Ползучесть сварных соединений паропроводов

Abstract

The results of studying the features of structural changes of welded joints of steam pipes from heat-resistant pearlitic Cr–Mo–V steels operated for a long time under the conditions of creeping are presented. The role of the influence of physicochemical processes occurring within the metal of welded joints of steam pipes on their structural changes is shown. The deformation of the metal of welded joints, which is ensured by the displacement of dislocations, is the largest in the area of incomplete recrystallization of their heat-affected zone (HAZ). The creep rate is mainly controlled by the displacement of dislocations and is dependent on the structural state of the metal of welded joints. The increase in the deformation of the metal of welded joints operated for a long time under the conditions of creeping of about 200000 hours is linear, and after, their time-dependent deformation character differs from the linear one.