A study of specimens from solebar material with boxlike cross sections using the acoustic-emission method

The results are presented of the investigation of fatigue crack growth in 200 × 100 × 10 mm specimens made from the upper chord of rejected solebars with boxlike cross sections. The specimens were placed in an MTS-50 electrohydraulic machine and alternately loaded with cyclic and static loads from the instant of fatigue-crack nucleation until specimen damage occurred. The data on nucleation and the development of fatigue cracks in the specimens were recorded using the method of acoustic-emission (AE) strain measurements. A piezo antenna consisting of four acoustic emission transducers (AET) was mounted on each specimen. Four wire strain sensors were glued near the saw cut that served as a stress concentrator. After specimen damage, chemical analysis of the material was performed and nonmetallic inclusions and the degree of impurity were evaluated. Micro- and macrofractographic analyses, which allowed determination of the character of damage, were performed.