Corrosion Resistance Of Alloy Research Articles

Micro-machining of Monel K500 using electrical discharge drilling: insights into hole tapering mechanism and surface morphology

Abstract Monel K500, a corrosion-resistant nickel-copper alloy, presents machining difficulties because of its hardness and toughness. Consequently, the efficacy of non-conventional machining processes on this material demands investigation. Substantial research on micro-feature manufacturing on Monel K500 utilizing the micro-electrical discharge drilling (MEDD) technique remains unreported. This investigation is an attempt to study the micro-machining performance of Monel K500 while fabricating through-micro-holes using MEDD process. The one-factor-at-a-time (OFAT) approach was adopted to arrive at the optimal combination of voltage (V), capacitance (C), tool speed (TS), and pulse duration (PD) for the best output responses. There is a scarcity of extensive investigations on the tapering mechanism in Monel K500 MEDD, such as the one conducted in this study. The value of material removal rate (MRR) at 160 volts was 7.73 × 10−5 g min−1 with 100 pF capacitance, 200 rpm tool speed, and 5 μs pulse duration. At 220 volts, the MRR increased by 50.06% with the same capacitance, tool speed, and pulse length values, reaching 11.60 × 10−5 g min−1. The values of V, C, TS, and PD corresponding to the optimal combination of MRR (35.68 × 10−5 g min−1) and machining time (MT) (16.19 min) were 220 volts, 10000 pF, 400 rpm, and 20 μs respectively. The micrographs of the machined specimens depicted deviation in hole diameter and the presence of tapering in the though-micro-holes. The study revealed that a micro-hole, machined at low discharge energy (DE), has a smoother surface and more uniform size than one machined at higher DE. Monel K500 is extensively utilized in the aerospace, marine, and chemical sectors because to its superior mechanical qualities and corrosion resistance. A standard set of efficient machining conditions can aid in the accurate manufacturing of Monel K500 components with intricate features via the MEDD process.

Structure and Corrosion Resistance of Fe40Al5Cr0.2TiB Alloy After Casting and After Homogenization Annealing

This article shows the results of research conducted on the corrosion resistance of the FeAl (Fe40Al5Cr0.2TiB) alloy in two variants: the alloy after casting and after homogenization annealing (1000 °C, 93 h). Analysis of the microstructure of these alloys was conducted on the light microscope, and the phase composition was determined by X-ray diffraction. Resistance to electrochemical corrosion was tested in a 5% NaCl solution using the potentiodynamic polarization technique and electrochemical impedance spectroscopy. The surface of alloys after corrosion tests was examined by scanning electron microscopy. Chemical composition tests were conducted using an energy-dispersive X-ray spectrometer. The structure analysis was made with an electron backscatter diffraction detector. Based on the studies, it was found that the corrosion resistance of the FeAl alloy after homogenization annealing was higher than that of the FeAl alloy after casting. This alloy showed a more non-homogeneous and coarse-grained microstructure compared to the alloy after homogenization annealing. The investigation of the surface condition of FeAl alloys after corrosion tests showed the presence of pits, particularly in the case of the alloy after casting.

Corrosion Resistance of Alloy 690 in High-Temperature Water with Various Dissolved Hydrogen Concentrations

Corrosion Resistance of Alloy 690 in High-Temperature Water with Various Dissolved Hydrogen Concentrations

Comparison of surface integrity, microstructure and corrosion resistance of Zr-4 alloy with various laser shock peening treatments

Comparison of surface integrity, microstructure and corrosion resistance of Zr-4 alloy with various laser shock peening treatments

Effect of Y₂O₃ content on microstructure, mechanical properties, and corrosion resistance of WC-Co hard alloys prepared by powder metallurgy

Effect of Y₂O₃ content on microstructure, mechanical properties, and corrosion resistance of WC-Co hard alloys prepared by powder metallurgy

Improving corrosion resistance of copper-nickel alloys by the microalloying-facilitated formation of protective corrosion product films

Improving corrosion resistance of copper-nickel alloys by the microalloying-facilitated formation of protective corrosion product films

Optimization of corrosion resistance of AZ31 Mg alloy through hydration-driven interaction between quinolin-8-ol and plasma electrolytic oxidation-formed MgO layer

Optimization of corrosion resistance of AZ31 Mg alloy through hydration-driven interaction between quinolin-8-ol and plasma electrolytic oxidation-formed MgO layer

Improving the electrochemical corrosion resistance of a high-Ca heat-resistant magnesium alloy by enhancing the barrier effect of the cathodic phase skeleton

Mg-Al-Ca-based alloys are highly susceptible to electrochemical corrosion due to the micro-galvanic corrosion induced by the large potential gap between the cathodic second phase and the anodic α-Mg matrix. This study reports a new strategy of improving their corrosion resistance by enhancing the barrier effect of the cathodic phase skeleton based on a Mg-5Al-3Ca-xZn alloy. The results indicate that the supersaturation of Zn in the C36-(Mg,Al)2Ca phase skeleton, combined with the further formation of Ca2Mg6Zn3 through a peritectic reaction, significantly increases the potential difference between the second-phase skeleton and the matrix, however, the corrosion rate of the alloy in the 3.5wt.% NaCl solution anomalously decreases accordingly. It suggests that the corrosion kinetics of this alloy are governed by the barrier effect of the continuous cathode phase skeleton, outweighing the micro-galvanic effect that dominates the corrosion process for most magnesium alloys. A new understanding of the barrier effect of the cathodic phase based on the local pH variation is proposed. This study offers a new perspective for the development of high-Ca magnesium alloys that exhibit superior electrochemical corrosion resistance.

Indented metallic bipolar plates for vanadium redox flow batteries

The standard industrial vanadium redox flow battery (VRFB) stack is made of thick graphite bipolar plates to support the flow field required for optimal circulation of electrolyte. These thick plates suffer from electrolyte seepage, poor mechanical properties, and high machining and processing costs. In the present study, we report on the use of metallic bipolar plates for the construction of the VRFB cell. We show, through comprehensive electrochemical and hydrodynamic investigations, that Hastelloy C276, a corrosion-resistant high Nickel alloy, is a suitable bipolar plate material in VRFB cells. We show further that surface texture modification, in the form of a mix of concave and convex spherical indentations on the metallic bipolar plate, can have beneficial effects on cell performance. Comparative experiments on medium-size cells of a nominal area of 440 cm2 operating in the current density range of 75–125 mA/cm2 show that discharge energy gains of 25% or higher can be obtained together with a 10–15% reduction in pressure drop in comparison with similar cells with flat bipolar plates. It is posited that the concave indentations spread over the entire area ensure uniform electrolyte circulation while regions of low and high electrode compression create flow channeling possibilities that lead to reduced pressure drop.

The elemental selection rules for corrosion-resistant Mg alloys from first-principles calculations

The elemental selection rules for corrosion-resistant Mg alloys from first-principles calculations

Review of Material Selection for Corrosion-Resistant Alloy Pipelines

Review of Material Selection for Corrosion-Resistant Alloy Pipelines

Advanced corrosion protection frameworks for offshore and onshore oil and gas infrastructure

Corrosion poses significant challenges to the operational integrity, safety, and economic sustainability of offshore and onshore oil and gas infrastructure. This paper presents an in-depth review of advanced corrosion protection frameworks tailored to address the unique environmental conditions and operational stresses faced by these facilities. It examines traditional methods, such as cathodic protection and protective coatings, while highlighting emerging technologies, including smart coatings, corrosion-resistant alloys, and nanotechnology-based solutions. The role of predictive analytics and machine learning in corrosion monitoring and risk assessment is also discussed, alongside the integration of real-time sensor networks for proactive maintenance strategies. Furthermore, the paper explores the impact of regulatory standards, cost considerations, and environmental factors on the adoption of these frameworks. By synthesizing multidisciplinary approaches, the study offers actionable insights to enhance the lifespan, efficiency, and environmental compliance of oil and gas infrastructure, paving the way for sustainable energy production.

Experimental and Numerical Study of Maximum Welding Joint Temperature Impacts in Alloy Steel Pipe Welding Microstructure, Distortion, Corrosion Resistance, and Mechanical Properties

Experimental and Numerical Study of Maximum Welding Joint Temperature Impacts in Alloy Steel Pipe Welding Microstructure, Distortion, Corrosion Resistance, and Mechanical Properties

Stress Corrosion Behavior of MIG Welded Joints of 6082-T6 Aluminum Alloy at Different Temperatures

6082-T6 aluminum alloy is a commonly used aluminum alloy material in the field of rail transit because of its good molding properties, high mechanical properties, excellent corrosion resistance and weldability. In the high temperature and humid environment, the temperature change is bound to affect the stress corrosion resistance of the aluminum alloy and their welded joint. However, the influence mechanism of temperature on its stress corrosion resistance has not been explained in the existing research. In this paper, the mechanical properties and stress corrosion behaviors of melt-inert gas welded (MIG) 6082-T6 aluminum alloy welded joints were systematically studied under various temperatures condition. Results indicated the temperature scarcely affected stress corrosion cracking susceptibility index (PSCC) of base metal, while significantly affected the welded joint and higher temperature caused lower PSCC. After slow strain rate tensile test, a corrosion layer was formed, which was a typical brittle-toughness mixed failure, and the degree of brittleness increased with the increasing of temperature. Electrochemical analysis showed that corrosion resistance of the joint slightly decreased due to aluminum alloy accelerated dissolution caused by increasing of temperature. The proposed research will provide a theoretical basis for solving aluminum alloys used in rail transit, ship accessories and other industrial fields.

Emerging boron nitride nanosheets: A review on synthesis, corrosion resistance coatings, and their impacts on the environment and health

Abstract The aim of this study is to assess the effectiveness of hexagonal boron nitride (hBN) coatings to enhance the corrosion resistance of metals as well as evaluate their crucial toxicological impacts on both the environment and human health. Organic coatings are extensively applied in the field of protecting metals against corrosion. They are preferred as corrosion inhibitors due to their carbonyl and hydroxyl group content, but they have drawbacks regarding brittleness, porosity, and oxidation susceptibility. In this review, we mainly focused on the synthesis, properties, and applications of hBN coatings and emphasized the way to improve corrosion resistance in metals and alloys. Furthermore, our discussion demonstrated that the boron nitride nanosheet (BNNS) coatings significantly improve corrosion resistance, hydrophobicity, and crack mitigation properties. The researchers achieved reduced coating porosity and enhanced protection against corrosive media by effectively dispersing BNNS in organic resin. This study also determines the protective mechanism of BNNS composite coatings against corrosion. Moreover, we addressed the impact of BBNS synthesis and its physicochemical properties on the environment and organisms. Finally, suggestions are made for future research and the sustainability of industrial use to broaden the scope of applications for BNNS composite coating.

Superhydrophobic Property and Corrosion Resistance of 1100 Aluminum Alloy With Peano Fractal Micro-Nano Textures

Abstract To enhance the corrosion resistance of aluminum alloy exposed to marine environment, a novel Peano fractal micro-nano texture was introduced. The Peano micro-nano textures with three depths were prepared by laser etching technology, and the textured surfaces were modified using an ethanol solution of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDS). The hydrophobic properties of aluminum alloy surfaces with Peano textures were measured. The wetting mechanism was analyzed via X-ray photoelectron spectroscopy (XPS) characterization, and the electrochemical experiments were performed to explore the corrosion resistance of a superhydrophobic surface. The results showed that LS-d30 (laser processed specimen with depth of 30 μm) exhibited the optimal superhydrophobicity, with a water contact angle of 169.3 deg and a sliding angle of 3.9 deg. The Peano micro-nano texture facilitated the adsorption of PFDS, resulting in the creation of CF2–CF2 and CF3–CF3 functional groups on the surface. These functional groups contributed to the enhancement of hydrophobic properties. The LS-d30 surface exhibited a superior corrosion inhibition rate of 84.16%. Additionally, electrochemical impedance spectroscopy (EIS) revealed a significant increase in the corrosion resistance of the Peano fractal micro-nano texture surface.

Effect of Heat Treatment on the Corrosion Behavior of Weld-Deposited Chromium Carbide-Based Hardfacing Alloys

The effects of heat treatment on the microstructure and corrosion behavior of chromium carbide-based hardfacing alloys deposited via gas metal arc welding were investigated. The hardfacing alloy, high chromium white iron (HCWI), containing 27 wt% Cr and 4.8 wt% C, was heat treated at 650 °C and 950 °C for six hours followed by natural cooling to room temperature. Microstructural characterization revealed that heat treatment promoted the transformation of austenite to ferrite and increased carbide precipitation. X-ray diffraction analysis identified the primary carbides as Cr7C3, which remained stable during heat treatment. Electrochemical corrosion testing in artificial seawater, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), demonstrated progressively improved corrosion resistance with heat treatment temperature. Both techniques confirmed that the specimen treated at 950 °C exhibited superior corrosion resistance compared to the 650 °C treatment and as-deposited condition, with the specimen treated at 950 °C exhibiting the highest charge transfer resistance (4711 Ω·cm2) compared to the 650 °C treatment (2608 Ω·cm2) and as-deposited condition (374.6 Ω·cm2). The enhanced corrosion resistance was attributed to the increased carbide precipitation and optimization of the matrix composition. While heat treatment at both temperatures improved corrosion performance, the 950 °C treatment yielded superior results, suggesting this could be an optimal temperature for enhancing the corrosion resistance of chromium carbide-based hardfacing alloys.

Corrosion and Cavitation Performance of Flame-Sprayed NiCrBSi Composite Coatings Reinforced with Hard Particles

To enhance the operational life of hydraulic machinery, protective coatings against wear, particularly cavitation erosion, and corrosion might be applied on the surfaces of components. The experiments conducted in this study aimed to assess the suitability of 80/20 NiCrBSi/WC-Co composite coatings for this purpose. A coating of NiCrBSi self-fluxing alloy, which served as the reference material, was deposited alongside a NiCrBSi coating reinforced with 20% WC-Co, both applied by flame spraying onto X3CrNiMo13-4 substrates, the martensitic stainless steel type frequently utilized in turbine blade manufacturing. The improved density of the coatings and adhesion to the substrate was achieved by remelting with an oxyacetylene flame. The cavitation and corrosion performance of both the reference and composite coating were evaluated through cavitation tests and electrochemical measurements conducted in the laboratory. The results demonstrate that the addition of 20% WC-Co significantly enhances the cavitation resistance of the composite material, as evidenced by the reduction to 3.76 times of the cumulative erosion (CE), while the stabilization rate remained at half the value observed for the reference self-fluxing alloy coating. Conversely, the addition of WC-Co into the NiCrBSi coating resulted in a slight decrease in the corrosion resistance of the self-fluxing alloy. Nevertheless, the corrosion rate of the composite coating (124.80 µm/year) did not significantly exceed the upper limit for excellent corrosion resistance (100 µm/year).

STUDY ON THE CORROSION RESISTANCE OF HOMOGENEOUS Mg-1Bi-0.5x (x=Nd,Ce,La) ALLOYS

Mg alloys are widely used in the aerospace and automotive industries, as well as in electronic products due to their low density and high specific strength. However, the poor corrosion resistance of Mg alloys limits their applications. Rare earth elements have been shown to improve the corrosion resistance of alloys. In this study, Mg-1Bi-0.5x (x = Nd, Ce, La) alloys were prepared by alloying with Bi, Nd, Ce, and La. The microstructure and corrosion behavior of Mg-1Bi-0.5x (x = Nd, Ce, La) alloys were investigated using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), hydrogen evolution tests, weight loss experiments, and electrochemical measurements. The results indicate that the Mg-1Bi-0.5Nd alloy exhibits higher corrosion potentials and lower corrosion current densities, indicating superior corrosion resistance. This improvement is attributed to the formation of a more stable and uniform film of corrosion products, which prevents further corrosion and enhances corrosion resistance.

Evaluation of the Degradation Properties of Plasma Electrolytically Oxidized Mg Alloy AZ31 Using Fluid Dynamic Accelerated Tests for Biodegradable Implants.

Magnesium alloys are promising biodegradable implant materials due to their excellent biocompatibility and non-toxicity. However, their poor corrosion resistance limits their application in vivo. Plasma electrolytic oxidation (PEO) is a powerful technique to improve the corrosion resistance of magnesium alloys. In this study, we present the accelerated degradation of PEO-treated AZ31 samples using a fluid dynamic test. The samples were prepared using different concentrations of KOH as an electrolyte along with NaSiO3. The anodizing time and the biasing time were optimized to obtain the increased corrosion resistance. The analysis of the degraded samples using microscopy, SEM EDX measurements, and by calculating mass loss and corrosion rates showed a significant increase in the corrosion resistance after the polymer (Resomer© LG 855 S) coating was applied to the anodized samples. The results confirm (or convince) that PEO treatment is an effective way to improve the corrosion resistance of AZ31 magnesium alloy. The fluid dynamic test can be used as an accelerated degradation test for biodegradable alloys in simulated body fluids at a physiological temperature. The polymer coating further improves the corrosion resistance of the PEO-treated AZ31 samples.