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In this study, the tribological behavior of Tungsten Inert Gas (TIG) welded Inconel 617 alloy has been studied using the Pin-on-disc tribometer. TIG welding was performed after imparting surface coatings to the Inconel 617 alloy which was coated with a blend of Silicon dioxide (SiO₂) and Titanium dioxide (TiO₂) in different proportions. Three samples were prepared by varying the coating composition and weld current. The Coefficient of Friction (COF), wear depth ($\mu$m) and hardness of the samples were estimated. Microstructure analysis and X-ray diffraction (XRD) analysis were also carried out on the samples. The wear depth of the Inconel 617 substrate, as well as weld bead samples 1, 2, and 3, were 2055.1, 415.39, 463.17, and 560.68 $\mu$m respectively. The COF for the Inconel 617 substrate and weld bead samples 1, 2, and 3 were determined as 0.384, 0.491, 0.471, and 0.455 respectively. By analyzing the results of the wear test, it was observed that ‘sample 1’ welded at the lowest heat input of 4.32 kJ/mm, exhibited superior tribological characteristics including reduced wear (415.39 $\mu$m) and an increased COF (0.491) compared to the other samples. The enhanced tribological performance could be attributed to factors such as the presence of carbides like TiC and notably the higher hardness (284.12HV) exhibited by ‘sample 1’.

The halide-activated pack cementation method was utilized to deposit aluminide or silicide coatings on Inconel 617 and Hastelloy X superalloys. Aluminide and silicide diffusion coatings were formed at 850${}^{\circ }$C for 2 h in nitrogen atmosphere, using a pack mixture containing pure aluminum (Al) or silicon (Si) and aluminum oxide (Al₂O₃) powders with activators of NH₄Cl and AlF₃. Aluminide-coated alloys showed homogeneous and uniform microstructures. Al diffused into the alloy inwards and aluminide diffusion coatings of $\sim$17 $\mu$m thick were formed inside the alloy. It was shown that the Al coatings played a key role in blocking off the excessive corrosion products at a high temperature for the alloys. The enhanced thermal stability and improved wear resistance were achieved in the aluminide coatings. In contrast to the aluminide coating, the silicide coating played a negative role, unable to provide the protective layer. The microstructural evolution and thermal stability of the aluminide- and silicide-coated alloys have been elucidated.

Aluminum diffusion coatings were applied to the Inconel 617 by a pack cementation. The effect of coatings on the thermal stability and wear resistance of the Inconel alloy after heat-treatment under an air and a helium atmosphere at 1000°C, 48 h has been studied. The aluminide-coated Inconel specimens are prepared at 850°C and 1000°C for 1 h. An aluminiding layer indexed as Al_xNi_1-x (x = 0.4–0.6) was formed near the surface region and it played a role as a barrier layer against the surface diffusion of Cr. The thin Cr₂O₃ film formed in situ on the alloy surface is protective inhibiting further oxidation at moderate temperatures. As the temperature increases further, the thermal stability of the Inconel alloy is limited by the instability of the Cr₂O₃ scale. The aluminide-coated Inconel 617 samples showed the better performances, the enhanced thermal stability and improved wear resistance, most likely due to the barrier layer formation with the reduced amount of Cr₂O₃ scale formation.

Inconel 617 alloy has been included in the boiler and pressure vessel (BPV) code of the American society of mechanical engineers (ASME) for its effectiveness in nuclear applications due to its ability to maintain strength at elevated temperatures. This study is based on the optimization of process parameters for activated flux tungsten inert gas (A-TIG) welding of 10-mm thick Inconel 617 material. Process parameters considered in this study include weld current (A), weld torch travel speed (mm/min), arc gap (mm) and flux powder (silicon dioxide (SiO${}_2)$ and titanium dioxide (TiO${}_2))$ combination. The bead on plate welding experiment was carried out by varying the combination of process parameters in each experimental trial. The Taguchi L16 orthogonal array was the design matrix used for the design of experiments (DOE). In the bead on plate welding experiment, a total of 16 experimental trials, each having a different set of process parameters was conducted. The weld bead samples corresponding to each trial were prepared for measurement of the responses which were measured from each of the 16 weld bead samples and included depth of penetration (DOP), bead width (BW), depth to width ratio (DWR), weld cross-sectional area (WA), and bead height (BH). The objective of this work was to maximize DOP, DWR, WA, BH and minimize BW. Analysis of variance (ANOVA) was used to identify the significance of process parameters. Optimization techniques including particle swarm optimization (PSO) and genetic algorithm (GA) were used in the study. The optimized process parameters and optimal solutions attained from each optimization technique were compared. It was found from the study that weld current was the most significant process parameter for all responses followed by weld torch travel speed, flux powder combination and arc gap. Optimal process parameters to achieve maximum DOP, DWR and WA were found to be weld current of 290 A, weld torch travel speed of 50mm/min along with an arc gap of 1mm and 100% TiO₂ as flux. The optimal solution for DOP, DWR and WA was found to be 7.04mm, 0.437 and 7.619mm² respectively. The optimal solution for BW and BH was 6.302 and 0.677mm, respectively. A confirmation test was conducted to validate the optimal solution obtained from this study. The results from the confirmation test agreed with the solution obtained by optimization techniques.

This work is based on a comparative study of the weldments fabricated by Activated Flux Tungsten Inert Gas (A-TIG) welding and autogenous Tungsten Inert Gas (TIG) welding of 10 mm thick Inconel 617 plates. Flux powders used for A-TIG welding were Titanium dioxide (TiO₂) and Silicon dioxide (SiO₂). Macrostructure and microstructure analyses and characterization of mechanical properties of both A-TIG and TIG weldments were investigated. The microstructure of Inconel 617 was made up of several secondary phases and fine austenitic grains. Mechanical testing carried out in this study included Bend Test, Tensile Test, Vicker’s Micro-Hardness Test and Charpy Impact Test at room temperature (RT) and a sub-zero temperature (SZT) of −50${}^{\circ }$C. The Bend test was found satisfactory for both A-TIG and TIG weldments. TIG weldments’ tensile strength and microhardness were determined to be 782 MPa and 265.44 HV, respectively. However, it was determined that the base metal had a tensile strength of 756 MPa and that the tensile strength and microhardness of the A-TIG weldment were 707 MPa and 252.73 HV, respectively. The TIG weldment was proved to have the highest tensile strength and microhardness due to the availability of strengthening elements like Molybdenum (Mo) and Chromium (Cr), as carbides in the fusion zone. Impact toughness of the A-TIG weldment was higher than that of the TIG weldment both at room and sub-zero temperatures due to the application of TiO₂ as flux and the high heat input during A-TIG welding. The ductile mode of fracture was observed in all weldments.

This work addressed the effect of CMT-GMAW multi-control welding of Inconel 617 alloy with different wire feed rates (8.9, 9.4, and 9.9 m/min) on the microstructure, hardness, and electrochemical properties. The weld joints are composed of columnar dendritic structure with cellular crystals. Electron backscattered diffraction (EBSD) study showed equiaxed dendrite at the center of weld metal with growth direction perpendicular to the fusion boundary. The weldments showed diffraction peaks at $43.53^{\circ }$, $50.12^{\circ }$, and $74.82^{\circ }$, and these peaks mainly represent gamma ($\gamma$) and gamma prime ($\gamma$’) phases along with the carbide peaks of Ti (C, N), M${}_{23}$C₆ and M₆C. The Base metal (BM) had a lower hardness (232 ± 10 HV${}_{0.2}$) and lower corrosion rate (0.212 mpy) than the weld joints. The increase in wire feed rate (WFR) results in the decrease of microhardness (267 ± 5 − 251 ± 6 HV${}_{0.2}$) and increase in corrosion rate (1.833-28.140 mpy). The base metal exhibited higher potential ($E$${}_{\text{corr}}$) and lower current density ($I$${}_{\text{corr}}$) than the weld joints. As wire feed rate (WFR) increases, heat input increases; solidification time increases, grain boundaries coarsen, resulting in a lower grain boundary (GB) density, and hence increased carbide precipitation and segregation in weld zone leading to higher stable anodic current density, which caused corrosion resistance to deteriorating. The BM was more corrosion resistant than the weld joints. The metallurgical and physical changes caused by the welding process affect the corrosion resistance of the weld joints. This leads to the weld metal corroding faster than the base metal.

This study analyzes the effects of Post Weld Heat Treatment (PWHT) on the mechanical properties and microstructure of Inconel 617 weldments produced by the Activated Tungsten Inert Gas (A-TIG) welding and Tungsten Inert Gas (TIG) welding. The TIG weld joints considered for this study were in an as-welded condition and underwent two different conditions of heat treatment including 1050^∘C for 3 and 5h, respectively. The A-TIG weld joints studied were the as-welded type and the weldment was heat-treated at 1050^∘C for 3h. The microstructure and the characterization of mechanical properties were performed for all weldments and a comparative assessment was made. Tensile strength and the hardness of the heat-treated samples were considerably higher than that of the as-welded samples. Impact toughness was slightly reduced after PWHT. Improvement in tensile strength could be attributed to the precipitation of the carbides and segregation of Chromium (Cr) and molybdenum (Mo).