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
References
[1]
R. E. Dolby and K. G. Kent, “Repair and reclamation,” in Proceedings of the Welding Institute Conference, London, UK, September 1984.
[2]
P. Blaskovito, N. A. Grinberg, J. Suchanek et al., “New hardfacing materials for arasive and erosive condition, metallurgy,” in Proceedings of the Process Autoration, XII- 1667-01, IIW, pp. 21–35, Liubljana, Slovenia, 2001.
[3]
J. D. Ayere, T. R. Tucker, and R. J. Schaefer, “Wear resisting surfaces by carbide particle injection, rapid solidification processing- principles and technologyies, II,” R. Mehrabian, B. H. Kear, and M. Cohn, Eds., p. 212, Claitor's Publishing Division, Baton Rouge, La, USA, 1980.
[4]
R. Viskanta and T. L. Bergman, “Heat transfer in material processing,” in Handbook of Heat Transfer, chapter 18, McGraw-Hill, New York, NY, USA, 1998.
[5]
S. Z. Shuja, B. S. Yilbas, and M. O. Budair, “Modeling of laser heating of solid substance including assisting gas impingement,” Numerical Heat Transfer A, vol. 33, no. 3, pp. 315–339, 1998.
[6]
N. Bianco, O. Manca, and S. Nardini, “Comparison between thermal conductive models for moving heat sources in material processing,” in Proceedings of the ASME International Mechanical Engineering Congress and Exposition, pp. 11–22, New york, NY, USA, November 2001.
[7]
G. E. Linnert, Welding Metallurgy, vol. 1, The American Welding Society, Miami, Fla, USA, 4th edition, 1994.
[8]
D. Rosenthal, “Mathematical theory of heat distribution during welding and cutting,” Welding Journal, vol. 20, no. 5, pp. 220–234, 1941.
[9]
T. W. Eager and N. S. Tsai, “Temperature fields produced by traveling distributed heat sources,” Welding Journal, vol. 62, no. 12, pp. 346–355, 1983.
[10]
J. F. Lancaster, The Metallurgy of Welding, Allen and Unwin, London, UK, 4th edition, 1987.
[11]
B. M. Patchett, “Control of microstructure and mechanical properties in SA and GMA weld metals,” in Proceedings of the International Symposium on Welding Metallurgy of Structural Steels, pp. 189–199, Denver, Colo, USA, 1987.
[12]
C. I. Nwoye, C. N. Anyakwo, E. Obidiegwu, and N. E. Nwankwo, “Model for assessment and computational analysis of hardness of the heat affected zone in water cooled aluminium weldment,” Journal of Mineral and Materials Characterization and Engineering, vol. 10, no. 8, pp. 707–715, 2011.
[13]
C. I. Nwoye, “Comparative studies of the cooling ability of hydrocarbon based media and their effects on the hardness of the heat affected zone (HAZ) in weldments,” Journal of Metallurgical and Materials Engineering, vol. 3, no. 1, pp. 7–13, 2008.
[14]
C. I. Nwoye and I. E. Mbuka, “Models for predicting HAZ hardness in cast iron weldment cooled in groundnut oil in relation to HAZ hardness of aluminium and mild steel weldments cooled in same media,” Materials Research Innovations, vol. 14, no. 4, pp. 312–315, 2010.
[15]
C. I. Nwoye, U. Odumodu, C. C. Nwoye, G. C. Obasi, and O. O. Onyemaobi, “Model for predictive analysis of hardness of the heat affected zone in aluminum weldment cooled in groundnut oil relative to HAZ hardness of mild steel and cast iron weldments cooled in same media,” New York Science Journal, vol. 2, no. 6, pp. 93–98, 2009.
[16]
C. I. Nwoye and I. E. Mbuka, “Quadratic and linear models for predicting the hardness of heat affected zone in air cooled cast iron weldment in relation to the HAZ hardness of aluminum and mild steel weldments cooled in same media,” Researcher Journal, vol. 1, no. 4, pp. 1–6, 2009.
[17]
C. I. Nwoye, “Quadratic model for predicting the hardness of heat affected zone in water cooled cast iron weldment in relation to similarly cooled aluminum and mild steel weldments,” Journal of Mineral and Materials Characterization and Engineering, vol. 8, no. 10, pp. 765–773, 2009.
[18]
C. I. Nwoye, C-NIKBRAN; Data Analytical Memory (Software), 2008.
