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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]

Post-weld heat treatment (PWHT) viz., annealing, normalizing and quenching was assessed regarding its effect on the microstructure and mechanical properties of pulsed Nd:YAG laser welded Hastelloy C-276/Monel 400 dissimilar sheets. The weld zone (WZ) microstructures of the different PWHT specimens exhibit finer dendrite grains along with Crrich carbides and Ni-rich oxide precipitates. The weld joints subjected to quenching attains near equal microhardness of the as-welded condition. During tensile testing, failures occurred in the WZ for quenched and normalized weld joints, whereas the Hastelloy C-276 fractured in annealed conditions, exhibiting ductile fracture mode. In corrosion studies the WZ of the weld joint subjected to annealing imparted superior corrosion resistance. [ABSTRACT FROM AUTHOR]

In industries including aerospace, automotive, and marine, a machined component's surface integrity is essential since it improves the corrosion resistance and fatigue life. Hastelloy C-276 is a superalloy based on nickel that is used in the chemical and petrochemical sectors due to its high hot strength, high heat resistance, and high corrosion resistance. In the present work, modelling and simulation of UAMAF process is done on flat work piece with the help of ANSYS Maxwell 16.0 software. The experimental setup for flat work piece on milling machine is modelled according to the dimensions of the experiment. These models are then simulated in ANSYS Maxwell 16.0. After validating the model, the obtained results of analysis were matched with the experimental output. If it is found that the simulation and experiment results vary within the acceptable range, then simulation models are accepted. [ABSTRACT FROM AUTHOR]

Extrusion technology is widely utilized in the rubber processing industry, with the extruder serving as the core equipment. As mixed rubber enters the extruder, it undergoes conveyance and plasticization, ultimately forming specific shapes and dimensions upon extrusion. The extruder head is a crucial component, playing a key role in achieving the final product's required size and shape. Factors such as its structure, materials, and manufacturing processes significantly impact the efficiency, product quality, and sustainability of the extrusion process. However, prolonged operation leads to severe wear of the extruder head, adversely affecting rubber product quality. Additionally, extruder head processing poses challenges, with maintenance and repair being complex procedures. Therefore, exploring a wear-resistant, long-lasting metal material for the extruder head without compromising mixed rubber performance is essential. This study focuses on severely worn extruder head metal materials, comparing wear levels after friction with STELLITE 6 alloy, Hastelloy C-276 alloy, 38CrMoAlA, and tungsten carbide with composite rubber. Results show that compared to the NR/BR composite material after Hastelloy C-276 alloy friction, rubber Payne effect increased by 4.4% (38CrMoAl), 3.2% (STELLITE 6), and 4.6% (tungsten carbide). Similarly, rubber dispersion decreased by 9.4% (38CrMoAl), 4.7% (STELLITE 6), and 9.8% (tungsten carbide). Rolling resistance increased by 18.1% (38CrMoAl), 16% (STELLITE 6), and 23.4% (tungsten carbide). Friction coefficient increased by 3.5% (38CrMoAl), 2.8% (STELLITE 6), and 4.3% (tungsten carbide). Wear volume increased by 39.3% (38CrMoAl), 45.3% (STELLITE 6), and 48.9% (tungsten carbide). Specifically, using Hastelloy C-276 alloy as the extruder head metal material yields the best NR/BR composite material dispersion, highest ten times tear strength, excellent anti-wet skid resistance, and minimum rolling resistance. Conversely, using the other alloys results in varying reductions in the physical and mechanical properties of NR/BR composite materials. This research is crucial for improving rubber product quality and extending extruder head lifespan. [ABSTRACT FROM AUTHOR]

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Superalloys are a much-needed material for abundant engineering fields, such as nuclear-powered reactor components and aeronautics. Owing to their exceptional characteristics, such as higher thermal conductivity, they can be difficult to machine using conventional processes. Modern approaches to machining have evolved to utilize these materials. One of the techniques studied in this project is electrical discharge in a wire machine. This process can help to reduce the energy consumption during machining and negative impact on the environment. In addition, shortening the operation time of the machine can help to minimize its impact on the environment. The duration of the pulse and applied current are independent factors considered in this study. Material removal rate, surface roughness, dimensional deviation, and form/orientation tolerance errors are deemed as performance measures. The goal of this investigation is to reduce the time required to machine and improve the surface finish of components by implementing a Grey-based artificial neural network model. This method is useful in foretelling the conditions of the Wire Electro Discharge Machining (WEDM) process. This paper uses the Taguchi design and Analysis of Variance (ANOVA) framework to analyze the model's variable inputs. The overall best coefficient of correlation (R = 0.9981) is fetched with an RMSE value of 0.0086. The material removal rate has been increased by decreasing the time taken for removal, which gives the possibility of consuming minimum energy. The finishing of the machined surface also improved. Moreover, this paper shows how to use an Artificial Neural Network (ANN) model with Grey Analysis. The results of the comparative analysis show that the values envisaged are closer with the actual values. The foretelling capacity of the evolved model is confirmed with the performance analysis of the developed model. [ABSTRACT FROM AUTHOR]

In present investigation, the impact of nanoparticle concentration on the machining accomplishment of Hastelloy C-276 has been examined in turning operation. The outputs like temperature, surface roughness, chip reduction coefficient (CRC), tool wear, and friction coefficient along with angle of shear have been estimated. The graphene nanoparticles (GnP) have been blended into soybean oil in distinct weight/volume ratio of 0.5, 1 and 1.5%. The experimental observations revealed that higher concentration of nanoparticles has enhanced the heat carrying capacity of amalgamation by 12.28%, surface roughness (27.88%), Temperature (16.8%), tool wear (22.5%), CRC (17.5%), coefficient of friction (46.36%) and shear angle (15%). Scanning electron microscopy identified nose wear, abrasion, adhesion and loss of tool coating. Further, lower tool wear has been noticed at 1.5% concentration, while the complete failure of insert has been reported during 116 m/min, 0.246 mm/rev having 0.5% concentration. ANOVA results exhibited that surface roughness is highly influenced by speed rate (41.66%) trailed by feed rate (28.16%) and then after concentration (13.68%). Temperature is dominated by cutting speed (69.31%), concentration (14.53%) and feed rate (13.25%). Likewise, tool wear was majorly altered by cutting speed (67.2%) accompanied by feed rate (23.90%) and thirdly concentration of GnP (5.03%).

Hastelloy C-276 is a nickel-based superalloy having high hot strength, high thermal and corrosion resistance and has led to its use in the chemical and petrochemical industries. In the present study, the ultrasonic-assisted magnetic abrasive finishing process (UAMAF) was used to finish Hastelloy C-276. In the UAMAF process, an additional attachment of ultrasonic horn was added to MAF that applies axial vibrations to the workpiece with a frequency of (10–30 kHz). In this process, normal force and power consumption were measured at different levels of voltage, abrasive percentage, speed, working gap, and power intensity using response surface methodology. The results of UAMAF were compared to responses of MAF under similar experimental conditions. The force and power consumption were increased by 26.8% and 26.6% respectively for UAMAF process compared to MAF process. However, the finishing time was reduced by 60% increasing the production rate. Furthermore, the grind surfaces after MAF and UAMAF were also analyzed by using SEM images. [ABSTRACT FROM AUTHOR]

In this study, UNS S31803 duplex stainless steel and Hastelloy C-276 nickel-based superalloy were joined by gas tungsten arc welding (GTAW) process. Nickel based ERNiCr-3 and ERNiCrMo-3 filler metals with different chemical compositions were used for joining the dissimilar metals. Metallurgical structures of the joint parts were determined by microstructural characterization studies. In mechanical characterization, both hardness and impact toughness were measured. Corrosion behavior of the welds were investigated by potentiodynamic polarization tests in 3.5% NaCl solution. Characterization studies showed that (i) weld metals had a dendritic/cellular solidification structure which changed due to thermal effects in all passes from the surface to the root, (ii) depending on the chemical composition of the filler metal, Nb-rich carbides and Laves phase were formed in the weld metal, (iii) the amount of Mo affected toughness, hardness, and corrosion resistance. [ABSTRACT FROM AUTHOR]

Austenitic stainless steel (ASS) grade is considered to be alternative material for Hastelloy C-276, due to its higher material and maintenance cost. Hence, the combination of joining the ASS and Hastelloy C-276 is advisable. In this investigation, Hastelloy C276 and 316L stainless steel materials were joined as similar weld of stainless steel 316 L and Hastelloy C276, as well as dissimilar joints between the Hastelloy C276 and 316L stainless steel using PCGTAW process. After welding, the specimens were characterized using optical microscopy and SEM with EDS. The cellular and columnar dendritic structure was obtained from Hastelloy C276—316L stainless steel dissimilar weldments. From the EDS results, it was confirmed that the Mo and Ni content was higher in sub-grain body as compared to the sub-grain boundary in the FZ zone of dissimilar joints. In the case of similar joints of SS 316 L, Mo content was low in sub-grain body, and Ni content was high, vice versa as compared to the sub-grain boundary. As compared to similar welded specimens, the UTS value was high (790 MPa) for Hastelloy C276—316L stainless steel dissimilar specimens prepared using PCGTAW. An improved micro-hardness value of 300 HV was found for Hastelloy C276-316L stainless steel dissimilar welded specimens, compared to similar joints in SS 316 L and HAS C-276. The recorded hardness value for similar (Hastelloy C276 and 316L stainless steel) joints is 230 HV and 245 HV, respectively. Based on the findings of this investigation, it is concluded that PCGTAW process is an appropriate welding technique for making sound welded joints between combinations of the two superior alloys Hastelloy C276 and 316L stainless steel. [ABSTRACT FROM AUTHOR]

• To simulate actual deep-water and large-scale repair conditions, damaged Hastelloy C-276 plates were repaired by UDMD technique at a pressure of 0.3 MPa with each layer re-covered by water. • Four gradient cooling rates (in-air DMD, in-air DMD with interlayer cooling, UDMD, UDMD with each layer re-covered by water) were used for repair of Hastelloy C-276 by DMD. • The differences in cooling rates of various samples were illustrated by the thermal histories obtained through simulation. • The acceleration effect of underwater environment on cooling rate was stronger than that of interlayer cooling. • The effect of faster cooling rate on microstructure was revealed as finer grains, higher dislocation density, higher content but smaller size carbides, etc. • The mechanical properties are positively correlated with the cooling rates. The Ni-based Hastelloy C-276 was repaired by in-air and underwater laser direct metal deposition (in-air DMD and UDMD) with four gradient cooling rates (in-air DMD, in-air DMD with interlayer cooling, UDMD and UDMD with each layer re-covered by water). The microstructure and mechanical properties of repaired samples were systematically characterized with respect to the cooling rates. All samples presented good metallurgical bonding and columnar dendrites with epitaxial growth. The underwater environment had a more pronounced acceleration effect on the cooling rate compared to interlayer cooling. The rapid cooling induced intense thermal cycling, resulting in increased dislocation density and grain refinement with primary dendrite arm spacing (PDAS) diminishing from 5.30 to 3.21 μm. Accelerated cooling rate contributed to precipitation of massive M 6 C carbides. Carbides coarsened (sizes from 257 to 354 nm) and exhibited a reduced content as cooling rate slowed down due to intrinsic heat treatment (IHT). The residual water film in UDMD repair promoted oxide formation. Samples with increased cooling rates exhibited superior mechanical performance. The improved microhardness, tensile and impact properties were primarily attributed to the enhanced fine grain strengthening and Orowan strengthening facilitated via reduced grain size, increased dislocation density and carbide content. Quantities of large-size carbides were detrimental to tensile and impact properties as displayed in the in-air DMD sample with interlayer cooling (carbide size of 341 μm). The study could serve as a reference for in-situ restoration in deep-water environments. [ABSTRACT FROM AUTHOR]

Hastelloy is categorized as difficult to cut superalloy widely used in aerospace, nuclear reactor components and chemical industry because of its magnificent strength and higher heat efficiency. Since, the machining of this material is quite difficult and hence suitable cooling systems are required to achieve sustainable manufacturing goals. The present investigation has been focused on the machining performance and sustainability assessment of turning Hastelloy C-276 in dry, flood and minimum quantity lubrication (MQL) environments. Taguchi L-9 array has been utilized to conduct and record the experimental output along with TOPSIS approach to evaluate the sustainability. The output responses viz. cutting forces, surface roughness, cutting temperature, energy consumption and carbon emission have been recorded at various levels of input variables. The experimental results revealed that MQL has minimized the cutting forces, surface roughness and temperature by margin of 20–38%. Likewise, energy expenditure and carbon emission was declined by 9–27% respectively compared to other conditions. Sustainability analysis explored best performance index during equal weightage criteria at 125 m/min, 0.246 and 0.8 mm doc under MQL. However, implementing assigned weightage system evaluated best condition for dry machining as 88 m/min and 0.246 mm/rev having same doc. SEM analysis of insert reported mainly abrasion and adhesion type of tool wear at all parametric range and machining conditions.

Surface integrity of a machining component is crucial in applications like aerospace, automobile and marine industries as it impacts corrosion and fatigue life. In this study, the Ultrasonic Magnetic Abrasion Finishing (UAMAF) setup along with a chemical coating was used to finish the Hastelloy C-276. The responses change in the surface finish (%∆Ra) and material removal (MR) were analyzed using different process variables such as power intensity, voltage, speed, wt.% of abrasives and working gap. Further chemical coating of yttrium acetate and di-ethanolamine was applied to UAMAF specimens using physical vapor deposition. Variables such as weight of etchant, chamber temperature and the number of coatings were considered in the coating process. From the experimental results, it was observed that the surface finish improved with all process parameters except the working gap. The surface finish first increased and then decreased with working gap in the UAMAF process. MR increased with wt.% of abrasives, power intensity, and voltage while it was decreased with working gap and speed. The initial average roughness of the workpiece was Ra = 1.3 µm, and after the MAF process it reduced to Ra = 0.325 µm; further, after UAMAF it reduced to Ra = 0.096 µm, and after chemo based UAMAF, it was reduced to Ra = 0.0224 µm. However, the %∆Ra improved by around 98.3 % before and after processing and the maximum MR observed was 22.19 mg. [ABSTRACT FROM AUTHOR]

Smart manufacturing is the demand of industry 4.0, in which the mass production of difficult-to-cut materials is of great concern to fulfil the goal of sustainable machining. Presently, the machining of superalloy is of upmost interest because of its wide application. However, the limited data on the turning of Hastelloy C-276 highlights its challenges during processing. Hence, the machining performance of superalloy considering surface quality, thermal aspects and chip reduction coefficient was examined with minimum quantity lubrication of several oils to address the sustainable development goal (SDG-12). The output responses were optimized through response surface methodology along with analysis of variance. The research exhibited that the output responses were dominated by cutting speed and feed rate having a percentage benefaction of 24.26% and 60%, respectively, whilst the depth of cut and lubricant type have an influence of 10–12%. No major difference in temperature range was reported during the different lubrication conditions. However, a substantial variation in surface roughness and the chip reduction coefficient was revealed. The percentage error evaluated in surface roughness, temperature and chip reduction coefficient was less than 5%, along with an overall desirability of 0.88, describing the usefulness of the model used. The SEM micrograph indicated a loss of coating, nose and flank wear during all lubrication conditions. Lastly, incorporating a circular economy has reduced the economic, ecological and environmental burden. [ABSTRACT FROM AUTHOR]

Hastelloy C-276 (UNS N10276) nickel-based alloy is widely employed in the fabrication of nuclear reactor components and corrosive resistant equipment. In this work Hastelloy C-276 sheets were butt welded by a pulsed Nd:YAG laser welding machine at different thermal energy conditions. The resulting variation in macrostructure, microstructure and mechanical properties are presented. The thermal energy supplied (beam power/weld speed) was altered by varying the operational parameters viz. weld speed (350 to 450 mm/min), laser beam energy (10 to 14 J) and laser beam pulse width (6 to 8 ms). The weld macrostructures were seen to be free from cracks and defects, exhibiting complete penetration and the crest (top width) of the weld increases with the thermal energy supplied. In the microanalysis, growth of dendrite grains from periphery to mid-section of the weld was observed. In addition, Mo rich compounds and carbides are witnessed in the weld zone (WZ) for higher thermal energy conditions. The tensile and yield strengths of the weld joints are inversely proportional to the thermal energy supplied. [ABSTRACT FROM AUTHOR]

Machining of difficult to cut materials at advanced range of machining variable is the requirement of industry 4.0 for achieving sustainable machining goals taking into consideration energy, ecology and economy. However, due to lack of information on the machining data the material is regarded as difficult to cut. Therefore, to enhance the machining performance of Hastelloy C-276 the experimental investigations have been conducted at different levels of input parameters using CNMG120408 cutting inserts under various cooling conditions. The RSM-based CCD approach has been used to to generate the design of experiment along with ANOVA analysis for finding the influence of input factors on the output signal. Investigations results exhibited that the less cutting temperature, better surface quality and lower chip reduction coefficient have been reported in vegetable oil MQL machining. Research pointed out that the S.R. is influenced by cutting speed, doc, cooling environments and feed rate; likewise the impact has been reported for cutting temperature, while the CRC is less dominated by doc compared to other parameter. The percentage errors evaluated for S.R, temperature and CRC have been reported as 0.53%, −1.52% and 1.81% indicates the significance of developed model. [ABSTRACT FROM AUTHOR]

Dissimilar joints of SS-316L and C-276 (Hastelloy) were developed using C-276 powder with microwave exposure 600 s in microwave applicator (2.45 GHz, 900 W). A multi-physics model was validated with experimental studies and simulation were carried out to analyse the microwave-joint interaction characteristics. The simulation results showed that a concentrated electric field (5.86 × 104 V/m) and higher resistive losses (3.07 × 107 W/m3) at the joint region facilitated rapid heat generation locally. Microstructural characterization of the joint revealed the formation of cellular grains such as Fe-Ni intermetallic phases with Mo, Cr and W-carbides along the grain boundaries. Joints exhibited average microhardness of 290 HV, and tensile strength of 425 ± 10 MPa and 14% elongation with failure due to both ductile and brittle fracture modes. [ABSTRACT FROM AUTHOR]

Machining is the most significant process for any manufacturing company to improve the quality of the finished component. The objective of this article is to analyse the process performance of Hastelloy C-276 using PVD (Physical Vapour Deposition) coated, uncoated and alumina-based ceramic tool inserts of high grade quality. Turning process was performed on NC (Numerical Control) machine by varying RPM, feed rate and depth of cut based on the Taguchi L9 orthogonal array approach. In this study, crank wear, flank wear, nose wear, SR (Surface Roughness), MRR (Material Removal Rate), tool temperature and feed force are examined during machining of hardened material and simultaneously static structural analysis of the tool insert along with the tool holder was performed using ANSYS mechanical. This research investigation helps in determining appropriate parameters with varied coated inserts to make the process easier, efficient and economical.

Hastelloy C-276 samples were cold-rolled with their thickness reduction of 7.5% and 15%, and then annealed at 1100 °C for 5–60 min in solid solution. The grain boundary character distributions (GBCDs) were characterized by a technique of electron back scatter diffraction (EBSD). Results indicated that, more convoluted Σ3 boundaries (i.e. incoherent Ʃ3 boundaries) are generated by reasonable annealing time in low strain (7.5%) sample during strain-induced boundary migration (SIBM) processing. They can induce higher Ʃ3n fraction and activate more interactions between special boundaries for GBE. Instead, more coherent Ʃ3 boundaries were produced by moderate strain (15%) and annealing treatment with the occurrence of static recrystallization (SRX). The recrystallized fine grains possess fewer incoherent Ʃ3 boundaries cannot promote to get more multiple twinning for optimization of GBCD. Therefore, reasonable deformation and annealing treatment parameters lead to more incoherent Ʃ3 boundaries would play an important role in the optimization of GBE.

Hastelloy C-276 nickel alloy is widely preferred for nuclear power plant applications where steam generators operate at 600 °C. However, stainless steels are still used for tubes in steam gas reformers which necessitates welds between dissimilar materials. In this study, hastelloy C-276 and SS 316 L alloys were joined using GTAW process. The welding parameters of GTAW were optimized to minimize the defects in samples of similar (SS 316 L-SS 316 L, HAS C-276-HAS C-276), and dissimilar (HAS C-276-SS 316 L) joints. SEM/EDS results confirm the presence of columnar dendritic and cellular structure in fusion zone for dissimilar weldments (HAS C-276-SS 316 L). EDS results also revealed the presence of larger amount of Mo, W and lower amount of Ni in the subgrain boundary as compared to the subgrain body. Compared to the similar (HAS C-276- Has C-276) and dissimilar (HAS C-276-SS 316 L) welded joints FZs, the enrichment of Mo is lesser in SS 316 L-SS 316 L similar welded joints. Higher UTS was obtained for dissimilar (HAS C-276-SS 316 L) GTAW joints 780 MPa compared to the similar welded joints of SS316 (552 MPa) and HAS C-276 (740 MPa). The average microhardness for the dissimilar SS 316 L and HAS C-276 is 220 Hv, which is higher compared to the similar welded joints, SS 316 L and HAS C-276, i.e., 190 Hv and 210 Hv, respectively. This study shows that GTAW process is suitable to fabricate sound weld joints of similar (SS 316 L- SS 316 L, HAS C-276-HAS C-276), and dissimilar (HAS C-276-SS 316 L) alloys which are useful for the nuclear power plant boilers. [ABSTRACT FROM AUTHOR]

In this paper, an effort is made to determine the optimized parameters in laser welding of Hastelloy C-276 using Artificial Neural Network (ANN) and Genetic Algorithm (GA). CO2 Laser welding was performed on a sheet of thickness 1.6 mm based on Taguchi L27 orthogonal array. Laser power, welding speed and shielding gas flow rate were chosen as input parameters and Bead width, depth of Penetration and Microhardness were measured for assessing the weld quality. ANN was applied for modeling the welding process parameters i.e. heat input, welding speed and gas flow rate. Various learning algorithms such as Batch Back Propagation (BBP), Incremental Back Propagation (IBP), Quick Propagation (QP) and Levenberg–Marquardt (LM) were comprehensively tested for estimating the output parameters and a comparison was also made among them, with respect to prediction accuracy. BBP method was found to be the best learning algorithm. Experimental validation test was performed based on the ANN and GA predicted optimized responses and this welding input parameters provided satisfactory weld metal characteristics in terms of penetration depth, bead width and microhardness. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) with better material utilisation efficiency and higher deposition rate was employed to fabricate bi-metallic structure (BMS) of non-stabilised austenitic stainless steel (SS904L), and solid solution strengthened Hastelloy C-276. The micrographs confirmed the existence of directionally elongated, columnar, and equi-axed dendrites in the BMS. Significant grain coarsening was observed in the re-melted layers. The tensile properties of Hastelloy C-276 and SS904L were comparable with wrought counterparts, while the bi-metallic interface sample fractured in the SS904L side. The presence of secondary phases and varying microstructure along the building direction is responsible for the anisotropy in mechanical properties. Microhardness results revealed the steep increase at the bi-metallic interface due to the dilution of elements between two materials. [ABSTRACT FROM AUTHOR]

Welding of Hastelloys using higher value of 'linear heat input' decreases corrosion resistance due to the increase in micro-segregation of elements in the weld zone. 'Melting efficiency' of heat source could be an important parameter to control the heat input and micro-segregation of elements in the weld zone. In the present study, bead-on-plate welding was carried out on 3-mm-thick Hastelloy C-276 sheet at constant laser power and varying scan speed in pulsed mode, and the melting efficiency was found to be 30%. A study of 'segregation ratio' of elements in the weld zone showed that the amount of micro-segregation of molybdenum was found to increase with the increase in linear heat input. Increase in the segregation of molybdenum could cause a decrease in corrosion resistance of the welded specimen. Hence, a confirmation test (i.e., corrosion test) was performed to study the effect of linear heat input on the corrosion resistance of the welded sample due to micro-segregation. It was observed that the increase in linear heat input causes an increase in micro-segregation as well as an increase in corrosion rate. X-ray diffraction analysis showed that the concentration of passivating phases was found to increase with the increase in scan speed. [ABSTRACT FROM AUTHOR]

• Corrosion rate (CR) of each zone analyzed using laser displacement sensor. • (CR) Weld zone > (CR) Base metal > (CR) Heat affected zone. • (Corrosion) Grain boundary + (Corrosion) Triple point → (Corrosion) Base metal. • (Corrosion) Triple point → (Corrosion) Heat affected zone. • (Corrosion) Dendrite body + (Corrosion) Dendrite arm → (Corrosion) Weld zone. The laser displacement sensor scan technique proposed in the present study helps to calculate the corrosion rate (CR), and subsequently, determine the susceptibility to intergranular corrosion, without preparing separate samples for the weld zone (WZ), adjacent heat affected zone (HAZ) and unaffected base metal (BM). Processing of the displacement data collected during laser displacement sensor scan of the electron beam welded Hastelloy C-276 sample before and after the corrosion test shows that the (CR) WZ > (CR) BM > (CR) HAZ. The (CR) WZ was found to higher due to the (a) lower concentration of Mo and Cr in the dendrite body (of WZ) and (b) higher non-uniformity in Mo concentration per unit length within the WZ. The weld thermal cycle did not cause sensitization of HAZ (i.e., the formation of Mo depleted regions), and hence, the intergranular attack was not evident along the grain boundaries of the HAZ and the (CR) HAZ was lower. [ABSTRACT FROM AUTHOR]

• Develop a numerical expression to predict the tensile strength of welded joint. • Fine dendritic grains and a narrow HAZ is witnessed in optimum condition. • Tensile strength of the dissimilar joints is reported. In this study, an empirical relationship is developed to predict the tensile strength of pulsed Nd: YAG laser welded Hastelloy C-276–Monel 400 alloy sheets by optimizing the process parameters viz., welding speed, pulse energy and pulse duration. Experiments were conducted based on a three factor, three level, central composite face centered design with full desirability. Analysis of Variance (ANOVA) results indicate that the welding speed holds the greatest influence on tensile strength, followed by pulse energy and pulse duration. Microstructural studies of the optimized condition reveal full penetration weld with finer dendritic grains and a narrow heat affected zone (HAZ). Tensile fracture surface of the optimized weld exhibits a ductile mode of fracture with high tensile strength. XRD analysis of weld zone exposed the formation of various Chromium-rich carbide and Nickel-rich oxides precipitates. [ABSTRACT FROM AUTHOR]

The present study investigates the effect of laser shock peening (LSP) to enhance the metallurgical and mechanical properties of weld joints in Hastelloy C-276. The joint was fabricated by the gas tungsten arc welding (GTAW) with ERNiCrMo-3 filler wire. LSP was carried out on the top surface of the fusion zone. An optical microscope and a scanning electron microscope (SEM) were used to compare the as-welded and laser shock peened microstructure on the fusion zone. The results show that the refined microstructure was observed in the laser shock peened fusion zone compared with the as-welded microstructure. The X-ray diffraction (XRD) result shows a 50% reduction in grain size after LSP. The effect of microsegregation also reduced in the laser shock peened zone. The laser shock peened zone shows slightly higher surface roughness, and improved hardness and strength compared to as-welded zone. [ABSTRACT FROM AUTHOR]

Effects of beam current and welding speed on weld morphology (e.g., bead geometry and microstructure) of electron beam welded joints for different types of alloys have been widely analyzed, however, the study of the role of accelerating voltage on weld morphology is limited. In the present investigation, bead-on-plate welding of 2.6-mm-thick Hastelloy C-276 sheet was carried out using the electron beam to study the effect of accelerating voltage on melt zone area and secondary-dendrite arm spacing. Real-time photographic images showing variation in the shape of the plasma plume (generated due to the interaction of electron beam with the substrate) with accelerating voltage were collected. Increase in interaction volume of the substrate with the electron beam at higher accelerating voltage might have increased the melt zone area. The possible phenomenon of increase in the secondary-dendrite arm spacing with accelerating voltage has been analyzed with the help of an index defined as the ratio of 'segregation ratio of element' to 'segregation ratio of nickel'. The index showed that the increase in molybdenum segregation with accelerating voltage might have caused under-cooling and increased the secondary-dendrite arm spacing. The temperature gradient of the melt pool normal to the scanning direction of the electron beam was derived (from Rosenthal's equation for three-dimensional heat flow) to study the variation in microstructure at the fusion line. As the temperature gradient decreases with increase in accelerating voltage, the grain morphology was found to change from cellular structure to cellule-like structure at the fusion line of the weld bead. [ABSTRACT FROM AUTHOR]

• Machining performance of Hastelloy C-276 by liquid nitrogen cooling. • Reduction in cutting temperature by 61–68%, cutting forces by 8–33% and surface roughness by 33% than that of dry turning. • Low order of tool wear occurred on all the cutting edge surfaces. This paper describes the machinability characteristics of turning Hastelloy C-276 with PVD coated nano-multilayer TiAlN cutting tool using dry turning and liquid nitrogen cooling methods. The turning operations were performed at a constant feed rate (0.111 mm/rev); depth of cut (1 mm) and three different cutting velocities (0.72, 1.17 and 1.97 m/s). The effects of liquid nitrogen cooling on cutting zone temperature, force components (Fz & Fx), roughness parameters (Ra, Rz & Rt), chip morphology and tool wear have been compared with those of dry turning. Turning of Hastelloy C-276 with liquid nitrogen cooling, reduction in cutting zone temperature by about 61–68%, the decrease in cutting force components by about 8–33%, and reduction in surface roughness parameters by 8–33% over dry turning were observed. Cryogenic cooling provided reduced serrated tooth formation for chips which was more than what was observed in dry turning. Improvement of cutting tool performance was achieved under liquid nitrogen cooling by control of wear mechanisms which, in turn, reduced the wear rate. The experimental results indicated the provisions of better performance than dry cutting by the machinability characteristics of Hastelloy C-276 under cryogenic cooling. [ABSTRACT FROM AUTHOR]

Abstract Ni-based Hastelloy C-276 was chosen as the material of the stator and rotor cans of a nuclear main pump for its excellent resistance to corrosive environments and superior mechanical properties. In the present work, the cavitation erosion (CE) behavior of the Hastelloy C-276 thin sheet weld joint was tested. The results indicate that both the CE damages of the weld metal and the base metal initiate at grain boundaries preferentially. The solidification grain boundaries (SGBs) of the weld metal and the twin boundaries (TBs) of the base metal are more susceptible to CE. For the weld metal, due to the microstructure inhomogeneity, regions that show the highest damage intensity are located near the central line of the weld surface where the columnar dendrites interact with the nearly equiaxed dendrites. For the base metal, grains with more TBs are damaged faster compare to other grains. The surface roughness of the eroded surfaces increases with exposure time, and the surface roughness of the base metal increases faster than that of the weld metal. Overall, the resistance to CE of the weld metal is better than that of the base metal. Highlights • The CE resistance of the weld metal is better than that of the base metal. • The CE damage initiates at grain boundaries preferentially. • Zones located near the central line of the weld surface are worst damaged. • Twin boundaries of the base metal are more susceptible to CE. [ABSTRACT FROM AUTHOR]

Hastelloy C-276 superalloy has a wide range of applications including petroleum and petrochemical industries. Since welding forms an essential fabrication method for joining different structures in these industries, selection of suitable welding parameters is a prime concern that is yet to be addressed for Hastelloy C-276. In the present study, optimization of process parameters for electron beam welding of 2.6-mm-thick Hastelloy C-276 sheet has been carried out to obtain weld bead having through-penetration and minimum weld (or melt) zone cross-sectional area. A simple optimization technique is employed in the present study to solve the multi-objective minimization problem. After carrying out the full factorial experiment using selected process parameters, various geometric elements of the weld bead are identified as the output responses. The regression equation is developed for each geometric element from the experimental data. The desired value of a geometric element is specified as a constraint for the corresponding regression equation. A number of regression equations (considering all the geometric elements) are solved in parallel to obtain an optimized set of process parameters, followed by a confirmation test. Further, the optimized melt zone is subjected to cyclic potentiodynamic polarization test to study its susceptibility to localized corrosion. It is observed that polarization curve characteristics of base metal and optimized melt zone are not significantly different; however, the repassivation potential of the melt zone is less than that of the base metal. A flowchart showing the layout of the employed optimization technique followed by corrosion test is attached. [ABSTRACT FROM AUTHOR]

Se analizó el comportamiento microestructural de la superaleación hastelloy C-276, la cual por su característica de resistencia a la corrosión, se emplea en un fluido que presenta diferentes elementos de concentración, además de la velocidad del mismo para su transporte. Se realizó el análisis de muestra sin estar expuesta a condiciones de trabajo y luego de retirada de servicio. Se determinó que entre los efectos más notables que afectan su funcionamiento están el fenómeno de la corrosión por picaduras y el intragranular, asociado al empobrecimiento de la capa de cromo en las áreas afectadas. Al establecer los perfiles de dureza, esta propiedad decrece en la medida que se encuentra la superaleación en contacto con el fluido.

Failure of as-welded Hastelloy C-276 specimen in uni-axial tensile test has been reported to occur at the weld joint with around 50% reduction in elongation length relative to that of as-received Hastelloy C-276 specimen. The proposed reason for such an occurrence is due to the micro-segregation of elements during solidification of the weld zone. Micro-segregation causes formation of brittle inter-metallic phases, mainly at the grain boundaries of the weld zone, leading to a change in deformation behavior of the welded specimen. Reduction in the linear heat input required for welding tends to reduce micro-segregation. Ytterbium fiber laser with its higher melting efficiency, requires lower linear heat input for welding, in comparison to other sources of heat. In the present investigation, Ytterbium fiber laser has been used for welding of 3 mm thick Hastelloy C-276 sheet and the tensile strength properties of the as-welded specimens have been studied. It is observed that the fiber laser as-welded specimens fail at the base metal, and the percent elongation is found to be increase twice as compared to that of previous reported literatures. Analysis of the fiber laser as-welded specimen showed (a) Reduction in micro-segregation within the weld zone due to high cooling rate (=1000 °C/s) of the melt pool; (b) Cooling time through the sensitization temperature range at the heat-affected zone was found to be 1.01 s as compared to 360 s required for precipitation of inter-metallic phase; (c) Ductile nature of the weld zone due to presence of inclined cellular dendrites at the weld centerline facilitating plastic deformation; and (d) Significant increase in elongation of heat-affected zone grains as compared to that of the base metal grains. [ABSTRACT FROM AUTHOR]

High temperature deformation characteristics of Hastelloy C-276 was investigated using compression tests at elevated temperature ranging from 900 °C to 1200 °C and strain rates covering quasi-static to quasi-dynamic regions (0.001 s −1 -10 s −1 ) to a final true strain 0.69 (50% Engineering strain). The flow curves at all strain rates and high temperatures (1100 °C, 1200 °C) exhibit a peak stress, confirming the dynamic recrystallization (DRX) phenomena. To predict and establish the safe hot workability window, processing maps were evaluated based on the dynamic material model and plotted for strain of 0.65. Based on the detailed microstructure analysis and the identification of the active softening mechanisms, the optimal hot workability window was found to be 1200 °C and 0.001 s −1 . Bulk texture analysis revealed presence of fiber textures < 011 > and < 001 > parallel to deformation axis (ND), which were prevalent at high temperature and low strain rate conditions. Using Arrhenius model, the apparent hot working activation energy ( Q HW ) was determined as 474 kJ/mol. Zener-Holloman parameter was calculated to gauge the deformation resistance and found to have a linear relationship with peak flow stress at given deformation conditions. [ABSTRACT FROM AUTHOR]

Preparing a highly textured, flawless YBaCuO (YBCO) layer by ion-beam-assisted deposition (IBAD) requires a substrate with a smooth surface. In this paper, smooth tapes of Hastelloy C-276, a common template alloy, were prepared by electrochemical polishing, and the surface roughness the tapes was investigating by atomic force microscopy and scanning electron microscopy. By analyzing these results, it was discussed how the processing parameters affect the surface roughness, and it is found the following optimized processing parameters: current density of 0.104 A·cm, temperature of 50 °C, plate spacing of 9 cm and time of 150 s. With these optimized parameters, the substrate roughness decreases to less than 5 nm, meeting the requirements of IBAD. [ABSTRACT FROM AUTHOR]

In the present investigation, an attempt has been made to join Hastelloy C-276 nickel-based superalloy and AISI 321 austenitic stainless steel using ERNiCrMo-4 filler. The joints were fabricated by continuous and pulsed current gas tungsten arc welding processes. Experimental studies to ascertain the structure-property co-relationship with or without pulsed current mode were carried out using an optical microscope and scanning electron microscope. Further, the energy-dispersive spectroscope was used to evaluate the extent of microsegregation. The microstructure of fusion zone was obtained as finer cellular dendritic structure for pulsed current mode, whereas columnar structure was formed with small amount of cellular structure for continuous current mode. The scanning electron microscope examination witnessed the existence of migrated grain boundaries at the weld interfaces. Moreover, the presence of secondary phases such as P and μ was observed in continuous current weld joints, whereas they were absent in pulsed current weld joints, which needs to be further characterized. Moreover, pulsed current joints resulted in narrower weld bead, refined morphology, reduced elemental segregation and improved strength of the welded joints. The outcomes of the present investigation would help in obtaining good quality dissimilar joints for industrial applications and AISI 321 ASS being cheaper consequently led to cost-effective design also. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hastelloy C-276 thick wall was successfully fabricated. • Pulsed current shows fine equiaxed and cellular structure. • Pulsed current mode minimized the segregation phenomenon. • Overall pulsed current provides better properties than continuous current. In this research, the Hastelloy C-276 thick wall component was successfully fabricated using wire arc additive manufacturing (WAAM) with both continuous current (CC) and pulsed current (PC) techniques. A defect-free components produced from appropriate process parameters. The CC-WAAM exhibits equiaxed structure in top and columnar in middle and bottom layers. PC-WAAM has fine-equiaxed and cellular structure. The controlled heat input from arc pulsing mode minimized elemental segregation between inter-dendritic and dendritic core regions. CC-WAAM wall have a maximum average grain size of 223.7 μm, while PC-WAAM wall have 189.2 μm. PC-WAAM has higher strength, hardness, and ductility than CC-WAAM. This paper presented a better gas tungsten arc welding (GTAW) based WAAM technique for industrial component manufacturing based on Hastelloy C-276 microstructure and mechanical integrity tests. [ABSTRACT FROM AUTHOR]

Hastelloy C-276 was subjected to low strain deformation and then annealed at 1100 °C for different time. The ∑3 and ∑9 boundary percentages and grain boundary plane distributions were characterized by electron back-scatter diffraction (EBSD) and a five-parameter analysis method. The results show that the ∑3 boundary evolves towards a more exact coincident-site lattice (CSL) misorientation and the ∑3 boundary plane is closer to low surface energy plane {111} with the increasing of annealing time. This is consistent with fine tuning mechanism. While the population of incoherent ∑3 boundary is increasing, the proportion of ∑9 boundary with larger deviations increase, too. And the distributions of grain boundary density planes for ∑9 boundary are more intensive on the whole [110] zone. [ABSTRACT FROM AUTHOR]

The metadynamic recrystallization (MDRX) behavior of a typical Ni-Cr-Mo-based superalloy Hastelloy C-276 was investigated using two-stage isothermal compression tests on a Gleeble thermal-mechanical simulator in the temperature range of 1050-1200 °C, the strain rate range of 0.1-5.0 s, the strains of 0.32, 0.45, and 0.6 at the first stage of compression, and the interval times of 0.5-30 s. The results show that the microstructure and the stress-strain relation of the studied superalloy vary during the interruption period due to the occurrence of MDRX. The MDRX softening fraction and recrystallized grain size increase rapidly with the increasing of interval time, deformation temperature, and strain rate. The effect of strain at the first stage of compression on MDRX is less pronounced. The kinetics of MDRX softening was established based on the flow stress curves, and the apparent activation energy of MDRX of Hastelloy C-276 is evaluated as 241 kJ/mol. [ABSTRACT FROM AUTHOR]

Present industrial scenario attempts to achieve the sustainable manufacturing goal considering economic viability, ecological vulnerability, technological suitability and social acceptability. Also, in current manufacturing paradigm, the machining of fatigue resistance material like Hastelloy C-276 possessing vast applications in aerospace, nuclear and petroleum industries is still challenging. Consequently, leads to uneconomical process and degradation of environment during dry machining and conventional lubrication methods. The present investigations have been focused on economic and ecological sense of machining Hastelloy C-276 with reference to tool damage, surface roughness and lubrication action using different lubricating oils. The flash point, viscosity, and pH values of different oils have been measured using Pensky Marten apparatus, Fann viscometer, measuring strips and a digital pH meter. Additionally, the appearance, odour, and flow ability have been examined physically. The experimental results depicted that surface roughness has been improved by 1.5–62% during vegetable oil and 22% in used oil compared to synthetic oil at lower range of machining parameters. However, at higher levels of process variables, synthetic oil performed better than used oil by 29.2%–98.9% respectively. SEM micrograph indicated 26.17%–50% lower flank wear during vegetable oil compared to synthetic oil. However, Synthetic oil has reduced the tool wear by 3.7%–61.74% than used oil. Further, the coefficient of friction among three oils has varied from 17 to 22.5% manifesting that used oil have considerable lubrication effect. Moreover, the ANOVA analysis revealed that feed rate and lubricant type have an appreciable impact on shear angle and coefficient of friction with maximum percentage error of 3.03% and 6.38% respectively. Finally, minimum quantity lubricant (MQL) of vegetable and synthetic oil has offered a sustainable perspective due to excellent machining performance, better work place conditions, and high-tech lubrication methodology. • Preparation of Environment adaptiable Lubricants (EAL). • Experimental investigation into tool wear and Surface roughness using environmental adaptable lubricants. • Influence of Process parameter on tool wear, surface roughness, shear angle and coefficient of friction. • Evaluation of lubrication and wear mechanism during different lubrication conditions. • An Outlook on the Global economic, ecology of MWF, and comparative statement of economic, ecological and technological Sustainability. [ABSTRACT FROM AUTHOR]