[en] Nondestructive evaluation of austenitic stainles steel weld metal is a very difficult problem. Mechanical anisotropy appears to be a major contribution and is caused by preferred local orientation of elongated subgrains and preferred crystallographic orientation. The result of this anisotropy is the directional dependence of the ultrasonic velocities (shear and longitudinal) and ultrasonic attenuation. The directional dependence of these ultrasonic parameters causes large errors in locating and sizing flaws in welds. Initial studies were carried out in a type 308 stainless steel electroslag weld to characterize this anisotropy. The apparent symmetry in the macrostructure of the electroslag weld leads us to expect orthotropic symmetry in elastic constants. A technique was developed to measure variations in velocity and attenuation with direction. The velocity data compared favorably to theoretical calculations using this orthotropic model. From the velocity data all elastic constants and engineering constants for this weld were determined. Studies of other types of welds showed that orthotropic symmetry is typical of austenitic welds. Data will be presented to show how anisotropy affects defect location and sizing in welds