Modeling the Lowest Hardness Point in a Steel Bar During Quenching

Abstract

The modeling of an axisymmetric industrial-quenched low-carbon steel bar based on the finite-element method has been produced to investigate the impact of process history on metallurgical and material properties. Mathematical modeling of a one-dimensional line (radius) element axisymmetric model has been adopted to predict temperature history and, consequently, the hardness of the quenched steel bar at any point (node). The lowest hardness point (LHP) is determined. In this paper, hardness in specimen points was calculated by the conversion of calculated characteristic cooling time for phase transformation t8/5 to hardness. The model can be employed as a guideline to the design cooling approach to achieve desired microstructure and mechanical properties, such as hardness. The developed mathematical model converted to a computer program. This program can be used independently or incorporated into a temperature history calculator to continuously calculate and display temperature history of the industrial-quenched steel bar and thereby calculate LHP. The developed program from the mathematical model has been verified and validated by comparing its hardness results with 2D mathematical model and with commercial finite-element software results. The comparison indicates reliability of the proposed model.