Mathematical modelling of temperature and stress evolution during cooling of a stainless steel Navy C-ring probe

Distortion is a common defect produced by inadequate heat treating practices. To evaluate distortion, dimensional changes in the Navy C-ring probe have been commonly used both in the laboratory and in industry. In this work, the evolution of the thermal and internal stress fields during cooling of a stainless steel Navy C-ring was studied using mathematical models. The thermo-mechanical model was validated by comparing the computed thermal response and final distortion with the experimental values measured upon cooling a probe in still water at 40°C. The models were then applied to understand the mechanisms responsible for the dimensional changes observed in the Navy C-ring. The simulations showed that distortion occurs initially due to thermal contraction of the tip of the probe followed by thermal contraction of the medium portion of the probe arm, displacing the tip towards the interior of the ring, resulting in a net decrease of the gap opening.