The Lowest Hardness Point Calculation by Transient Computer Simulation of Industrial Steel Bar Quenched in Oil at Different Austenitizing Temperatures

Quenching of steels in general has been and continues to be an important commercial manufacturing process for steel components. Temperature histories must be performed in order to obtain accurate transformation kinetics. The modelling of an axisymmetric industrial quenched steel bar based on finite element method has been produced to investigate the impact of process history on metallurgical and material properties. A two dimensional 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, which is at half the length at the centre of the bar. Experimentally, this hardness value is almost impossible to determine and previous methods only calculate hardness at the surface. This surface hardness value is normally higher than the (LHP) which can cause deformation and failure of the component under certain conditions. The model can be employed as a guideline to design cooling approach to achieve desired microstructure and mechanical properties such as hardness.