De. Bray et P. Junghans, APPLICATION OF THE L(CR) ULTRASONIC TECHNIQUE FOR EVALUATION OF POST-WELD HEAT-TREATMENT IN STEEL PLATES, NDT & E international, 28(4), 1995, pp. 235-242
Ultrasonic travel times obtained with the L(CR) wave are able to disti
nguish between stress relieved and non-stress relieved 13 mm (1/2 in)
thick, steel plates. Two 1.22 m (48 in) square plates were patch welde
d in the centre to create a residual stress field, and one of the plat
es was stress relieved. The L(CR) ultrasonic technique sends a critica
lly refracted longitudinal wave travelling beneath the plate surface,
and the stresses in the plate affect the travel times through the acou
stoelastic relationship. The L(CR) travel-time measurements not only d
istinguished between residual stress states in the plate, but also gav
e some information on their distribution and magnitude. Neither textur
e nor localized residual stresses affect the results. These findings d
emonstrate the potential usefulness of the technique for evaluating th
e state of post-weld heat treatment in structural steels.