In Situ Characterisation of the Strain Distribution Produced Around GTAW Welds

In fusion welding, differential thermal expansion and contraction across the component leads to the generation of residual stresses that may limit the fatigue life of the component. This issue continues to motivate considerable research to characterise and model residual stresses in a wide variety of welds. However, to date almost all characterisation of weld-induced stresses has been carried out ex situ. This approach is not always satisfactory as the spatial distributions of stress, temperature, composition and phases produced during welding lead to microstructures, mechanical properties and residual stress fields that are often difficult to predict a priori.

In this work, diffraction-based methods have been used in conjunction with spatially resolved pyrometry to determine the thermal and deviatoric strains distributions that exist around a weld in situ. Results of studies performed on welds made on ferritic and austenitic steels will be presented and the relative merits of different approaches in performing such experiments will be discussed.