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Cracking of conductive brass accessories in substations causes overheating or an open circuit, seriously affecting the safe and stable operation of the power grid system. A deep understanding of failure mechanisms could provide more safety, as well as lower down costs and save time for the power grid system, which have been seldomly involved in the literature. This paper presents a cracking analysis of a brass clamp in service for seven years that is mounted on the main transformer. The fracture morphology, chemical composition, and metallographic structure of the brass clamp were systematically analyzed, and the stress conditions were obtained by finite element simulation. The clamp exhibits transgranular brittle fracture with high oxygen content in the fracture, containing a crack propagation along the Pb particle connecting pathways, and the stress concentration was confirmed at the crack position. It is concluded that the failure was a result of the stress corrosion cracking and excessive content of Pb. Suggestions were proposed to avoid malfunction of the main transformer caused by the clamp crack. [ABSTRACT FROM AUTHOR]

In order to effectively reduce and retard corrosion of the power transmission and transformation equipment in Chengdu power grid and to improve power supply reliability, Q235 carbon steel material which is the most widely used metal material in power grid was selected as the targeted research object in this article. Exposure experiments were performed in urban atmospheric environment of Chengdu city in the southwest region of China. The corrosion behavior of Q235 carbon steel material was investigated at different seasons. The macro- and micromorphologies after corrosion were observed using a digital camera and scanning electron microscopy (SEM), respectively. Element distribution of the rust layer and the corrosion products was characterized by energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR); the corrosion mechanism was also briefly analyzed. [ABSTRACT FROM AUTHOR]