Alloy Inconel Research Articles

Mechanical properties of laser powder bed fusion processed Inconel alloy IN718 in different heat treatment conditions through small scale specimen testing

Mechanical properties of laser powder bed fusion processed Inconel alloy IN718 in different heat treatment conditions through small scale specimen testing

Application of ANN Concepts for Prediction of Crack Growth and Remaining Life of Circumferentially Cracked Piping Components under Different Loading Scenarios

This paper presents the details of Artificial Neural Network (ANN) based models to predict crack depth and remaining life of circumferentially part-through cracked piping components used in the nuclear industry. Crack growth data from experimental studies on (i) straight pipes made up of SA 312 Type 304LN stainless steel having part-through circumferential notch under combined bending and torsion and (ii) dissimilar metal pipe weld joints having circumferential through-wall crack in the weld were used. The dissimilar metal pipe weld joint is made up of SA312 Type 304LN austenitic stainless steel and SA508 Gr. 3 Cl. 1 low alloy carbon steel and joined by Nickel-rich Inconel alloy weld. About 75% of the mixed experimental data has been used for development of model and the remaining data for validation. For the development of ANN model, (i) back propagation technique (ii) sigmoidal transfer functions and (iii) Levenberg-Marquardt algorithm are used. The maximum percentage difference observed between the predicted and the experimental results for crack depth and remaining life was 19.59% and 15.78% respectively. The efficiency of the developed model was verified using several statistical parameters. The developed models are useful for the structural integrity assessment of piping components under different loading scenarios.

Heat treatments-induced wear resistance of Inconel 718 superalloy fabricated via Laser based Powder Bed Fusion

Laser based Powder Bed Fusion (LPBF) stands out among Additive Manufacturing (AM) techniques for its ability to fabricate intricate geometries with high precision. However, LPBF produced parts, particularly Inconel 718 (IN718) superalloys, demand further exploration in microstructural and mechanical properties aspect. This study explores the effect of heat treatments on LPBF fabricated Inconel 718. Three distinct heat treatments involving diverse solutionizing temperatures and ageing steps were applied to the LPBFed IN718 alloy. As-printed samples showed columnar dendritic microstructure. The heat treatments led to precipitation of strengthening γ′′ and γ′ phases. A substantial increase in microhardness was observed after heat treatments. Wear tests revealed as-printed specimens suffered higher wear loss (∼889 μm) and coefficient of friction (COF) (∼0.627) attributed to Laves phase and low hardness of the matrix. However, heat-treated specimens exhibited substantially lower wear loss (∼217 μm) and COF (∼0.342), with HT2 condition demonstrating superior wear resistance attributed to a homogeneous microstructure.

Comparative analysis of the wear behaviour of TiN/TiAlN, TiAlVN, and TiAlYN coated tools in milling operations of Inconel 718

Abstract Milling is widely used in the aeronautical and aerospace industries, due to the possibility of producing parts with good dimensional stability and surface quality. Because of its exceptional mechanical qualities and limited thermal conductivity, Inconel 718 is a nickel superalloy that is regarded as a challenging material to process. Due to the flexibility of milling, this is the most commonly used process for machining INCONEL alloys. However, high levels of tool wear can be observed. Coatings can be deposited on the cutting tools to improve process performance. Nonetheless, doping elements such as yttrium and vanadium when added to TiAlN-based coatings can increase the coating's resistance. Furthermore, multilayer coatings tend to be very promising resistance to crack propagation. Thus, this work intends to compare three coatings deposited via PVD, in terms of the quality of the machined surface and wear resulting from the process: TiAlVN, TiAlYN, and TiN/TiAlN. The cutting speed (Vc), feed per tooth (fz), and cutting length (Lcut) were varied. It was possible to verify that the multilayer coating had better results, in terms of average roughness (Ra) and in measuring wear (VB3) and its characterisation. On the other hand, the TiAlVN coating showed the worst results. It was concluded that due to the TiN layer, the TiN/TiAlN coating has better resistance to crack propagation, as its adhesion to the substrate is good and there is no delamination.

On the Role of Substrate in Hydroxyapatite Coating Formation by Cold Spray

The deposition of agglomerated hydroxyapatite (HAp) powders by low-pressure cold spray has been a topic of interest in recent years. Key parameters influencing the deposition of HAp powders include particle morphology and impact kinetic energy. This work examines the deposition of HAp powders on various metal surfaces to assess the impact of substrate properties on the formation of HAp deposits via cold spray. The substrates studied here encompass metals with varying hardness and thermal conductivities, including Al6061, Inconel alloy 625, AISI 316 stainless steel, H13 tool steel, Ti6Al4V, and AZ31 alloy. Single-track experiments offer insights into the initial interactions between HAp particles and different substrate surfaces. In this study, the results indicate that the ductility of the substrate may enhance HAp particle deposition only at the first deposition stages where substrate/particle interaction is the most critical factor for deposition. Features on the substrate associated with the first deposition sprayed layer include localized substrate deformation and the formation of clusters of HAp agglomerates, which aid in HAp deposition. Furthermore, after multiple spraying passes on the various metallic surfaces, deposition efficiency was significantly reduced when the build-up process of HAp coatings shifted from ceramic/metal to ceramic/ceramic interactions. Overall, this study achieved agglomerated HAp deposits with high deposition efficiencies (30–60%) through single-track experiments and resulted in the preparation of HAp coatings on various substrates with thickness values ranging from 24 to 53 µm. These coatings exhibited bioactive behavior in simulated body fluid.

On corrosion and passivity of Inconel alloy 625 in HNO3 solution

Exploring the passivity and electrochemical behavior of Inconel alloy 625 in nitric acid solution could open up possibilities for potential applications, either in bulk form or as claddings. Hence, this research investigates corrosion behavior and passivity of Inconel alloy 625 in nitric acid solutions of varying concentrations (0.01–1.00 mol/L) using a range of analytical techniques, including potentiodynamic polarization testing, chronoamperometry measurement, Mott-Schottky (MS) analysis, X-ray diffraction (XRD) approaches, and point defect modeling (PDM). Results demonstrate that corrosion current density does not necessarily decrease with increasing electrolyte concentration (Please check it out). Additionally, the alloy exhibits higher passive film transpassive potentials in more concentrated solutions. Potentiostatic polarization tests reveal an increase in steady-state current densities attributed to the passive films formed in more concentrated solutions. Lower electrolyte concentrations lead to the formation of more intact bilayered passive films. In this context, the formation of passive films is elucidated by examining the generation and annihilation of point defects. The semiconducting behavior of passive layers is further examined through XRD patterns and electrochemical properties. According to PDM, the diffusivity of point defects within the passive films and their respective donor densities can be closely correlated.

Crystal plasticity-driven evaluation of notch fatigue behavior in IN718

The aim of this study was to establish a method for evaluating notch fatigue behavior through crystal plasticity finite element (CPFE) simulations based on the actual microstructure of the nickel-based alloy Inconel 718 (IN718). Initially, the equivalent plastic strain, εeps, which reflects the comprehensive slip at the grain scale, was employed to analyze the fatigue crack initiation mechanism of IN718, revealing that twinning and triple junctions of grain boundaries were high-risk locations for fatigue crack initiation. Next, fatigue simulations were performed on notched specimens using the CPFE model, with a material-level CPFE model particularly employed at the notch root. The increment of εeps, Δεeps, in a stable cycle was used as the fatigue damage control parameter and correlated with the fatigue life, Nf, revealing that the Δεeps-Nf relationship at material-level satisfied the form of the Mason-Coffin model. Finally, fatigue life prediction of IN718 notched specimens was carried out based on the Δεeps-Nf relationship, with the predicted results falling within the 2-fold scatter band, demonstrating good prediction accuracy.

INNOVATIVE APPROACH TO ENSURING THE QUALITY OF GAS TURBINE ENGINE PARTS PRODUCED BY SELECTIVE LASER SINTERING FOR UAV

The research objects are gas turbine engines parts, manufactured using an innovative method of additive manufacturing – selective laser sintering. The main problem solved in this work is the low quality of the surface layer and the residual porosity of the parts obtained by this method, which significantly limits their operational characteristics and durability. As a result of the experimental studies, rational operating parameters of diamond smoothing were established. This allowed to significantly improve the surface quality and increase the operational characteristics of parts made of heat-resistant alloys INCONEL 718 and an intermetallic alloy based on titanium aluminide OX45-3ODS. The effectiveness of diamond smoothing is explained by local plastic deformation and compaction of the surface layer of parts under the influence of high contact pressures and temperatures. This leads to a significant reduction in surface roughness, an increase in the surface hardness due to strain hardening and a significant reduction in the size and number of residual pores. A characteristic feature of the obtained results is the ability to control the quality parameters of the surface layer by varying the diamond smoothing operating parameters – smoothing force, feed, radius, and geometry of the smoother's working part. The established regularities of the smoothing operating parameters have an impact on the quality characteristics of the surface. This information can be utilized in the development of highly efficient technological processes for the production and restoration of gas turbine engines, critical components of unmanned aerial vehicles, obtained through selective laser sintering. Implementing the elaborated technological recommendations will permit broadening the range of goods produced by additive manufacturing and enhancing their capacity and dependability during operation under conditions of cyclical loads and extreme temperatures.

The influence of anisotropy on the character of hardening in additive high-strength alloys

The purpose of this work is to establish the dependence of the coefficients of planar anisotropy on the intensity of localized deformations in various loading ranges of transverse and longitudinal sections of samples of heat-resistant powder alloy Inconel 718 manufactured using SLM technology. The role of technological anisotropy of samples characteristic of SLM technology and its effect on the hardening of Inconel 718 alloy products is evaluated. Methods. To achieve this goal, the deformation diagrams of Inconel 718 powder alloy samples manufactured using SLM technology, measured during their stretching according to GOST 11701-84, were analyzed. Flat samples with a dividing grid applied to their surface were subjected to loading. During the tests, localized deformation of the samples in different sections was determined by measuring the geometry of the images of the dividing grid. A specially developed photo and video recording technology was used to capture these images. Results. The statistical analysis of the type and parameters of the deformation diagrams made it possible to determine the nature of changes in the intensity of stresses and deformations of the samples of the studied material. The linear character of its tensile hardening in the region of small values of strain intensity and the power-law character of hardening in the range of strain intensity from 0.03 to 0.17 were established. Conclusion. A significant effect of the technological anisotropy of Inconel 718 heat-resistant powder alloy samples obtained using SLM technology on the intensity of deformations is shown. The necessity of taking this fact into account in the development of technological processes for the production of responsible products from the studied material has been revealed.

Investigation of the high temperature molten salt corrosion properties of Inconel625 alloy with Al

The Inconel625 (In625) alloy is one of the main materials in heat receivers of concentrated solar power (CSP). To further improve the corrosion resistance of heat receivers in molten salt, Al element that can form an oxide film was added into In625 alloy. In this study, In625 alloy with 3 wt% Al was prepared, and its corrosion resistance in carbonate (Li2CO3-Na2CO3-K2CO3) at 650 °C was studied. Results showed that a continuous dense oxide protective film (Al2O3 + LiAlO2) in surface of sample was formed by adding Al element during high temperature molten salt corrosion, which reduced the corrosion rate of In625 alloy. The corrosion rate of In625 alloy with 3 wt% Al corroded for 48 h and 120 h were 44 μm/year and 89 μm/year, respectively.

Evaluation Methods and Coupled Optimization at Macro- and Micro-Scales for Profiled Ring Rolling of Inconel718 Alloy.

The forming quality of profiled ring rolling not only encompasses macroscopic accuracy but also emphasizes the microstructure. Due to the multiple process parameters and complex metal flow during profiled ring rolling, the various forming defects are difficult to control and difficult to study theoretically. The objective of this study is to establish a comprehensive method for evaluating the forming quality of profiled rings, which considers both the macroscopic forming accuracy and the microstructure. Firstly, the synthetic size factor was defined, and the evolutionary relation between the section forming rate and the diameter growth rate of E-section ring rolling was analyzed in detail. The synthetic size factor can be used to describe the dimensional evolution and evaluate the forming accuracy of the profiled ring rolling process. Taking into full consideration the features of intermittent deformation in local areas, a microstructure evolution model of the Inconel718 alloy during E-section ring rolling, which can accurately predict the recrystallization volume fraction and average grain size of the final ring, was established. Then, combined with finite element simulation, the influence of the rotation speed of the driving roll on the macro-size evolution and microstructure was systematically analyzed. The results indicate that there is often a discrepancy between dimensional accuracy and microstructure uniformity in the optimization trend. For instance, the higher the rotation speed of the driving roll is, the more uniform the microstructure is, but the more difficult it is for the section profile to form. Finally, combined with response surface methodology (RSM), multi-parameter optimization was carried out with section forming accuracy and grain uniformity as the optimization objectives. By using the optimal parameters, an E-section ring with a complete profile and a uniform microstructure was obtained, with a maximum prediction error of the recrystallization volume fraction lower than 5%. The results show that the macroscopic and microscopic quality evaluation methods proposed in this study, as well as the optimization method combining RSM, can be effectively applied to the process optimization of profiled ring rolling.

Microstructural Stability of IN625 Reinforced by the Addition of TiC Produced by Laser Powder Bed Fusion after Prolonged Thermal Exposure.

This paper deals with the development and characterization of an Inconel 625 (IN625) reinforced with 2 wt.% of sub-micrometrical TiC particles produced by the laser powder bed fusion (LPBF) process. IN625 and IN625 2 wt.% TiC microstructural evolution was evaluated in the as-built, solution-annealed (2 h at 1150 °C), and prolonged heat-treated (2 h at 1150 °C + 100 h at 1000 °C) conditions. The IN625 and IN625 + TiC samples were successfully produced with low residual porosity (<0.15%). In the as-built conditions, both materials developed mainly columnar grains elongated to the building direction with melt pools, fine dendric structures, and small fractions of recrystallized grains. Some TiC segregations were observed in the composite, preferentially located at the melt pool boundaries. The heat treatments led to a different microstructural evolution between the base alloy and the composite. After solution annealing, the IN625 alloy was subjected to full recrystallization with a drastic reduction in hardness. Afterward, the prolonged thermal exposures for 100 h at 1000 °C provoked the formation of carbides, increasing the hardness. On the contrary, the composite retained the as-built microstructure with columnar grains in the solution-annealed and prolonged heat-treated conditions, revealing a limited formation and growth of carbides, thus resulting in a reduced hardness variation. The addition of TiC inside the IN625 enhanced the microstructural stability of the composite, preventing the recrystallization and the growth of phases occurring under prolonged thermal exposures. The current study therefore reported the effect of TiC particles on the microstructural stabilization of LPBFed IN625, with a peculiar focus on the prolonged thermal exposure at 1000 °C.

On the Development of a Heat Treatment for Inconel Alloy X-750 Produced Using Laser Powder Bed Fusion

On the Development of a Heat Treatment for Inconel Alloy X-750 Produced Using Laser Powder Bed Fusion

Evaluating Ti-6Al-4V for Laser Direct Energy Deposition: Insights from Powder Metallurgy Techniques

Laser Direct Energy Deposition (LDED) is a highly precise additive manufacturing technique that enables the creation and repair of complex metal components by melting and depositing metal powders. This study comprehensively evaluates Ti-6Al4V alloy within the LDED framework, highlighting its performance relative to other metals such as stainless steel, Inconel, and aluminum alloys. Ti-6Al-4V, a titanium-based alloy known for its exceptional strength-to-weight ratio, fatigue resistance, and corrosion resistance, is scrutinized for its advantages and limitations in the LDED process. The research includes a detailed comparison of mechanical properties, thermal behavior, and cost-effectiveness of Ti-6Al-4V against other common LDED metals. Additionally, the study explores the impact of powder metallurgy techniques on the deposition quality and performance of Ti-6Al-4V, focusing on aspects such as powder production methods, particle size distribution, and alloying effects. Real-world applications and case studies from industries including aerospace, automotive, and medical engineering are examined to illustrate the practical advantages of Ti-6Al-4V. The paper concludes by identifying key challenges and opportunities associated with Ti-6Al-4V in LDED and offering recommendations for future research and practical applications. This comprehensive evaluation aims to enhance understanding of Ti-6Al-4V's role in LDED and guide its optimized use in advanced manufacturing contexts

Fabrication and tribological behavior of laser cladding Cu/Ti3SiC2 reinforced CoCrW matrix composite coatings on Inconel718 surface

To satisfy the need for high wear resistance of Inconel718 alloy under harsh working conditions, laser cladding technique was adopted to fabricate the Cu/Ti3SiC2-CoCrW metal matrix composite coatings on that surface. The phase composition, microstructure, microhardness, surface energy, and tribological properties of the composite coatings were systematically analyzed by characterization methods such as XRD/ SEM/ EDS/ XPS and performance test methods such as high-temperature friction and wear test, and the wear mechanism at different temperatures was deeply discussed. The research results indicate that the microhardness of coatings is increased by 2.2–2.9 times compared to the substrate, which is mainly owing to the solid solution strengthening effect and the diffusely distributed hard reinforcing phases such as Cr7C3, WCx, and TiC. Regarding the wear resistance, the wear rate of coatings is significantly reduced by 1–2 orders of magnitude over the substrate. Among them, the Co-based coating adding 10 wt% Cu - 10 wt% Ti3SiC2 exhibited the lowest wear rates at room and high temperatures, which were 0.22 and 3.23 × 10−5 mm3/ N·m, respectively, with 98.22 % and 88.19 % reductions in comparison with the substrate. The low surface energy (27.94 mN/m) was one of the main reasons for the good tribological properties. When the friction environment changes from room temperature to 600 °C, the primary wear mechanism of coatings changes from abrasive and adhesive wear to oxidative wear.

Prediction of circularity of the holes in electrical discharge machining of inconel alloy using machine learning technique

Prediction of circularity of the holes in electrical discharge machining of inconel alloy using machine learning technique

Thermal Analysis of Micro-Channel Internal Cooling in Cutting Tools: A Machine Learning Approach

The use of coolants for cutting process in metal cutting operations is customary. Turning causes high cutting heat in nickel base super alloy Inconel 718. Nonetheless, it should be acknowledged that although flooding techniques are commonly used in the machining of super alloys, these flood cooling methods have extremely poor efficiencies. Another alternative to increase the cooling capabilities of fluids would be an internal-cooling approach that would enable to lower machining temperatures significantly. The heat dissipation ability in the tool is also greatly influenced by the micro-channel diameter of tool which further causes a significant effect on the coolant outlet velocity. A design of an internal-cooling single point cutting tool with micro channel structures for enhanced coolant heat transfer capability and reduced machining temperature is used for turning Inconel 718 under dry, flooded cooling and internal cooling to study the effects of cooling conditions on cutting force, cutting temperature and surface quality. A regression model is built using the Random Forest (RF) and Support Vector Regression (SVR) methods in machine learning framework. These models were then used to forecast input parameters, such as channel diameter and inlet pressure, which made it easier to obtain output data, such as pressure and maximum velocities at different notches. Eighty percent of the data in the dataset is used to train the model and with the remaining twenty percent set aside for evaluating the model's functionality. When comparing internal-cooling technology to traditional flood cooling, there are clear benefits including increased heat transfer efficiency, which leads to lower cutting temperatures, less cutting force, and better surface quality. More specifically, in the internal-cooling configuration, a direct relationship is shown between rising coolant inlet pressure and falling cutting force and temperature over time. Further highlighting the advantages of this cooling strategy is the relationship between increased intake pressure and decreased surface roughness.

Multiple cracking, crack coalescence and fatigue lifetime – Model and experiments on an austenitic steel and on a nickel base alloy

In many metals and alloys, low-cycle fatigue (LCF) and thermomechanical fatigue (TMF) generate a large number of surface microcracks. Using the replica technique, we document their growth and coalescence in the austenitic steel 1.4550 and the nickel base alloy Inconel 100. A model based on elastic–plastic fracture mechanics is developed, which considers the growth and coalescence of many coplanar semi-elliptical surface cracks. The results of the model are consistent with the experiments. An important conclusion is that the fatigue lifetime predicted by the multi-crack model is not substantially shorter than that predicted by a corresponding model assuming only a single semi-circular surface crack. This means that lifetime assessment can still be based on single-crack data, if one considers a factor 2 to include scatter and multiple-crack effects.

Influence of alloying elements on stacking fault energy in Ni and Ni-based alloy: A first–principles study

The study of the reliability of Ni-based alloys and their performance under high-temperature radiation environments is crucial for nuclear reactor application. The first-principles study has been utilized to investigate the effect of individual alloying elements (Cr, Fe, Mo, Nb) on the stacking fault energy (SFE) of pure Ni in order to understand their specific contribution in the superalloy Inconel 718 (IN718). The result shows that the addition of an alloying element in pure Ni reduces the SFE value with the most significant reduction seen in IN718 alloy. The role of individual alloying element in the reduction of the SFE in IN718 is conjectured. The DOS at EF of all the elemental substitution configurations were also calculated and significant change is seen in the alloy IN718. Such reduction is due to the interrupted distribution of d-electrons and atomic bonding on the stacking fault planes, reflected in the SFE value.

Modeling of bonding pressure based on the plastic deformation mechanism of interfacial voids closure in solid-state diffusion bonding

The model of the diffusion bonding pressure was established using the analysis calculation method and further verified by the finite element analysis (FEA) and the experiments. The normalized temperature was defined as the ratio of temperature and the melting point of the base materials. And the normalized bonding pressure was defined as the ratio of the applied bonding pressure and the yield strength at the bonding temperature. The contribution of the plastic deformation to the void closure expressed a linear relationship with the normalized bonding pressure, of which the slope was 3. The relationship was appropriate in TiAl6V4, pure copper C11000, aluminium alloy AA6061, stainless steel SUS 304, and Ni-based alloy Inconel 617 using analysis calculation. The diffusion bonding pressure design range can be summarized as σn = 0.05–0.577. Subsequently, the analytic computational model was verified by FEA. The results showed that the maximum stress was concentrated in the position of the void neck. And the linear relationship between the normalized bonding pressure and the bonded ratio was also tenable. There was a stable static error existed between FEA and the analytic computational analysis. Furthermore, the experimental verification showed the verification and accuracy of the analytic computational analysis results.