Journal of Welding Science

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This paper investigates the effect of boehmite nano-particles surface adsorbed byboric acid (BNBA) along with other input welding parameters such as welding current, arc voltage, welding speed, nozzle-to-plate distance on weld penetration. Weld penetration modeling was carried out using multi-layer perceptron artificial neural network (MPANN) technique. For the sake of training the network, 70% of the obtained data from experimentation using five-level five-factor central composite rotatable design of experiments was used. The performance of the network shows a good agreement between the experimental data and the data obtained from the network. Hence, it is to be concluded that MPANN is highly accurate in predicting the weld penetration in SAW process.

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Welded tubular joints are widely used in various industry structures for high efficiency subjected to pressure, bending and twisting.Welded structures are the main parts of structures, buildings, bridges, gas pipes, pressure vessels and power transmission equipment in the ship building, construction, oil, gas, petrochemical industries and power plants.A sample of pipe-welded joints is a X-tubular joint that has been investigated in this study.The main objective of the present work is to investigate the heat transfer and residual stress caused by the three-stage welding process in X-tubular joint made of St52 using Simufact Welding software.The welding process involves three welding steps using arc welding. The finite element model contains the thermal and mechanical properties of base metal and welding metal as a function of temperature.Also, advanced modeling tools such as mesh adaptation during the process and meshing compatible with the welding site, the birth and death technique of the element and the source of heat transfer have been used.Welding simulation showed that significant residual stresses were created in the joint after welding. Comparison of the results shows that the numerical results and empirical measurements are in good agreement with each other and the existing model can provide a good prediction of temperature distribution and stress control in this welding process.

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Nickel-based superalloys are among the most critical materials used in high-temperature components of gas turbines, where their replacement costs and potential turbine damage necessitate effective protection and repair strategies. Optimizing repair methods to enhance efficiency and reduce costs has therefore been a continuous focus. The aim of this study is to improve the repair process of Inconel 738LC superalloy by reducing the susceptibility to liquation cracking. Activated tungsten inert gas (A-TIG) welding was performed on Inconel 738LC using a welding current of 60 A. Titanium dioxide (TiO₂) powder was employed as an activating flux, and weldments with four flux concentrations were examined. The microstructure w:::::as char:::::acterized using optical microscopy and scanning electron microscopy. The results revealed that flux concentration had a significant influence on penetration depth, with a concentration of 1 g/mL producing the maximum effect. At this concentration, weld penetration increased by 68% and weld pool volume by 63%, while the heat-affected zone width decreased by 12%. Arc imaging and quantitative/qualitative analysis demonstrated a constricted and focused plasma arc column in the presence of TiO₂ flux. Microstructural examinations further revealed suppression of columnar dendrite growth. It was found that TiO₂ flux enhances weld penetration and pool volume by constricting the arc and activating a reversed Marangoni flow, while simultaneously reducing HAZ width. However, the increased weld pool volume also intensified contraction stresses, leading to liquation cracking in the weld with the largest pool volume.