This study used a hybrid combination of kenaf and hemp fibers and the multi-walled carbon nanotube (MWCNT) reinforcements in the matrix phase to synthesize the composites. A kenaf/hemp fiber blend with MWCNTs in epoxy was used for the specific concentration. The procedure used three composite materials chosen from pilot trials. The ratio of MWCNT filler particles was altered up to the agglomeration limit based on initial trials. Two specimens (2 and 3) were supplemented with MWCNTs in a concentration range of 0.5 wt. % to 1 wt. %, with the fiber concentration being maintained in equilibrium with the epoxy resin, all of the materials were tested under the same conditions. The hybrid nanocomposite was characterized for its morphological and mechanical properties; the tensile properties were higher for 1% MWCNTs concentration (specimen 2), while the flexural properties were higher for 0.5% MWCNTs, with values of 43.24 MPa and 55.63 MPa, correspondingly. Once the MWCNT concentration was increased to 1 wt. %, the maximum impact strength was achieved (specimen 3). In the limits of the Shore-D scale, the kenaf fiber and hemp fiber matrix composite (specimen 1) gained a hardness index of 84. Scanning electron microscopy was carried out to analyze the morphological features of the fractured samples and to assess the adhesion between the fiber, matrix, and surface. Among the various fillers tested, the kenaf fiber/hemp/MWCNT composite (specimen 3) demonstrated superior binding and reduced the incidence of fiber pull-out, breakage, and voids. In addition to the comparative analysis, the addition of 0.5 wt. % MWCNTs resulted in better mechanical properties compared to the other two combinations.

Aramid fibers are widely used in fiber-reinforcement due to their high fracture toughness, low coefficient of thermal expansion and high wear resistant. However Aramid fibers are available in the form of yarn and in powder state because of which it is unsuitable for most of the direct application. In this work, Aramid reinforced Nylon was used as a liner element for a sliding bearing, printed by Fused Deposition Modeling (FDM) and was tested for the effort needed to slide in comparison with the sliding-ball bearing. Spool with 3milimeter (mm) diameter containing Aramid 2% (weight) with Nylon was extruded and the sliding liner element was printed by FDM at full density with orientations of 0° and 90° to the travel direction. The surface finish of the contact surface was narrowed down to the least possible Ra value by optimizing the printing parameters including the road width, build plane and print temperature. The part with 0^° orientation (along the travel path) with Ra of 0.6μm exhibited the least effort of 0.721 Newton (N). The polymer composite was also tested for its Tribological properties that exhibited a higher wear resistance of 0.3 gm/min. An improvement in the surface finish of the printed sliding element was achieved by optimizing the process parameter through Taguchi technique.

This study investigates the applicability of mechanized Pulsed Gas Metal Arc Welding (m-PGMAW) for the girth welding of API 5L X65 subsea pipelines intended for sour service. Welds were fabricated using ER70S-6 filler wire and augmented process parameters, yielding defect-free joints with a controlled heat-affected zone (HAZ). Hardness mapping confirmed a maximum of 210 HV10, well below the industry standard threshold (250 HV10) for sulfide stress cracking resistance. Tensile testing demonstrated strength matching between weld and base metal, with improved properties at sub-zero temperature (−11 °C). Fatigue crack growth rate (FCGR) tests revealed significantly accelerated crack propagation in a sour environment compared to air, attributed to hydrogen embrittlement. The findings provide critical experimental data for Engineering Critical Assessments (ECA), ensuring conservative flaw acceptance criteria and long-term structural integrity of subsea S-lay pipelines operating in aggressive sour environments, and it validates the robustness of the developed m-PGMAW procedure.

Wire Arc Additive Manufacturing (WAAM) has emerged as a promising metal additive manufacturing technology for fabricating large-scale structural components owing to its high deposition rate, excellent material utilization, and cost-effectiveness. Compared with powder-based processes, WAAM offers significant advantages for producing complex metallic parts in aerospace, marine, automotive, energy, and oil and gas industries. However, challenges related to microstructural heterogeneity, mechanical anisotropy, residual stress, dimensional accuracy, and process repeatability continue to limit its widespread industrial adoption. This review critically examines recent advances in WAAM, emphasizing the relationships between processing parameters, microstructure evolution, mechanical behavior, intelligent process monitoring, hybrid manufacturing, and sustainability. The reviewed literature demonstrates that heat input, cooling rate, interpass temperature, and deposition strategy govern grain morphology, phase evolution, porosity, and residual stress, thereby significantly influencing the mechanical performance of aluminum, titanium, steel, and nickel-based alloys. Recent developments, including pulsed arc modes, Cold Metal Transfer (CMT), controlled cooling, and interlayer deformation, have shown considerable potential for reducing anisotropy and improving tensile properties and structural reliability. Furthermore, the integration of intelligent sensing techniques, machine learning algorithms, and digital twin technologies enables real-time process monitoring, predictive defect detection, and data-driven process optimization. Hybrid additive–subtractive manufacturing has also emerged as an effective strategy for enhancing dimensional accuracy, surface quality, and manufacturing efficiency while reducing post-processing requirements. Overall, this review highlights current industrial applications, sustainability benefits, existing technical challenges, and future research opportunities, demonstrating that the convergence of advanced process control, artificial intelligence, and hybrid manufacturing will be essential for achieving reliable, intelligent, and sustainable WAAM systems.