Bulk melt textured YBCO samples in the shape of disks were developed f
or use as trapped field magnets. The trapped field in single grains wi
th diameter of 24 mm reached maximum values up to 0.56 T at 77 K and a
value of 5.5 T at 30 K, Degradation of the trapped field was observed
in samples after the activation process at 20 K in a high applied mag
netic field. This is interpreted in the framework of a model of magnet
ic stress induced damage.