NDT of cyclically loaded metal structures

摘要

The necessity of giving industrial buildings and constructions safe service life is an important engineering problem. Durin operation cyclically loaded metal structures build up mechanical, corrosion and fatigue deteriorations; the change of structure loading conditions as well as of properties of steels and welded joint zones take place. As a result of the inspections performed the operation process of the most of cyclically loaded metal structures such as crane secondary trusses (CST) of the oxygen converter steel-making, deck girders of transporter cranes and others was found to be carried out with fatigue cracks existing in the welded joints, zones of a thermic effect of welding and in the basic metal. For evaluation of the residual life from positions of a failure mechanics first of all it is necessary to have data of the actual state of stress and strain (SSS) of the material in zones of possible fatigue failures. For the experimental investigations crane secondary trusses with spans of 24 and 36 meters and deck girders of the transporter cranes the Magnitogorsk Steel Plant, Orsk-Khalilovsk Steel Plant and Petropavlovsk TETs-2 have been chosen.