The effects of chromium concentration on magnetically polarized heat-treated steel torque transducer shafts

We have discovered that a large enhancement in transducer sensitivity can be gained by increasing the chromium concentration of the steel to as high as the 12% level (with nickel concentrations under 1%), without the sacrifice of any essential mechanical properties. Beyond this optimal concentration level, the enhancement in the sensitivity appears to have saturated and then gradually disappears as additional chromium is added. Among the steel shafts we investigated were four types, W-1, S-7, D-2, and F-255, with transducer sensitivities of 15.1, 40.3, 71.1, and 25.2 ∞G/psi, respectively. Additionally, the S-7 and D-2 magnetic transducers exhibited still further increases in their sensitivity following their standard heat treatments, with the greatest increase occurring for the D-2 sample.