Acta Metallurgica Slovaca, Vol. 19, 2013, No. 2, p. 105-111 105 DOI 10.12776/ams.v19i2.94 p-ISSN 1335-1532 e-ISSN 1338-1156 MODELING THE EFFECT OF RADIUS ON TEMPERATURE HISTORY OF TRANSIENT QUENCHED BORON STEEL Abdlmanam S. A. Elmaryami 1)* , Badrul Omar 1) University Tun Hussein Onn Malaysia, Mechanical Engineering Department 86400 Parit Raja, Batu Pahat, Johor, Malaysia Received: 14.01.2012 Accepted: 26.02.2013 * Corresponding author: e-mail: damer604@yahoo.com, Tel.: +60177781775, Faculty of Mechanical and Manufacturing Engineering, University Tun Hussein Onn Malaysia, Malaysia Abstract One-dimensional (1D) model of an axisymmetric unsteady state industrial quenched boron steel 50B46H bar based on finite element method (FEM) has been applied to investigate the influence of process history on its material properties. The effect of four different radii on its temperature history is determined. The model can be employed as a guideline to design cooling approach to achieve desired microstructure and mechanical properties such as hardness. A computer program of the model is developed, which can be used independently or incorporated into a temperature history software named (LHP)-software to continuously calculate and display temperature history of the boron steel bar and thereby to study the effect of radius on temperature history. The developed program based on (1D) FEM model has been verified by comparing its results with commercial finite element software results. The comparison indicates its validity and reliability. Keywords: steel, quenching, FEM, unsteady state heat transfer 1 Introduction Mathematical models are used particularly in the natural sciences and engineering disciplines (such as thermal engineering, heat treatment of unsteady state industrial quenched steel bar as in this work). A mathematical model is an abstract model that uses mathematical language to describe the behaviour of a system. A model may help to explain a system and to study the effects of different components, and to make predictions about behaviour; in this paper modelling the effect of radius on temperature history of transient quenched boron steel as shown in Fig. 1 is studied. Models allow us to predict behaviours or results that are as yet unseen or unmeasured such as LHP is unseen and unmeasured before as shown in Fig. 1. The key steps in modelling process are shown in Fig. 1. Mathematical modelling is a method of simulating real-life situations with mathematical equations to forecast their behaviour. In this manuscript the heat transfer analysis is carried out in three dimensions (3D). The (3D) analysis is reduced to a 1-D axisymmetric analysis to save cost and computer time. This is achievable because in axisymmetric conditions, the temperature deviations are only along radius (R) while there is no temperature variation in the (Ɵ) and (Z) directions. The Galerkin weighted residual technique is used to derive the verified mathematical model [1-6].