[6A3] The effects of thermal gradients on in-process ultrasonic inspection of fusion welding
Zhen Qiu, Yashar Javadi, Richard O’Leary, Ehsan Mohseni, David Lines, Charles MacLeod, Randika Vithanage, Momchil Vasilev, Gareth Pierce and Anthony Gachagan
Centre for Ultrasonic Engineering (CUE), Department of Electronic and Electrical Engineering, University of Strathclyde, UK
The manufacturing and inspection of fusion welds are currently two separate processes in the supply chain, but there is increasing awareness that performing Non-Destructive Evaluation/Testing (NDE/T) of welds at the point of manufacturing during and after each weld pass could result in significant reduction of manufacturing rework and improvement in productivity. However, the deployment of in-process inspection of welds using ultrasonic sensing technology faces many challenges, including inspection in a high temperature environment, the non-uniform temperature distribution within the weldment and the varying weld geometry as the multi-pass weld is built up. Among these challenges, this work focuses on how non-uniform thermal distribution associated with welding processes affect ultrasonic wave propagation within the weldment and the resulting contribution to low signal to noise ratio and potential for poor defect localization in the resultant image.
A Finite Element (FE) modelling framework was set up in this work to address this issue. The scenario of an angled beam shear wave inspection of a 15 mm thick steel plate with single V-grooved weld was designed and modelled in OnScale Finite Element package. The thermocouple measurements indicate that the temperature on the weldment surface can vary from 920oC to 105oC across the distance to weld centre from 30 mm to 120 mm, at the point of the multi-pass welding process. Such thermal distribution profiles were converted into segmented velocity maps which then imported into the acoustic model for shear wave beam profile investigation. Both time shift and amplitude reductions were predicted when non-uniform thermal distributions were considered. A maximum of 6° beam inspection angle shift and 46% energy reduction were observed and deemed sufficient to affect the localization and identification of true-positives from defects. The information extracted from the model will be used to provide temperature compensation ultimately on an integrated system consists of automated welding cell and in-process ultrasonic inspection.
A Finite Element (FE) modelling framework was set up in this work to address this issue. The scenario of an angled beam shear wave inspection of a 15 mm thick steel plate with single V-grooved weld was designed and modelled in OnScale Finite Element package. The thermocouple measurements indicate that the temperature on the weldment surface can vary from 920oC to 105oC across the distance to weld centre from 30 mm to 120 mm, at the point of the multi-pass welding process. Such thermal distribution profiles were converted into segmented velocity maps which then imported into the acoustic model for shear wave beam profile investigation. Both time shift and amplitude reductions were predicted when non-uniform thermal distributions were considered. A maximum of 6° beam inspection angle shift and 46% energy reduction were observed and deemed sufficient to affect the localization and identification of true-positives from defects. The information extracted from the model will be used to provide temperature compensation ultimately on an integrated system consists of automated welding cell and in-process ultrasonic inspection.
