This study investigates the influence of tool rotational speed and feed rate on the corrosion behaviour of ZE41‐AZ31 friction stir welded (FSW) dissimilar joints using immersion testing, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) analysis. Results show that higher rotational speeds, particularly 1200 min −1 combined with lower feed rates (20 mm·min −1 ‐ 30 mm·min −1 ), significantly enhance corrosion resistance. The optimal condition of 1200 min −1 and 20 mm·min −1 yielded the lowest corrosion rate (2.097 mm·yr −1 ), highest open circuit potential (~ ‐1.575 V), largest Nyquist semicircle diameter, and lowest I corr , indicating improved passive film formation and charge transfer resistance. In contrast, lower speeds and higher feed rates (800 min −1 , 40 mm·min −1 ) resulted in poor corrosion performance due to insufficient heat input and weld defects. Overall, a high rotational speed with a low to moderate feed rate optimizes electrochemical stability and corrosion resistance in ZE41‐AZ31 friction stir welding joints.
Multiscale modelling enabled a systematic investigation of titanium alloy (Ti-6Al-4V) single-lap adhesive joints using Araldite 2015 epoxy reinforced with multi-walled carbon nanotubes (MWCNTs) and single-walled boron nitride nanotubes (SWBNTs). A hybrid approach integrates Digi-mat's nanoscale mean-field homogenization for predicting effective nanocomposite properties with Abaqus-based macroscale joint simulations under mechanical loading. Six adhesive configurations are analyzed, neat epoxy, multi-walled carbon nanotubes-reinforced (1 wt.-%-3 wt.-%), and single-walled boron nitride nanotubes-reinforced (1 wt.-% and 3 wt.-%). Results demonstrate progressive longitudinal modulus enhancements of 8.69 %, 16.22 %, and 23.89 % for 1 wt.-%-3 wt.-% multi-walled carbon nanotubes, outperforming single-walled boron nitride nanotubes (8.50 % at 1 wt.-%, 23.53 % at 3 wt.-%). The 3 wt.-% multi-walled carbon nanotubes adhesive achieved optimal performance, increasing the peel stress concentration by 10% and shear stress localization by 1.2 %, compared to neat epoxy, attributed to improved load transfer and crack resistance. Stress pattern analysis shows that the multi-walled carbon nanotubes more effectively reduce edge stress singularities, with 3 wt.-% balancing viscosity limitations and mechanical gains. Single-walled boron nitride nanotubes exhibit reduced efficiency despite quality modulus gains at 3 wt.-%, highlighting multi-walled carbon nanotubes superior reinforcement capacity. These outcomes overview the practicality of 3 wt.-% multi-walled carbon nanotubes-epoxy adhesives for aerospace and automotive industries, offer higher peel strength than neat epoxy while keeping up lightweight characteristics.
Duplex stainless steels are broadly employed in harsh environments because of their excellent combination of mechanical strength and corrosion resistance. But, exposure to temperatures near 475 degrees C can trigger microstructural degradation within the ferritic phase, which results in development of chromium enriched and Iron enriched nanophases. This transformation is known to cause embrittlement and significantly diminish corrosion resistance, affecting the durability. In this experimental study, the electrochemical performance of duplex stainless steel thermally aged at 475 degrees C was systematically evaluated, with emphasis on pitting corrosion resistance in both aerated 3.5 weight percent sodium chloride solution and carbon dioxide-saturated simulated oilfield brines. Electrochemical techniques were used to measure pitting breakdown potentials, while x-ray photoelectron spectroscopy was employed to characterize the passive film and investigate chloride ion incorporation. Results reveal a significant decline in corrosion resistance associated with thermally induced embrittlement. These outcomes emphasize need of carefully considering thermal exposure effects when deploying duplex stainless-steel components in service environments prone to aging.
This study employed selective laser melting technology to fabricate four lattice structures (body centered cubic, body centered cubic with simple cubic, face centered cubic, and face centered cubic with simple cubic) of Ti6Al4V, and systematically compared their porosity, phase composition, microstructure, and properties. The research results showed that the actual porosity of all structures was lower than the theoretical design value. All structures primarily consisted of acicular α′ martensite with a small amount of residual β phase. The Body centered cubic structure exhibited the shortest acicular flat noodles and the most uniform microstructure; the Body centered cubic with simple cubic structure had hole defects at the nodes. The Face centered cubic with simple cubic structure exhibited the highest tensile strength, while the Body centered cubic structure had the lowest tensile strength; the Face centered cubic with simple cubic structure had the best compressive properties. The addition of the simple cubic structure suppressed excessive bending of the oblique struts and promoted a partial transition from bending to tensile dominant mechanism, thereby improving the ductility and collapse resistance of the structure; the addition of the simple cubic structure significantly enhanced the impact resistance of the formed parts.
Magnesium alloys are promising candidates for lightweight structural applications; however, their limited hardness and wear resistance restrict wider use, particularly in power train and transmission system components. In this study, friction stir processing (FSP) was employed to improve the surface properties of squeeze‐casted Mg–3Zn alloy. Optical microstructural analysis revealed significant grain refinement in the processed zone, with the average grain size reduced from 55 μm to 6 μm due to dynamic recrystallization. The refined equiaxed grains and increased high‐angle grain boundary density contributed to grain‐boundary strengthening, consistent with the Hall–Petch mechanism, resulting in a 76 % increase in surface microhardness (67 HV to 118 HV). Tribological evaluation under applied loads of 15 N–45 N demonstrated superior wear resistance of the friction stir processed alloy, with a 48.5 % reduction in wear loss at 15 N and lower coefficients of friction compared to the as‐cast alloy. Worn surface analysis indicated abrasion and oxidation at lower loads, while delamination dominated at higher loads. The enhanced tribological performance confirms the suitability of friction stir processed Mg–3Zn alloy for lightweight power train and transmission applications.
