%0 Journal Article
%T Factorial Analysis of Welding Current Influence on Heat Affected Zone Hardness of Cast Iron, Aluminium, and Mild Steel Weldments Cooled in Palm Oil
%A C. I. Nwoye
%A J. U. Odo
%A E. M. Ameh
%A S. O. Nwakpa
%J Journal of Metallurgy
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/245312
%X Factorial analysis of heat affected zone hardness of some metals was evaluated. Three models were derived and used as tools for evaluating the welding current influence on the predictability of HAZ hardness in aluminium, cast iron, and mild steel weldments similarly cooled in palm oil. It was discovered that on welding these materials, and similarly cooling their respective weldments in palm oil, the model predicts aluminium weldment HAZ hardness by multiplying the determined general current product rule (GCPR) with the ratio: HAZ hardness product of cast iron and mild steel/HAZ hardness sum of cast iron and mild steel . Computational analysis of experimental and model-predicted results indicates that aluminium, cast iron, and mild steel weldment HAZ hardness per unit welding current as evaluated from experiment and derived model are 3.3917, 4.8333, and 2.7944 and 3.3915, 4.8335, and 2.7946 (VHN) A£¿1, respectively. Deviational analysis shows that the maximum deviation of model-predicted HAZ hardness from the experimental results is less than 0.007%. This invariably implies over 99.99 % confidence level for the derived models. 1. Introduction In many industries today, engineers are concerned with ways or how to prolong the life of the structure, with the repair and reclamation of its worn-out surface on its broken components [1]. Interestingly, in some cases, the extent of damage or worn is so small and localized that the components involved are repaired economically by welding [1]. In the past, restoration of worn-out industrial components has been achieved by weld surfacing. And so the wide range of consumables available for use with the many welding processes requires careful selection to suit a given working environment [2]. Restoration is ultimately achieved when welding is done at a low cost compared with replacement costs especially when the component is large and/or expensive. Studies [1, 3] have revealed consideration and applicability of suitable welding procedures as well as fulfilling the metallurgical requirements as the first two vital factors for successful repair. Analytical and numerical models for the prediction of the thermal fields induced by the stationary or the moving heat sources are useful tools for studying the fore mentioned problems [4]. In some laser beam applications, such as surface heat treatment, the contribution of convective heat transfer must also be taken into account [5]. Quasi-steady state thermal fields induced by moving localized heart sources have been widely investigated [6], whereas further attention seems to
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