Degradation of Steels of the Reloading Equipment Operating Beyond Its Designed Service Life.

We analyze the specific features of evaluation of the in-service degradation of rolled steel sheets of the reloading equipment. It is shown that impact toughness, as an indicator of brittle-fracture resistance, is one of the determining mechanical characteristics for guaranteeing the serviceability of metal structures. Its catastrophic drop is caused by microdelaminations between the fibers of the structure and elongated nonmetallic inclusions. In order to increase the sensitivity of evaluation of the degree of degradation of steels, it is preferred to tests specimens transverse with respect to the direction of rolling. For the structures operating beyond their designed service life, it is recommended to use the limit value of impact toughness fixed on a level of 30 J/cm2 for which the hazard of uncontrolled fracture becomes high. [ABSTRACT FROM AUTHOR]