A non-linear, anelastic stress-strain relationship, hereafter called mechanical hysteresis, which leads to a significant error in the output signal of electrical resistance strain gauge force transducers, has been confirmed to be a general phenomena in precipitation-hardened stainless steels. The mechanism of mechanical hysteresis has been found to be due to the material behaviour; nevertheless, the design of the force transducer and details of the electrical resistance strain gauges could impose further minor effects on the size of the error. Some of the secondary influencing factors (for example loading and mounting details) have been eliminated in the course of the investigation. Using a specially developed heat treatment process, it has been possible to substantially reduce the hysteresis error, which in turn improves the force transducer accuracy.