Results of acoustic emission during mechanical and thermal loadings of vessel components and their fracture mechanical interpretation.

AE measurements are presented which were performed at pressure vessel components during different loadings: thermal shocking, hydrotest, cyclic loading. The tests were executed with the IzfP AE system. With this it is possible to locate the AE sources and to identify two source mechanisms: crack growth and flank friction. The AE results are discussed and compared with the results of calculations about the residual stress in a cladded vessel wall: AE signals originating from crack growth processes are detected very sensitively. During thermal shock a lot of crack border friction occurs in consequence of compressive stresses on the crack flanks. However, during the hydrotests no crack border friction appears, because the crack flanks are mainly under tensile stresses. (IZFP