Kowari
(strain scanner)
ANSTO scientists, as part of a 15 member Consortium, have been awarded a major grant through the Australian Governments Industry Cooperative Innovation Program to develop a weld with the lowest as-welded residual stress.
Excessive residual stress is a major concern in the production of alumina from bauxite by the Bayer refining process in which exposure of welded steel plant components to large quantities of sodium hydroxide results in Caustic Stress Corrosion Cracking.
Kowari has been successfully used to record the 3-dimensional weld internal structures and stress map features in steel with a stress accuracy of 10 MPa and spatial resolution of 2 mm. As Kowari can achieve these stress scans non-destructively it is being used to optimise welding methods, thus avoiding the need for expensive and time-consuming post-weld heat treatment of welded steel plant components.
The image above illustrates the longitudinal stress component map (min. -120 MPa, max. 600 MPa) overlaying the cross-section of a weld. Plate thickness, vertical dimension, is 20 mm.