This work presents a comparison between the Remote Field Testing (RFT) and Internal Rotary Inspection System (IRIS) non-destructive testing (NDT) techniques. Such a comparison aims to assess the influence of the inspector experience on the RFT inspection process, as well as to evaluate whether the RFT technique has an inspection capability equivalent to the IRIS test. By using inspection data, a statistical analysis was conducted based on the results from three different RFT inspectors. Then, considering a third technique (3D Scanning) applied to sections extracted from tubes (destructive case) as a reference basis, the statistical equivalence of both NDT techniques was evaluated. Finally, to assess the accuracy of the analyses conducted by the RFT inspectors and the comparison between the RFT and IRIS techniques, artificial intelligence (AI) tools were employed to measure the success and error rates of corrosion detection via the RFT case. The results show equivalence between the NDT techniques and, despite the interpretation challenges with the RFT case, the subjectivity by the inspectors with its inspection process was considered low. The AI classification results indicated that the generated network was capable of classifying the corrosion effectively, hence supporting the equivalence between the RFT and IRIS techniques.
Residual stress evaluation in welded joints is of major importance, since its underestimation or lack of control can lead to deformations of welded components, to its mechanical properties' deterioration or even to failure in service. Various destructive and non-destructive techniques exist for measuring residual stress, each differing in complexity, cost, and accuracy. This study investigates the applicability of the hole-drilling method combined with Electronic Speckle Pattern Interferometry (ESPI) for residual stress evaluation specifically in welded joints, where surface conditions and material properties differ from the base metal due to reinforcement convexity, surface irregularities, and microstructural changes. The methodology involved initial equipment calibration using known strain levels, followed by residual stress measurements on bead-on-plate samples - produced with and without filler material. The analysis focused on different weld regions (fusion zone, heat-affected zone, and base metal), considering both longitudinal and transverse stress components. Calibration results showed a mean measurement error of 5.8% and a coefficient of variation around 6%. For the welded beads, the ESPI-based hole-drilling method demonstrated coherent residual stress distributions consistent with theoretical models. Higher precision was observed for the transverse stress component and in samples welded without filler material, while the longitudinal stresses in the heat-affected zone of the welds with filler addition exhibited greater variability due to local metallurgical and geometrical effects. Overall, the study confirms that the combined hole-drilling and ESPI technique is a viable and reliable approach for residual stress measurement in welded joints, provided that factors such as measurement depth, surface condition, and local stress gradients are carefully managed.
Friction stir welding (FSW) is the most widely used solid-state joining method for sheet and plate-like materials, valued for being a highly adaptable, environmentally sound, and energy-efficient process. The literature has repeatedly shown that FSW is a reliable joining technique for high-demand technological applications, particularly for high-strength aluminum and titanium alloys used in aerospace, which are difficult to join with traditional fusion welding methods. To describe the microstructural changes caused by solid-state FSW, many studies analyze mechanical parameters of FSW joints, including tensile strength, bending, torsion, elasticity, and fatigue responses. In recent years, the push to expand FSW's use, broaden the range of compatible alloy systems, and improve the resulting mechanical properties has led to significant advancements in this joining method. Accordingly, this review study provides a comprehensive investigation into the methodology and the materials relevant to this specific field.
Macrosegregations in welds are metallurgical imperfections that often form during the joining of dissimilar materials, potentially compromising the quality of the welded region. This study aimed to analyze the formation of macrosegregations during simulated welding repairs in areas degraded by cavitation, using different variants of the MIG/MAG process and involving the joining of an austenitic stainless steel to a martensitic stainless steel. Bead-on-plate deposits were carried out employing various metal transfer modes: conventional short-circuit with and without weaving, Cold Metal Transfer (CMT), globular, spray, and pulsed. Austenitic stainless steel AISI 309 was used as filler metal, and martensitic stainless steel CA-6NM was used as the base material. Microstructural characterization revealed the presence of macrosegregations in the form of islands and peninsulas at the welded interface between the materials. These imperfections were less pronounced in the CMT and conventional short-circuit without weaving processes compared to the other variants. Among the various transfer modes analyzed, the short-circuit mode, both conventional and CMT-controlled, stood out for presenting lower macrosegregation formation, with CMT being the most effective in achieving low dilution levels.
Hybrid Laser Arc Welding (HLAW) has been used globally in various sectors due to its high welding speeds and reduction in the number of passes, leading to increased productivity and reduced manufacturing costs. However, in Brazil, its industrial application has been questioned due to the high cost of equipment and the complexity of the process. Additionally, there are few studies discussing the use of the HLAW process in the welding of Thermo-Mechanical Controlled Processing (TMCP) steels. This study evaluated the hybrid welding process in different configurations and its effect on the mechanical properties, such as tensile strength and hardness, of SINCRON (R) BHS-485W steel, a high-strength material produced by Usiminas via TMCP for the manufacture of metal structures. The results indicate that the hybrid process is an excellent option for the welding of structural steels as it allows the welding of joints in a single pass and the use of high welding speeds, significantly optimizing the manufacturing of welded structures. Furthermore, the HLAW process caused minimal degradation in the properties of SINCRON (R) BHS-485W steel compared to Gas Metal Arc Welding (GMAW), making it a viable alternative for the welding of high-strength weathering TMCP steels.
