Consistent and Repeatable Property and Residual Stress Control in Forged and Heat Treated Railway Wheels

Consistent process control of wheel hardness and residual stresses developed during heat treatment are particularly important considerations for service life and safety of railway wheels. This paper details the process controls strategically located throughout an integrated, fully automated heat treatment system that can heat treat up to 65 railway wheels per hour. New, innovative technology such as in-line temperature measurements that control key process steps, uniform wheel heating and cooling, and quench water temperature and pressure control have resulted in wheel hardness and residual stress values with less statistical variation than older, traditional heat treat methods. Automatic serial number tracking and temperature measurement allow for statistical analysis of heat treat processes. Two years after the commissioning of this $18M facility, the quality and productivity benefits realized are discussed.