Hastelloy C-276 Research Articles

Preparation of MgO Self-Epitaxial Films for YBCO High-Temperature Coated Conductors.

Ion beam-assisted deposition (IBAD) has been proposed as a promising texturing technology that uses the film epitaxy method to obtain biaxial texture on a non-textured metal or compound substrate. Magnesium oxide (MgO) is the most well explored texturing material. In order to obtain the optimal biaxial texture, the actual thickness of the IBAD-MgO film must be controlled within 12nm. Due to the bombardment of ion beams, IBAD-MgO has large lattice deformation, poor texture, and many defects in the films. In this work, the solution deposition planarization (SDP) method was used to deposit oxide amorphous Y2O3 films on the surface of Hastelloy C276 tapes instead of the electrochemical polishing, sputtering-Al2O3 and sputtering-Y2O3 in the commercialized buffer layer. An additional homogeneous epitaxy MgO (epi-MgO) layer, which was used to improve the biaxial texture in the IBAD-MgO layer, was deposited on the IBAD-MgO layer by electron-beam evaporation. The effects of growth temperature, film thickness, deposition rate, and oxygen pressure on the texture and morphology of the epi-MgO film were systematically studied. The best full width at half maximum (FWHM) values were 2.2° for the out-of-plane texture and 4.8° for the in-plane texture for epi-MgO films, respectively. Subsequently, the LaMnO3 cap layer and YBa2Cu3O7-x (YBCO) functional layer were deposited on the epi-MgO layer to test the quality of the MgO layer. Finally, the critical current density of the YBCO films was 6 MA/cm2 (77 K, 500 nm, self-field), indicating that this research provides a high-quality MgO substrate for the YBCO layer.

Hot Deformation Behavior of Hastelloy C276 Alloy: Microstructural Variation and Constitutive Models.

Isothermal deformation experiments of the Hastelloy C276 alloy were executed using the Gleeble-3500 hot simulator at a temperature range of 1000-1150 °C and a strain rate range of 0.01-10 s-1. Microstructural evolution mechanisms were analyzed via transmission electron microscope (TEM) and electron backscatter diffraction (EBSD). Results reveal that the influences of hot compression parameters on the microstructure variation features and flow behaviors of the Hastelloy C276 alloy were significant. The intense strain hardening (SH) effects caused by the accumulation of substructures were promoted when the strain rates were increased, and true stresses exhibited a notable increasing tendency. However, the apparent DRV effects caused by the annihilation of substructures and the increasingly dynamic recrystallization (DRX) behaviors occurred at high compressed temperature, inducing the reduction in true stresses. In addition, a physical-based (PB) constitutive model and a long short-term memory (LSTM) model optimized using the particle swarm optimization (PSO) algorithm were established to predict the flow behavior of Hastelloy C276 alloy. The smaller average absolute relative error and greater relation coefficient suggest that the LSTM model possesses a higher forecasting accuracy than the PB model.

Comparative study on microstructure and properties of laser welding and argon arc welding Hastelloy C-276/SS304 with filler wire

Comparative study on microstructure and properties of laser welding and argon arc welding Hastelloy C-276/SS304 with filler wire

A novel study on the influence of graphene-based nanofluid concentrations on the response characteristics and surface-integrity of Hastelloy C-276 during minimum quantity lubrication

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%).

Influence of heat treatment on microstructure and mechanical properties of pulsed Nd: YAG laser welded dissimilar sheets of Hastelloy C-276 and monel 400

The study involved using a pulsed Nd:YAG laser welded Hastelloy C-276-Monel 400 dissimilar sheet by the process parameters viz. a pulse energy of 10 J, pulse repetition rate of 20 Hz and pulse duration of 0.006 s under spot weld mode. The objective was to investigate the effects of various post weld heat treatment (PWHT) conditions on the welded sheets. Microscopic analysis showed that the fusion zone and interfaces between the two metals contained smaller dendritic grains containing chromium-rich carbides and nickel-rich oxides. Both the Hastelloy C-276 and Monel 400 interfaces exhibited these traits. The PWHT of the quenched weld (water cooling) produced higher mechanical strength, while the annealed weld (furnace cooling) resulted in lower strength. Tensile failures were observed in the fusion zone for quenched and normalized welds, and in the base alloy of Hastelloy C-276 side for annealed weld under ductile fracture mode. XRD analysis showed the presence of more secondary phases and intermetallic compounds in the fusion zone and Hastelloy C-276 side in the annealed weld. The corrosion study indicated that the fusion zone and Monel 400 side had better corrosion resistance, followed by the Hastelloy C-276 side.

Evaluation of tribological performance of MQL technique combined with LN₂, CO₂, N₂ ecological cooling/lubrication techniques when turning of Hastelloy C22 superalloy

Sustainability specifically addresses using ecological cooling/lubrication techniques in the manufacturing industry. Dry, MQL, CO2, LN2, N2, CO2 +MQL, LN2 +MQL, and N2 +MQL techniques were preferred for ecological cooling/lubrication. To determine the effects of cooling/lubrication techniques on machining performance, cutting speed (Vc 80 m/min), feedrate (f 0.12 mm/rev), and cutting depth (ap 0.5 mm) were taken as constants. Cutting tool wear and mechanisms, surface roughness and topography, cutting temperature, and vibration peak values are preferred as machining performance characteristics. At the end of the turning experiments performed with sustainable cooling/lubrication techniques: N2 +MQL hybrid cooling/lubrication technique performed better performance in cutting tool wear (0.226 mm), surface roughness (1.658 µm), and vibration (48.017 m/sec2), while LN2 cooling technique showed the best performance (87 °C) in cutting temperature. Compared to dry condition, the N2 +MQL hybrid cooling/lubrication technique reduced tool wear, surface roughness, and vibration by 73.50%, 53.9%, and 42.4%, respectively.

An attempt towards green machining of Ni-based Hastelloy C4 alloy: Effect of vegetable oils and their combination with TiO2 and SiO2 nanoparticles on outputs

The importance of nickel-based superalloys has increased day by day due to their use in special applications. However, the difficulties in the machinability of these alloys bring some concerns about parts quality and efficiency. Although researchers have tried ways (such as the use of high-performance cutting fluids) to overcome these challenges, their sustainability is still controversial. Therefore, this experimental research aims to contribute to the sustainable machining of nickel-based superalloys. In this regard, the present study investigates the effectiveness of vegetable-based fluids (sunflower, olive, hazelnut, and corn oils) and nanofluids (SiO2 + sunflower oil, SiO2 + olive oil, SiO2 + hazelnut oil, SiO2 + corn oil, TiO2 + sunflower oil, TiO2 + olive oil, TiO2 + hazelnut oil, and TiO2 + corn oil) during the machining of Ni-based Hastelloy C4 alloy. The study was carried out in three stages. In the first stage, all cutting fluids' pH and thermal conductivity values were measured. In the second stage, machinability tests were conducted under the prepared cutting fluids. Later, friction-wear tests of the cutting fluids that offered the best performance in the previous stage were done. As a result, the pH change was significantly increased with the addition of nanoparticles (TiO2 and SiO2) to corn oil. TiO2 nanoparticles allowed further improvement of thermal conductivity. Compared to dry machining, improvements of 58.57%, 34.88%, 53.18%, and 36.1% in surface roughness, cutting temperature, tool wear, and power consumption were achieved with corn oil+TiO2 nanofluid, respectively. It was determined that adhesion, BUE, BUL, and chipping were dominant damage types. Also, an adhesive is the dominant wear mechanism.

Evaluation of corrosion and wear performance of Fe-based coating and hastelloy C276 in H2S environment on 304 stainless steel substrate

In order to improve the performance of 304 stainless steel for use in oil and gas field applications and broaden its applicability, Fe-based coatings with small amounts of amorphous structures were prepared by high-velocity oxygen-fuel spraying onto stainless steel substrates. The wear resistance and hydrogen sulfide corrosion resistance of the coatings were tested and compared to the preferred corrosion resistance of Hastelloy C276 coatings. Samples with two kinds of coatings were subjected to 720 h of corrosion in a 40 °C H2S solution. The effects of corrosion on the microstructure and phase composition of the sprayed coatings were analyzed using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The mechanical properties of the materials were characterized using nano-indentation, a friction-abrasion testing machine, and confocal laser microscopy. The results showed that both coatings provided excellent resistance to H2S corrosion (0.14, 0.15 mm/y), but the Fe-based coating was more effective at enhancing the hardness (twice as much as C276 coating), Young's modulus, and wear resistance of the stainless steel. Given its higher wear resistance and lower cost, the Fe-based coating was concluded to be more effective in protecting 304 stainless steel for use in oil and gas applications.

Investigation on the physical and electrochemical properties of typical Ni-based alloys used for the bipolar plates of proton exchange membrane fuel cells

The phase, mechanical properties, corrosion resistance, hydrophobicity, and interface contact resistance of three typical Ni-based alloys (Hastelloy B, Hastelloy C-276, and Monel 400) and 304 stainless steels were experimentally studied to evaluate their service performances as bipolar plate materials of proton exchange membrane fuel cells. All four alloys exhibit single-phase face-centered cubic structure, high strength, good ductility, and high hardness. Hastelloy C-276 has the best ductility with an uniform elongation of 72.5% and highest hardness of 363.7 HV. Hastelloy B has the highest ultimate tensile strength of 913.6 MPa. The hydrophobicity of all four alloys is not good, although Monel 400 has the highest water contact angle of 84.2°. Hastelloy B, Hastelloy C-276, and 304 stainless steel exhibit unsatisfying corrosion resistance in a simulated acidic work environment of proton exchange membrane fuel cell (0.5 M H2SO4+2 ppm HF, 80 °C, H2) and high interface contact resistance. By contrast, Monel 400 demonstrates excellent corrosion resistance with a corrosion current density of 5.9 × 10−7 A cm−2 and a low interface contact resistance of 7.2 mΩ cm2 at 140 N/cm2. In terms of comprehensive performance, Monel 400 is the best uncoated material for the bipolar plates of proton exchange membrane fuel cells among typical Ni-based alloys.

Experiment analysis of A-TIG welding and comparison between TIG, Double-TIG, and A-TIG of Hastelloy C-276

The present study Hastelloy C276 welding performs using tungsten inert gas (TIG) and activated flux-TIG (A-TIG) welding technique. A nickel (57%), molybdenum (15 to 17%), chromium (14.5 to 16.5%), Iron (4 to 7%) and tungsten (3 to 4.5%) alloy called Hastelloy C-276 has outstanding all-around corrosion resistance and is easy to work with. Reverse marangoni and the arc concentration effect both considerably increased the depth of penetration during ATIG welding with SiO2 flux. The Macro structural analysis and hardness survey of weld bead profile of TIG, Double TIG and ATIG performed and find out that ATIG welding have greater depth of penetration and high hardness value than normal TIG welding. A TIG welding produced better hardness; the difference in hardness values was about 8.45%.

High temperature brazing of C/C using Hastelloy C-276 as filler and joint formation mechanism

To increase servicing temperature of brazed C/C joint, a commercial Hastelloy C-276 (Ni-15.5Cr-16Mo-5Fe-4W, wt. %) with high melting point was used as filler in high-temperature brazing (HTB). The fast HTB process with a soaking time of 2 min was performed at four levels 1250 °C, 1300 °C (bellow solidus), 1350 °C and 1400 °C (over liquidus). Joint shear strength of 23.5 MPa (under 1400 °C) and 20 MPa (under 1250 °C) were obtained due to significant dissolution of C/C, dense interface, infiltration, and MC in-situ reinforced C-rich Ni-based bond seam. Joint microstructure evolution examination indicated that carbon could rapidly diffuse into C-276, inducing segregation of the active elements Cr and Mo at C-276 grain boundaries, triggering C-(Ni, Fe)-(Cr, Mo) eutectic reaction in the grain. All joints fractured mainly within infiltrated zone. The study demonstrated that using Ni-based alloy containing Cr and Mo as filler was feasible.

Welding investigations on mechanical property and microstructure of TIG and A-TIG Weld of Hastelloy C-276

Hastelloy C-276 is a nickel-based alloy with high strength and corrosion resistance at cryogenic to high temperatures. The issue of Hastelloy C-276 shallow penetration by Tungsten Inert Gas (TIG) welding was addressed in the current investigation by applying A-TIG welding with variable oxide flux. In the current investigation, constant welding conditions were used to perform TIG and A-TIG welding using SiO2, TiO2, and a 50% mixture of SiO2 + TiO2 flux. The weld bead width and depth of penetration of the weld bead profile were measured, and the mechanical and metallurgical properties of the weld metal was investigated. SiO2 flux attained the highest D/W ratio and depth of penetration during A-TIG welding when compared to other fluxes used. A-TIG welding using SiO2 flux improved the depth of penetration and the D/W ratio by 118% and 263%, respectively, in comparison with conventional TIG welding. Additionally, the A-TIG welded sample with SiO2 flux had an ultimate tensile strength of 738.295 MPa and a percentage of elongation of 52.75%.

Melting efficiency calculation of “finite-element-modeled” weld-bead and “experimental” weld-bead for laser-irradiated Hastelloy C-276 sheet

Melting efficiency calculation of “finite-element-modeled” weld-bead and “experimental” weld-bead for laser-irradiated Hastelloy C-276 sheet

Study on deviation distribution of Σ3 and Σ9 boundaries in Hastelloy C-276 superalloy with different hot rolling reductions

In this study, the deviation distributions of Σ3 and Σ9 grain boundaries in a Hastelloy C-276 sheet were measured using electron backscatter diffraction technology (EBSD) and the grain boundary plane orientation was analyzed using a five-parameter technique after hot rolling at 900 °C with different thickness reductions. The results show that the relative areas of Σ3 grain boundary planes reveal a strong peak at the (111) twist position, and the corresponding intensity significantly decreases as the reduction increases. The hot rolling generates dislocations, resulting in significant deviation of Σ3 grain boundary orientations and the loss of special properties. However, the Σ9 grain boundary plane distribution (GBPD) becomes more diffused with increasing deformation, and the multiples of random distribution (MRD) value is ∼2. In addition, the large deviation of the Σ9 grain boundary orientation varies across the different strain samples. In low-strain samples, the deviation of the Σ9 grain boundary orientation may be affected by the Σ3 grain boundary deviation with construction of the Σ3–Σ3–Σ9 triple junction. The deformation microstructures mainly determine the deviation of the Σ9 grain boundary orientation in high-strain samples. Moreover, the distorted grain boundaries act as potent nucleation sites of dynamic recrystallization (DRX) during the hot rolling process.

Microstructure and wear resistance of laser cladding nano TiC/micro TiB2/C-276 composite coatings on 316L stainless steel

Four metal-ceramic composite coatings were prepared by laser cladding (LC) using Hastelloy C-276, nano-TiC and micro-TiB2 as raw materials to improve the surface properties and extend the service life of 316L stainless steel. The microstructure and mechanical properties were analyzed by metallographic microscopy, scanning electron microscopy (SEM), x-ray diffraction (XRD), Vickers hardness experiments, and friction and wear testing. The TiC and TiB2 phases were detected in the coating, exhibiting homogenous distribution as their content increased. As a result, the strengthening effect of the coating was enhanced, improving microhardness relative to that of the 316L substrate. The wear test revealed that the Hastelloy coating exhibited poor wear resistance, but the addition of TiC and TiB2 particles improved the wear resistance by reducing the wear rate. The lowest average coefficient and wear rate were attained at 50% and 70% ceramic contents, respectively. However, abundant hard particles on the surface easily fell off during the wear, which further impeded the surface degradation and increased the friction coefficient.

The Joining of Alumina to Hastelloy by a TiZrCuNi Filler Metal: Wettability and Interfacial Reactivity

A systematic microstructural characterization of alumina joined to Hastelloy C22® by means of a commercial active TiZrCuNi alloy, named BTi-5, as a filler metal is reviewed and discussed. The contact angles of the liquid BTi-5 alloy measured at 900°C for the two materials to be joined are 12° and 47° for alumina and Hastelloy C22® after 5 min, respectively, thus demonstrating good wetting and adhesion at 900 °C with very little interfacial reactivity or interdiffusion. The thermomechanical stresses caused by the difference in the coefficient of thermal expansion (CTE) between the Hastelloy C22® superalloy (≈15.3 × 10-6 K-1) and its alumina counterpart (≈8 × 10-6 K-1) were the key issues that had to be resolved to avoid failure in this joint. In this work, a circular configuration of the Hastelloy C22®/alumina joint was specifically designed to produce a feedthrough for sodium-based liquid metal batteries operating at high temperatures (up to 600 °C). In this configuration, adhesion between the metal and ceramic components was enhanced after cooling by compressive forces created on the joined area due to the difference in CTE between the two materials.

Performance investigations for sustainability assessment of Hastelloy C-276 under different machining environments

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.

Hot Corrosion Behavior of TWAS and HVOF NiCr-Based Coatings in Molten Salt.

In order to extend the life of boilers by applying an anti-corrosion coating without the need to dismantle them, it is advisable to find coatings that can be applied using cheaper and portable techniques, such as Twin Wire Arc Spray technology (TWAS). In this study, we compare selected NiCr-based coatings and two uncoated steel substrates (steel 1.7715 and 1.4903). Two coatings, Cr3C2 - 25% NiCr and Hastelloy C-276 are deposited using High velocity oxygen-fuel technology (HVOF) and three coatings, NiCrTi, NiCrMo, and Inconel 625, are deposited using TWAS. In addition to the corrosion weight gain during 50 cycles of loading in an 18% Na2SO4 and 82% Fe2(SO4)3 salt environment at 690 °C evaluated using the gravimetric method, the microstructure and phase composition of the coatings were analyzed on the samples after the exposure in order to compare the properties and gain a deeper understanding of the corrosion kinetics. Coating cross-sections and free-surfaces were observed with a scanning electron microscope (SEM) with an energy-dispersive (EDX) system. The phase composition was investigated using X-ray diffraction (XRD) and Raman spectroscopy. No significant differences were observed between the TWAS and HVOF coating methods for the coatings compared. Due to the similar corrosion products found on all coatings, a very effective corrosion protective layer was formed on the surface, forming a barrier between the corrosive environment and the coating regardless of the used deposition technology. Therefore, for industrial use on the inner surface of coal-fired boilers we recommend NiCrTi, NiCrMo, or Inconel coatings prepared with the more cost-effective and portable TWAS technology.

Effect of continuous and pulsed current techniques on wire-arc additive manufacturing of a nickel-based superalloy

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 structureintop and columnar inmiddle 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.

The hot deformation behaviors and constitutive modeling of Hastelloy C276

Hastelloy C276 is widely used in the new generation of nuclear power plants, and hot deformation is the optimum way to form the C276 part. In this investigation, the hot deformation and constitutive modeling of Hastelloy C276 alloy are researched, and the processing maps are drawn. The results show that strain rate and hot deformation temperature have remarkable impacts on the deformation behaviors of the Hastelloy C276 alloy. The yield behavior and the flow stress are predicted based on the Arrhenius constitutive equation, and the correlation coefficients are 0.9613 and 0.9837, indicating the high prediction ability of the established constitutive equation. Rising the deformation temperature can decrease the unstable deformation area, and the studied alloy can be deformed at low strain rates. With the increased strain rate, flow localization occurs, which is not suitable for the hot deformation.