Failure analysis of overhead power line yoke connector

摘要

This paper deals with investigation of failure reasons of yoke connectors of overhead power lines. These components were produced by cold bending of steel plates (grade S355J2+AR) and their subsequent hot-dip galvanizing. Approximately 6 months after production, sudden failures of the connectors occurred by manual manipulation during assembling. The failures were localized in bent parts of the connectors. Performed investigations included metallographic analyses, semi-quantitative chemical microanalyses, microhardness measurements and numerical simulations. It was found out that the failures were caused by several degradation processes related to liquid metal assisted cracking which occurred during the galvanizing from the initial small surface cracks induced during bending. Remedial action to the production process should involve a systematic control of bending tool functional surface.