Inconel Research Articles

Composition and Element Distribution Mapping of γ' and γ″ Phases of Inconel 718 by High-Resolution Scanning Transmission Electron Microscopy and X-ray Energy-Dispersive Spectrometry.

The main strengthening mechanism for Inconel 718 (IN718), a Ni-based superalloy, is precipitation hardening by γ' and γ″ particles. It is thus essential, for good alloy performance, that precipitates with the desired chemical composition have adequate size and dispersion. The distribution of the γ' and γ″ phases and their chemical composition were investigated in the nickel-based Inconel 718 superalloy by taking advantage of the new capabilities of scanning transmission electron microscopy and energy-dispersive X-ray spectrometry using a windowless multiple detector, a high-brightness Schottky electron gun, and a spherical aberration corrector in the illumination probe optics. A small routine was developed to deconvolute the respective compositions of γ' and γ″ nanoprecipitates embedded in the γ matrix. Keeping the electron probe current low enough-a few hundred pA-prevented excessive irradiation damage during the acquisition of element maps and brought their spatial resolution down to the atomic column level to track their element compositions. The present results agree with and complement atomic probe tomography observations and Thermo-Calc predictions from the literature. The presence of an Al enrichment at the γ'/γ″ interface-which may control the γ″ phase coarsening-is observed in the last row of Al-Nb-Ti columns along this interface. In addition, a few columns with similar composition changes are found randomly distributed in the γ' phase.

A Comparative Study of Ratcheting Fatigue Behavior of Modified 9Cr–1Mo Steel and Inconel 617 Alloy at Homologous Temperature of 0.42

The modified 9Cr–1Mo steel and Inconel (IN) 617 superalloy are high‐temperature alloys of prime importance in several industrial applications. Both of these are used at elevated temperature for various piping and tubing components and undergo asymmetric cyclic loading; therefore, it is highly essential to assess their resistance to accumulation of inelastic strain (ratcheting) under asymmetric stress cycling. In this study, ratcheting behavior of these alloys is compared at the homologous temperature of 0.42, under uniaxial asymmetric stress loading with positive mean stress. Deformation behavior of the tested samples is analyzed by transmission electron microscope. While there is homogeneous deformation in the modified 9Cr–1Mo steel, there is intersection of slip bands and presence of dislocation tangles in the IN 617 alloy. Fracture surface of the modified 9Cr–1Mo steel, tested under asymmetric cyclic loading, reveals typical ductile fracture resulting from tensile loading, whereas there is characteristic fatigue fracture of the IN 617 alloy.

Laser melting deposition of Inconel625 to Ti6Al4V bimetallic structure via vanadium interlayer

Inconel 625 (IN625) nickel-based high-temperature alloy and Ti6Al4V (TC4) titanium alloy are widely used in the aerospace industry due to their respective excellent properties. Developing the IN625/TC4 bimetallic structure (BS) has more apparent benefits and broader application prospects. Still, it has been challenging for industry research to connect these two materials successfully. In this study, IN625/TC4 BS without metallurgical defects such as cracks was successfully fabricated by adding the V interlayer using laser melting deposition (LMD) technique, and its microstructure and mechanical properties were investigated. The results indicate that IN625/TC4 BS can be divided into five regions from the IN625 side to the TC4 side, namely IN625 region, IN625/V transition region, rich V region, V/TC4 transition region, and TC4 region. The phase evolution of the five regions is as follows: γ-Ni + laves → γ-Ni + (Ni2Cr)V + TiNi3 + (V, Cr, Ni) solid solution → (V, Cr, Mo) solid solution + TiNi → β-Ti + TiNi + Ti2Ni → α-Ti + β-Ti. The Vickers hardness in the transition region is not uniformly distributed, with the highest value reaching 955 HV. The tensile strength of IN625/TC4 BS via V interlayer is approximately 267.6 MPa. The fracture location is located at the interface between rich V region and V/TC4 transition region, and its fracture morphology displays features of a quasi-cleavage fracture.

Role of δ-phase on recrystallisation behaviour of Inconel 718

The present work investigates the annealing behaviour of prior-coldworked Inconel 718 (IN718) sheets over wide reduction and temperature ranges by performing cold-rolling and isothermal annealing, followed by mechanical testing and structural characterisation. The study reveals that, with increasing annealing temperature, the prior-coldworked alloy shows non-monotonic M-Type variation with double peak-hardening at 0.3 Tm and 0.6 Tm. The study discovers that the first peak is due to the ‘static–strain–aging phenomenon’ that precedes recovery-softening. The second peak-hardening is due to precipitation-hardening, following which, the alloy softens due to recrystallisation. Supported by SEM, electron back-scattered diffraction and X-Ray diffraction results, the investigation suggests that the precipitation of fine rod-shaped δ-phase creates numerous nucleation sites at the shear bands that cause recrystallisation-burst at 0.75 Tm. However, above 0.75 Tm absence of the δ-phase activates grain-boundary migration resulting in rapid grain-coarsening.

Temperature Dependant Mechanical Property Characterisation Using Digital Image Correlation and Infrared Thermography

Accurate mechanical property charac-terisation of high-temperature high-performance materials, such as additively manufactured (AM) Inconel 718 (IN718), is crucial to ensure the reliability of components. A sudden drop in strength accompanied by significant embrittle-ment occurs in wrought IN718 near 700 ◦C. It is not clear whether AM IN718 exhibits this behaviour. The high cost of these materials and manufacturing methods necessitate the development of specimen-efficient testing techniques that allow material properties to be extracted simultaneously over a range of testing conditions. This paper presents a test setup, which is used to determine high-temperature mechanical properties over a range of operating temperatures by integrating digital image correlation (DIC) and full-field infrared thermography (IR). A purpose-designed specimen is resistively heated using a Gleeble 3800 thermomechanical simulator to create a thermal gradient across the length of the specimen. A high-temperature DIC setup and IR camera are used to capture the specimen surface’s displacement and full-field IR data. These datasets are temporally synchronised using a common triggering system and spatially correlated to allow for the extraction of temperature-dependent properties for a range of up to 100 ◦C from a single tensile test. The setup is shown to successfully capture the strength drop-off and embrittlement of AM IN718. Keywords: Full-field, Digital Image Correlation, Infrared Thermography, High-Temperature, Inconel 718

Influence of laser power on mechanical properties of FGM of SS316L and IN625 fabricated by direct metal deposition

Direct Metal Deposition (DMD) is a metal Additive Manufacturing (AM) process. It is used for producing sustainability Functionally Graded Materials (FGM) and repairing of sophisticated parts. In this present research, a commercially available DMD machine deposited three partial FGM blocks of size 26 mm wide × 34 mm thick × 32 mm heights. The commonly influence parameters on Ultimate Tensile Strength (UTS) are scan velocity and laser power. The powders used for deposition were Stainless Steel 316L (SS316L), Inconel 625 (IN625), and their three different compositions. ASTM E8 tensile samples were cut from those blocks by wire cut-EDM. Micro-tensile tests were carried out on ASTM E8 samples using a SHIMADZU micro-tensile machine. The results revealed that partial FGM sample-2 had high sustainability UTS of 532 MPa as compared to remaining two samples. It is illustrated that for joining two dissimilar materials to obtain high UTS thick layered (i.e., thickness more than 1 mm) gradient path method should be selected at the medium laser power available on the DMD machine. However, the sample-3 has higher hardness at high laser power.

Surface integrity analysis on selective removal by EDM of near-circular shapes from deterministic lattice structures fabricated by LPBF

The utilization of lattice structure in engineering components by additive manufacturing (AM) is gaining attention due to its lightweight design, high strength-to-weight ratio, and effective material utilization. Producing holes in additively manufactured lattice structures with dimensional accuracy is challenging. In the current study, we fabricate near circular through-holes on deterministic lattice structured components fabricated by laser powder bed fusion by utilizing electric discharge machining (EDM). In the additively manufactured Inconel 718 (IN718) lattice structure, nodes are connected by strut leaving voids/pores amongst different nodal points. Due to EDM, the nodes at the boundary of the hole experience concentration plasma interaction, heating, and rapid cooling, which causes a substantial change in the microstructure. The selective removal of material from different nodal positions causes uncharacteristic recast layers, partial damages, and uncontrolled cracking of the struts. In the present study, we investigated and characterized the differential behaviour and mechanism of various surface integrity issues associated with the selective material removal of LPBF IN718 lattice structures and their elements (nodes and struts).

Interfacial characteristics of multi-material SS316L/IN718 fabricated by laser powder bed fusion and processed by high-pressure torsion

This study focuses on investigating the microstructure and mechanical properties across the interface of a multi-material, Austenitic Stainless Steel 316 L (SS316L) and Inconel 718 (IN718), fabricated using laser powder bed fusion (LPBF) additive manufacturing (AM) technique. Challenges such as distortion, porosity, and intermetallic formation are common in such structures. To address these challenges, high-pressure torsion (HPT), a severe plastic deformation (SPD) process, was employed to eliminate porosity and create a homogeneous microstructure. The samples underwent HPT with varying numbers of turns, namely quarter, half, one, five, and ten turns, at room temperature and under 6 GPa of pressure at a speed of 1 rpm. The process aimed to create ultrafine and nano-grains in the microstructure and reduce the defects. A comprehensive characterization approach was adopted to analyze the interface. The results showed reduced porosity, improved bonding, and enhanced material density through HPT. X-ray diffraction (XRD) analysis confirmed the retention of the austenitic face-centered cubic (FCC) phase in both materials. The dislocation density reached a saturation point of 1.85 × 1015 m−2, while the crystallite size decreased to 26 nm. Transmission electron microscopy (TEM) analysis provided insights into the microstructure, showing dislocation networks at lower torsional strain and homogenous nano-grains at higher torsional strain. Vickers microhardness and nanoindentation measurements demonstrated an increase in hardness with increasing torsional strain, with the peripheral region exhibiting rapid hardness saturation and the central region showing lower hardness due to reduced strain. Overall, this study provides valuable insights into the effects of HPT on multi-material SS316L/IN718, contributing to the understanding of their interfacial characteristics and enhanced utilization of multi-materials in various engineering applications.

Microstructural Evaluation of Inconel 718 and AISI 304L Dissimilar TIG Joints

Dissimilar welding joints of Inconel 718 (IN718) nickel superalloy with low-carbon AISI 304L austenitic steel (SS304L) were conducted using the Tungsten Inert Gas (TIG) welding process. The present investigation focuses on the effect of different welding currents on the produced dissimilar joints’ microstructure and mechanical properties. The microstructure study was carried out by light optical (LOM) and scanning electron microscopy (SEM), coupled with energy-dispersive spectroscopy (EDS) analysis. The nanoscale investigation was performed via a high-resolution transmission electron microscope (TEM). The mechanical behavior of the TIG joints was investigated via Vickers hardness testing. In all cases, the morphology and the microstructure of the fusion zone (FZ) and the corresponding heat-affected zones (HAZ) of the TIG-welded IN718 and SS304L verified the absence of porosity or other metallurgical defects. Except for carbides and carbonitrides, hard and brittle Laves phases ((FeNiCr)2(NbMoTiSi)) were also identified, which were dispersed in the interdendritic spaces in the form of elongated islands. Prolonged exposure to high temperatures and a slower cooling rate due to higher initial heat input led to the precipitates’ coarsening both in FZ and HAZ and, thus, to the consequent gradual embrittle of the dissimilar joints.

Enhanced tribological performance of laser directed energy deposited Inconel 625 achieved through laser surface remelting

Inconel 625 (IN625) is an essential material for the manufacture of turbine blades and seals, aircraft ducting systems, engine components, and pressure valves. Laser Directed Energy Deposition (LDED) process has shown the potential to fabricate IN625 parts with superior mechanical properties and higher corrosion resistance when compared to those fabricated using conventional manufacturing techniques. However, the poor surface quality limits the practical application of LDED fabricated parts, especially in sectors that demand high tribological performance. To this end, this study focuses on improving the surface quality and tribological performance of LDED fabricated IN625 components using Laser Surface Remelting (LSR) as a postprocessing operation. The tribological performance was evaluated using a linear reciprocating ball-on-flat wear test setup. The surface roughness, remelting depth (RD), microstructure, hardness, and tribological performance (coefficient of friction and wear rate) of the remelted (RM) samples were compared with that of as-deposited (AD) samples. Microstructural characterization revealed that LSR resulted in grain refinement, reduced dendrite size, and primary dendritic arm spacing (PDAS). Laser scanning speed effects RD, dendrite size and PDAS via its effect on cooling rates. SEM + EDS analysis confirmed the presence of Laves phase in both AD and RM samples. XRD analysis of RM samples showed an increase in the amount of Laves phase. The refinement in microstructural features and the increased amount of Laves phase among the RM samples led to improvement in microhardness when compared to AD samples. Wear test results revealed a reduction in the coefficient of friction (COF) and wear rate after LSR with wear mechanism being either abrasive or delamination. Reduction in the size of dendrites and refinement in grain size are attributed to the enhanced tribological performance after LSR.

The Effect of Precipitates on the Stress Rupture Properties of Laser Powder Bed Fusion Inconel 718 Alloy

Improving the high-temperature stress rupture properties of Inconel 718 (IN718) alloys is crucial for enhancing aircraft engine performance. By using the laser powder bed fusion (LPBF) technique, IN718 alloys were crafted at varying volumetric energy densities (VED) in this study. The dendrite growth mode, reinforcing phase distribution and high temperature stress rupture properties of various VED samples were investigated. The results showed that the stress rupture life and the uniform elongation of the samples both first increased and then decreased with the increase in VED. When the VED was 60 J/mm3, the maximum rupture life and elongation of the sample were 43 h and 3.8%, respectively. As the VED increased, the angle of dislocation in the dendrite decreased while the spacing between primary dendrite arms increased, resulting in an increase in the size and volume fraction of the Laves phase. Following a heat treatment, the δ phase would nucleate preferentially around the dissolved Laves phase causing an increase in the volume fraction of the δ phase with the increase in VED. The creep voids readily formed around the δ phase are distributed along the grain boundaries, while the inhomogeneous δ phase and fine grains facilitated crack initiation and propagation. Furthermore, a significant quantity of the δ phase consumed the Nb element, thereby hindering adequate precipitation in the γ″ phase and causing cracks.

Unique Yttria Nanoparticle Strengthening in an Inconel 718 Superalloy Fabricated by Additive Manufacturing

AbstractOxide dispersion strengthened (ODS) nickel (Ni)‐based superalloys are advanced materials known for their outstanding tensile and creep performance at temperatures exceeding 1000 °C. Nevertheless, their conventional synthesis presents a longstanding challenge in cost‐effectively producing intricate components for critical applications. In this work, electrostatic self‐assembly (ESA) of powders with the laser powder bed fusion (LPBF) process are successfully combined to produce yttria ODS Inconel 718 (IN718) alloy for the first time. This approach demonstrates a significant contribution of yttria to the strength of IN718 after the solid solution heat treatment, as evidenced by ≈50% improvement in room temperature yield strength with a 0.5 wt.% yttria addition. The addition of yttria by this process leads to a heterogeneous microstructure. This heterogeneous microstructure comprises two distinct grain areas with varying amounts of yttria nanoparticles and dislocation storage. The results show that the yield strength increase can be predicted by the combination of both Y2O3 dispersion strengthening and dislocation strengthening mechanisms. These findings offer an effective approach to tailor heterogeneous microstructures, unlocking new opportunities for cost‐effectively producing high‐performance ODS Ni‐based superalloy products with excellent mechanical properties.

Dry and Minimum Quantity Lubrication Machining of Additively Manufactured IN718 Produced via Laser Metal Deposition

Inconel 718 (IN718), a Ni-based superalloy, is immensely popular in the aerospace, nuclear, and chemical industries. In these industrial fields, IN718 parts fabricated using conventional and additive manufacturing routes require subsequent machining to meet the dimensional accuracy and surface quality requirements of practical applications. The machining of IN718 has been a prominent research topic for conventionally cast, wrought, and forged parts. However, very little attention has been given to the machinability of IN718 additively manufactured using laser metal deposition (LMD). This lack of research can lead to numerous issues derived from the assumption that the machining behavior corresponds to conventionally fabricated parts. To address this, our study comprehensively assesses the machinability of LMDed IN718 in dry and minimum quantity lubrication (MQL) cutting environments. Our main goal is to understand how LMD process variables and the cutting environment affect cutting forces, tool wear, surface quality, and energy consumption when working with LMDed IN718 walls. To achieve this, we deposited IN718 on SS309L substrates while varying the following LMD process parameters: laser power, powder feed rate, and scanning speed. The results unveil that machining the deposited wall closer to the substrate is significantly more difficult than away from the substrate, owing to the variance in hardness along the build direction. MQL greatly improves machining across all processing parameters regardless of the machining location along the build direction. Laser power is identified as the most influential parameter, along with the recommendation for a specific combination of power feed rate and scanning speed, providing practical guidelines for optimizing the machining process. While MQL positively impacts machinability, hourly energy consumption remains comparable to dry cutting. This work offers practical guidance for improving the machinability of LMDed IN718 walls and the successful adoption of LMD and the additive–subtractive machining chain. The outcomes of this work provide a significant and critical understanding of location-dependent machinability that can help develop targeted approaches to overcome machining difficulties associated with specific areas of the LMDed structure. The finding that MQL significantly improves machining across all processing parameters, particularly in the challenging bottom region, offers practical guidance for selecting optimal cutting conditions. The potential economic benefits of MQL in terms of tool longevity without a substantial increase in energy costs is also highlighted, which has implications for incorporating MQL in several advanced manufacturing processes.

Residual Stresses in Alloy IN718 Produced Through Modulated Laser Powder Bed Fusion

BackgroundLaser powder bed fusion (L-PBF) additive manufacturing (AM) is used for building metallic parts layer-by-layer and often generates non-uniform thermal gradients between layers during fabrication, resulting in the development of residual stresses when parts are cooled down.ObjectiveThe impact of modulated laser used during the L-PBF process on residual stresses in Inconel 718 (IN718) material was investigated. The impact of build directions on residual stress is also determined.MethodsThe contour method is employed to measure the full-field residual stress component on the cross-section of samples. A complementary residual stress measurement method, incremental hole drilling, was employed for obtaining in-plane residual stress components.ResultsThe results show that the residual stress distribution is sensitive to the build direction, with a higher magnitude of residual stress in the direction of build than that in the transverse direction. Multiple measurements with the same manufacturing parameters show good repeatability.ConclusionResidual stresses in the as-built parts are significant and hence a further consideration regarding relieving residual stresses is required when post-thermal treatments are developed.

Laser powder bed fusion of Inconel 718-based composites: Effect of TiB2 content on microstructure and mechanical performance

The laser powder bed fusion (LPBF) additive manufacturing process has been extensively used to manufacture various nickel-based metal components because it offers the capability of manufacturing three-dimensional structures with complex shapes directly from raw materials. Although LPBF-fabricated Inconel 718 (IN718) superalloys have been successfully applied in the aerospace field, IN718-based composites can offer an alternative pathway to further enhance high-temperature performance. This systematic study examined the effect of various TiB2 contents on the microstructure and mechanical performance of IN718 fabricated by LPBF. Pure IN718 (IN718-P), IN718-1 wt% TiB2 (IN718-1) and IN718-2 wt% TiB2 (IN718-2) composites were nearly fully dense, with relative densities of 99.71%, 99.34% and 99.67% respectively, when fabricated under the optimal process parameters. The degree of grain size refinement was greater for IN718-2 than for IN718-1, and the IN718-1 grains were mainly refined in the width direction, while the IN718-2 grains were refined in both the width and length directions. The proportion of low-angle grain boundaries was significantly higher for the composites than for IN718-P, and it increased with increasing proportions of TiB2. Compared with the IN718-P sample, the microhardness, yield strength and ultimate tensile strength of IN718-2 at room temperature were increased by 19.93%, 24.83% and 11.07%, respectively, while the yield strength and ultimate tensile strength of IN718-2 at a high temperature of 650 °C were increased by 31.76% and 17.62%, respectively. This indicated that the enhancement of mechanical performance was more noticeable at high temperature than at room temperature. By contrast, less improvement in mechanical properties was achieved by adding 1 wt% TiB2 particles than by adding 2 wt% TiB2 particles. These findings indicate an alternative way to manufacture IN718 superalloys with improved mechanical properties through the synthesis of composite materials.

Optimized Inconel 718 pressure vessel manufactured with laser powder bed fusion

Laser powder bed fusion (L-PBF) is one of the most novel additive manufacturing methods used for a wide range of industrial grade metallic materials. The process can produce end-use metal parts with desirable qualities and mechanical properties. L-PBF however, remains a complicated and expensive manufacturing method. Design for additive manufacturing (DfAM) is a key aspect leveraging the uptake of advantages and possibilities offered by AM in augmenting its competitiveness against conventional manufacturing (CM) methods. Inconel 718 (IN718) is a nickel-based superalloy boasting high temperature strength, good oxidation, and corrosion resistance at elevated temperatures. IN718 is commonly used for high performance applications, such as power and process industry parts, and gas turbine components. High inherent toughness, hardness, work hardening, and low thermal conductivity properties make the material difficult to manufacture through conventional machining methods. The layer-by-layer building of powder metals via L-PBF makes it possible to build different geometrical intricacy. The offered manufacturing flexibility for complex high-end metal structures for variety of applications makes L-PBF an alternative manufacturing method for high performance metals. This study investigates use of DfAM for a small-scale pressure vessel with predefined geometry, dimensions, design space and load condition. The aim is to introduce and exploit contemporary design optimization methods and their feasibility with AM. Structures, such as lattices and stress field driven geometries based on finite element analysis are investigated in this study. The designs are virtually tested under predefined pressure load of 50 bar. All four design options are manufactured on EOS M290 and IN718 powder. The result of the study shows the different optimizations decrease weight and improve material savings without compromising the linear load capacity. Optimized designs could also be made in such a way that it does not increase the manufacturing duration or add additional steps to it.

Mechanisms of Heat-Treatment-Induced Cracking in Additively Manufactured IN738 Alloy

The present study conducts a comprehensive study on heat-treatment-induced cracking of Inconel 738 (IN738) alloy fabricated by laser powder bed fusion (LPBF) using scanning electron microscopy (SEM), energy dispersion spectrum (EDS), and electron backscatter diffraction (EBSD). The results indicate that the macroscopic crack is dominantly triggered by the strain-age cracking mechanism and propagates along grain boundaries. The initiation of cracking is facilitated by the superimposition of residual stress induced by the LPBF process and contraction stress induced by precipitation, while the reopening of compress pores at grain boundaries weakens the grain boundaries and provides fast channels for cracking. These results revealed the coupling effects in triggering heat-treatment-induced cracking, offering a fundamental guideline for crack control during heat treatment of additively manufactured IN738 alloy.

Quantitative Characterization of Elemental Segregation in Inconel 718 Superalloy by Micro-Beam X-ray Fluorescence Spectroscopy and Its Correlation Study.

Inconel 718 (IN718) nickel-based superalloy is widely used in aerospace and nuclear applications owing to its excellent comprehensive mechanical properties, oxidation resistance, and hot corrosion resistance. However, the elemental segregation caused by heterogeneous solidification during casting has great influence on the mechanical properties. Therefore, accurately characterizing the segregation behavior is necessary. Traditional quantitative characterization of elemental segregation uses various sampling methods, in which only macroscopic segregation results are obtained. In this study, micro-beam X-ray fluorescence (μ-XRF) is used for the quantitative characterization of element micro-segregation in IN718 superalloy. The concentration distributions of Cr, Fe, Mo, Nb, and Ti in IN718 alloy are determined with optimized testing parameters, and the degree of elemental segregation in different regions of the analytical area is calculated. It is found that the segregation degree of Nb and Ti in the testing area is larger than other alloying elements. The correlation between the microstructure distribution and the segregation degree of Nb and Ti has been studied using scanning electron microscopy (SEM) combined with energy-dispersive spectrometry (EDS). There is severe segregation of Nb and Ti in areas where Nb-containing precipitates are accumulated. The distribution of abnormal signals of Nb with a high fluorescence intensity has a close relationship with the area of precipitates-enriched Nb.

Unusually high room and elevated-temperature tensile properties observed in direct aged wire-arc directed energy deposited Inconel 718

Wire-arc directed energy deposition (DED) processed Inconel (IN) 718 is known to have coarse columnar grains, strong texture, and significant chemical and microstructural inhomogeneity in the as-fabricated condition. Homogenization treatment is commonly used prior to aging to eliminate the inhomogeneity and detrimental precipitation for better mechanical properties. In this study, however, direct aging (DA) at 700 °C without homogenization has resulted in room-temperature yield strength, ultimate tensile strength (UTS), and elongation that are comparable to wrought condition and among the highest reported properties for wire-arc DED IN718. The DA samples at between 650 and 750 °C aging also demonstrates remarkable ductility when deformed at elevated temperatures. In addition, when aged below 750 °C the DA IN718 possesses significantly higher UTS compared to those with homogenization treatment. These superior mechanical properties are highly likely due to the non-uniform and hierarchical precipitation consisting of disk-shaped γ″ in diameter from a few to tens of nm in the dendritic core area and micron-sized Laves phase and carbides in the inter-dendritic region.

Microstructural features and corrosion behavior of Inconel 625 components fabricated using Wire and Arc Additively Manufacturing (WAAM)

Wire and arc additive manufacturing (WAAM) is the predominant technique to process Nickel-based superalloys due to its low cost and high flexibility. This article discusses the microstructural features and corrosion resistance of two Inconel 625 parts manufactured using the WAAM technique. Using the WAAM process, two single-walled Inconel 625(IN625) components were produced additively for inter-pass layer temperatures (IPT) of 200 °C and 300 °C. The grain size changed with a change in IPTs, according to an investigation using electron backscatter diffraction (EBSD). The preferred grain orientation changed from the texture {001} < 001> to {001} < 101> as the IPT increased. Potentiodynamic polarization was used to evaluate the corrosion behavior. The corrosion rate of the IPT 300 °C sample is 0.007255 mmpy, while the corrosion rate of the IPT 200 °C sample is 0.01315 mmpy. Tafel’s extrapolation technique calculated the corrosion current density and corrosion current potential. The scanning electron microscope (SEM) explored the corroded area, and the energy-dispersive X-ray spectroscope examined the elemental composition.