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'.

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 5[Formula: see text]h, respectively. The A-TIG weld joints studied were the as-welded type and the weldment was heat-treated at 1050 ∘ C for 3[Formula: see text]h. 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).

Many diverse components are deployed for contemporary applications, ranging from the production of cars and other vehicles using sheet metal to heavy engineering using thick sections. These components are fabricated by welding high-strength micro-alloyed steels. The current study characterizes the microstructure of the controlled-rolled, 25 mm-thick micro-alloyed steel plate's tight gap weld joints. A controlled-rolled, micro-alloyed steel plate with dimensions of 250 × 100 mm is used for the welding process. By properly milling the plates, conventional gaps with width of 25 and 20 mm (CG-25 & CG-20) and narrow gaps with width of 13 mm (NG-13) are created as per the desired design. The root pass is created by gas tungsten arc welding (GTAW) process with autogenous technique, further filling passes are created by GTAW, and successive filling passes are made by pulsed current gas metal arc welding technique. It is found that increasing mean current ( I m ) from 160 to 230A reduces the dendrite fraction while increasing the reheat refined region in the matrix. However, at a particular I m , an increase in dimensionless factor ( ϕ ) and heat input (Ω) from 0.15 to 0.23 and 5.28-7.61 kJ/cm, respectively, has no effect on the matrix.

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 degrees 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.

Inconel 617 alloy is known for its impressive resistance to numerous corrosive environments and is widely used in high-temperature applications. This study analyses the microstructure and corrosion behaviour of the Inconel 617 weldments fabricated by activated flux tungsten inert gas (A-TIG) welding and TIG welding. Potentiodynamic polarisation (PDP) test in a 3.5% NaCl solution and intergranular corrosion (IGC) test was conducted to analyse the corrosion behaviour of the base metal (BM) and weldments. In accordance with the PDP test evaluation, the BM, TIG weld and A-TIG weld samples had corrosion rates of 0.0028, 0.0156 and 0.0043 mpy, respectively. PDP test results showed that all three samples had outstanding corrosion resistance. According to IGC test findings, the A-TIG weld sample had a greater corrosion resistance of 15.1 mpy when compared to BM and the TIG weld sample, which had corrosion resistances of 19.78 and 23.2 mpy, respectively. Chromium depletion at the grain boundaries caused by carbide formation was the reason for the TIG weld sample's poor corrosion resistance.

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[Formula: see text] and titanium dioxide (TiO[Formula: see text] 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 50[Formula: see text]mm/min along with an arc gap of 1[Formula: see text]mm and 100% TiO2 as flux. The optimal solution for DOP, DWR and WA was found to be 7.04[Formula: see text]mm, 0.437 and 7.619[Formula: see text]mm2 respectively. The optimal solution for BW and BH was 6.302 and 0.677[Formula: see text]mm, 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.

Non-dendritic equiaxed zone (EQZ) evolution and its influence on tensile properties of tungsten inert gas (TIG) welded joint of dissimilar A6061-T6 and A6082-T6 are studied. EQZ is observed in A6061-T6 interface whereas it is completely absent at the A6082-T6 interface. The distribution of fine Si eutectic phases along the grain boundaries (GBs) of EQZ of A6061-T6 interface appearing as discontinuous fine particles but as a continuous layer at most of the dendrite boundaries (DBs) at the center of the weld metal zone (WMZ). The improvement in strength of A6082-T6 interface compared to A6061-T6 interface is mainly attributed to the absence of EQZ in the former interface.

Cold Metal Transfer (CMT) welding of dissimilar Al-2.6 Mg-0.5Mn (A5754) and Al-4.5 Mg-1.0Mn (A5083) aluminium alloys has been performed with ER5356 filler wire. The microstructure and mechanical properties of the weld-metal zone (WMZ) and interface regions are correlated. The microstructure reveals epitaxial grains at the edge of the partially molten zone (PMZ) and equiaxed dendritic structure at the center of the WMZ. Energy dispersive spectroscopy (EDS) results show that the WMZ and PMZs are composed of a-Al, Al3Mg2 and Al6Mn phases. The WMZ exhibits higher hardness and strength due to the existence of equiaxed dendrite structure, dilution effect and absence of defects. The interface region of A5083 side exhibits higher hardness and strength due to the presence of finer grains and higher volume fine secondary phases in the PMZ and HAZ of this side than at the other side. Fracture surface of all the samples exhibits dimples indicating a ductile fracture. (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Smart and Sustainable Developments in Materials, Manufacturing and Energy Engineering.

The joints are made with UNS32750 super duplex stainless steel plate. The joints are also made by superimposing high frequency current to these welding techniques namely CC-GTAW, constant current gas tungsten arc welding with superimposed high frequency current (CC-GTAWHF), pulse current gas tungsten arc welding (PC-GTAW) and pulse current gas tungsten arc welding with superimposed high frequency current (PC-GTAWHF) respectively. The thermal characteristics and its effects are further correlated to corrosion resistance. The correlation between thermal characteristics and pitting corrosion resistance in all weld joints was established using weight loss method and potentiodynamic polarisation experiment. The effective thermal impact and consequently corrosion rate has been found minimum in PC-GTAWHF. EDS shows that there is reduction in Ni and increase in Mo content in the weld metal which have also an effect on corrosion of weld.

AISI 310 is a highly alloyed austenitic stainless steel used for high-temperature applications. The high chromium and nickel contents give this steel excellent oxidation resistance as well as high strength. In the present work, the material was welded using shielded metal arc welding (SMAW), Pulsed Gas Metal Arc welding (P-GMAW) and Double Pulsed Gas Metal Arc welding (DP-GMAW). A comparative study has been carried out on the basis of chemical, mechanical, metallurgical and corrosion properties of base metal and all other welded samples. SMAW process has high heat input and hence dilution effect is more prominent in this process. The mechanical properties evaluated in terms of maximum tensile strength, impact energy and hardness was obtained for DP-GMAW sample. This superior mechanical behaviour of DP-GMA welded sample was attributed to the better grain refinement occurred due to double pulsation effect. However, the DP-GMAW process showed highest corrosion rate when compared to other two welded samples.

Fusion boundary microstructure evolution and its effect on tensile properties of cold metal transfer (CMT) welded joint of dissimilar A5754 and A5083 is studied. Non-dendritic equiaxed fine zone (EQZ) is newly evolved and located between PMZ and weld metal zone (WMZ). The Si films are distributed as continuous layers at grain boundaries (GBs) of EQZ, these films are comparatively less and are distributed in a non continuous manner at GBs of partially melted zone (PMZ). EQZ of A5083 side exhibits finer grains than A5754 side. The narrower EQZ width, finer grains at EQZ, finer dendrites at WMZ interface and larger distribution of secondary phase particles at PMZ and heat affected zone (HAZ) increase strength of A5083 side. (c) 2020 Elsevier B.V. All rights reserved.

Alloy 304HCu is an austenitic stainless, developed from TP304H with the addition of copper and niobium for power plant applications. Solidification cracking is major issue in welding of austenitic stainless steels. In this paper, solidification cracking behaviour of alloy 304HCu with three different fillers viz., nickel fortified near-matching alloy 304HCu, ER NiCrCoMo-1 and ER NiCrMo-3 using Varestraint weldability testing. The solidification cracking behaviour of the parent material and different welds were assessed under different strain rates and the mechanisms were discussed, addressing the microstructural evolution and compositional changes. The weld materials were characterized for their mechanical properties both at ambient conditions and at elevated temperature, highlighting their usefulness in the power sector.

This study reports the effect of 650 °C exposure on microstructural evolution and creep behavior of post-weld heat-treated dissimilar welds between the alloys T92 and Super304H. The dissimilar welds were exposed for durations of 24 h, 100 h, 250 h, 500 h, and 1000 h to investigate the thermal stability of the microstructure. Creep tests were carried out at 650 °C and 120 MPa on the post-weld heat-treated and on 1000 h exposed dissimilar metal welds. The isothermal exposure degraded the microstructure of T92-HAZ, resulting in type IV failure at an accelerated rate under creep conditions. Further, accelerated recovery of martensitic laths and extensive precipitation of Laves phase on M23C6 carbides sitting at the grain boundaries of the fine-grained heat-affected zone (FGHAZ) during creep deformation were observed. The isothermal exposure on Super304H-HAZ showed no significant microstructural changes except precipitation of thick M23C6 carbides at the grain boundaries. These prominent microstructural changes in the HAZ of T92 lead to the accelerated void formation in the FGHAZ and are responsible for consequent premature failure.

A6061-T6 and A6082-T6 dissimilar aluminium alloys are welded using CMT (Cold metal transfer) process and the interface microstructure of the individual alloys is correlated with mechanical properties. Microstructures indicate that dendrites next to the PMZ (Partially melted zone) of A6082-T6 side are finer than the dendrites next to the PMZ of A6061-T6 side. Liquation at grain boundaries and within the grains is clearly visible in the PMZ of A6061-T6 interface, whereas the PMZ of A6082-T6 interface does not reveal liquation phenomenon at grain boundaries and grain interiors. Among the interface regions, the A6082-T6 side shows superior mechanical properties as compared to the A6061-T6 side. (c) 2020 Elsevier B.V. All rights reserved.

The finite element (FE) simulations for the evaluation of thermal fatigue life of 9Cr1Mo steel boiler header is presented. Boiler headers experience load fluctuation during operation which leads to a significant magnitude of stress being experienced at the ligament region between two stubs in the header. The effect of load fluctuation during cold, warm and hot start on the peak stress has been computed for different ligament sizes. The stress magnitude is found to increase as the ligament size is decreased. When the thermal stress magnitude exceeds the yield strength of the material, it results in plastic deformation. From the cyclic variation of the stress and strain due to load fluctuations, the thermal fatigue life computed based on the Coffin-Manson relation. A reduction in the circumferential radial angle between stubs in the header is found to result in a reduction of thermal fatigue life.

Ni based super alloy 617 is widely used in transition liners in both aircraft and land-based gas turbines, power plant applications because of its high temperature strength, oxidation resistance and creep properties. Ni based alloys are highly susceptible to hot cracking like solidification and liquation racking issues. In this present work, the susceptibility of alloy 617 to solidification cracking is studied based on the varestraint test. Results of this weldability test proved that in addition to the solidification cracking susceptibility alloy 617 is prone to liquation cracking also. Keywords: Varestraint test, Alloy 617, Solidification cracking, Liquidation cracking.

S304HCu stainless steel is inevitable materials in super heater and reheater tubes in steam power boiler industries. The major challenge in welding of T92 steel and S304HCu stainless steel is the selection of the appropriate filler wire and establishing welding procedures especially in dissimilar welding such that the weld joints meet the service requirements at high temperatures. This present work is aimed to study the effect of welding current and wire feed rate on weld bead geometry produced with hot wire gas tungsten arc welding (HW-GTAW) process using different filler wires of 0.8mm diameter viz., ERNiCrFe-7A (IN 52M) and ERNiCrCoMo-1 (IN 617) on S304HCu stainless steel tubes. These weld bead depositions were made at hot wire current of 30A with two different welding currents viz., 130A and 110A at a constant wire feed rate and travel speed. From the results, it is established that temperature distribution and the presence of surface active elements are the causes for the formation of weld beads in different shapes.

In this article, Welding of AA2219 aluminium alloy using Gas tungsten arc welding process (GTAW) and evaluation of metallurgical, mechanical and corrosion properties of the joints are discussed. The weld samples were subjected to ageing process at the temperature range of 195°C for a period of 5 h to improve the properties. AA2219 aluminium plates of thickness of 25 mm were welded using gas tungsten arc welding (GTAW) process in double V butt joint configuration. The input parameters considered in this work are welding current, voltage and welding speed. Tensile strength and hardness were measured as performance characteristics. The variation in the properties were justified with the help of microstructures. The same procedures were repeated for post weld heat treated samples and a comparison was made between as weld condition and age treated conditions. The post weld heat samples had better tensile strength and hardness values on comparing with the as weld samples. Fracture surface obtained from the tensile tested specimen revealed ductile mode of failure.

It is well known that, the major limitation of conventional short circuiting gas metal arc welding process (GMAW) for welding of various ferrous and non-ferrous materials is poor bridgeability and generation of large number of spatters. To overcome these difficulties, in recent years, waveform controlled technology has been introduced in GMAW process for specific application to meet required quality and productivity. However, the specific advantage of the process for various welding application primarily depends on the waveform parameters such as peak current, background current, time and voltage. It is often found that, irregular control of waveform leads defects like porosity, undercut and burn through etc. which impairs the weld joint quality. Thus, it is very important to study the effect of different waveform on bead geometry and microstructure. In this regard, in the present investigation aimed to carry out various waveforms on root pass welding of carbon and alloy steels. The bead appearance, soundness, macro and micro structure analysis has been carried out. Based on the results the optimum range of waveform has been derived and appropriately correlated with process parameters.

S304HCu stainless steel is extensively used for superheater and reheater applications in power plants due to its superior creep strength and oxidation resistance which are derived from the coherently dispersed precipitates formed in austenite matrix. In addition to the beneficial precipitates, chromium carbide precipitates can also form. Formation of chromium carbide precipitates during service will lead to sensitization. In this investigation, S304HCu samples were solutionized at 1100 degrees C and 1200 degrees C for 1 h, and further aged at 750 degrees C for upto 400 h to introduce sensitization and subsequent healing. The influence of ageing time and grain size on the degree of sensitization (DOS) was evaluated by using oxalic acid and double loop electrochemical potentiodynamic reactivation (DLEPR) tests. DOS initially increased up to 10 h of ageing and subsequently was reduced due to healing and attained a steady value at 50 h. Faster and higher DOS was observed in coarse grain structure than in the fine grain structure. However, healing was largely delayed in coarse grained structure. The difference in solute and excess vacancy concentration and shifting of the nose in TTP curve were attributed to the difference in the kinetics of sensitization and healing. The extent of the attack on the grain boundary was analyzed using AFM. (C) 2017 Elsevier B.V. All rights reserved.