Corrosion Damage Analysis and Material Characterization of Sherman and Centaur - The Historic Military Tanks

A study of corrosion damage and material characterization of two historic military tanks, the Sherman and Centaur is reported. Experiments were conducted to analyse surface corrosion and corrosion propagation from surface to sub-surface. Significant surface corrosion was found, this phenomenon was further facilitated by delamination failure mechanisms. Corrosion depth for the Sherman was approximately 110 µm, where sulphide inclusions were detected in the sub-surface analysis. The Centaur’s analysis showed corrosion pits at 100 µm depth. These pits possess random geometrical configurations with evidence of sulfur, sodium and calcium

Anomalous behavior of the Debye temperature in Fe-rich Fe-Cr alloys

Debye temperature, $\Theta_D$, of Fe-rich Fe$_{100-x}$Cr$_x$ disordered alloys with $0\le x \le 22.3$ was determined from the temperature dependence of the central shift of M\"ossbauer spectra recorded in the temperature range of 60 -- 300 K. Its compositional dependence shows a maximum at $x \approx 5$ with a relative increase of $\sim 30$% compared to a pure iron. The composition at which the effect occurs correlates well with that at which several other quantities, e. g. the Curie temperature and the spin-wave stiffness coefficient, $D_0$, show their maxima, but the enhancement of $\Theta_D$ is significantly greater and comparable with the enhancement of the hyperfine field (spin-density of itinerant $s$-like electrons) in the studied system. The results suggest that the electron-phonon interaction is important in this alloy system

Time Dependent Surface Corrosion Analysis and Modelling of Automotive Steel Under a Simplistic Model of Variations in Environmental Parameters

This research presents time-dependent corrosion analysis of automotive steel utilised in a large military vehicle in real operating environment, followed by simulated environmental tests and simplistic surface corrosion modelling. Time-dependent surface corrosion accumulated on this specific component was observed to be approximately 250 µm thick, with the identification of surface contaminants such as chlorine and sulphur. Simulated environmental tests considering temperature and relative humidity variations were performed to evaluate quantitative corrosion damage to the structure of the vehicle. The relationship of various temperatures and relative humidity with respect to time, within the context of corrosion initiation and propagation, has been presented. A mathematical model to incorporate corrosion accumulation on the surfaces derived from the simulated environmental tests is presented

Global and local corrosion of welded joints of high-strength low-alloy automotive steel

Global and local corrosion techniques were used to study the corrosion behaviour of weld joints of a high strength low alloy steel (LNE500), typically employed in the automotive industry, in Brazil. The welded joints were prepared by gas metal arc welding (GMAW). Two welding transfer modes were used in order to obtain different heat inputs (HI): pulsed (PUL) and cold metal transfer (CMT). Local and global corrosion analysis techniques presented complementary information. While the local in-situ analysis (scanning vibrating electrode technique) revealed the weld metal (WM) as the region where corrosion started, conventional electrochemical techniques (Potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS)) revealed a higher corrosion rate in the coarse-grained heat affected zone (CGHAZ), which was preferentially corroded. A superior corrosion resistance of the weld metal obtained using CMT over the PUL transfer mode was revealed by EIS and PP. In addition, the results from CMT and PUL samples show that austenite grain size affects the propagation of the corrosion process. The results are discussed based on microstructural and compositional aspects of the different regions that characterize the welded joints

A Novel Route for Electrolytic Production of Very Branchy Copper Dendrites under Extreme Conditions

Copper electrodeposition in a form of powder was examined using the pulsating overpotential (PO) regime from the sulfate electrolyte without or with an addition of various concentrations of chloride ions. Morphological and structural characteristics of the produced particles were analyzed by the scanning electron microscope (SEM) and the X-ray diffraction (XRD) method. The final morphology of Cu powders was determined with two parallel processes: a) suppression of hydrogen evolution reaction due to pause duration considerably longer than the deposition time, and b) catalytic effect of added chlorides. Depending on the amplitude of overpotential applied, addition of chlorides into the solution led to either an appearing of dendrites or to formation of verybranchy dendrites, what confirms a catalytic effect of these ions on the process of Cu electrolysis. The novel forms of copper dendrites, such as the needle-like and the 2D (two dimensional), were identified in this investigation, and the catalytic effect of chlorides on copper electrodeposition has been just discussed by morphological analysis of these dendritic forms. The XRD analysis of the copper dendrites obtained with an addition of chlorides showed predominantly oriented the Cu crystallites in (111) plane.This is the peer-reviewed, accepted version of the manuscript: Karimi Tabar Shafiei, F., Jafarzadeh, K., Madram, A. R.,& Nikolić, N. D. (2021). A Novel Route for Electrolytic Production of Very Branchy Copper Dendrites under Extreme Conditions. Journal of The Electrochemical Society, 168, 043502. [https://doi.org/10.1149/1945-7111/abf064]Published version: [https://cer.ihtm.bg.ac.rs/handle/123456789/4526