Failures of Forged End Bells on Large Electric Generators

Abstract

Forged austenitic steel rings used on rotor shafts in two 100,000 kW generators burst from overstressing in a region of ventilation holes. A variety of causes contributed to the brittle fractures in the ductile austenitic alloy, including stress concentration by holes, work hardened metal in the bores, and a variable pattern of residual stress.