An application of machine vision, incorporating neural networks, which aims to fully automate real-time radiographic inspection in welding processes is described. The current methodology adopted comprises two distinct stages the segmentation of the weld from the background content of the radiographic image, and the segmentation of suspect defect areas inside the weld region itself. In the first...

Mathematical models and associated numerical techniques have been developed to investigate the complicated transport phenomena in spot hybrid laser-MIG keyhole welding. A continuum formulation is used to handle solid phase, liquid phase, and the mushy zone during the melting and solidification processes. The volume of fluid (VOF) method is employed to handle free surfaces, and the enthalpy meth...

Evaluation of the low cycle fatigue life by the small specimen test technique (SSTT) and some other properties (metallographical structure and Vickers hardness) for the TIG (tungsten inert gas) weld of F82H IEA-heat were carried out. The TIG-weld was distinguished into seven regions with different metallographical structure and hardness, which were the base metal (BM) region (region with almost...

In fusion arc welding the final weld shape is influenced by welding parameters, mode of metal transfer, number of welding wires used and their arrangement in the contact tube, type of material to be welded, type of shielding medium and similar. In some articles, descriptions of investigations on the influence of the kind of material and the type of shielding medium used on the weld shape and si...

An improved welding electrode for producing weld metal having low amount of hydrogen therein so that hydrogen assisted cracking in weld zone is minimised. This is especially beneficial for welding high strength steel having tensile strengths of about 70000 psi or above. The reduction of slag /metal reaction temperature during welding have been found to have additional advantage of reducing the ...

The common commercial charge coupled device (CCD) camera is combined with a composite light filter to form a vision sensing system of low cost. It can capture the whole image of a weld pool clearly during constant-current gas tungsten arc welding (GTAW). Based on the imageprocessing algorithm, the edges of the weld pool under different welding conditions can be extracted. Calibration is made to...

Weld residual stresses often approach, or exceed, the yield strength of the material, with serious implications for the integrity of engineering structures. It is not always feasible to measure residual stresses, so integrity assessments often rely heavily on numerical models. In ferritic steels, the credibility of such models depends on their ability to account for solid-state phase transforma...

Observing the weld pool and measuring its geometrical parameters are important issues for automated and robotic welding, wherein the visual detection and localization of weld pool are critical steps. Previous methods of visual measurement of weld pool usually assume that the weld pool exists in a predefined area, and its contour should be a specific geometric shape and size. Furthermore, previo...

A substantially successful technology that has emerged is the use of electro-optics, which has been expanded into the realm of ‘machine vision’ with the rapid advance in optical sensor technology and computer processing power. The basic principle of the optical sensor has remained unchanged over the years. Charge-Coupled Devices (CCDs), laser diodes and microprocessors form the basis of this ty...