The effects of heat treatment on the magnetic behavior of ring-type magnetoelastic torque sensors

Experiments have been performed to determine the effects of appropriate sequential heat treatment steps on thin maraging steel rings shrink-fitted onto stainless steel shafts for use as magnetoelastic torque transducers. The transducer response was found to be linear and reproducible. Subsequent to heat treatment, the transducer function was remarkably improved, exhibiting a more than twofold increase in sensitivity. By measurements of the axial hysteresis, this enhanced sensitivity can be traced to a corresponding decrease in axial coercive force. Measurement of the circumferential hysteresis also showed a more than fourfold increase in circumferential coercive force, which contributes to improved sensor integrity.