Real-time recognition of weld defects based on visible spectral image and machine learning

The quality of Tungsten Inert Gas welding is dependent on human supervision, which can’t suitable for automation. This study designed a model for assessing the tungsten inert gas welding quality with the potential of application in real-time. The model used the K-Nearest Neighborhood (KNN) algorithm, paired with images in the visible spectrum formed by high dynamic range camera. Firstly, projecting the image of weld defects in the training set into a two-dimensional space using multidimensional scaling (MDS), so similar weld defects was aggregated into blocks and distributed in hash, and among different weld defects has overlap. Secondly, establishing models including the KNN, CNN, SVM, CART and NB classification, to classify and recognize the weld defect images. The results show that the KNN model is the best, which has the recognition accuracy of 98%, and the average time of recognizing a single image of 33ms, and suitable for common hardware devices. It can be applied to the image recognition system of automatic welding robot to improve the intelligent level of welding robot.

Dissimilar tungsten inert gas welding between Inconel 718 and commercially pure titanium using a vanadium interlayer

A weight reduction of aero engines, in order to enhance their efficiency would be possible if the commercially pure titanium in the low-temperature region of the compressor could be welded with Inconel in the high-temperature portion. This joining of titanium/Inconel is challenging owing to the formation of hard TixNiy intermetallic compounds, the suppression of which is not possible using the conventional weld process optimization approach. In recent years, a number of approaches have been developed to reduce or eliminate these intermetallic compounds during welding and one approach is the use of an interlayer during the welding operation. The insertion of a V interlayer at the root side remarkably suppressed Ti and Ni diffusion across the interlayer. NiV3 and (Ti, V) solid solutions were present in the interfacial microstructure of V/Inconel 718 and V/commercially pure titanium, respectively, as characterized by scanning electron microscope and X-ray diffraction. The tensile strength of the weldment was 190 MPa (approx. 59% of the commercially pure titanium base metal) with an elastic modulus comparable with that of the base alloys. The joint exhibited brittle fracture at the Inconel 718 side near the V/Inconel 718 interface due to intermetallic compounds.

Influence of Pitting Corrosion on TIG Welded Joints of AA2024 Aluminum Alloy Joints

In this investigation, AA2024 alloy was welded by tungsten inert gas welding. Access the influence of pitting corrosion on TIG weld; the joints were heat-treated after welding with different techniques. Moreover, the corrosion test was carried out with 3.5% NaCl solution under different pH values such as pH:5, pH:7, and pH: 12. From the experimental results, the joint treated with solution treatment with pH: 7 showed high corrosion resistance than its counterparts.

Analysis of Mechanical, Microstructural Properties and Weld Morphology of A-TIG Welded AH-36 Marine-Grade Steels with Oxide and Duplex Flux Coating

The current study investigates the metallurgical, mechanical properties and weld morphology of AH36 marine grade steel (with a thickness of 8 mm) by activated-tungsten inert gas (A-TIG) butt joints, with the application of different fluxes (MoO3, V2O5, and duplex of MoO3 and V2O5) at various process parameters. The welding speed was kept constant at 120 mm/min, and current varied from 160 A to 220 A uniformly to optimise process parameters to achieve desired mechanical properties, weld morphology, and lowest possible heat input. The study also focused on comparing tensile strength, impact strength, and microhardness, heat input during welding, weld bead depth and width between conventional TIG welding and activated flux TIG welding processes at various operation parameters. Tensile results reported that fracture occurs at the base region in ordinary TIG welding and the activated tungsten inert gas welding process. It was noticed that a higher depth to width ratio attained MoO3 and V2O5 duplex flux coated weldments. There is evidence that the depth of weld joints is enhanced because of stable arc, Marangoni effect, and arc constriction. Microhardness results reported that the fusion zone has a higher microhardness in the activated tungsten inert gas welding than the ordinary TIG welding. It was concluded that out of all fluxes, MoO3 and V2O5 duplex flux coating produce better butt welds of AH36 steel.

Weld Joint of Tantalum Sheet by Tungsten Inert Gas Welding

The 0.6 mm tantalum sheet was welded under argon atmosphere by Tungsten Inert Gas Welding (TIG) in order to obtain a welded joint with high-quality and high-reliability. Metalloscope, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were applied to analyze the joint. The results showed that the grain size of the base metal which affected by the welding heat remained the original size or enlarged slightly to 40-70 μm. What’s more, the weld zone was found to be composed of two components with different oxidation degree. And the distribution of these two components was related to the protection atmosphere of the location. The fusion line of the two tantalum sheets was clear which means high welding quality.

Optimization of Activated Tungsten Inert Gas Welding Process Parameters Using Heat Transfer Search Algorithm: With Experimental Validation Using Case Studies

The Activated Tungsten Inert Gas welding (A-TIG) technique is characterized by its capability to impart enhanced penetration in single pass welding. Weld bead shape achieved by A-TIG welding has a major part in deciding the final quality of the weld. Various machining variables influence the weld bead shape and hence an optimum combination of machining variables is of utmost importance. The current study has reported the optimization of machining variables of A-TIG welding technique by integrating Response Surface Methodology (RSM) with an innovative Heat Transfer Search (HTS) optimization algorithm, particularly for attaining full penetration in 6 mm thick carbon steels. Welding current, length of the arc and torch travel speed were selected as input process parameters, whereas penetration depth, depth-to-width ratio, heat input and width of the heat-affected zone were considered as output variables for the investigations. Using the experimental data, statistical models were generated for the response characteristics. Four different case studies, simulating the real-time fabrication problem, were considered and the optimization was carried out using HTS. Validation tests were also carried out for these case studies and 3D surface plots were generated to confirm the effectiveness of the HTS algorithm. It was found that the HTS algorithm effectively optimized the process parameters and negligible errors were observed when predicted and experimental values compared. HTS algorithm is a parameter-less optimization technique and hence it is easy to implement with higher effectiveness.

Study of Cross-Combination and Square-Combination Configuration Magnetic Field on Tungsten Inert Gas Welding

In this study, cross-combination and square-combination configuration of the permanent external magnet were used in tungsten inert gas welding process. The external magnetic field effect to the arc plasma was observed using two cameras from the front view and side view. The depth of penetration and weld profile was investigated after welding. In this study, two types of magnets were employed; a 3 mm magnet with intensity ranging from 270-280 mT and a 5 mm magnet with 400-415 mT. Each configuration has three sub-configurations: forward, backward, and side, so there were 12 parameters in this study. The result shows that a cross-combination 5 mm magnet can increase weld penetration in any position, forward, backward or side deflection, and improve the depth-to-width ratio, however using 3 mm magnet did not influence the penetration significantly. Cross-combination has more stiffness and stability of the arc than square-combination. Most configurations have the same size weld bead width. Square combinations had fluctuated result, stiffness and stability of the arc was poor. This investigation aims to enlarge our understanding of the magnetic field effect on the arc plasma and the weld profile. In future, the arc blow effect from the external magnetic field can be controlled and regulated to improve TIG welding performance.