Nickel Alloys Research Articles

Heat transfer enhancement with additively manufactured rough surfaces: Insights from large-eddy simulations

To study the impact of additively manufactured (AM) roughness on fluid flow and heat transfer, we performed a series of high-fidelity large-eddy simulations on turbulent heat transfer over a three-dimensional AM rough surface with varying bulk Reynolds number and average roughness height values. We considered rough surfaces created using AM techniques at Siemens based on Nickel Alloy IN939 material with four different mean roughness heights, ks= 1.594, 1.992, 2.630, and 3.984 mm, and the simulations were performed at five bulk Reynolds numbers of 1000, 3000, 6000, 11 700, and 18 000. The temperature was treated as a passive scalar with a Prandtl number of 0.71. To better understand the effect of wall roughness on the momentum and heat transfer mechanism, mean temperature and velocity profiles as well as heat fluxes are presented. The wall-normal Reynolds stress, ⟨ux′ur′⟩, and heat flux, ⟨ur′Θ′⟩, decrease for larger wall roughness heights, Ra, and their respective magnitudes remain very similar for different Ra. A similarity rule for friction factor and heat transfer is used to correlate and interpret the numerical results and compare them with previously existing results, both theoretical and experimental. The assessment of the thermal performance factor illuminates the improvement in heat transfer with the existing surface roughness. By studying the probability density functions of the instantaneous Stanton number, the recirculation zones, which are the result of an adverse pressure gradient, were found to have a profound effect on heat transfer. This is important as it leads to the wall-scaled mean temperature profiles being of larger magnitude than the mean velocity profiles both inside and outside the roughness layer. This means that the temperature wall roughness function, ΔΘ+, differs from the momentum wall roughness function, ΔU+.

Influence of cutting edge microgeometry on the cutting forces when machining difficult-to-cut materials

The paper presents research investigating the influence of cutting tools microgeometry on the cutting forces when milling difficult-to-cut materials. Austenitic stainless steel AISI 316L and nickel alloy Inconel 718 were machined with cemented carbide tools with various cutting edge rounding size while measuring the cutting forces during the process. From the standpoint of milling difficult-to-cut materials lowering the cutting forces load on the tool can be difficult to achieve without significant reduction of cutting parameters. Previous research into the cutting edge microgeometry suggests that modification of the cutting edge of milling tools can substantially extend the effective tool life, reduce cutting forces in the process and ensure higher quality of the machined surface. Results of long term wear tests of tools with cutting edge rounding sizes of 15, 30 and 45 µm are compared to the results of a sharp unprepared cutting tool, and the results of each machined material are also compared. Possible influence of cutting edge radius on the process for both materials was tested for cutting conditions constituting finishing operation. The most effective cutting edge radius size differed between the materials, with 15 µm rounding performing the best for AISI 316L and the sharp unprepared tool performing the best for the Inconel 718 alloy.

Distinct Evidence of Hydrogen-Enhanced Defect Formation on Pre-Strained Nickel Alloy 625 during In Situ Electrochemical Nanoindentation Test

Distinct Evidence of Hydrogen-Enhanced Defect Formation on Pre-Strained Nickel Alloy 625 during In Situ Electrochemical Nanoindentation Test

Localized Corrosion Resistance of Nickel Alloy 718 in Chloride-Containing Environments

Resistant to aggressive reducing environments and combining excellent mechanical properties, the age-hardenable Alloy 718 is the most broadly used nickel alloy in the oil and gas industry. Nevertheless, its localized corrosion resistance in oxidizing halide-containing environments has yet to be thoroughly investigated, with conflicting results discussed in the literature. In this regard, Alloy 718 has a relatively low pitting resistance equivalent, limiting in practice its use, where localized corrosion is expected, particularly in seawater applications. This work quantified the localized corrosion resistance of the alloy in chloride-containing environments. The potentiodynamic-galvanostatic-potentiodynamic (PD-GS-PD) technique was used to determine the crevice corrosion repassivation potential (ER,CREV) in deaerated natural seawater at different temperatures for two Alloy 718 grades (i.e., aerospace, as per ASTM B670, and oil and gas, as per API 6ACRA, grades). Additionally, PD polarization testing was conducted for the API 6ACRA grade in acidified solutions with varying chloride concentrations to simulate pit/crevice-like conditions. In the aerospace heat treatment condition, Alloy 718 suffered crevice corrosion at temperatures as low as 10°C, while the API 6ACRA grade remained unaffected at the same testing temperature. Stable crevice corrosion occurred at 20°C and 50°C for both grades.

Aluminum Co-Deposition via DC Magnetron Sputtering for Enhanced Pitting Resistance of Copper–Nickel Alloys

To investigate the improvements in the resistance of Cu–Ni alloys to surface pitting corrosion, Cu–Ni thin films containing Al were fabricated via DC magnetron sputtering. The morphologies of the fabricated samples were obtained using a scanning electron microscopy, which yielded information on the crystal size and sample surface before and after corrosion tests. X-ray diffraction was employed for the structural characterization of the as-deposited films, and vibrational spectroscopy was used to verify the corrosion products. The corrosion behaviors of the Cu–Ni and Cu–Ni–Al samples were examined using electrochemical polarization and cyclic corrosion tests. The Al co-deposited samples showed a refined crystal size as compared to the Cu–Ni sample, suggesting that they are more susceptible to the formation of a passivation film. The corrosion current density of the Cu–Ni–Al was reduced, and the corrosion potential was lower than that without Al content. The negative shift in the corrosion potential of the Al-containing samples indicates that the Al2O3 film suppressed the cathodic reaction, resulting in a decrease in the corrosion rate. These results are consistent with the cyclic corrosion test results, in which no pitting corrosion is observed in the Cu–Ni–Al sample.

Molecular dynamics simulations of a nanobubble’s collapse-induced erosion on nickel boundary and porous nickel foam boundary

Nickel (Ni) alloys and their foam composites are extensively acknowledged materials utilized in the construction of propellers and hulls for the shipbuilding industry. Erosion caused by bubble collapse, a well-documented form of damage on ship rudders, propellers and hulls, can alter the physical properties of Ni and its foam, consequently constraining their potential applications. The present study aims to investigate the process of nanobubble collapse and its impact on the mechanical and thermal properties of Ni boundary and porous Ni foam boundary. To achieve this, a molecular dynamics (MD) simulations was used to study nanobubble collapse dynamics near the boundaries. Results indicated that the nanobubble collapses due to the contrasting pressure and velocity at the interface between the shock wave and the nanobubble surface. As the nanobubble collapses, its volume decreases, resulting in the formation of a water nano-hammer with a pressure and temperature of approximately 30 GPa and 5000 K. The high impact of the nano-hammer leads to erosion in the case of the Ni boundary and compression in the porous Ni foam boundary. The mechanical stability of an eroded Ni boundary decreases due to the creation of dislocations under the impact of the nano-hammer. However, the thermal stability of the Ni boundary remains relatively unaffected by the erosion process. The compressed Ni foam boundary exhibits a lower specific surface area, smaller cell size, and shorter struts compared to the uncompressed Ni foam boundary, resulting in increasing of the mechanical and thermal stability.

Platinum–Nickel Alloy Nanowire Electrocatalysts Transform into Pt-Skin Beads-on-Nanowires Keeping Oxygen Reduction Reaction Activity During Potential Cycling

Platinum–Nickel Alloy Nanowire Electrocatalysts Transform into Pt-Skin Beads-on-Nanowires Keeping Oxygen Reduction Reaction Activity During Potential Cycling

Effect of dilution on the microstructure and high-temperature wear resistance of self-lubricating nickel alloy claddings

In this study, the impact of substrate dilution on the microstructure and tribological properties of tungsten inert gas (TIG)-deposited self-lubricating claddings was investigated. The dilution of Ti content on cladding increased as the TIG current increased, and the microhardness of the cladding decreased. The content of intermetallic phases such as TiNi and TiC increased with the increase in TIG current. The tribological studies revealed that coating dilution at higher TIG currents has prominent effects on wear behaviour at elevated temperatures. In both clads, the percentage decrease in hardness from higher TIG current to lower TIG current was noted as 31%. The higher dilution of Ti content in the cladding was found to be beneficial in tribological studies performed, especially at higher temperatures (≥400). Also, solid lubricants such as MoS2 and BaF2 encapsulation in the nickel alloy were found to be beneficial at both low and high temperatures.

The Performance of Different Etchants on the Carbides of Ni600 and Ni625

Nickel-based alloys that contain chromium are widely used in corrosion-resistant applications in industry, but they are sensitive to the environment when the passive chromium oxide layer is damaged. In Ni600 and Ni625 alloys, precipitates can deplete the surface layer of chromium oxide. To better characterize and analyze the nickel alloy surfaces and their chromium carbides, chemical etching with different etchants and electrolytic etching were applied to sample surfaces. This paper revealed their efficacy in etching various carbides within the nickel alloys, and orange phases ranging from 2 to 20 μm in optical micrographs were identified as titanium-containing compounds. Carbides located on the grain boundaries were determined to be Cr23C6 and were surrounded by chromium-depleted zones. The findings and figures in this paper provide a more intuitive reference for future analysis of carbides and titanium nitrides, enhancing the understanding of their impact on the corrosion resistance of these alloys, which will not only contribute to the material science field but also aid in developing the Ni-based alloys for industrial applications.

Evaluation of the Surface Topography and Deformation of Vertical Thin-Wall Milled Samples from the Nickel Alloy Inconel 625.

During the production of components, manufacturers of structures are obliged to meet certain requirements and ensure appropriate quality characteristics. It is especially important during the manufacturing of thin-walled structures, which are subject to many errors during machining due to the reduced rigidity of the products, including the deformation of thin walls, which may be the result of the vibration of the system. The appearance of vibrations reduces the quality of the machined surface affecting the increase in the values of surface topography parameters-waviness and roughness. Thin-wall structures-titanium or nickel alloy, among others-play a key role in the aerospace industry, which constantly strives to reduce the weight of the entire structure while meeting requirements. The present work focuses on the evaluation of the parameters of surface topography, dimensional and shape accuracy during the milling of nickel alloy Inconel 625 samples containing a thin wall in a vertical orientation. The experiment was conducted under controlled cutting conditions using a constant material removal rate. As part of the surface topography section, the distribution of waviness, Wa and Wz, and roughness, Ra and Rz, was determined in selected measurement areas in the direction parallel to the direction of the feed motion. Dimensional deviations, measured with a 3D optical scanner, were determined in selected cross sections in the direction perpendicular and parallel to the bottom of the sample presenting the deflection of the thin-walled structure. The results provide information that the used parameter sets affect the measured quantities to varying degrees.

IMPROVEMENT OF FORMABILITY AND SURFACE FINISH OF CUPRO–NICKEL (70/30) ALLOY DURING SINGLE POINT INCREMENTAL FORMING PROCESS USING CHROME STEEL LASER ABLATED BALL

Cupro–nickel alloy of 70/30 grade was experimented for its formability by SPIF tests, namely straight groove test and wall angle test using a ball attached tool, to emphasize the concern on formability and surface roughness. Two different types of ball were used, one ball was used in polished form and another one was surface-textured using Nd-Yag laser. The cupro–nickel alloy has excellent corrosion resistance and popularly used in marine environments. In this research, an attempt has been made to study the formability when using Chrome steel laser ablated ball. The results concluded that Chrome steel laser ablated ball with oil as lubrication has avoided the occurrence galling and at the same time improved the formability. When experimenting with chrome steel polished ball, the tool and sheet contact is high and the lubricating oil will be less and it is causing the sheet to get heated. The dimples on the ball’s surface made by the laser retain more lubricating oil and thereby decreasing the friction which eventually leads to the delayed fracture. It is found that the formability was increased by 16% in straight groove test, 4.8% for wall angle test and surface roughness values were decreased by 1.4%.

Welding investigation of Hastelloy C-276 and parametric optimization using integrated MRA-TLBO algorithm during A-TIG process

A-TIG welding is a modified form of GTAW process that has become popular due to its ability to create high-quality welded joints with minimal cracks and distortion. This technique is commonly used to join various metals, including stainless steel, aluminum, titanium, and nickel alloys like Hastelloy C-276, which is used in fabrication of complex components across marine, nuclear, aerospace, and chemical industries. In this investigation, A-TIG welding of Hastelloy C-276 was studied using three parameters - welding current, welding speed, and gas flow rate - at three distinct levels. The impact of these parameters were analyzed on two responses, namely penetration depth and width of weld. Macrostructural investigation, sensitivity analysis, and parametric studies revealed that welding current (I) had the most influence, followed by speed of welding (S) and flow rate of gas(G). Full quadratic multiple regression analysis-based models were developed for both responses, which were found to be suitable with a higher coefficient of determination and an average percentage error of 2.165% and 2.624%, respectively. Additionally, a teaching learning based optimization algorithm was integrated with these models to identify the most effective A-TIG parameter combination for higher penetration depth and lower weld width. The MRA-TLBO integrated approach resulted in an optimal parametric combination of I (170A), S (180 mm min−1), and G (11.37 l min−1) that resulted in a penetration depth and weld width of 4.503 mm and 4.684 mm, respectively. Validation at this optimal setting showed an improvement of 3.365% and 1.284% for weld width and penetration depth, respectively, suggesting the robustness of the developed methodology.

Highly Conducting Surface-Silverized Aromatic Polysulfonamide (PSA) Fibers with Excellent Performance Prepared by Nano-Electroplating.

In this work, bilayer nanocoatings were designed and constructed on high-performance aromatic polysulfonamide (PSA) fibers for robust electric conduction and electromagnetic interference (EMI) shielding. More specifically, PSA fibers were first endowed with necessary electric conductivity via electroless nickel (Ni) or nickel alloy (Ni-P-B) plating. Afterward, silver electroplating was carried out to further improve the performance of the composite. The morphology, microstructure, environmental stability, mechanical properties, and EMI shielding performance of the proposed cladded fibers were thoroughly investigated to examine the effects of electrodeposition on both amorphous Ni-P-B and crystalline Ni substrates. The acquired results demonstrated that both PSA@Ni@Ag and PSA@Ni-P-B@Ag composite fibers had high environment stability, good tensile strength, low electric resistance, and outstanding EMI shielding efficiency. This indicates that they can have wide application prospects in aviation, aerospace, telecommunications, and military industries. Furthermore, the PSA@Ni-P-B@Ag fiber configuration seemed more reasonable because it exhibited smoother and denser silver surfaces as well as stronger interfacial binding, leading to lower resistance (185 mΩ cm-1) and better shielding efficiency (82.48 dB in the X-band).

Study of composite coatings based on nickel alloy

A composite coating Inconel-625/WC on a VT6 nickel alloy is obtained by laser cladding. Studies of laser tracks of composite composition in a wide range of concentrations of the carbide phase and at different values of technological para meters of the process are carried out. Based on the results of quantitative metallographic analysis, optimal coating compositions are selected and intervals of technological parameters are established, allowing to obtain nonporous coatings with minimal penetration of the substrate and a given geometry of the cross-section of the laser track.

Optimization of wire spark erosion machining of Grade 9 titanium alloy (Grade 9) using a hybrid learning algorithm

Manufacturing has grown challenging because of the increased usage of harder materials, such as titanium alloys, in many industries, such as aerospace, automobiles, and marine. Conventional material removal procedures are not suitable for these tough materials due to their increased hardness and slow machinability. Wire Electrical discharge machining (WEDM) is a modern approach for material removal, particularly for harder materials, such as titanium alloys, nickel alloys, hard particle reinforced metal matrix composites, etc. The research design was performed by deeming the independent factors, such as duration of pulse and applied current. The removal rate of material, surface roughness of the machined region, dimensional deviation, and tolerance errors in form/orientation are considered performance metrics. Taguchi’s approach was engaged to assess the process variables, and the importance of the process factors was established using analysis of variance approach. The purpose of this research is to create an AI based decision making tool, which can be utilized to anticipate the various parameters that impact the WEDM material removal process. The discoveries of the present exploration allowing the manufacturers to make better-informed decisions with a developed model’s capability by demonstrating that the model’s predicted values were in close confirmation to the actual values.

Effect of TIBW anti-wear coating on cutting tools for milling of nickel alloys on tool wear and integrity of state of the technological surface layer

In the article, research was carried out to determine the impact of the TiBW anti-wear coating on the operational properties of cutting tools for machining nickel alloys. The dynamics of tool wear were determined based on changes in the components of the total cutting force, microscopic observation of wear on the flank surface, and observation of wear based on SEM images. The condition of the technological surface layer was also determined in the form of changes in the microstructure morphology and hardening of the surface layer. The research was compared to a reference tool with the same geometry with an AlTiN coating. It was shown, among other things, that TiBW coatings can be used successfully for cutting tools for machining nickel alloys, and that the wear dynamic is similar to those of tools with the AlTiN coating. The analyses confirmed the significant thermomechanical impact of the cutter during machining, manifested by chipping and a tendency to strengthen the processed material. Based on observations of the microstructure of the surface layer after processing, it was shown that the thermal conductivity of the TiBW coating may be lower than that of the AlTiN coating, which is reflected in the different depths of the thermomechanical interaction zones.

A Study On Stress Management Among Employees Towards Alloy Industries With Reference To Coimbatore

In order to boost strength or corrosion resistance, two or more metallic components are mixed to form an alloy, which is a type of metal. A metallic material composed of two or more elements is called an alloy, sometimes known as a compound or a solution. Although the non-metal carbon is an essential part of steel, the constituents of alloys are normally metals. Alloys are often created by melting the mixture of components. According to customer specifications and drawings, Alloys Industries manufactures and exports a variety of machined and un-machined castings made of Carbon Steel, Stainless Steel, Low Alloy Steel, Heat Resistant Steel, Martensitic Stainless Steel (CA6NM), Precipitated Hardened Steel (CB7Cu-1), Nickel Alloy, and Duplex Stainless Steel. The phrase "stress managements" is broad and includes training, facilitation, and education about the effects that stress has on an individual or group. The study of stress management fosters and encourages the development of coping mechanisms. Employees' physiology and psyche are stressed out by organisational elements such management-labor relations, working conditions, resource distribution, the role of trade unions, employee behaviours, etc. The working practises and policies of an organisation are among its most important influencing variables. This study examined the occupational stress experienced by Alloy Industries in Coimbatore, employees in great detail.

Accurate prediction analysis of steel alloy elements by femtosecond laser-ablation spark-induced breakdown spectroscopy and out-of-bag random forest regression

Femtosecond laser-ablation spark-induced breakdown spectroscopy (fs-LA-SIBS) and out-of-bag random forest regression (OOB-RFR) were developed for accurate quantitative analysis of the elements manganese (Mn), chromium (Cr), and nickel (Ni) in steel alloys.

High temperature gas and salt corrosion of nickel alloy

High temperature gas and salt corrosion of nickel alloy

Effect of h-BN on corrosion behavior of nickel-copper alloy coatings prepared by high-speed laser cladding

Nickel-copper alloy is widely used because of its strong corrosion resistance in marine environment. There are great potentials to prepare NiCu alloy coatings on the surface of structural steel to replace cast NiCu alloys due to its high cost. High-speed laser cladding has characteristics of fast melting rate, low surface roughness, fine microstructure and low dilution ratio. However, nickel alloy coatings has the problem of solidification cracks. In this study, a series of composite coatings were prepared by using NiCu powders with different h-BN contents, then the effect of h-BN on structure and anti-corrosion of coatings was analyzed. The study shows that the structure of the NiCu composite alloy coatings was equiaxed crystals, columnar crystals and planar crystals from top to bottom portion. After adding h-BN, the coating had a lower oxygen vacancy mobility rate, resulted in the optimal corrosion resistance of passive film.