Simulation of Tempcore Process for 500 MPa Steel Bars

Abstract

Tempcore process is an environmental friendly, simple and energy efficient technology for producing high strength reinforcing steel rebars without requiring costly alloying addition. The mechanical properties of Tempcore treated steel rebar have been previously investigated using various models, although they are still restricted to specific steel compositions, bar sizes, and/or process parameters. In this study, a methodology is developed to predict the internal microstructure and overall mechanical properties (i.e., hardness, ultimate tensile strength, and yield strength) of Tempcore treated bars for any steel compositions, bar sizes, process parameters, and simulation assumptions. Three sequential models are proposed: (1) thermal model to predict thermal profiles of bars using computational fluid dynamics CFD simulation, (2) metallurgical model to estimate the internal microstructure change across the bar section using both; the JMatPro® and a derived equation that calculates the martensite volume fraction (Vm%) of a functionally graded steel bar, and (3) Regression models based on the rule of mixture to predict mechanical properties. The validation results show a good agreement between calculated and experimental results; the mean absolute percentage errors are 2.8% for hardness, 2.8% for ultimate stress and 3.8% for yield stress. Eventually, the proposed methodology presented a sustainable, easy, fast, and cost-efficient solution to attain the required mechanical properties of a steel bar treated by Tempcore process.