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

Abstract

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.

Parameter Identification for Thermo-Mechanical Constitutive Modeling to Describe Process-Induced Residual Stresses and Phase Transformations in Low-Carbon Steels

“…As shown in Figure 1, the martensite that is generated during the initial quenching step sustains from 200 °C up to 600 °C in the following tempering step. The austenite in the core experiences slow cooling and would start transforming at A c3 ; hence, it was tested in the temperature regime above and slightly below A c3 [2,19,23].…”

An Approach to Predict Geometrically and Thermo-Mechanically Induced Stress Concentrations in Ribbed Reinforcing Bars

“…Recent modeling approaches [29][30][31][32][33][34][35][36] to examine the TempCore TM process thus far are restricted to the analysis of the heat conduction problem and the microstructural evolution as well as to unribbed rebars. The mechanical properties at room temperature are predicted based on the phase fractions of the constituting phases and the phase properties.…”