An elaborate study has been conducted in this article to estimate the cooling rate of the Gas Tungsten arc (GTA) welded steel butt joints of grade AISI 1090. The temperature dependent thermal parameters has been investigated in connection with developed rate of cooling. Experiment has been carried out ffto determine the thermal cycle formed along the longitudinal direction from weld bead. Implementing experimental temperatures, Adams empirical cooling rate correlation has incorporated to analyze rate of cooling. A correlation has been suggested in this study, derived from thick plate temperature distribution model. To find out the heat loss from the joint, Vinokurov’s empirical combined heat transfer coefficient has been utilized and with it has verified with conventional heat transfer coefficient based on convection and radiation. Cooling rate has been found out to be very rapid at z = 36mm to z = 108mm based on thick plate model and it has completely agreed with the variation of Adams correlation. At higher temperatures above 800ºC, heat loss due to radiation completely dominates the convection and lower temperatures convection heat loss influences much than radiation. Heat loss due to convection and radiation fully justified with the results produced based on cooling rate and rapid cooling near the fusion boundary exists only for 5s-10s.
The paper’s primary contribution is finding the cooling rate and its effect on related thermal properties in Gas Tungsten Arc (GTA) welding of high carbon steel joints. Basically in present analysis, 0.9% C containing high carbon steel (AISI 1090) butt weld joint has been prepared and experimental temperature distribution has been analyzed. The effect of rapid temperature cycle formed and its dynamic effect on temperature dependent properties such as thermal conductivity, rate of cooling based on convection, radiation and evaporation has been studied. Cooling rate has been estimated by ’Thick Plate Model’, due to its close validation with experimental temperature cycle. This study reveals that all the temperature dependent properties are very randomly changing near the heat affected zone within the time range of 5s-10s. This article gives parametric study of effect of cooling rate and temperature dependent parameters developed in GTA welding of butt joints.
J. A. Goldak and M. Akhlaghi, Computational welding mechanics. Spring Street, New York 100013, USA: Springer Science+Business Media Inc, 2005.
D. Rosenthal, "The theory of moving sources of heat and its applications in metal treatments," Trans. ASME., vol. 68, pp. 849 -865, 1946.
M. B. C. Quigley, "Heat flow to the workpiece from a TIG welding arc," J. Phys. D:Appl. Phys., vol. 6, pp. 2250-2258, 1973.
L. E. Svensson, "An analysis of cooling curves from the fusion zone of steel weld deposits," Sc. and J. Metallurgy, vol. 15, pp. 97-103, 1986.
G. H. Little and A. G. Kamtekar, "The effect of thermal properties and weld efficiency on transient temperatures in welding," Computers and Structures, vol. 68, pp. 157 -165, 1998.
R. Komanduri and Z. B. Hou, "Thermal analysis of arc welding process: Part II. Effect of thermophysical properties with temperature," Metallurgical and Materials Transactions B., vol. 33B, pp. 483 - 499, 2001.
K. Poorhaydari, "Estimation of cooling rate in the welding of plates with intermediate thickness," Welding Journal, vol. 84, pp. 149s-155s, 2005.
D. Gary, "Effect of welding speed, energy input and heat source distribution on temperature variations in butt welding," Journal of Material Processing Technology, vol. 167, pp. 393 - 401, 2005.
A. Arora, "Cooling rate in 800 to 500°C range from dimensional analysis," Science and Technology of Welding and Joining, vol. 15, pp. 423-427, 2010.
M. I. Onsoien, "Residual stresses in weld thermal cycle simulated specimens of X70 pipeline steel," Welding Journal, vol. 89, pp. 127-132, 2010.
Y. Zhang, "Estimating of cooling rates of spot welding nugget in stainless steel," Welding Journal, vol. 91, pp. 247-251, 2012.
C. S. Pathak, "Analysis of thermal cycle multipass arc welding," Welding Journal, vol. 91, pp. 149s -155s, 2012.
S. P. Lu, "Highly ef?cient TIG welding of Cr13Ni5Mo martensitic stainless steel," Journal of Material Processing Technology, vol. 213, pp. 229 - 237, 2013.
P. Schempp, "Solidification of GTA aluminum weld metal: Part 2 — thermal conditions and model for columnar-to-equiaxed transition," Welding Journal, vol. 93, pp. 69-77, 2014.
S. G. K. Manikandan, "Effect of weld cooling rate on laves phase formation in inconel 718 fusion zone," Journal of Material Processing Technology, vol. 214, pp. 358-364, 2014.
N. Yadaiah and S. Bag, "Development of egg-con?guration heat source model in numerical simulation of autogenous fusion welding process," International Journal of Thermal Sciences, vol. 86, pp. 125-138, 2014.
S. Kou, Welding metallurgy. Willey-interscience, 111 river street, 2nd ed. Hoboken, New Jersey 07030: A John Willey and Sons Inc. Publication, 2003.
N. R. Mandal, Welding and distortion control, 1st ed. New Delhi: Narosa Publishing House, Darya Ganj, Delhi Medical Association Road, 2004.
H. S. Carslaw and J. S. Jaeger, Conduction of heat in solids, 2nd ed. Oxford, United Kingdom: Oxford University Press, 1959.
R. S. Desai and S. Bag, "Influence of displacement constraints in thermomechanical analysis of laser micro-spot welding process," Journal of Manufacturing Process, vol. 16, pp. 164 - 275, 2014.
G. E. Dieter, Mechanical metallurgy, 3rd ed.: McGraw Hill Education Pvt. Ltd.