Thermomechanical treatment is widely employed to enhance the mechanical performance of medium-carbon steels; however, it often compromises their corrosion resistance and shortens service life, particularly in corrosive environments. The present study aims to simultaneously improve the mechanical and electrochemical properties of 45CrNi high-strength steel through optimized thermomechanical treatment. The as-received steel exhibited a pearlitic microstructure within a ferritic matrix, with an average grain size of 151 µm. After thermomechanical treatment with tempering at 470 °C, the steel developed a refined microstructure with an average grain size of 9.4 µm, comprising 71 vol.

The mechanochemical origin of intergranular corrosion (IGC) in AlSi10Mg additively manufactured by laser-based powder bed fusion (PBF-LB) has been investigated using electrochemical, microstructural, and stress analyses. A combined framework of electrochemical and microstructural characterizations, along with the residual stress analysis, has been employed to correlate the microstructural heterogeneity with corrosion performance. It is found that melt pool boundaries (MPBs) are characterized by a fine grain size, which results in increased susceptibility to the IGC attack. Scanning electrochemical microscopy measurements show that IGC initiates within MPBs, where fine grains and the microgalvanic difference between the Si-rich network and the Al matrix generate localized electrochemical activity. Electrochemical data reflect the IGC trends, with MPBs yielding a higher corrosion current density, lower charge-transfer resistance, and deeper IGC attack. An aggressive peroxide-enriched environment induces oxide film breakdown and deeper IGC penetration, diminishing the influence of variations in PBF-LB parameters. These findings demonstrate that IGC in AlSi10Mg produced by additive manufacturing arises from the combined influence of melt pool structures, residual stresses, and electrolyte chemistry.

While friction stir welding (FSW) is a sustainable method for joining aluminum alloys, the effect of rotational speed on the combined microstructural, mechanical, and corrosion behavior of 5083 Al-Mg alloy is not well established. Most studies treat these properties separately, creating a gap in understanding their interdependence. Closing this gap is essential for optimizing FSW parameters for durable marine applications. Therefore, this study investigates the impact of varying rotational speeds (600, 700, and 800 RPM) on the metallurgical evolution, mechanical performance, and electrochemical behavior of friction stir welded 5083 Al-Mg alloy. Welds were produced using a butt joint configuration with a fixed tool traverse speed of 180 mm min-1. Comprehensive analyses were conducted, encompassing x-ray diffraction analysis, mechanical testing, and electrochemical corrosion evaluations. The findings reveal that a rotational speed of 800 RPM delivers the most optimal weld characteristics compared to 600 RPM and 700 RPM. Specifically, the weld fabricated at this speed exhibited the highest tensile strength (342.48 MPa), minimal residual stresses, a highly uniform phase formation, and exceptional corrosion resistance, evidenced by an impressively low corrosion rate of 0.01 mpy.

This study investigates the effect of fabrication methods on the microstructural, mechanical, and electrochemical durability of nickel alloy IN718, aiming to establish it as a cost-effective electrode material for direct seawater electrolysis using renewable energy sources. Selective laser melting (SLM) and conventional casting methods were used to fabricate IN718 alloy electrodes. Microstructural and mechanical characterization results show SLM samples have better compaction with maximum average hardness and densification of 347 (HV 0.5) and 99.2 %, respectively. This attribute is due to ultra-fast cooling rate and high-temperature gradient during sintering of 3D-printed samples in a layer-by-layer fashion. The electrochemical durability was investigated in 3.5 wt% NaCl electrolyte solution as a function of temperature (30, 50, and 80 degrees C). Electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization (PD) tests were conducted to evaluate electrochemical behavior. It was found that 3D printed samples have lower corrosion current density (52 mu A/cm2) and dissolution rate (21.26 mpy) at higher temperatures. Protective film capacitance increases with reduced film thickness due to finegrained and desirable microstructure. Therefore, modern technology (3D printing), compared to conventional production methods, offers advantages and has the potential to produce low-cost and efficient electrode material (nickel-based alloys) for energy conversion systems and other modern engineering applications.

The corrosion behavior of hot-rolled AZX311 magnesium (Mg) alloy was studied in sodium chloride and sodium sulfate solutions (0.15 M and 0.25 M concentrations) at 30 degrees C and 50 degrees C. Microstructural analysis of the hotrolled alloy revealed uniformly distributed Al2Ca precipitates within the alpha-Mg matrix. Electrochemical tests revealed higher corrosion rates in sodium chloride, attributed to the chloride-induced breakdown of the protective magnesium hydroxide film. Corrosion accelerated with increasing temperature and concentration, with the highest rate (4.14 millimeters per year) observed in 0.25 M sodium chloride at 50 degrees C, accompanied by severe localized attack in hydrogen evolution analysis. Moreover, the presence of Al2Ca precipitates contributed to the stabilization of the passive surface film in sulfate-containing solutions. In contrast, these precipitates acted as sites for galvanic coupling with the alpha-Mg matrix, thereby intensifying localized corrosion processes, particularly under elevated temperatures within chloride-containing environments.

Magnesium (Mg) alloys are used in many structural and automotive applications, though the high susceptibility toward corrosion poses a bottleneck toward its diverse applications. Microalloying Mg is often reported to improve the corrosion resistance of Mg. In this work, the effect of Ca on the microstructure and corrosion characteristics of AZ31 magnesium alloy is investigated. The electrochemical testing of AZ31 and AZ31-0.5Ca was studied in NaCl and Na2SO4 electrolytes with different concentrations (0.5 M to 0.25 M) and various temperatures (30 degrees C to 50 degrees C). The electrochemical corrosion behavior was evaluated by the potentiodynamic polarization. The microstructural investigations revealed the formation of laves phases ((Mg, Al)2 Ca) in the AZ31-0.5Ca. The electrochemical tests showed that the effect of chloride ions was more vigorous than sulfate ions. The measured average corrosion rates for AZ31 and AZ31-0.5Ca alloys were 55.68 mpy and 78 mpy in 0.05 M NaCl, and 22 mpy and 60 mpy in Na2SO4 at 30 degrees C, respectively. Notably, the corrosion rate increased with increasing electrolyte concentration and temperature, consistent with the principles of the Arrhenius law. AZ31-0.5Ca showed superior corrosion resistance as compared to AZ31 in both electrolytes at all of the testing conditions. The improved corrosion resistance was attributed to the formation of (Mg, Al)2 Ca, which reduced the overall fraction of beta-Mg17-Al12.

Owing to the low cost, ease of fabricability, good mechanical properties, corrosion resistance and biocompatibility of the 316L stainless steel (SS), this material is considered a suitable choice for orthopedic applications. Based on its properties and large utilization in orthopedics, this review focuses on the importance of additively manufactured (AM) 316L stainless steel. Owing to the large flexibility of the additive manufacturing process, the microstructure of the 316L SS can be easily tuned to modify the mechanical, corrosion and biological properties. To elucidate the benefits of additively manufactured 316L stainless steel, the properties of the selective laser melted (SLM) 316L stainless steel and wrought 316L stainless steel are compared. Particularly, the unique features of the SLM 316L stainless steel have been discussed in detail. The existing challenges associated with the additive manufacturing processes and implications of their widespread application are also highlighted. A brief overview of the biological properties and reactions sequence of the host immune system, i.e. tissue response, the activation of acute and chronic inflammatory processes and immunological reactions, is also provided to understand the reasons for implant failure or rejection by the body.

The corrosion behavior of AZ61 Mg alloy with two different CaO concentrations (0.5 wt% and 1 wt%) was investigated in Ringer's lactate solution at 37 +/- 1 degrees C. Electrochemical characterization techniques, including open-circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and Potentiodynamic polarization (PDP), were employed to assess corrosion kinetics and mechanisms. Additionally, a 10-day immersion test, incorporating hydrogen evolution and weight loss measurements, was conducted to evaluate long-term dissolution resistance. The results demonstrated a clear enhancement in corrosion protection with increasing CaO content. AZ61 Mg alloy exhibited the most negative OCP (-1.370 V) and the highest corrosion current density (225 mu A/cm(2)), corresponding to a corrosion rate of 196 mpy. In contrast, AZ61-1CaO Mg alloy displayed the least negative OCP (-1.260 V) and the lowest corrosion current density (53 mu A/cm(2)), significantly reducing the corrosion rate to approximately 45 mpy. EIS analysis confirmed these findings by revealing larger semicircles and higher charge-transfer resistance for the AZ61-1CaO Mg alloy. Weight loss and hydrogen evolution tests further supported the electrochemical results, indicating that the AZ61-1CaO Mg alloy exhibited the least weight loss, minimal hydrogen evolution, and the most stable and protective corrosion product layer. Biocompatibility analysis (MTT assay, live/dead staining) demonstrated > 80 % cellular viability with low cytotoxicity in all alloys, confirming that CaO addition does not interfere with cell proliferation or morphology.

Cathodic cage plasma nitriding (CCPN) is a proficient and cost-effective technique for surface modification of metallic samples that has been in use for the last two decades. The effectiveness of CCPN depends upon different controlled parameters. The main objective of the current study was to investigate the effect of temperature on CCPN performance. Copper (Cu) samples were nitrided at various temperatures (100–400 °C) for a fixed time of 4 h. The treated samples were investigated using a micro-hardness tester, x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, ball-on-disc wear tester, and potentiodynamic polarization. An improvement in hardness, wear resistance, and corrosion resistance has been reported with an increase in temperature. The treated samples possessed aluminum nitride (AlN), copper(I) nitride (Cu3N), copper(I) azide (CuN3), copper(II) azide (CuN6), and AlCu4 phases with intensity increasing with temperature. The current study clarified the reactivity of the CCPN system on treated samples in a broad manner. Untreated samples have shown abrasive wear at low temperatures, whereas adhesive wear is the predominant mechanism at high temperatures. At high temperatures, a low friction coefficient has been achieved due to smoother surfaces. Nitrided samples have shown an overall increased corrosion resistance with an increase in temperature.

This study investigates the corrosion resistance of LPBF-fabricated AlSi10Mg alloy, focusing on the interplay between process parameters and heat treatments. Volumetric energy densities ranging from 32 to 117 J/mm3 were employed, resulting in different microstructural features and defect types, including lack-of-fusion and keyhole pores. Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP) tests conducted in a 3.5 wt.

In this study, cubic Hastelloy-X was manufactured by laser powder bed fusion process. A systematic investigation focused on the microstructure and anisotropic electrochemical corrosion behavior along the building direction was conducted. Distinctive columnar dendritic features across melt pool boundaries were consistently observed in the top (HX-T), middle (HX-M), and bottom (HX-B) regions along the building direction. A significant reduction in Mo content from the HX-T to the HX-B was observed, attributed to preferential segregation of Mo during the solidification process. Typical fish-scale molten pool was observed in the HX-B and HX-M, while HX-T consisted of strip molten pool in addition to fish scale molten pool. All samples showed the typical characteristics of Goss texture <110> // BD. HX-M sample showed the largest grain size, highest intensity ∼6.35 mrd and lowest kernel average misorientation value as compared to HX-T and HX-B associated with the remelting of the former solidified layer due to the newly deposited layer. Electrochemical analysis including electrochemical impedance spectroscopy and potentiodynamic polarization scans were conducted in 10 wt.% NaCl electrolytes at constant temperature of 25 ± 1 °C. HX-T showed the lowest corrosion rate as compared to HX-M, HX-B (0.55, 23.16 and 16.01 mpy for HX-T, HX-M and HX-B, respectively). The surface morphology of corroded samples revealed that the formation of a compact passive film due to the presence of high atomic % of Mo in HX-T restricted the chloride ions from the electrolyte to penetrate and react with the metal samples subsequently enhancing the corrosion resistance.

The Al-Zn sacrificial anodes are widely used for cathodic protection in marine steel structures. This study evaluates the impact of bismuth addition on the electrochemical properties of the Al-Zn sacrificial anode in artificial seawater. The microstructure analysis confirms the presence of uniformly distributed intermetallic β-AlFeSi and spherical Bi particles within the α-Al matrix. The open circuit potential (OCP) comparison between Al-Zn-Bi and carbon steel reveals a potential difference of approximately 400 mV, indicating sufficient cathodic protection for the steel. Electrochemical impedance measurements indicate the initial hindered dissolution of the anode due to surface film formation, which later dissociates due to the aggressive attack of Cl– species in the electrolyte. The sufficiently negative surface potential (-0.875 V vs. Ag/AgCl) observed at 10 mA/cm² demonstrates the suitability of anode for fulfilling the cathodic protection criteria of steel structures.

Aluminum–lithium 2060 alloy is an ideal structural material for aeronautical components. Friction stir welding (FSW) of 2-mm-thick 2060 Al-Li alloy plates having a welding speed of 600 mm/min and rotation speed of 400 rpm exhibits better joining properties, compared to other conventional welding processes. In the FSW process, three zones are formed due to the stirring of tool and axial force that are the stir zone (SZ), thermo-mechanical affected zone (TMAZ), and heat-affected zone (HAZ), along with base metal (BM). BM showed a lamellar structure of lath-shaped α-Al phase arranged along the rolling direction. The microstructure of SZ appeared as fine and equiaxed grains, which is a distinctive feature of severe plastic deformation at high temperatures. The TMAZ, a transition zone surrounding the weld nugget, experiences a combined action of friction heating and high bending. The equipment was designed and fabricated to investigate the stress corrosion cracking behavior in a simulated environment. The electrochemical properties of FSW welded Al-Li 2060 alloy were determined in 3.5 wt.

Pure iron (Fe) was subjected to singly charged 1 MeV Gold (Au+1), Nickel (Ni+1), Cobalt (Co+1), Copper (Cu+1), and Yttrium (Y+1) ions irradiation at a constant dose of 5 x 1014 ions/cm2. X-ray diffraction analysis revealed polycrystalline nature of Fe with ions-induced changes in its crystallinity. Improvement in the crsytallinity of Fe due Au+1 irradiation was more significant as compared to the others. Similarly, the crystallinity of Fe was greatly decreased due to the impact of Y+1 ions. The Fe surface morphology indicated the surface defects in the form of pits, cavities and protruded structures after ions irradiation. Potentiodynamic Polarization (PDP) revealed an increase in the corrosion resistance of Fe after irradiation. The Au+1 ions irradiated specimen was found more effective in terms of high corrosion resistance than other specimens. The surface hardness of Fe exhibited Classical Hall-Petch relation, which demonstrated that the larger the crystallite size (26-83 nm), the smaller would be the surface hardness (190-182 HV) and vice versa.

Vanadium samples were irradiated with Nd-YAG laser in vacuum, argon, oxygen, helium, and nitrogen environments to investigate changes in the structural, morphological, and electrochemical properties of the material. Irradiation was performed for 100 laser shots with a pulse energy of 150 mJ, a pulse width of 6 ns, and a repetition rate of 10 Hz. X-ray diffraction study revealed that the largest crystallite size was found in the case of Vanadium irradiated under helium, while the smallest crystallite size was observed in the nitrogen environment. The preferred orientation of the Vanadium remained unchanged in different gas environments. The surface morphology of the laser-irradiated Vanadium displayed cones, bubbles, cracks, cavities, droplets, grooves, dips, micropillars, ripples, and wave-like structures. The surface hardness of the Vanadium irradiated with laser in nitrogen was higher compared to the other samples. Electrochemical tests in 0.9

This article examines the influence of 0.2 wt% bismuth addition on the corrosion behavior of Al-4.2 wt% Zn sacrificial anode in artificial seawater. Corrosion behavior was assessed by electrochemical methods such as open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy. Approximately 400 mV potential difference between anode and steel confirmed the effective protection capacity of the anode. The absence of an inductive loop at low frequency of the impedance spectra and a decrease in charge transfer resistance suggested that the addition of Bi could suppress hydrogen evolution, confirming uniform dissolution of the sacrificial anode.

In this research work, the corrosion tendency of stainless steel (SS 304) caused by the Pseudomonas aeruginosa ZK (PA-ZK) and Bacillus subtilis S1X (BS-S1X) bacterial strains is investigated. The topographical features of the biofilms and SS304 substrate achieved after 14 days of incubation at 37 °C were examined by scanning electron microscopy (SEM). Fourier Transform Infrared Spectroscopic (FTIR) analysis of the extracellular polymer substance (EPS) was also carried out to estimate the chemical composition of the biofilm. Electrochemical Impedance Spectroscopy (EIS) and Tafel Polarization test methods were applied to understand the in-situ corrosion tendency of the SS304 in the presence of PA-ZK and BS-S1X strains. Compared to the biofilm produced by the PA-ZK, the EPS in the BS-S1X containing bacteria was porous and non-uniform as revealed in the SEM analysis. The improved hydrophobicity and uniformity of the PA-ZK containing biofilm retarded the corrosion of the underlying SS304 sample. Appreciably large resistance of the PA-ZK biofilm (~ 6.04 kΩ-cm2) and hindered charge transport (11.12 kΩ-cm2) were evident from the EIS analysis. In support of these results, a large cathodic Tafel slope (0.2 V/decade) and low corrosion rate (1.69 µA/cm2) were corroborated by the inhibitive properties of the PA-ZK containing biofilm. However, the formation of porous biofilm and non-homogeneity of the EPS layer produced by the BS-S1X bacteria facilitated localized corrosion. Also, low charge transfer resistance, a high corrosion rate and pitting of the surface under BS-S1X biofilm were comparable to the surface features of SS304 obtained after exposure to a controlled medium. These results highlighted the poor corrosion inhibitive properties of the BS-S1X biofilm compared to the PK-ZK bacterial strain.

In this work, effects of laser irradiation on several characteristics of vanadium (99.999%) are examined. The square-shaped vanadium samples were irradiated using pulsed Nd:YAG laser (532 nm, 6 ns) at a high fluence (7.46 J/cm2) with 100, 200, 300, and 400 laser shots under vacuum. X-ray diffraction results revealed the preferred orientation of the unirradiated vanadium along (200) plane that remained un-changed upon laser irradiation. The crystallite size varied in the range 30–62 nm and the average diameter of laser-ablated region was decreased with the increase of laser shots. On the contrary, the heat-affected area around the ablated region and the surface roughness progressively increased on increasing the number of laser shots. The morphological features of the laser-irradiated vanadium comprised of cavities, microcones, cracks, grooves dips, bubbles, droplets, ripples, micro-pillars, and wave-like structures. The hardness of the samples (166–184 HV) was decreased with increase of the crystallite size (30–62 nm) and vice versa. The samples irradiated with the laser for 100 and 200 shots exhibited a higher corrosion rate as compared to the un-irradiated sample. However, the corrosion rate was reduced as the number of laser shots were increased to 300 and then 400, demonstrating an improvement in the vanadium corrosion resistance.

The rubber bands used in the track chains of excavators, known as track pin rubber bands, frequently experience failures due to factors such as their heavyweight, fast speed, sharp objects on off-road paths, shocks, vibrations, accumulated heat (generated during operation), and track tension. To identify the main cause of these failures, we conducted a failure analysis by evaluating their chemical compositions, morphological, mechanical, and thermal properties. For this study, four different types of failed rubber bands, designated as RB1, RB2, RB3, and RB4, were collected from the track pins of four distinct excavator track chains. None of the selected rubber bands passed the 1000 km running trial. RB1 failed after covering 650 km, RB2 failed after 250 km, RB3 after 400 km, and RB4 after 800 km. Both mechanical and thermal properties are dependent on the chemical formulations of the rubber bands, and all the failed rubber bands exhibited poor chemical formulations. RB1 showed a Schallamach wave on the outer used surface, indicating significant plastic deformation before fracture. In contrast, the other failed rubber bands (RB2, RB3, and RB4) displayed severe mechanical degradation with surface defects such as deep grooves, catering or pitting, micro-cracks, and scars. Thermogravimetric analysis further supported the cause of failure, revealing higher total mass loss and lower residue mass percentages.