Magnetic Barkhausen noise (MBN) represents a powerful non-destructive testing and material characterization methodology enabling quantitative assessment of microstructural features, mechanical properties, and stress states in ferromagnetic materials. This comprehensive review synthesizes recent advances spanning theoretical foundations, sensor design, signal processing methodologies, and industrial applications. The physical basis rooted in domain wall dynamics and statistical mechanics provides rigorous frameworks for interpreting MBN signals in terms of grain structure, dislocation density, phase composition, and residual stress. Contemporary instrumentation innovations including miniaturized sensors, multi-parameter systems, and high-entropy alloy cores enable measurements in challenging environments. Advanced signal processing techniques—encompassing time-domain analysis, frequency-domain spectral methods, time–frequency transforms, and machine learning algorithms—extract comprehensive material information from raw Barkhausen signals. Deep learning approaches demonstrate superior performance for automated material classification and property prediction compared to traditional statistical methods. Industrial applications span manufacturing quality control, structural health monitoring, railway infrastructure assessment, and predictive maintenance strategies. Key achievements include establishing quantitative correlations between material properties and stress states, with measurement uncertainties of ±15–20 MPa for stress and ±20 HV for hardness. Emerging challenges include standardization imperatives, characterization of advanced materials, machine learning robustness, and autonomous system integration. Future developments prioritizing international standards, physics-informed neural networks, multimodal sensor fusion, and wireless monitoring networks will accelerate industrial adoption supporting safe, efficient engineering practice across diverse sectors.

High-strength naval steel panels were coated by spraying with five commercial antifouling paints. The first set of coated specimens was subjected to electrochemical measurements and the anticorrosion properties of the paints were evaluated under controlled laboratory conditions. A second series of coated samples was statically exposed for nine months in thirteen different harbors, located in the Mediterranean Sea and the Atlantic Ocean, where their in-field antifouling efficiency was determined. The corrosion performance obtained by the electrochemical measurements provides predictions that best match the fouling protection observed at the field sites. The results indicate that the corrosion’s resistivity values determined in the laboratory were in a good agreement with the fouling level observed by examining the sea samples. The reported complementary data show that the laboratory measurements are representative of the sea-field conditions and confirm the originality of the proposed approach, which might lead to the development of innovative low-drag antifouling coatings for the hulls of ships, vessels, and speed crafts.

Biofouling of the hulls of ships and vessels, caused by the colonization of animals and plants, is an ongoing problem for the shipping industry. Biofouling evokes surface roughness, which results in higher fuel consumption, emissions, and operating costs. Mitigation of biofouling is a complex problem and the effectiveness of any given approach depends on many factors. Compared to complex anti-fouling technologies, the use of anti-fouling coatings presents the most viable solution, both in terms of cost and efficiency. Nevertheless, due to the modest performance of most modern antifouling hull coatings, frequent maintenance, and dry-docking intervals are still required. In addition, application costs are often not negligible. New antifouling technologies, such as low-drag antifouling paints with broad spectrum activity are urgently required in order to promote smoothness of the surface as well as provide adequate protection against biofilm formation. The development of innovative nanocomposite coating structures which combine low-drag film surfaces with antimicrobial components within water-soluble matrices may be a drastic solution to the above problem. Moreover, applying such structures directly on the hulls of ships and marine vessels without the use of primers is a long-awaited possibility, which could have a tremendous impact on reducing application costs.

This work presents a comprehensive evaluation of corrosion progression in DH36 naval steel through the integration of electrochemical impedance spectroscopy (EIS), weight loss, scanning electron microscopy (SEM), and advanced magnetic non-destructive techniques under artificial seawater (ASW, ASTM D1141) and natural marine conditions. Quantitative correlations are established between corrosion layer growth, electrochemical parameters, and magnetic permeability, demonstrating the magnetic sensor’s capacity for the real-time, non-invasive assessment of marine steel degradation. Laboratory exposures reveal a rapid initial corrosion phase with the formation of lepidocrocite and goethite, followed by the densification of the corrosion product layer and a pronounced decline in corrosion rate, ultimately governed by diffusion-controlled kinetics. Notably, changes in magnetic permeability closely track both the thickening of non-magnetic corrosion products and microstructural deterioration, with declining μmax and increased hysteresis widths (FWHM) sensitively indicating evolving surface conditions. A direct comparison with in situ marine immersion at Rafina confirms that the evolution of corrosion morphology and the corresponding magnetic response are further modulated by biofilm development, which exacerbates the attenuation of measured surface permeability and introduces greater variability linked to biological activity. These findings underscore the robustness and diagnostic potential of magnetic non-destructive sensors for the predictive, condition-based monitoring of naval steels, bridging laboratory-controlled observations and complex real-world environments with high quantitative fidelity to corrosion kinetics, phase evolution, and microstructural transformations, thus guiding the strategic deployment of protection and maintenance regimens for naval fleet integrity.

This study involved covering naval steel samples with a biocide-free, innovative antifouling coating, which were subsequently immersed in either artificial seawater or a Greek maritime environment for durations ranging from 1 to 50 weeks. The objective was to assess the efficacy of the coating as an anticorrosion and antifouling barrier on the steel samples. Non-coated samples were analyzed alongside the coated samples for comparative purposes. The findings indicate that a reduction in coating thickness during static immersion in laboratory settings leads to the removal of precipitated corrosion products, exposing a fresh layer of “pristine” coating. This layer decreases the corrosion rate by almost 90% throughout extended immersion durations. The efficacy of the coating is validated through trials conducted in natural maritime environments, demonstrating an operational performance of 99% for the coated samples after 50 weeks of continuous exposure to seawater. In fact, the coated samples showed only soft fouling, in contrast to the uncoated samples which were characterized by a strong presence of hard fouling within a short period of time after immersion.