Prediction of Tempcore Rebar Strength Using a Thermomechanical Simulator with a Designed Hollow Specimen

In the Tempcore process, reinforcing bars are produced by short and intensive cooling. This rapid quenching converts the surface layer of a steel bar to a hardened structure. The exact simulation of the Tempcore process by a thermomechanical system is difficult to achieve because its cooling capacity is generally not sufficient to follow the Tempcore cooling rate. Therefore, herein, a hollow specimen is designed to increase the cooling rate. A series of thermomechanical tests following predetermined cooling curves provided by the thermal model is performed. The measured hardness of the thermomechanical-tested specimen is used to predict the tensile strength of a Tempcore rebar based on the rule of mixture. The results show that the prediction of the strength of a Tempcore rebar by tailored cooling with a hollow cylindrical specimen is feasible with a high degree of reliability.