specimen's layers have varying microstructures. The bottom layer exhibits a blocky or equiaxed microstructure because of the faster solidification rate, while the upper zone generated elongated and discontinuous dendrites because of the slower solidification rate. This difference in the microstructure in the top and bottom zones directly influence the ultimate tensile strength, where the bottom zone has more tensile and yield strength than the top zone. Also, the presence of cracks in the top zone, which is found during the fractography test, also correlated the top zone's ultimate tensile strength. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate how weld overlays with nickel superalloys are important for the integrity, due the high temperatures and corrosive environments that can be experienced in mineral processing environments, of mining and processing equipment. The Ni-Cr-Mo superalloy Inconel 686 overlays are fabricated through automatic gas metal arc welding with variations in arc voltage and travel speed (i.e., heat input), and they have overlap between adjacent weld tracks for applications in the mining and minerals sector. The impact of variations in the process parameters and the size of the weld overlapping on the dilution, solidification morphology, microsegregation, and microhardness were investigated. Both geometric and chemical composition definitions were used to quantify the extent of the weld dilution. Subsequently, the weld geometry and dilution were correlated with the solidification microstructure and phase transformations. The maximum dilutions were measured to be 13.63% (1/2 overlap, 5.96 kJ·cm−1) and 15.39% (1/3 overlap, 4.77 kJ·cm−1), which shows that less of an overlap increases the dilution level. Scanning electron microscopy and chemical composition analysis revealed that an increase in weld heat input and dilution level led to higher levels of microsegregation for Mo and Cr, as well as the volume fraction of Mo- and Cr-rich phases in the interdendritic/intercellular regions in the overlay layer. Analysis of the weld overlays in the current study revealed strong and unprecedented connections between the weld overlay process conditions, the resultant metallurgy (i.e., dendrite arm spacing, microsegregation, and phase formation), and the hardness of the overlay. It was concluded that the optimal weld overlays in the processing window studied in this investigation were fabricated at mid-level heat inputs (i.e., 4–5 kJ·cm−1) and a 1/2 track overlap. [ABSTRACT FROM AUTHOR]

For nickel (Ni) superalloys, including Inconel 738, electrochemical machining (ECM) is commonly used. However, the mechanisms behind ECM surface flattening and improved surface quality have not been fully elucidated, and the relationship between corrosion and ECM is weakly established without microstructural correlation. To bridge this knowledge gap, we have systematically investigated the electrochemical dissolution behavior of wrought Inconel 738 superalloy in the selected NaNO3 solution and narrowed down the optimal ECM parameters (i.e., 12 V, 0.8 mm/min, and 0.8 MPa). The results show that the precipitates and secondary phases of the Inconel 738 superalloy dominate the final surface quality and the ECM efficiency. Importantly, we have confirmed that a core–shell precipitate phase with shell-layer Ti and Mo enrichment remains on the surface even after the 12 V ECM, limiting the final roughness. This novel finding clarifies why the morphology differs under two representative conditions (i.e., anodic dissolution at 1.3 V, 1500 s and optimal ECM with 12 V, 0.8 mm/min, and 0.8 MPa), and how the core–shell precipitates evolve during the non-equilibrium 12-V ECM condition leads to a totally different flattening process. This ECM analysis method, with solid electrochemical theory and detailed microstructural investigation, reveals the microstructure-dependent ECM flattening mechanisms at precipitate scale and demonstrates how the microstructures influence the ECM processing quality. This novel finding plays a guiding role in improving the quality of ECM processing, shows great value for various industrial applications, and helps strategically break the current surface roughness limit. [ABSTRACT FROM AUTHOR]

Purpose: Wire arc additive manufacturing (WAAM) is one of the most researched and fastest-growing AM technique because of its capability to produce larger components with medium complexity. In recent times, the use of WAAM process has been increased because of its ability to produce complex components economically when compared with other AM techniques. The purpose of this study is to investigate the capabilities of wire arc additive manufacturing (WAAM), which has emerged as a recognized method for fabricating larger components with complex geometries. Design/methodology/approach: This paper provides a review of process parameters for optimizing and analyzing mechanical properties, hardness, microstructure and corrosion behavior achieved through various WAAM-based techniques. Findings: Limited analysis exists regarding the mechanical properties of various orientations of Inconel 625 alloy. Moreover, there is a lack of studies concerning the corrosion behavior of Inconel 625 alloy fabricated using WAAM. Originality/value: The review identifies that the formation of intermetallic phases reduces the desirability of mechanical properties and corrosion resistance of WAAM-fabricated Inconel 625 alloy. Additionally, the study reported notable results obtained by various research studies and the improvements to be achieved in the future. [ABSTRACT FROM AUTHOR]

Purpose: The net power delivered to the surface of parts (i.e. the actual heat flux) is a key parameter in the laser melting process and its exact control has a great impact on the numerical solutions. In this paper, the impact of laser additive manufacturing parameters including laser power, scanning speed and powder injection rate on thermal efficiency, net power delivered to the part and power loss due to powder flow has been investigated. Design/methodology/approach: The response surface method was applied to measure the net laser power in laser deposited Inconel 718 using k-type thermocouples. The temperature history obtained by thermocouples was used to calculate the net power delivered by inverse analysis method. The applied model is Rosenthal's optimized model, in which all the thermal properties of the material are considered to vary with temperature. Findings: The results indicated that the thermal efficiency, power delivered to the part and power loss can be optimized simultaneously at laser power of 400 W, scanning speed of 2 mm/s and powder injection rate of 200 mg/s. The microstructure analysis indicated that a high-quality sample without microstructural defects was formed under optimal condition of parameters. Moreover, the primary dendrite arm spacing for the optimal sample was higher than that obtained for other samples. Originality/value: The novelty of this research summarized as follows: Prediction of the thermal efficiency and power loss during the laser metal deposition of Inconel 718 superalloy using the inverse analysis. Finding the optimal values of thermal efficiency, power delivered to the surface and power loss in the laser metal deposition of Inconel 718 superalloy. Investigating the effect of laser power, powder injection rate and scanning speed on the thermal efficiency and power loss of Inconel 718 superalloy during the laser metal deposition. [ABSTRACT FROM AUTHOR]

In elevated conditions, austenitic stainless steels suffer intense damage by corrosion because of the severe oxide scale development. Giving stainless steel a corrosion‐resistant surface coating can prevent excessive damage. In this case, welding‐based overlaying is a potential method to restore the damaged parts as it has a higher productivity rate. This investigation articulates the corrosion resistance behavior of the multiple overlapped Inconel 625 (IN625) weld overlays on the AISI 316L substrate plate. The corrosion resistance at elevated temperatures was investigated with kinetic curves, further revealing the corrosion products from the sample surface. Characterization techniques like scanning electron microscopy with energy‐dispersive spectroscopy, X‐ray diffraction, and Raman spectroscopy were employed to analyze the corrosion products. Hot corrosion kinetics in the molten salt environment (Na2SO4 + V2O5) revealed that the IN625 overlay samples gained a weight of 40.15 mg/cm2, and the substrate had a weight gain of 65.42 mg/cm2. From the hot oxidation kinetics, it is evident that the mass gained by the substrate is more than twice that of the Inconel overlay sample. Furthermore, the formation of oxides and spinel phases rich in nickel (NiO, NiCr2O4) highly influenced the corrosion kinetics of the multiple overlapped IN625 overlay sample. The AISI 316L substrate sample revealed the existence of critical oxide phases such as Fe2O3 and Cr2O3, which were lesser and did not influence the corrosion resistance at 900°C. In the present investigation, the multiple overlapped IN625 weld overlay offered excellent corrosion resistance at high temperature compared to the AISI 316L. [ABSTRACT FROM AUTHOR]

This study explores the numerical analysis of effective stress and distortion (dimensional variations) in bulk deposited structures of Inconel 625 alloy with seven different deposition strategies using wire arc additive manufacturing (WAAM) process. Due to the challenges in detecting in-situ stress changes during bulk deposition, numerical analysis is employed to approximate stress distribution. The goal is to investigate stress and distortion (dimensional variations) in the build direction (BD), longitudinal and transverse directions, and understand their impact on anisotropy and asymmetry. The findings reveal distinct patterns in effective stress, with initial decrease in bottom, followed by a gradual increase at the middle and rapid increase thereafter, regardless of deposition strategies. Parallel and contour deposition strategies exhibit lower effective stress compared to spiral strategies. Distortion (dimensional variations) along the BD increases with height, and parallel strategies result in higher distortion. The parallel strategies show increasing distortion from one edge to the other, while spiral and contour strategies lead to high distortion at the center. The parallel and contour deposition strategies exhibit higher compressive stress at the bottom and middle compared to the spiral strategies. Anisotropy analysis indicates higher stress anisotropy in parallel and contour patterns, but lower distortion anisotropy compared to spiral patterns. Empirical equations are developed to understand the relationship between stress, distortion (dimensional variations) and hardness. The study suggests that higher effective stress can adversely affect material yielding behavior. This study undertakes a comparison between FEA and analytical model which reveals a close alignment in the residual stress distributions in the build direction. [Display omitted] ● Residual stress and distortion behaviour of seven deposition strategies are numerically analyzed. ● Residual stress in bulk deposition decreases at bottom, increases in middle and top. ● Parallel strategies result in lower horizontal stress and distortion compared to spiral and contour. ● The compressive stress in the parallel and contour strategies is significantly higher than that the spiral. ● Parallel and contour strategies exhibit greater stress anisotropy but lower distortion anisotropy. [ABSTRACT FROM AUTHOR]

With the flood cooling technique approach, it is impossible to fulfill the concerned environmental regulations and increase productivity while machining material that is infamously tough to cut. To address the conscious environmental regulation in the metal cutting industry, an effect must be made to reduce the industry process impact on environmental pollution along with manufacturing process optimization. Therefore, an eco-friendly MQL technique was investigated associated with machinability characteristics and compared results with dry condition while end milling of Inconel 825 material. The results revealed that MQL significantly reduced cutting temperature (CT) and surface roughness (Ra) to maximum levels of 70% and 43%, respectively. Further, optimum conditions were found using Taguchi method under MQL cooling. Additionally, using 3D surface plots, the interaction impact of process parameter on "Ra" has been investigated. For end milling Inconel 825 material, the MQL machining method has been proven as the most feasible alternative over dry condition. [ABSTRACT FROM AUTHOR]

Copyright of Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım ve Teknoloji is the property of Gazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Functional grading (FG) is often used to bond dissimilar metals. However, that approach is complicated from a manufacturing perspective, and the associated challenges can outweigh the benefits of FG. Here, we investigate a directly bonded interface by transitioning from stainless steel 304L (SS304L) to Inconel 625 (IN625) using powder-feed directed energy deposition with a laser beam energy source (DED-LB). Both cracking and the presence of carbide phases have been reported in this multi-materials system. Conditions that unambiguously achieve crack-free joints have not yet been established. With DED-LB, we consistently observe solidification cracking in melt pools containing > 50 wt pct SS304L, while no cracking is observed in melt pools with < 40 wt pct SS304L. Variations on the most up-to-date solidification cracking model are applied to gain insight into the cracking dependencies. Parameters that give rise to defect-free single layers also enable defect-free multilayer prints despite the additional thermal cycling. Upon printing and testing full-sized ASTM E8 tensile specimens, the interface is sufficiently strong that failure occurs solely within the SS304L region, indicating a joint strength of > 650 MPa. Thus, a simple method to attain high strength joints for these dissimilar metal alloys is demonstrated. [ABSTRACT FROM AUTHOR]

This study investigates the effect of laser power applied for a remelting scan in the laser powder bed fusion process on the formation of a bimodal microstructure and its impact on the mechanical properties of Ni-based Inconel 625 superalloy. Comparison of primary and remelting scans at similar surface energy densities revealed that the melt pools obtained in the remelting scan are smaller than in the primary scan. To achieve comparable remelted melt pool sizes, the 25 pct increase in energy is required. The shape and size of the remelted melt pools significantly affect the microstructure and material texture. The lower surface energy density in laser powder bed fusion favors the formation of a bimodal microstructure with large columnar grains and fine grain bands. Application of higher energy results in the formation of large columnar grains with Goss texture along build direction and separated by a large amount of low angle grain boundaries. Remelting scan also affects reduction of porosity and increasing of the area fraction of nanometric oxide inclusions. The study revealed that the samples subjected to a remelting laser scan and tensile tested along the direction of columnar grains exhibited higher ductility, which was associated with a slight decrease in the ultimate tensile strength compared to the samples that were not remelted. It was demonstrated that the remelting scan in the laser powder bed fusion process offers the possibility of improving the reliability of additively manufactured Inconel 625 superalloy by reducing porosity and tailoring its microstructure towards single-crystal-like, and thus improving the mechanical properties. [ABSTRACT FROM AUTHOR]

The research objects are gas turbine engines parts, manufactured using an innovative method of additive manufacturing - selective laser sintering. The main problem solved in this work is the low quality of the surface layer and the residual porosity of the parts obtained by this method, which significantly limits their operational characteristics and durability. As a result of the experimental studies, rational operating parameters of diamond smoothing were established. This allowed to significantly improve the surface quality and increase the operational characteristics of parts made of heat-resistant alloys INCONEL 718 and an intermetallic alloy based on titanium aluminide OX45-3ODS. The effectiveness of diamond smoothing is explained by local plastic deformation and compaction of the surface layer of parts under the influence of high contact pressures and temperatures. This leads to a significant reduction in surface roughness, an increase in the surface hardness due to strain hardening and a significant reduction in the size and number of residual pores. A characteristic feature of the obtained results is the ability to control the quality parameters of the surface layer by varying the diamond smoothing operating parameters - smoothing force, feed, radius, and geometry of the smoother's working part. The established regularities of the smoothing operating parameters have an impact on the quality characteristics of the surface. This information can be utilized in the development of highly efficient technological processes for the production and restoration of gas turbine engines, critical components of unmanned aerial vehicles, obtained through selective laser sintering. Implementing the elaborated technological recommendations will permit broadening the range of goods produced by additive manufacturing and enhancing their capacity and dependability during operation under conditions of cyclical loads and extreme temperatures. [ABSTRACT FROM AUTHOR]

Depending on the 3D-printing orientation, the anisotropy of the elastic characteristics of the Inconel 625 alloy generated with selective laser sintering from powders is investigated. The impact of the original powder combination and the following heat treatment (post-printing treatment) on the anisotropy of the alloy elastic characteristics is assessed. As demonstrated, the suggested treatments can lessen the anisotropy of the alloy elastic characteristics. Based on knowledge of the elastic constants of the single crystal and x-ray texture features, the results of a theoretical estimation of the elastic and shear moduli, Poisson's ratio, and their anisotropy in the horizontal and vertical directions of 3D printing are provided. As demonstrated, the obtained theoretical values differ by 6-10% from the corresponding experimental values. The calculated stress-strain state can be more accurately calculated with the use of the estimated elastic characteristics and their anisotropy. The strategy for 3D-printing complicated components from Inconel 625 alloy may be made more effective. [ABSTRACT FROM AUTHOR]

Laser beam welding (LBW) is a highly demanded process for premium-quality joints in aeronautic, energy, or industrial sectors, where flexibility and low-heat-affected zones are required. One of the main applications of LBW in the near future is expected to be the welding of new turbine engine components, which are typically made of Nickel-based superalloys. However, parameter setup is time- and resource-consuming, where experiment-based methods are typically employed. Therefore, the process development is far from an efficient resource utilization. In the present work, an LBW numerical model is developed and experimentally validated through a machine-integrated monitoring system. The LBW model is based on solving the heat transfer problem produced by the laser and provides the resulting temperature field, as well as the weld bead dimensions. The model includes a variable heat source that automatically adapts to the welding regime, conduction, or keyhole. For the model validation, two Inconel 718 sheets of different thicknesses are butt-welded and an error of around 10% is obtained, which ensures the validity of the model. [ABSTRACT FROM AUTHOR]

Inconel 706 (IN706) alloy is commonly used in aircraft engines and power plant components that must meet very high performance requirements. The stabilization treatment has a significant effect on the precipitation and evolution of the reinforcing phases of the alloy, favoring the creep properties and adversely affecting the room-temperature tensile properties. However, the mechanism of the effect of the stabilization treatment on the mechanical properties of the alloys remains unclear. In this study, the effect of stabilization treatment time on the microstructure and tensile properties of IN706 alloy was investigated. The results showed that as the stabilization time gradually increased, the tensile strength remained basically unchanged (about 1250 MPa), the yield strength decreased from 1031 MPa to 985 MPa, and the plasticity decreased from 28.2% to 20.2%. The stabilization treatment induces the precipitation of granular, rod-shaped, and needle-like η phases at grain boundaries, accompanied by the appearance of a precipitate free zone (PFZ). Since the η phase is enriched with Ti and Nb, its precipitation along the grain boundary results in the depletion of Ti and Nb in the surrounding regions, thereby constraining the precipitation of the γ′ and γ″ phases, resulting in the appearance of PFZ. With increasing stabilization time, the size increase and volume fraction decrease in γ′-γ″ co-precipitates due to the precipitation of η-phase precipitates, leading to a decrease in their yield strength. Combined with in situ tensile tests, it was found that the decrease in the elongation of the stabilization treatment samples was due to the presence of η phase at the grain boundaries, which induced stress concentration and cracking at the grain boundaries. The results show that the mechanical properties of the material were gradually enhanced as the stabilization time decreased. This means it can help to choose the suitable process for IN706 alloy in different service conditions. [ABSTRACT FROM AUTHOR]

An Inconel 740H nickel-based alloy was fabricated via wire arc additive manufacturing. The as-welded and heat-treated samples were analyzed to investigate their phase composition, microstructure, crystal structure, and mechanical properties. After heat treatment, the sample exhibited a columnar crystal zone microstructure consisting of a γ matrix + precipitated phase, the remelting zone metallographic structure was a γ matrix + precipitated phase, and the HAZ metallographic structure was a γ matrix + precipitated phase. Transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) were used to show that the welded sample exhibited many dislocations, a few inclusions, and carbides, nitrides, and γ' precipitates in its crystal structure. In contrast, the crystal structure of the heat-treated sample exhibited a lower number of dislocations and significantly higher carbide and γ' precipitate content. Moreover, the mechanical performance of these samples was excellent. This heat-treatment process improved the sample strength by about 200 MPa, leading to better high-temperature mechanical properties. This work is anticipated to offer theoretical and experimental support for using additive manufacturing methods in the manufacturing of nickel-based superalloy components. [ABSTRACT FROM AUTHOR]

This study investigated the impact of electric pulse treatment (EPT) on the microstructure and mechanical properties of laser powder bed fused Inconel 718 (IN718). Through a comprehensive experimental characterization, we found that EPT induced significant improvements in the microstructure of IN718. In the YOZ plane of EPT-700, the molten pool diminished and replaced by a grain boundary with granular Ni3Nb precipitates, and the dislocations increased while the irregular porosity decreased. Concurrently, enhanced mechanical properties of EPT-700 were obtained, including a hardness of 354.7 HV, an ultimate tensile strength of 930.21 MPa, and an elongation of 34.35%. Fractographic analysis revealed a transition in fracture mechanisms, highlighting the intricate relationship between microstructural modifications induced by EPT and mechanical response under load. These findings underscore the potential of EPT as a promising post-processing technique for optimizing the microstructure and mechanical properties of IN718 components fabricated via laser powder bed fusion additive manufacturing. This study contributes to the advancement of knowledge in the field of additive manufacturing and provides valuable insights for the development of high-performance metallic components. [ABSTRACT FROM AUTHOR]

The technique of selective laser melting has garnered significant interest due to its capacity to fabricate metal parts of any shape using a single printing process. In this study, a scan strategy was proposed for printing the inner structure part based on the varying performance of the Inconel 718 alloy part produced using different scan techniques. The test findings indicated that the surface quality of the printed material along the scan line exhibited significantly superior performance in comparison to that produced in a vertical direction to the scan line. Regarding the scan strategy, it is evident that the zigzag shape scan strategy exhibited superior performance in terms of the microstructure of the printed part. This is attributed to the more consistent cooling rate on each scan track. On the other hand, the square-framed scan strategy demonstrated a relatively optimal condition for the bending deformation of the printed part compared to other scan strategies. This is due to the more appropriate behavior of the molten pool during the outer edge printing process. After considering all of these criteria, a novel scan approach was created that included various scan strategies. The test findings indicated that the component produced using this novel scanning technique exhibited the combined benefits of both the square-shaped and zigzag-shaped scanning strategies. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Production Engineering / Revista Brasileira de Engenharia de Produção is the property of Brazilian Journal of Production Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work investigates the impact of different heat treatments on the evolution of the microstructure, tensile properties, and residual stresses of Inconel 625 (IN625) processed by laser powder bed fusion (LPBF). Applying a heat treatment is an essential step to mitigate the high residual stresses in the components produced by LPBF and, simultaneously, to design the mechanical properties of the components. A high magnitude of residual stress can involve deformation and reduce the fatigue resistance of the components. In the current work, heat treatments performed at 600, 800, and 870 °C provided minimal modification on the dimensions of the grains but involved the formation of new phases, which increased the tensile strength. The results showed mitigation of the residual stresses at 800 and 870 °C correlated with the formation of Cr-rich M23C6 carbides and δ phases, respectively. Finally, the solution annealing at 1150 °C triggered recrystallization with the formation of sub-micrometric carbides, reducing the residual stresses. The solution annealing treatment involved an improvement of the ductility and a reduction in tensile strength. This work provides a guide to understanding the microstructure, residual stress, and mechanical properties evolution of the IN625 alloy under heat treatments. [ABSTRACT FROM AUTHOR]

Production of dissimilar weldments using microwave hybrid heating is currently gaining immense impetus in the field of advanced welding. This is because such heat source could provide benefits like cost-effectiveness, rapid, volumetric, uniform and selective heating, and efficient throughput which would be significant to various industries. Till-date researchers have carried out joining of dissimilar general purpose engineering materials using microwave hybrid heat source. But attention has not been paid on the joining and characterization of dissimilar exotic-general purpose materials using the aforementioned heat source and the promising applications of the weldments. Therefore, the present article is focused on the joining of dissimilar materials- Inconel 625 and SS 304 alloys using selective microwave hybrid joining (SMHJ) technique. In SMHJ, nickel-based powder is used as a filler material, Silicon carbide (SiC) block and SiC powder are used as susceptor to increase the initial temperature. The developed weldments through SMHJ are characterized using various physico-chemical diagnostic methods. The results reveal the average micro-hardness of joint was found to be 303 ± 17 HV owing to the presence of various carbides and nitrides phase like NbC, Cr23C6, Cr2Ni3, Ni8Nb, and Fe3Ni2 in the joint zone which is evident from XRD. The average UTS of the joints found to be 448.6 MPa with an elongation of 10.93% and flexural strength observed to be 435 MPa. Further, fractography study reveals, the joint regions have mixed mode of failure. The failure was attributed to the existence of secondary phases in the joint zone. [ABSTRACT FROM AUTHOR]

The selective orientation of grains during laser powder bed fusion (L-PBF) leads to anisotropy in mechanical properties. The current understanding of the evolution between the different morphologies of the grains is still limited. The present work is aimed at revealing the grain evolution process through the development of a coupled discrete elemental method-computational fluid dynamics-metacellular automata model. The results show that most of the grains observed through characterization experiments are irregularly shaped columnar grains and exhibit anisotropy in mechanical property tests. The grains observed in the simulations can be generalized into four types: V-shaped grain, slanted grain, vertical grain, and equiaxial grain. During the overlapping of interlayer and intertrack, some of the slanted grains are retained and others grow into V-shaped grains. In addition, some of the V-shaped grains coarsen during remelting and resolidification and subsume the slanted grains in the direction in which they grow, eventually developing into coarse vertical grain. Therefore, an appropriate increase in hatch distance is beneficial to reduce anisotropy. This study contributes to an in-depth understanding of grain transformation during remelting and resolidification and guides the design of specific microstructures. [ABSTRACT FROM AUTHOR]

The article presents a study of the tribocorrosion phenomenon and its effects on Inconel 718 alloy produced conventionally by extrusion and additively manufactured using the laser powder bed fusion method. In addition, the samples were subjected to a heat treatment process to change their properties. The research was carried out using the pin-on-disk method in 3.5% NaCl. Based on the study, it was found that the material made with additive technology is more resistant to tribocorrosion phenomenon, and the difference from conventionally made material is about 50%. The synergistic effect between friction and corrosion (ΔZ) occurred. However, heat treatment in the AA-2 variant ensures higher hardness and reduces purely mechanical wear (ZM) and the synergy effect (ΔZ). [ABSTRACT FROM AUTHOR]