Alloy C-276 Research Articles

Nanoscale Characterization of Stress Corrosion Cracking in a Failed Alloy C-276 Component

A failure analysis was performed on an Alloy C-276 pull rod which underwent unexpected brittle, intergranular fracture after exposure to 280°C to 300°C aqueous solutions designed to replicate secondary side environments in nuclear energy systems: Pb-containing alkaline (pH300°C 8.5 to 9.5), and sulfate-containing acidic solutions (pH280°C 3 to 5). The component was characterized using advanced electron microscopy methods to demonstrate the benefits of these techniques for determining the nanoscale chemical, mechanical, and material factors contributing to failure, and to provide insight into the mechanisms of stress corrosion cracking (SCC) responsible for failure. Site-specific transmission electron microscopy specimens containing crack tips were prepared using focused ion beam. Nanoscale chemical characterization methods revealed that Pb was present in some oxidized regions of cracks, suggesting that the element may be inhibiting or impairing the passivity of the Cr-rich oxide. Complementary nanoscale microstructural analysis was performed. At an intergranular to transgranular cracking mode transition, it was observed that the transgranular crack (and corrosion process) propagated along the (110) crystallographic plane. Also, the cracking mode was highly dependent on the tensile stress direction relative to grain boundary orientation, the crystallographic orientation of grains, and geometrically necessary dislocation structures. A comparison of results with proposed mechanisms for SCC of Ni alloys in similar environments are discussed; the highly directional nature of cracking is consistent with a slot-tunnel corrosion mechanism.

The Effect of Heat Treatment on the Microstructures and Mechanical Properties of Inconel 713C Alloy Vacuum Investment Castings

The Effect of Heat Treatment on the Microstructures and Mechanical Properties of Inconel 713C Alloy Vacuum Investment Castings

Development of arc welding technique to preclude microsegregation in the dissimilar joint of Alloy C-2000 and C-276

Hastelloy C-2000 and C-276 are widely used in Flue Gas Desulphurization (FGD) system and Chemical Processing Industries (CPI). Current work is focused on weld microstructure, and mechanical properties (structure-property relationship) of the dissimilar combination of alloy C-2000 and C-276. Multi-pass Pulsed Current Gas Tungsten Arc (PCGTA) welding was adopted for joining the dissimilar alloys using the filler ERNiCrMo-17. Microstructural characteristics of the weld joint were assessed by Optical and Scanning Electron Microscope (SEM). Weld interface microstructure examination revealed the presence of grain coarsening near the Heat Affecting Zone (HAZ) of the alloy C-276 side. SEM analysis shows the absence of secondary Topologically Closed Packed (TCP) phases in the Inter-Dendritic (ID) regions of the dissimilar weld. Micro-segregation of alloying elements in the weldment was assessed by Energy-Dispersive X-ray Spectroscopy (EDS). X-Ray Diffraction (XRD) analysis had been carried out to identify the phase constitution and average grain size. Strength, toughness, and hardness of the dissimilar weld were evaluated with the support of the tensile test, Charpy impact test, and Vicker’s hardness test. Tensile study showed that all the tensile fracture occurred at the base metal side of alloy C-276. The average toughness of the dissimilar alloy joint was noted about 84 J. Hardness test results indicated that fusion zone (FZ) hardness value was 6.19% and 2.27% superior to the candidates’ material (C-276 and C-2000) employed in this study. The refined grain structure and absence of microsegregation resulted in the highest hardness in the dissimilar weld FZ. Results revealed the substantiated use of PCGTA welding for the effective joining of dissimilar alloys of C-2000 and C-276 through the evaluation of metallurgical and mechanical characteristics.

A parametric study on the design factors influencing the thermal performance of nickel alloy C263 sandwich panels

ABSTRACT To protect the airframe and the payload of hypersonic cruise vehicles from aerothermal heating and aerodynamic loading, metallic thermal protection systems (MTPS) are intended to be used. MTPS are composite structures containing a combination of insulating material and two sandwich panels placed on top and bottom of it. There are numerous design factors influencing the (a) thermal performance and (b) density of these sandwich panels (SP). In the current study, the effect of six important geometric design parameters of nickel alloy C263 sandwich panel viz., (A) core cell shape, (B) core cell size, (C) core cell height (D) core sheet thickness, (E) top and (F) bottom face sheet thickness were evaluated and analysed using Taguchi-based design of experiments (DOE) approach. The results obtained were analysed using standard statistical analysis techniques in order to identify the optimum combination of design parameters and to ascertain the influence of each aforementioned design parameters on the performance of C263 sandwich panels. Further, the optimum combination of sandwich-panel design parameters that provides the best thermal performance with lowest density has been identified using an algebraic model and validated. The results obtained are presented and discussed here.

Control of deformation and annealing process to produce incoherent Σ3 boundaries in Hastelloy C-276 alloy

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.

Flow stress prediction of Hastelloy C-276 alloy using modified Zerilli−Armstrong, Johnson−Cook and Arrhenius-type constitutive models

Abstract To better understand the hot deformation behaviors of Hastelloy C-276 alloy under elevated temperatures, hot tensile tests were carried out in the temperature range of 1223−1423 K and the strain rate range of 0.01−10 s−1, respectively. Based on the modified Zerilli−Armstrong, modified Johnson-Cook, and strain-compensated Arrhenius-type models, three constitutive equations were established to describe the high-temperature flow stress of this alloy. Meanwhile, the predictability of the obtained models was evaluated by the calculation of correlation coefficients (r) and absolute errors (Δ), where the values of r for the modified Zerilli−Armstrong, Johnson−Cook, and Arrhenius-type constitutive models were computed to be 0.935, 0.968 and 0.984, and the values of Δ were calculated to be 13.4%, 10.5% and 6.7%, respectively. Moreover, the experimental and predicted flow stresses were compared in the strain range of 0.1−0.5, the results further indicated that the obtained modified Arrhenius-type model possessed better predictability on hot flow behavior of Hastelloy C-276.

A Review on Influencing Welding Parameters of Super Alloys

Manufacturing industries play a vibrant role in economic development and significant growth of a country. Among all different industries, sheet metal industry is irreplaceable in our routine life. Sheet metal applications include in automobiles, aircrafts, computer panels, building roofs etc. Various manufacturing process of sheet metal industry consists of shearing, bending, welding and deep drawing. Welding is one of the vital process in engineering business. Welding is the best operative method of joining similar and dissimilar components together. Choice of influencing process parameters is very much critical in welding for the purpose of obtaining good quality weldments with preferred mechanical properties and enhanced serviceability. This is impossible with single welding method that yields the optimum weld in all conditions. The choice of welding process depends upon the service environment, time, cost, and deposition rate. Superalloy is an alloy having greater mechanical strength and high corrosion resistance in high temperature applications. Superalloys are of, Nickel, Cobalt and Iron built possessing the crystal structure of Face Centered Cubic (FCC) austenitic. Typical examples of super alloys include Inconel, Hastelloy, Waspaloy, Rene alloys, Incoloy. Among these, Hastelloy is a nickel based superalloy containing the major proportion as Nickel 57%, Chromium 15.5% and Molybdenum 16% with the remaining in smaller proportions. Hastelloys are employed by the chemical industries for their Corrosion-Resistant property. The characteristics of Hastelloy include high resistance to localized corrosion in welding and fabrication. Hastelloy are of different grades optimised for specific purpose. Hastelloy alloys of “C-type” alloys are the most versatile. Hastelloy C276 alloy is a nickel alloy engaged in petro chemical and related industries possessing corrosive chemicals. Hastelloy C276 is ductile in nature, suitable for welding, forming and has high resistance to corrosion. Hastelloy C276 alloy is welded by the fusion welding process. The low quantity of carbon existence prevents carbide precipitation to keep resistance to inter granular attack in thermally affected zones. Every industry requires to attain a good quality of weld with great productivity and low processing cost with commanding weld joint.

Microstructure, mechanical and corrosion properties of TIG welded Hastelloy C-276

Abstract Hastelloy C-276 is a corrosion resistant nickel based solid solution hardened industrial alloy which has superior mechanical and corrosion properties. In this study, Hastelloy C-276 alloy was welded via the GTAW (Gas tungsten arc welding) method using ERNiCrMo-4 filler metal. Tensile, bending and notch impact tests were performed to determine the mechanical properties. The microstructure of the weld metal was investigated by light microscopy (LM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The impact toughness values of the heat affected zone (HAZ) showed a better performance than those of the weld metal. In addition, the corrosion properties of the weld metal and the base material were investigated by potentiodynamic polarization tests. Electrochemical potentiodynamic polarization parameters were determined according to corrosion behavior and microstructure properties. In particular, the corrosion rate of the weld metal increased because of the Mo-rich phases deposited in the weld metal microstructure.

Performance comparison of artificial neural network and multiple regression models for wire electrical discharge machining of haste alloy

Haste Alloy C276 is a difficult to machine materials and exclusively employed to numerous engineering files such as gas, aerospace and nuclear applications. Since it has better strength and lower thermal conductivity, it has the tendency of reduced life of tool and poor machining performance by the use of traditional machining processes. Unconventional methods of material removal have been developed for overcoming the difficulties of traditional machining and claimed to be a suitable alternate approach for traditional method of material removal. Wire Electrical Discharge Machining (WEDM) is one among the available contemporary machining process that has been specifically adopted for machining of hard materials. Proper utilization of artificial decision making tools helps the manufacturer to attain benefits in manufacturing fields. This present exploration describes the development of neural network models and multiple regression models for WEDM process. The experimental runs are devised and analyzed by Taguchi’s approach. Grey Relational Analysis (GRA) is adopted for attaining the Grey Relational Grade (GRG) for representing a multi-performance index. An Artificial Neural Network (ANN) model and multiple regression models have been proposed to predict the Grey Relational Grade (GRG). Grey Relational Coefficient (GRC) values which are generated by the GRA method, considered as input for developing the Neural Network (NN) model to predict the multi-performance index (GRG). The closeness among the actual and predicted values are derived with the help of a comparative analysis. Finally, predicted values of GRG by NN models and regression models have been compared with actual values and the outcomes prove that neural network model offers better predictive control over regression models.

Development of neural network models for wire electrical discharge machining of Haste alloy

Unconventional methods of material removal have been developed for fulfilling the difficulties of traditional machining and appealed to be a suitable alternate approach for traditional material removal. Wire Electrical Discharge Machining (WEDM) is one among the available advanced machining process that has been mainly adopted to machine hard materials. Proper use of intelligent decision making tools helps the manufacturer to attain benefits in manufacturing fields. Haste Alloy C276 is a nickel alloy, known as difficult to machine materials and exclusively used to various engineering files such as nuclear, gas and aerospace applications. Since it has higher strength and lower thermal conductivity, it has the tendency of reduced life of tool and poor machining performance by the use of traditional machining processes. This present investigation describes the analysis on process variables and development of neural network models for WEDM process. The experimental runs are planned and analyzed by Taguchi’s approach. Grey Relational Analysis (GRA) is adopted for attaining the Grey Relational Grade (GRG) for representing a multi-performance index. An Artificial Neural Network (ANN) model has been proposed to predict the Grey Relational Grade (GRG). Grey Relational Coefficient (GRC) values which are generated by the GRA method, given as input data for developing the Neural Network (NN) model to predict the desired multi-performance index (GRG). The closeness among the actual and predicted values are derived with the help of a comparative analysis.

Nickel alloy C-263 protection by WC[sbnd]Cr3C2[sbnd]Ni coatings against high-temperature wear in nuclear applications

Over the years, substantial improvement in the thermal efficiency resulted in higher operating temperatures for Generation IV nuclear reactors. Therefore, reliable material demanded by designers that could sustain at elevated temperatures environment in nuclear applications. The high-temperature friction and wear behaviour of Ni-based alloy C-263 has been comparatively investigated with WCCr3C2Ni coatings. The commercially available WCCr3C2Ni powder deposited by atmospheric plasma spray (APS) and high-velocity oxy-fuel (HVOF) processes. The high-temperature tribometer used for unidirectional sliding tests at 400 °C, 600 °C and 750 °C. The alloy shows higher specific wear rates compared to both coatings at every temperature interval. Development of tribo-film is responsible for the specific wear rates of both the coatings declined after 600 °C. Consequently, the superior wear resistance than Ni-alloy up to 750 °C recommends WCCr3C2Ni coatings for high-temperature gas-cooled nuclear reactors.

An Investigation on Constitutive Relation and Dynamic Recrystallization of Hastelloy C-276 Alloy During Hot Deformation

Hot compression tests of Hastelloy C-276 alloy were conducted at the temperature ranging from 1000 to 1250 °C and strain rate ranging from 0.01 to 10 s−1. The constitutive relation and critical points of dynamic recrystallization (DRX) of the Hastelloy C-276 alloy were analyzed. The flow stress curves were corrected to tackle the problems of the influence of the adiabatic heating and friction. It was revealed that a five-order polynomial was suitable to solve the problem of the influence of strain. The critical strains of DRX could be expressed by the calculation from strain hardening rate as $$ \varepsilon_{c} = 7.67 \times 10^{ - 4} Z^{0.144} {\text{and }}\varepsilon_{c} \approx 0.78\varepsilon_{p} $$ . Microstructural evolution revealed that the development of DRX of the alloy was complete at high temperature and low strain rate and the DRX grain size increased with the increase in temperature. The volume fraction of DRX was increased, and the grain size of DRX was also slightly increased with the increase in strain. The main nucleation mechanism of DRX was discontinuous dynamic recrystallization (DDRX), which was characterized by the grain boundary bowing nucleation mechanism coupled with the twinning-induced nucleation mechanism. Σ3 twins also contribute to the grain refinement and homogenization during hot deformation. The grains of C-276 alloy were refined significantly, and the microstructural homogeneity was improved effectively during hot deformation at high temperature and low strain rate. By choosing the suitable hot working processing parameters, the refinement and uniform distribution of grains of Hastelloy C-276 alloy could be obtained.

Microstructure, mechanical and corrosion properties of TIG welded Hastelloy C-276

Abstract Hastelloy C-276 is a corrosion resistant nickel based solid solution hardened industrial alloy which has superior mechanical and corrosion properties. In this study, Hastelloy C-276 alloy was welded via the GTAW (Gas tungsten arc welding) method using ERNiCrMo-4 filler metal. Tensile, bending and notch impact tests were performed to determine the mechanical properties. The microstructure of the weld metal was investigated by light microscopy (LM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The impact toughness values of the heat affected zone (HAZ) showed a better performance than those of the weld metal. In addition, the corrosion properties of the weld metal and the base material were investigated by potentiodynamic polarization tests. Electrochemical potentiodynamic polarization parameters were determined according to corrosion behavior and microstructure properties. In particular, the corrosion rate of the weld metal increased because of the Mo-rich phases deposited in the weld metal microstructure.

Corrosion Behavior of a Ni–Cr–Mo Alloy Coating Fabricated by Laser Cladding in a Simulated Sulfuric Acid Dew Point Corrosion Environment

For this study, aimed at proposing a potential direction to prevent sulfuric acid dew point corrosion, a Ni–Cr–Mo alloy Hastelloy C22 coating was fabricated by coaxial laser cladding technology. The phase composition, microstructure, and corrosion behavior in a simulated sulfuric acid dew point corrosion environment were investigated and compared with a Hastelloy C22 alloy, a titanium alloy TC4, and 09CrCuSb steel (ND). The results showed that the phase composition of the C22 coating is essentially similar to that of the C22 alloy, consisting of a γ-Ni solid solution and Ni6Mo6C1.06. The finer microstructure of the C22 coating mainly contains eutectic and dentrite, presenting a typical solidification feature of laser cladding. The corrosion resistance of the C22 coating is very close to that of the C22 alloy, and outclasses that of TC4 and ND. The corrosion behavior of the C22 coating is intergranular corrosion resulting from the segregation of molybdenum, chromium containing corrosion products, and smaller anode micro-batteries.

Effects of WC-Co reinforced Ni-based alloy by laser melting deposition: Wear resistance and corrosion resistance* *Project supported by the National Key Research and Development Program of China (Grant No. 2017YFB1103604), the Industrial Transformation and Upgrading Funds of the Ministry of Industry and Information Technology, China (Grant No. RZJC-XM19-004), the Tianjin Municipal Special Program of Talents Development for Excellent Youth Scholars,

WC-Co reinforced C276 alloy composite coatings are fabricated on Q235 steel by laser melting deposition. The microstructure, hardness, wear performance, and electrochemical corrosion behavior of composite coating are studied. The results show that WC-Co particles are mostly uniformly distributed in the coating and provide favorable conditions for heterogeneous nucleation. The microstructure of C276/WC-Co composite coatings is composed of γ-Ni solid solution dendrites and MoNi solid solution eutectics. The WC-Co particles can effectively improve the hardness and wear resistance of C276 alloy. The average hardness of the composite coating containing 10-wt% WC-Co (447 HV0.2) are 1.26 times higher than that of the C276 alloy (356 HV0.2). The wear rate of composite coating containing 10-wt% WC-Co (6.95 × 10−3 mg/m) is just 3.5% of that of C276 coating (196.23 × 10−3 mg/m). However, comparing with Hastelloy C276, the corrosion resistance of C276/WC-Co composite coating decreases.

Optimization of Cutting Parameters Based on Surface Roughness and Cutting Force During End Milling of Nimonic C-263 Alloy

The surface integrity of machined surfaces greatly influences the functional properties of the components such as fatigue life, etc. Nickel-based superalloy such as Nimonic C-263 is termed as difficult to machine material due to its unique properties as well as high strength at elevated temperatures. This study intends to optimize the cutting parameters (cutting speed, feed, depth of cut) during the end milling of Nimonic C-263 and the machining has been carried out using solid tungsten carbide tool coated with TiAlN and Vertical Machining Center. Experimentation is carried out using Taguchi L9 orthogonal array technique and based on signal to noise ratio data, optimum machining parameters were achieved for preferred observable characteristics such as cutting force and surface roughness. Additionally, Multi-purpose optimization (Grey analysis) of the observable characteristics was conducted to predict the optimum machining parameters combination which offers better producible surface finish and lowest cutting force requirement. Further, the analysis of variance (ANOVA) reveals that the feed rate is the farthest influencing factor followed by the depth of cut, cutting speed, and the variations in cutting force and surface roughness are confirmed through chip morphology using Scanning electron microscopy.

Microstructure and mechanical properties of wire arc additively manufactured Hastelloy C276 alloy

In this study, a Hastelloy C276 thin-wall structure was fabricated by wire arc additive manufacturing (WAAM). The microstructure and mechanical properties of the as-deposited structure were evaluated in detail using specimens extracted from different orientations and locations along the deposition direction. The results show that the primary dendrite arm spacing, dislocation density, and second-phase precipitates change along the deposition direction of the material, and they are responsible for the occurrence of anisotropy and heterogeneity in the observed mechanical properties. However, the well-distributed hardness values generated in the as-deposited sample are considered to be due to the uniform directional dendrites. This study enables a better understanding of the WAAM processing-microstructure-properties relationship for the nickel-based alloy, providing useful information for process optimization and improvement in the resultant mechanical properties.

Performance evaluation of MQL with AL2O3 mixed nanofluids prepared at different concentrations in milling of Hastelloy C276 alloy

Since some deficiencies in mist lubri-cooling techniques i.e., minimum quantity lubrication (MQL) in heavy cutting conditions have been noticed, recently nano-cutting fluids which have enrich thermal conductivity than base fluid, are begun to be used in MQL system. One of the critical issues arising in this process is the addition of the appropriate nanoparticle ratio to the base liquid. Therefore, this study aimed to find the optimum distribution rate of Al2O3 nanoparticles having excellent properties and machining parameters. For this purpose, by adding Al2O3 nanoparticles to vegetable-based cutting fluid, nano-cutting fluids were prepared in different volumetric concentrations (0.5, 1.0 and 1.5 vol%). These prepared nanofluids were used in the MQL system when milling of Hastelloy C276. Three cutting speeds (60, 75 and 90 m/min) and three different feed rates (0.10, 0.15 and 0.20 mm/rev) were added to the experimental design to study the performance of nanofluids under several cutting parameters. Apart from this experimental design, to clearly see the effect of concentration rates on tool wear and tool life, three experiments were carried out at each concentration ratio by keeping the machining parameters. Eventually, 1 vol% Al2O3 concentration clearly provided an improvement by up to 23% and 10% in tool life, compared to 0.5 vol% and 1.5 vol% concentration, respectively. In addition, while chipping/fracture, attrition wear and peeling of coating were observed under all cutting conditions, there was no evidence for workpiece material adhesion at 1 vol% and 1.5 vol% Al2O3 based nanofluid-MQL.

High Temperature Corrosion Behaviors of 20G Steel, Hastelloy C22 Alloy and C22 Laser Coating under Reducing Atmosphere with H2S

High-temperature corrosion behaviors of 20G steel, Hastelloy C22 alloy and C22 laser coating was evaluated by corrosion mass gain measurements at 450 °C. The corrosive atmosphere is 0.2 vol% H2S–0.1 vol% O2–N2, which simulated the severe high-temperature corrosion environment occurred under low-NOx combustion in pulverized-coal furnaces. Experimental results showed that the corrosion resistance of the C22 laser coating and the C22 alloy was obviously better than 20G steel. Furthermore, it should be noted that the C22 laser coating fabricated in this study displayed a higher corrosion resistance than the commercial C22 alloy although they had the same chemical composition. The severe pitting corrosion was observed in 20G steel with the corrosion products consisting of FeS2, Fe2O3 and Fe3O4. The C22 alloy and C22 laser coating exhibited the uniform corrosion and their main corrosion products were NiS2, CrS and a small amount of chromium and manganese oxides.

Investigation of Machining Characteristics and Drilling Parameters Optimization in Drilling of Nimonic C-263 Alloy

This paper contains the investigation of machining characteristics and machining parameters optimization while drilling Nimonic C263 alloy. The proposed method is designed as per Taguchi’s Design and drilling trials are conducted utilizing ALCRONA coated drills. An empirical model has been proposed for process performance prediction via RSM (Response Surface Methodology). The optimization of multi response has also been carried out depends on function of desirability approach. The optimized cutting conditions were established. Confirmation tests were conducted to confirm the modelling results.