Dissimilar Joining of 316L and A131 Steel by Shield Metal Arc and Tungsten Inert Gas Welding to Evaluate Bending and Tensile Behavior

Prediction of anisotropic property of activated metal inert gas welding by employing different supervised machine learning models.

Effect of alternating magnetic field on full-penetration laser welding with double-sided shielding gas of aluminum alloy

Dual angle magnetic arc blow estimation in keyhole tungsten inert gas welding using high dynamic range imaging and a lightweight vision transformer network with coordinate attention and multiple auxiliary branches

Virtual reality (VR) welding simulators provide safe and cost-effective training environments, but precise torch tracking remains a key challenge. Current commercial systems are limited in accurate bead simulation and posture feedback due to tracking errors of 3–10 mm, while external motion capture systems offer high precision but suffer from high cost and installation complexity issues. Therefore, a new approach is needed that achieves high precision while maintaining cost efficiency. This paper proposes an IMU-SLAM fusion-based tracking algorithm. The method combines Inertial Measurement Unit (IMU) data with visual–inertial SLAM (Simultaneous Localization and Mapping) for sensor fusion and applies a drift correction technique utilizing the periodic weaving patterns of the welding torch. This achieves precision below 5 mm without requiring external equipment. Experimental results demonstrate an average 3.8 mm RMSE (Root Mean Square Error) across 15 datasets spanning three welding scenarios, showing a 1.8× accuracy improvement over commercial baselines. Results were validated against OptiTrack ground truth data. Latency was maintained below 100 ms to meet real-time haptic feedback requirements, ensuring responsive interaction during training sessions. The proposed approach is a software solution using only standard VR hardware, eliminating the need for expensive external tracking equipment installation. User studies confirmed significant improvements in tracking quality perception from 6.8 to 8.4/10 and bead simulation realism from 7.1 to 8.7/10, demonstrating the practical effectiveness of the proposed method.

Abstract Weak-line quasars (WLQs) represent a subset of type 1 quasars distinguished by remarkably weak high-ionization broad emission lines, yet exhibiting normal optical/UV continua. This study establishes a physically motivated definition of WLQs using 371,091 quasars from the Sloan Digital Sky Survey Data Release 16 catalog. By analyzing outliers in three key relations, the L 1350 Å –C iv blueshift relation, the Baldwin effect, and the log L 2500 Å − α ox relation, we identify two critical thresholds in C iv equivalent width (EW): 8.9 ± 0.2 Å and 19.3 ± 0.3 Å. Quasars with EW(C iv ) < 8.9 ± 0.2 Å are defined as WLQs, exhibiting enhanced C iv blueshifts, significant deviations from the Baldwin effect, and a high fraction of X-ray weak objects (nearly half of this population). Quasars with EW(C iv ) > 19.3 ± 0.3 Å show normal quasar properties, while objects with intermediate C iv EW (8.9–19.3 Å) are defined as “bridge quasars,” showing transitional behaviors. Systematic analysis of emission-line attenuation of WLQs reveals a clear positive correlation between the attenuation factor and ionization energy, with high-ionization lines (HILs; e.g., He ii , C iv ) suppressed by factors of ∼3 σ –4 σ compared to low-ionization lines (LILs; e.g., Mg ii , O i ). This ionization-stratified attenuation supports the shielding gas model, where geometrically thick inner accretion disk obscures high-energy photons, suppressing HIL emission, while the LILs remain less affected. Based on this accretion-disk geometry, we argue that WLQs and normal quasars defined in our framework generally correspond to the slim disk and standard thin disk regimes, respectively, while the bridge quasars represent a transitional phase between the two states. This work establishes a unified observational criterion for WLQs and discusses their physical implications, highlighting the role of accretion-driven shielding gas in shaping their unique spectral features.

In the field of modern industrial manufacturing, welding is an important method for permanently joining metals into specified structures. The mechanical properties of the weld joint formed at the welding point will directly affect the performance of the connecting structure. Therefore, it is necessary to ensure the performance of the welding joint. This paper briefly introduces metal inert gas (MIG) welding and laser-MIG hybrid welding in alloy welding, followed by experimental analyses. MIG welding and laser-MIG hybrid welding were performed on three grades of aluminum alloys, namely 7A52, 7055, and 6082, respectively. The tensile properties, fatigue properties, and corrosion properties of the welding joints were then tested. The results showed that the welding joints produced by the laser-MIG hybrid welding method had better tensile properties, fatigue resistance, and corrosion resistance. In conclusion, the laser-MIG hybrid welding technology can be used to weld various types of alloys, providing sufficient connection strength and stability.

Nowadays, the application of hydrogen as an energy carrier has become important as a result of decreasing availability of oil and gas fields as well as increasing demands on sustainable energy carriers. Providing an adequate hydrogen transportation infrastructure is a key step. During transportation, many different materials can interact with hydrogen, but in order to transport high quantities of hydrogen at higher pressures, the use of steels is preferred. However, hydrogen has many negative effects on steel, thus extensive research needs to be performed before hydrogen can be transported safely. Solubility of hydrogen in steel depends on the temperature, pressure, and the crystal structure of steel, so welding is also an important subject. Since most of the steel structures are welded, welded joints should also be examined for exposure to hydrogen. In the case of welding, a number of factors can decrease the hydrogen resistance of the welded joint and thus increase the risk of degradation by hydrogen. In this research work, hydrogen damage, and hydrogen traps will be reviewed. Possible ways to reduce the diffusible hydrogen content will also be summarized, as well as aspects of the filler material and shielding gas selection. In addition, an overview will be provided on welding technology aspects of carbon steels related to hydrogen, such as heat input, preheating, t 8/5 cooling time, heat-affected zone size, number of weld runs, effect of discontinuities, etc. In general, filler material with the lowest possible diffusible hydrogen content should be used; for electrode coatings and fluxes, special care should be taken to ensure proper baking; for wire electrodes, care should be taken to ensure surface cleanliness; in case of shielding gas the use of the purest possible shielding gas is recommended, and the use of shielding gas containing hydrogen is prohibited; and strict attention must also be paid to the purity of the base material. In addition, other important considerations for welding technology development will be outlined for carbon steels. Such as pipelines, where the most important technological aspects of welding will also be discussed, e.g. low heat input, multi-pass weld design, etc.

Lightweight steel structural systems like trusses or built-up beams, made of thin gage steel elements, are highly efficient, with ease of handling and construction. Self-drilling screws are commonly used for connecting thin-walled elements, but the time and manpower required for numerous connections necessitate an improved solution. One possible solution is to use welding technology, but the conventional methods are not suitable for joining thin sheets. Manufacturing defect-free, mechanically sound welding joints remains challenging due to defects like porosity and undesired microstructural phases in the heat-affected (HAZ) and fusion zones (FZ). Conventional welding processes increase heat input, causing difficult challenges. Brazing, a relatively new joining process, offers the advantages of lower heat input for thin and zinc-coated steel sheets. Therefore, the paper aims to present the effect of MIG brazing parameters on the macro-and microstructural properties of Cu-Al-based weld seams manufactured for joining thin sheets with thickens in the range of 0.8-2 mm. The weld seams were manually fabricated using a MEGAPULS FOCUS 330 compact equipped with TBI XP 363S/4m welding torch, focusing on optimal welding regimes. The macro-and microstructures of the joints were evaluated along with the mechanical properties in terms of hardness, confirming that MIG brazing is a promising method for manufacturing lightweight steel structural systems.

Experiments were conducted to investigate the microstructure and properties of Ti‐6Al‐4V rotational arc welded joints using tungsten electrodes with varying eccentricities. The arc's rotation during welding expanded the heated area around the groove, increasing the heat‐affected zone (HAZ) width. The weld zone primarily consists of lath martensite. Increasing electrode eccentricity reduces low‐angle grain boundaries and causes a nonlinear change in grain size. At 0.75 mm eccentricity, the average grain size reaches a minimum of 0.72 μm. The dislocation angle range for the α phase in the weld zone is 1.05°–4.35°, 55.6°–65.3°, and 88.3°–90.45°. Static tensile strength values for the HAZ and weld zones exceed the base metal by over 97% (940 MPa), with elongation after fracture reaching 80% (11.14%) of the base metal's value. Impact toughness also surpasses over 80% (490.25 KJ m −2 ). Furthermore, at 0.75 mm eccentricity, impact toughness increases by more than 10% compared to other eccentricities, emphasizing the strengthening effect of fine grains on material impact toughness.

Abstract Lack of sidewall fusion (LOSWF) is a critical defect in arc welding that compromises structural integrity, especially in multi-pass welds where buried discontinuities require highly advanced volumetric imaging techniques for detection. Traditional non-destructive testing (NDT) methods are often unable to identify such defects until fabrication is complete, increasing rework rates and overall build time. This study presents a novel approach, combining in-process ultrasonic imaging with controlled experimentation to enable LOSWF detection capability during welding. An experimental setup is introduced in which a static phased array probe is positioned ahead of the welding torch, allowing B-scan acquisition in real-time, during welding. Characteristic signal loss is observed prior to sidewall fusion, followed by echo recovery upon solidification—providing a dynamic indicator of fusion status, with a distinct amplitude drop from 60 to 0%, highlighting the binary nature of the monitoring. To benchmark detection limits, artificial LOSWF flaws were introduced into single-layer welds and evaluated using a roller probe configuration. In addition, experiments were performed to analyze signal degradation and recovery due to thermal disturbance, captured through C-scan sidewall echo analysis. The results demonstrate that ultrasonic imaging deployed during welding can offer both predictive and confirmatory information about fusion quality. This integrated approach provides a foundation for automated, embedded weld inspection systems that can identify fusion defects earlier in the process chain.

Welding is the process of permanently joining materials and tungsten inert gas (TIG) welding is widely used due to its precision, controlled heat input, and cost-effectiveness. This study investigates the stress corrosion behavior of TIG-welded 304L stainless steel in a saline environment, analyzing factors contributing to material degradation. The research involved tensile testing and fractographic analysis to characterize fracture modes and determine the key influences on mechanical strength. Additionally, a microstructural analysis of the heat-affected zone (HAZ) was conducted to assess changes induced by welding. The results indicate that exposure to a chloride-rich environment led to a reduction in mechanical properties, primarily due to the formation of corrosion-related compounds and material thinning. Fractographic analysis revealed a transition in fracture modes, highlighting the influence of corrosion on failure mechanisms. Furthermore, microstructural examination showed significant alterations in the HAZ, which affected the overall integrity of the welded joints. These findings contribute to a better understanding of corrosion-induced degradation in welded 304L stainless steel and provide insights for optimizing welding parameters to improve durability.

This study investigates seven advanced hybrid composite thermal protection system (TPS) prototypes, featuring an innovative internal air chamber design that reduces heat conduction and enhances overall thermal protection performance. Specimens were manufactured by fused deposition modeling (FDM), an additive manufacturing technique, using a fire-retardant thermoplastic. Selected configurations were reinforced with continuous carbon or glass fibers, coated with ceramic surface layer, or hybridized with carbon fiber reinforced polymer (CFRP) layers or a CFRP laminate disk. To validate performance, a harsh oxy-acetylene torch (OAT) protocol was implemented, deliberately designed to exceed the severity of most reported typical ablative assessments. The exposed surface of each specimen was subjected to direct flame at a 50 mm distance, recording peak temperatures of 1600 ± 50 °C. Two samples of each configuration were tested under 60 and 90 s exposures. Back-face thermal readings at potential payload sites consistently remained below 85 °C, well under the 200 °C maximum standard threshold for TPS applications. Several configurations preserved structural integrity despite the extreme environment. Prototypes 4.1 and 4.2 demonstrate the most favorable performance, maintaining structural integrity and low back-face temperatures despite substantial thickness loss. By contrast, specimen 6.2 exhibited rapid degradation following 60 s of exposure, which served as a rigorous and selective early-stage screening tool for evaluating polymer-based ablative TPS architectures.

Additive manufacturing (AM), particularly laser-based powder bed fusion (PBF-LB), enables the production of high-strength, lightweight components made of aluminum alloys such as AlSi10Mg. However, joining these parts via welding remains a significant challenge due to weld seam porosity caused by hydrogen entrapment. This study investigated the influence of the PBF-LB process parameters, tungsten inert gas (TIG) welding settings, filler material, and post-weld T6 heat treatment on the tensile strength and porosity of welded AlSi10Mg components. Using two different layer heights (30 µm and 60 µm), plate thicknesses (3 mm and 5 mm), and varying welding conditions, a series of 10 TIG-welded sample groups were fabricated and analyzed. Microstructural, hardness, porosity, and tensile tests revealed that porosity was high across all samples (11–19%). A subsequent T6 heat treatment improved the tensile strength. Higher layer heights and thinner plates led to a higher tensile strength of the weld seam, while the addition of a filler material showed limited benefits. No other influencing factors or interactions could be found. The results emphasize the need to optimize hydrogen control in the processes, melt pool dynamics, and weld seam geometry to receive reliable joints in lightweight manufacturing of PBF-LB AlSi10Mg parts.

Abstract This study investigated the influence of TaC additions on the densification, mechanical properties, and ablation behavior of HfC–SiC composites fabricated via pressureless sintering. Incorporating TaC shows a measurable improvement in thermo‐mechanical performance. At 20 wt.% TaC, hardness increased from 13.0 ± 1.7 GPa to 18.0 ± 2.1 GPa, while flexural strength rose from 303 ± 30 MPa to 377 ± 18 MPa. Ablation testing using an oxyacetylene torch at ∼2400°C for 10 min further demonstrated improved thermal stability: thickness change improved from –0.05 ± 0.01 mm (0 wt.% TaC) to +0.24 ± 0.001 mm, while mass loss decreased from –0.20 ± 0.05 g to –0.15 ± 0.01 g for 20 wt.% TaC. Post‐ablation characterization revealed specific microstructural effects: TaC promoted silicon retention at the surface and facilitated the formation of protective oxides, notably HfSiO 4 and Hf 6 Ta 2 O 17 , together with Ta 2 C nanoparticles. These nanoparticles were found embedded within interlaced Hf‐rich and Si‐rich amorphous regions. This refined microstructure suppressed SiO volatilization, sealed surface porosity, and limited oxygen ingress, by developing a dense and adherent protective layer. The interplay of solid solution strengthening, oxide‐scale stabilization, and a network of finely distributed phases collectively accounts for the improved ablation resistance of HfC–SiC–TaC composites compared to baseline HfC–SiC. These findings set the stage for a deeper discussion of the context and significance within the field of ultra‐high‐temperature ceramics.

Corrigendum to “Microstructure and ablation behavior of graphite/SiC–TaC/Si–TaSi2 composites under oxyacetylene torch” [Carbon 247 (2026) 1–12 121075

This study aims to evaluate the cold cracking resistance of SKD 11 cold work tool steel during Metal Active Gas (MAG) welding. The experiments were conducted using implant testing in accordance with ISO 17642-3. The investigation focuses on critical factors, including tensile stress levels, lower critical stress (LCS), and time to failure (TTF). Additionally, the influence of tempered welds (Double weld passes) on fracture behavior was investigated. The experimental results revealed that the fracture surfaces of the specimens could be distinctly categorized into quasi-cleavage and final rupture region. These regions varied based on stress levels and the application of tempering heat treatment. Implant testing showed that fracture predominantly occurred in the coarse-grained heat-affected zone (CGHAZ). The time to failure of implant specimens increased as the stress level decreased. Tempered welds exhibited a lower TTF rate compared to single welds. Specifically, the LCS of single welds was approximately of 70 MPa, meanwhile tempered welds exhibited an LCS of approximately of 72 MPa. Hardness profiles were measured across the weld metal, heat-affected zone (HAZ), and base metal. The highest hardness values were observed in the CGHAZ, with an average peak of 770 HV10. However, in the case of tempered welds, the hardness value reduced to 650 HV10. Microstructural examination of the HAZ indicated a predominant martensitic matrix. The tempered weld-HAZ exhibited a finer structure with a mixed size distribution of alloy carbide particles within the martensitic matrix. These findings clearly demonstrate the high hardenability of SKD 11 cold work tool steel. The hardness value in the CGHAZ suggests its susceptibility to lower cold cracking resistance. Based on LCS experiments, tempering of the weld insignificantly enhances cold cracking resistance. This research provides valuable insights for designing suitable welding procedures to avoid cracking risks in future applications.

In mechanical processing workshops, fire hazards gravely threaten safety and property. Existing assessment methods fail to comprehensively account for multi-factor interactions. This study innovatively applies the Bayesian network model to this field for the first time. The model, featuring 20 tertiary and 5 secondary nodes, covers hazardous gas storage, operational norms, and equipment conditions. Empirical analysis reveals a 0.16 probability of fire due to improper hazardous gas cylinder storage at the secondary level. Sensitivity analysis shows that "uninspected oxygen and acetylene cylinders upon entry" significantly impacts "non-standard gas welding operations", while hose aging and backfire preventer damage also strongly influence risks. Forward inference identifies key fire-causing factors, with probabilities up to 0.22 at the tertiary level and 0.3 at the secondary level. Reverse inference indicates improper hazardous chemical cylinder storage as the most likely cause during a fire. This study confirms that non-standard operations and equipment aging are pivotal. The Bayesian network's multi-level design and bidirectional inference enable precise risk quantification, offering a scientific basis for safety management and paving the way for dynamic evaluations.

This study investigates the fabrication of a Cu-Mn-Al alloy coating on 27SiMn steel using Cold Metal Transfer (CMT) technology with an innovative Ar-B(OCH3)3 mixed shielding gas, focusing on the effect of the gas flow rate (5–20 L/min). The addition of B(OCH3)3 was found to significantly enhance process stability by improving molten pool wettability, resulting in a wider cladding layer (6.565 mm) and smaller wetting angles compared to pure Ar. Macro-morphology analysis identified 10 L/min as the optimal flow rate for achieving a uniform and defect-free coating, while deviations led to oxidation (at low flow) or spatter and turbulence (at high flow). Microstructural characterization revealed that the flow rate critically governs phase evolution, with the primary κI phase transforming from dendritic/granular to petal-like/rod-like morphologies. At higher flow rates (≥15 L/min), increased stirring promoted Fe dilution from the substrate, leading to the formation of Fe-rich intermetallic compounds and distinct spherical Fe phases. Consequently, the cladding layer obtained at 10 L/min exhibited balanced and superior properties, achieving a maximum shear strength of 303.22 MPa and optimal corrosion resistance with a minimum corrosion rate of 0.02935 mm/y. All shear fractures occurred within the cladding layer, demonstrating superior interfacial bonding strength and ductile fracture characteristics. This work provides a systematic guideline for optimizing shielding gas parameters in the CMT cladding of high-performance Cu-Mn-Al alloy coatings.

Influence of Inconel 625 Interlayer on the Development of Functionally Graded Weld Joints Between Ferritic/Martensitic Steel and Austenitic Stainless Steel via Activated Tungsten Inert Gas Welding