Cast Nickel Aluminium Bronze Research Articles

An Investigation of Thermomechanical Behavior in Laser Hot Wire Directed Energy Deposition of NAB: Finite Element Analysis and Experimental Validation

Laser Hot Wire (LHW) Directed Energy Deposition (DED) Additive Manufacturing (AM) processes are capable of manufacturing parts with a high deposition rate. There is a growing research interest in replacing large cast Nickel Aluminum Bronze (NAB) components using LHW DED processes for maritime applications. Understanding thermomechanical behavior during LHW DED of NAB is a critical step towards the production of high-quality NAB parts with desired performance and properties. In this paper, finite element simulations are first used to predict the thermomechanical time histories during LHW DED of NAB test coupons with an increasing geometric complexity, including single-layer and multilayer depositions. Simulation results are experimentally validated through in situ measurements of temperatures at multiple locations in the substrate as well as displacement at the free end of the substrate during and immediately following the deposition process. The results in this paper demonstrate that the finite element predictions have good agreement with the experimental measurements of both temperature and distortion history. The maximum prediction error for temperature is 5% for single-layer samples and 6% for multilayer samples, while the distortion prediction error is about 12% for single-layer samples and less than 4% for multilayer samples. In addition, this study shows the effectiveness of including a stress relaxation temperature at 500 °C during FE modeling to allow for better prediction of the low cross-layer accumulation of distortion in multilayer deposition of NAB.

Additive manufacturing nickel-aluminum bronze alloy via wire-fed electron beam directed energy deposition: Enhanced mechanical properties and corrosion resistance compared to as-cast counterpart

In the present work, a wall-structured nickel-aluminum bronze (NAB) alloy was fabricated via electron beam directed energy deposition (EB-DED) additive manufacturing with a single-pass multi-layer deposition strategy. A comprehensive comparative analysis of microstructure, mechanical properties, and corrosion resistance was conducted against a conventionally cast NAB alloy. The inherent rapid solidification and cyclic thermal processing of the EB-DED technique profoundly influenced the microstructural evolution of the NAB alloy. The as-deposited NAB alloy exhibited a fine-grained microstructure, devoid of the martensitic β′ phase, accompanied by the spheroidization of partial κIII precipitates, and a homogeneous distribution of alloying elements. These distinctive microstructural attributes synergistically enhanced the strength, hardness, and toughness of the NAB alloy, conferring superior mechanical properties compared to its cast counterpart. Furthermore, the as-deposited alloy demonstrated remarkable corrosion resistance in a 3.5 wt% NaCl solution, significantly outperforming the cast alloy. The underlying mechanisms governing the structure-property relationships were elucidated. This comprehensive investigation provided insights into the unique characteristics and potential applications of EB-DED fabricated NAB alloys, positioning them as promising candidates for high-performance components subjected to severe mechanical and corrosive service conditions.

Microstructural transformation and corrosion–cavitation behavior of ultrasonic nanocrystal surface modified nickel aluminum bronze (NAB)

In this study, nickel–aluminum bronze (NAB) is optimized by ultrasonic nanocrystal surface modification (UNSM), and its surface microstructural evolution, surface hardness, electrochemical corrosion behavior, and cavitation erosion behavior are investigated. The potentiodynamic polarization curves and electrochemical impedance spectra before and after UNSM treatment of NAB are measured using a typical three-electrode system. The cavitation erosion process is simulated through the vibration of ultrasonic waves underwater, and the cavitation erosion resistance performance of various specimens is evaluated. UNSM significantly refines the coarse and heterogeneous multi-phase structure of the cast NAB, providing a relatively uniform and dispersed structure. Simultaneously, severe plastic deformation rapidly increases micro-strains on the NAB surface, which effectively improves its surface hardness from 211 to 360 Hv. After UNSM treatment, the corrosion potential increases slightly; and the passivation potential and current decrease considerably, dropping from 207 to 103 mV and from 5.23 to 2.41 mA/cm2, respectively. This is primarily because of the slowdown of selective-phase corrosion and the uniform formation of an oxide film. Additionally, UNSM parameters affect corrosion potential by regulating surface roughness. A smoother surface corresponds to a higher corrosion potential at the same load. UNSM treatment significantly improves the cavitation corrosion resistance of NAB, primarily because an increase in hardness and uniform distribution of structure effectively slows the speed of crack formation and propagation, which is a result of the synergistic improvement of mechanical and corrosion resistance properties.

Biofouling and corrosion rate of welded Nickel Aluminium Bronze in natural and simulated seawater

Updated understanding on the effect of biofouling on corrosion rate is needed to protect marine structures as climate change is altering seawater physiochemistry and biofouling organism distribution. Multi-disciplinary techniques can improve understanding of biofouling development and associated corrosion rates on metals immersed in natural seawater (NSW). In this study, the development of biofouling and corrosion on welded Nickel Aluminium Bronze (NAB) was investigated through long-term immersion tests in NSW, simulated seawater (SSW) and air. Biofouling was affected by geographic location within the marina and influenced corrosion extent. The corrosion rate of NAB was accelerated in the initial months of exposure in NSW (1.27 mm.yr−1) and then settled to 0.11 mm.yr−1 (annual average). This was significantly higher than the 0.06 mm.yr−1 corrosion rate measured in SSW, which matched published rates. The results suggest that corrosion rates for cast NAB should be revised to take account of biofouling and updated seawater physiochemistry.

Enhancing microstructure and mechanical properties of nickel aluminium bronze alloy through tin addition

This article describes the changes in the microstructure, cooling curve characteristics and mechanical properties of cast Nickel Aluminium Bronze alloy (NAB) alloy that were produced by the addition of various amounts of Tin (Sn). The solidification parameters were recorded using a computer-aided cooling curve analysis setup, and optical and scanning electron microscopes were utilised to study the evolution of the microstructure. The chemical composition of different phases generated in the NAB alloy with and without Tin was investigated using an X-ray diffraction technique. With the addition of tin, the alloy's microstructure changed from columnar to equiaxed grain structures, and the ideal microstructure was produced at a Tin concentration of roughly 1.0 weight percent. The formation of the high temperature α and the grain boundary Sn rich phases across the alloy microstructure as a result of further addition has a considerable impact on the alloy's increased hardness (upto 69%) and tensile strength (upto 28.4%) compared to untreated NAB alloy. Influence of Sn on microstructure transformation is confirmed by the decline in alloy nucleation temperatures, the reduction in undercooling intensity, and the decrease in cooling rate during solidification. The addition of Tin to the NAB alloy caused morphological changes in the kappa (K) phases, which are also reported in the this article. In addition to this, the research makes an attempt to describe the mechanism underlying the formation of equiaxed grains and phase transformations in Sn-treated NAB alloys.

Evaluation of physical, mechanical and sliding wear properties of in-situ AB-TiC composite: a comparison with NAB alloy

The purpose of the present study is to evaluate the physical, mechanical and sliding wear properties/response of cast in-situ aluminium bronze (AB)-TiC [(Cu10Al3Fe)5TiC] composite and compare with cast nickel aluminium bronze (NAB) [Cu10Al5Ni5Fe] alloy. Sliding wear tests were conducted in dry and partially lubricant conditions using a pin-on-disc machine. A test material in the form of pin was evaluated against a rotating heat-treated EN-31 steel disc. Wear loss, frictional heating and friction coefficient properties were examined. The NAB alloy showed higher tensile strength (32.7%), compressive strength (7.68% at room temperature. and 4.18% at 500 °C), hardness (8.78%) and density (3.17%), whereas thermal conductivity of the AB-TiC composite was found 4.89% higher than NAB alloy. In dry sliding condition, composite outperformed NAB alloy in terms of wear resistance up to a critical applied load and/or sliding speed. Beyond this point, the wear behavior altered. Increasing sliding speed caused to reduce wear transition load. While friction coefficient showed mixed trend. Under lubricated wear test conditions, AB-TiC composite displayed considerably higher wear resistance (50.08%, 44.41% & 51.55%) and friction coefficient (26.37%, 40.75% & 14.96%) than the NAB alloy when tested in only oil, oil with 100 μm graphite and oil with 7–10 μm graphite respectively. Arrival of seizure in general caused significantly higher wear loss and temperature rise. In addition, it caused large adhesion of the specimen material to the disc surface. The reported wear behaviour of the samples has been validated using the features of wear surfaces and subsurface regions. The latter also permitted to comprehend the working wear processes. The analysis significantly shows good impacts of the oil lubrication (with and without solid particles) in terms of decreasing wear rate, frictional heating, and friction coefficient. Formation of steady lubricating film/layer was reported to be responsible for the better wear performance of the samples. Furthermore, irrespective of material composition and microstructure there exists a precise set of test parameters (e.g. load and speed) leading to optimal wear performance wherein the beneficial impacts of load bearing capability, thermal stability of various phases predominates.

Microstructure and Mechanical Properties of Nickel-Aluminum Bronze Coating on 17-4PH Stainless Steel by Laser Cladding

Bimetallic copper-steel composite could be an effective structural material to improve the performance of traditional nickel-aluminum bronze (NAB) ship propeller due to its high structural strength and corrosion resistance. In this work, the defect-free NAB coatings has been successfully fabricated by laser direct depositing technique on the 17-4PH stainless steel substrate. The phase constitution, microstructure characteristics and hardness properties were investigated in details. The XRD results showed that the coatings mainly consisted of α-Cu, Fe and intermetallic κ phases despite the diffraction peaks shifted more than 0.5°, which may due to the influence of the Ni, Fe and Al atoms dissolved into Cu-matrix. The microstructures of the coatings were affected significantly by laser energy density according to SEM and EDS results. The top region of the coating was more undercooled during solidification, therefore the grains at this region was much finer than that at the bottom region. The higher energy input would lead to coarser grains. Fe-rich dendrites and spherical particles were found in the Cu matrix, which could be a result of liquid separation. The hardness of the coating is in the range of 204 HV0.2–266 HV0.2 which is higher than traditional as- cast NAB. The uneven distribution of Fe-rich phases as well as the hard κ phases could be the main reasons for the fluctuations of the hardness value. Tensile fracture occurred at bronze side, not at transition zone, which shows there is a good interfacial bonding between the two metals produced by laser cladding.

Selective corrosion of cast nickel–aluminum bronze in seawater

AbstractBased on a failure analysis of cut‐off valves, this study investigated the selective corrosion behavior of cast nickel–aluminum bronze (NAB) by an immersion corrosion test and explained it with energy dispersive spectroscopy and microanalysis. Fracture analysis and finite element numerical simulation results showed that the joints of valve discs and seal rings were corroded first. Cast NAB contains α, β, and κ phases with different chemical compositions. Chemical component segregation is the fundamental reason for the difference in corrosion potential in seawater. After the ferric chloride immersion corrosion test, the corrosion cracks appeared at the grain boundary between the α phase and κ phase. Galvanic corrosion cells are formed at the phase boundary, and cracks and corrosion occur preferentially at the grain boundary.

Process Modelling And Characterisation Of Friction Surface Deposit Of Extruded nickel Aluminum Bronze Over Cast Nickel Aluminum Bronze

ABSTRACTCast Nickel Aluminium bronze widely finds its application in marine components because of ease its of fabrication in complex shapes and geometries. The cast alloys are prone to erosion-corrosion failures in the marine environment. To enhance the corrosion resistance of these alloys, surface modification techniques are being used. Friction surfacing is one such newly developed technique which can be employed to improve the erosion-corrosion resistance of cast NAB alloys. In this investigation an attempt has been made to deposit extruded NAB alloy over cast NAB alloy by friction surfacing technique. The influencing process parameters like plunge rate, rotational speed and transverse speed of tool (extruded NAB alloy rod) were mathematically modelled and empirical relationships were developed using response surface methodology (RSM). These parameters were further optimised using Particle Swarm optimization (PSO) to attain the maximum bonding strength. The Ram tensile strength carried on the surfaced alloy had maximum strength of 245 MPa. The mathematically modelled methods provided results nearing to the experimental values. The values were in good agreement with the experimental values with error deviation of 5%. The erosion corrosion property of the friction surfaced NAB alloy improved than the cast alloy.

Influence of processing on the microstructure of nickel aluminum bronze (NAB)

Nickel-aluminum bronze (NAB) alloys are commonly used for marine applications such as propellers by the U.S. Navy. These NAB components are conventionally manufactured using casting techniques, but recent interest has shifted to the possibility of additive manufacturing (AM) processes. The following literature review discusses the microstructural evolution of (nominally) Cu-9Al-5Ni-5Fe-1Mn NAB alloys in the cast, wrought, friction stir processed, arc-welded, electron beam welded and laser-welded conditions. NAB alloys exhibit a complex microstructure, consisting of a mixture of five κ precipitates distributed in an α or β’ martensitic matrix. The size, morphology, and distribution of these phases are sensitive to changes in cooling rate and thermal history such as those imposed by AM and welding. Although the microstructure is well documented under casting conditions, no continuous cooling diagrams have been developed to describe phase transformations under arc and laser processing conditions for NAB. As such, this review investigates recent reports related to arc, electron beam and laser-based additive manufacturing processes and the associated microstructures and properties. Studies have reported additively manufactured NAB alloys with improved properties compared to cast material, associated with differences in microstructure. At moderate cooling rates, such as those associated with arc-based processing, the microstructure consists of Widmanstätten α and various κ phases, which become more refined with increasing cooling rate. This leads to an improvement in the tensile properties of wire-arc direct energy deposited NAB, with > 17% increase in yield strength and > 90% increase in ductility when compared to cast material. At rapid cooling rates representative of laser-based and electron beam processing, the microstructure consists primarily of a twin-related β’ martensite with nanoscale κ phases. This leads to a significant increase in yield strength (>60–100%) at the expense of ductility (<−30%) when compared to cast material. Additionally, previous studies have reported that the refined microstructure from these high cooling rate processes leads to an improvement in the corrosion resistance of as deposited NAB. There is also evidence that the conventional heat treatments for cast NAB alloys need to be optimized for additively manufactured materials. The report includes the methods and challenges associated with characterizing NAB alloys under these processing conditions and provides recommendations for future research.

The constitutive relations and thermal deformation mechanism of nickel aluminum bronze

A Gleeble3500 thermal simulator investigated the flow behavior of cast nickel aluminum bronze(NAB) with quasi-static test and a split Hopkinson pressure bar (SHBP) with strain rates of 2000–16000 s−1 and a temperature range of 298–1073 K. The relationship between the flow stress and the deformation temperature, strain, and strain rate was exhibited by Johson-Cook (JC) constitutive model. It's found that the strengthening and softening parameters were variables at the high strain rate and hot deformation. The modification was employed, and the modified JC model showed a more precise prediction demonstrated by the higher average absolute relative error. The coupling effect of strain rate strengthening and thermal softening mechanism resulted in the flow stress evolution under different strain rates and temperatures. The dislocation theory was used to explain the strain rate strengthening that under the high strain rate over 102s−1, the main obstacle was the viscous damping mechanism. The quasi-static tests evaluated the thermal softening mechanism associated with the microstructure evolution. The dynamic recovery and recrystallization's synergistic effect dominated the thermal softening. During the thermal deformation, dense dislocations tangled around the κ phases, apt to be the nucleation of the dynamic recrystallization. The κIV phase dissolution contributed to the grain growth at 1073 K.

Failure analysis of a butterfly valve made with nickel aluminum Bronze (NAB) and manganese aluminum Bronze (MAB)

Butterfly valves installed at the seawater system used to cool the fresh water of cooling medium in an offshore oil platform type Floating Production Storage and Off-loading (FPSO) failed in an unexpected way after periods of three to six months of operation. When closed, the valve faces were kept in contact with water injection on one side, and with untreated seawater on the other side. Moreover, they were totally exposed to seawater when opened. One failed valve was sent for metallurgical failure analysis and the damage appeared in the valve body in the position of sealing. The body and the disc of the failed valve were made of a cast Nickel Aluminum Bronze alloy (NAB) type ASTM B148 UNS C95800, and the sealring attached to the disk was made of Ni superalloy 625 with polytetrafluoroethylene (PTFE). The investigations conducted in the failure analysis revealed that the material of the seat area was different from the material of the body, since a large ring of NAB was welded to the body, using a Manganese Nickel Bronze (MAB) alloy as feed metal. The failure was associated to three distinct problems. First, several welding defects were observed. Second, an adequate post weld heat treatment was not performed in the seat part, leading to the presence of β retained phase (β’) which decreases the corrosion reistance of NAB and MAB alloys. Third, galvanic corrosion also ocurred since the Ni superalloy 625 is nobler than the NAB, and they were in close contact. Additional corrosion tests revealed that NAB alloy was very susceptible to de-alloying in 3.5 %NaCl solution.

Micromechanical characterization of wire-arc additive manufactured and cast nickel aluminum bronze: Ambient and intermediate temperatures

Instrumented indentation is a semi-destructive and robust technique to assess micromechanical characteristics (e.g., local properties) of metallic materials at ambient and elevated temperatures. In the present study, the instrumented indentation is employed to assess and compare the micromechanical response and fundamental mechanisms of plastic deformation (e.g., rate-controlling plasticity) in wire-arc additively manufactured (WAAM) and cast nickel aluminum bronze (Cu–9Al–4Fe–4Ni–1Mn) at ambient and intermediate temperatures. Two separate sets of indentation-based test schedules are employed to investigate these mechanisms. In the first set of experiments, load-controlled (peak load of 500 mN) indentation tests are performed under various loading rates (5–50 mN/s) at a constant (25 °C) temperature. In the second set of experiments, load-controlled indentation tests (peak load of 200 mN) at various temperatures of 25, 200, and 300 °C are performed under a constant loading rate. Indentation load versus indentation depth and time data are analyzed to collect a wealth of information including indentation stress, indentation strain rate, size effect, dislocation activation energy, and activation volume to assess fundamentals of governing mechanisms of plastic deformation. Optical, scanning, and transmission electron microscopy are utilized to provide microstructural evidence for the proposed micromechanical mechanisms of plastic deformation based on dislocation activities and interactions. The nanoindentation hardness results show that the strength of the WAAM alloy is higher than the cast counterpart. However, neither cast nor WAAM-NAB materials are rate-sensitive at ambient (room) temperature. When the temperature is raised, both alloys become softer, and the indentation size effect becomes less pronounced. The activation volume and the activation energy data show that a steady-state microstructure does not necessarily exist around the indentations, and the nature of rate-limiting obstacles (against dislocation activities) may vary in the course of the indentation.

Further studies into the flow corrosion cathodic mass transfer kinetics of copper and nickel-aluminium bronze wall-jet electrodes

This work has investigated the corrosion performance and mass transfer of oxygen on copper and nickel-aluminium bronze surfaces within a wall-jet flow cell assembly. Limiting currents of the dissolved oxygen mass-transfer kinetics as a function of volume flow rate at a wall-jet electrode were examined for copper and nickel-aluminium bronze in a 3.5 wt.% NaCl solution. Mass transfer kinetics for the reduction process studied was compared with rotating disc and cylinder electrode data. The wall-jet electrode mass transfer coefficients for commercially pure copper and cast nickel-aluminium bronze were determined to be 0.01-0.06 cm s–1 and 0.01-0.05 cm s–1, respectively.

Selective laser melting of nickel aluminium bronze

Nickel aluminium bronze (NAB) is widely used in naval applications due to its combination of excellent corrosion resistance in sea water applications and medium strength levels. These alloys have complex microstructures of α and β solid solution phases together with different forms of the intermetallic κ phase. In this work, selective laser melting (SLM) of Cu-9.8Al-5.2Ni-4.6Fe-0.3 Mn (wt. %) NAB powder was optimised to produce dense NAB specimens. The as-built specimens consisted of martensitic microstructures. Through the application of various heat treatment conditions, α + κ microstructures typical of traditional NAB alloys, were obtained and the mechanical and electrochemical properties were characterized. A heat treatment at 700 °C for 1 h on the as-built structure yielded NAB specimens with superior corrosion performance and mechanical properties than conventional wrought or cast NAB. This work shows that SLM of NAB alloys is possible and the components obtained exhibit properties at least as good as their cast or wrought counterparts. This opens up the possibility of using NAB components fabricated by SLM in engineering applications.

Corrosion and Cavitation Erosion Behaviours of Cast Nickel Aluminium Bronze in 3.5% NaCl Solution with Different Sulphide Concentrations

The effect of sulphide (Na2S) concentration (SC) on the corrosion and cavitation erosion behaviours of a cast nickel aluminium bronze (NAB) in 3.5% NaCl solution is investigated in this study. The results show that when the SC exceeds 50 ppm, the hydrogen evolution reaction dominates the cathodic process, and a limiting current region appears in the anodic branch of the polarisation curve due to the formation of a copper sulphide film, which is a diffusion-controlled process. After long-term immersion, the increased mass loss rate of NAB with the sulphide additions of 20 and 50 ppm is attributed to the less protective films, which contains a mixture of copper oxides and sulphides. Moreover, NAB undergoes severe localised corrosion (selective phase corrosion, SPC) at the β′ phases and eutectoid microstructure α + κIII. By comparison, NAB undergoes general corrosion and a copper sulphide film is formed in 100 and 200 ppm sulphide solutions. Cavitation erosion greatly increases the corrosion rate of NAB in all solutions and causes a negative potential shift in 3.5% NaCl solution due to the film destruction. However, a positive potential shift occurs in the solutions with SC higher than 50 ppm due to the accelerated mass transfer of the cathodic process. The cavitation erosion mass loss rate of NAB increases with the increase of SC. The occurrence of severe SPC decreases the phase boundary cohesion and causes brittle fracture under the cavitation impact. The corrosion–enhanced erosion is the most predominant factor for the cavitation erosion damage when the SC exceeds 50 ppm.

Concast C95500

Abstract Concast C95500 is a cast nickel-aluminum bronze alloy. Aluminum bronze is the highest strength standard copper-based alloy. The nickel content in C95500 greatly enhances its mechanical strength, and wear and corrosion resistance, making it suitable for heavyduty applications. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as machining and joining. Filing Code: Cu-900. Producer or source: Concast Metal Products Co..

Influence of Age Hardening on Mechanical Properties of Cast Nickel-Aluminum Bronze Containing Shrinkage Porosity

In this study, the effect of porosity on hardness and strength of as-cast and aged nickel-aluminum bronze (alloy C95800) has been investigated. Optical and scanning electron microscopes were used to examine the microstructures and to characterize the fracture surfaces of the alloy, respectively. After aging, α grains in the microstructure were refined, distribution of eutectoid particle phases became more uniform and volume fraction of β’ phase was increased. Hardness testing revealed that optimum aging was achieved at 350 °C with more than 90% increase compared to the as-cast alloy. In order to eliminate the effect of pores on tensile data, and to evaluate aging process in terms of tensile strength, the concept of “effective area” was introduced as the total cross-sectional area minus the projected area of pores as obtained by fractography. Based on this concept, the effective strength of the cast alloy was calculated. The effective strength was also obtained by Ghosh’s model; comparison of the results indicated good agreement of both methods. It was concluded that effective strength presented in this research could be an appropriate reference value when considering mechanical properties of porous casting alloys.

Cavitation erosion behavior of friction stir processed nickel aluminum bronze

In this investigation, cast nickel aluminum bronze (NAB) was subjected to friction stir processing (FSP). The mechanical properties and the cavitation erosion behavior of the as-cast and FSP NAB alloy were investigated. The results showed that the initial microstructure of the as-cast NAB transformed to the fine and homogeneous microstructure after FSP, therefore improving the microhardness, yield strength, ultimate tensile strength, and elongation of as-cast NAB alloy. The cavitation erosion test showed that the FSP improved the cavitation erosion resistance of the as-cast NAB alloy in the distilled water. Furthermore, the cavitation erosion mechanisms in as-cast and FSP NAB alloy were investigated and understood in terms of schematic diagrams in this research.

Effect of Process Parameters on Microstructure and Mechanical Properties of Friction Stir Welded Cast Nickel Aluminum Bronze Alloy (C95800)

Effect of Process Parameters on Microstructure and Mechanical Properties of Friction Stir Welded Cast Nickel Aluminum Bronze Alloy (C95800)