Environment-assisted corrosion damage of steel bridges: a conceptual framework for structural integrity

A framework is presented in this paper to assess the structural integrity of steel bridges for environment-assisted corrosion damage. Forms of corrosion of steel bridges and their effects, possible locations of occurrence, and most appropriate inspection techniques are first studied and the lessons learned from past steel bridge failures are discussed. A review of the corrosion damage of steel bridges, including causes, effects, and control measures, is presented along with guidelines for the recognition and investigation of environment-assisted cracking (EAC) of steel bridges. Experimental approaches are proposed to investigate the EAC of structural steel. The proposed approach is used to investigate the EAC susceptibility of cathodically protected ST52 steel. In addition, the feasibility of the proposed approach is tested. Hence, the conceptual framework is proposed. The framework aims to support the inspection and maintenance practices of steel bridges.

Memorization and other Transient Effects of ST52 Steel and its FE Description

This contribution presents main results of experimental tests realized on smooth specimens made of ST52 steel under strain controlled uniaxial cyclic loading and compares these results with numerical simulations performed using a modified Chaboche model by finite element method. The effects of NonMasings behavior, memorization, cyclic hardening/softening and mean stress relaxation have been studied at room temperature. The experiments were realized on the reconstructed hydraulic fatigue testing machine INOVA 100 at the Laboratory of modern materials testing and defectoscopy of VŠB-TU Ostrava. Developed mixed hardening material model includes a memory surface stated in stress-space, which makes possible to significantly improve prediction of effects studied.

Microstructure and Wear Properties of Fe-Cr-C and Fe-Cr-Si-C Clads on Carbon Steel by TIG Surfacing Process

In the present study, the surface of St52 steel was alloyed with preplaced powders Fe-Cr-C and Fe-Cr-Si-C by using a tungsten-inert gas (TIG) heat source. Then microstructure of the alloyed surfaces was investigated. Following the surface alloying, conventional characterization techniques, such as optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction were employed to study the microstructure of the alloyed surface. Microhardness measurements were performed across the alloyed zone. The tribological behavior of the coatings was compared in room temperature dry sliding wear tests. It was found that the as-deposited coatings consisted of higher volume fraction of carbides (Cr7C3). No crack formation was found on the coatings. As a result, TIG arc heat source can be used effectively for performing surface alloying on St52 steel with a preplaced powder in order to improve its surface wear resistance.