Characterization of “Humping” in the GTA welding process using infrared images

Abstract A real-time methodology is proposed for monitoring the occurrence of defects such as “humping” in GTA welding based on temperature gradient analysis, as observed by a thermographic camera. A technique based on the isotherm geometry for identifying defects that can be observed in a region around the arc and weld pool is provided. Isotherms between 1200 and 1400 °C were analyzed. The temperature field near both of these values varied during seamless weld bead deposition and induced a weld bead with “humping”. Abrupt changes in the temperature distribution are identified as being indicative of this type of defect in an on-line monitoring system. The use of thermographic techniques for monitoring the presence of weld defects is a promising tool that can be used for the on-line detection and control of welding process discontinuities.

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