Correlation between Process Variables in Shielded Metal-Arc Welding (SMAW) Process and Post Weld Heat Treatment (PWHT) on Some Mechanical Properties of Low Carbon Steel Welds

J. O. Olawale, S. A. Ibitoye, K.M. Oluwasegun, M. D. Shittu, R. C. Ofoezie

Department of Materials Science and Engineering, Obafemi Awolowo University, Ile-Ife, Nigeria.

DOI: 10.4236/jmmce.2012.119084                

Abstract

This investigation was conducted to correlate process variables in shielded metal-arc welding (SMAW) and post weld heat treatment on some mechanical properties of low carbon steel weld. Three hundred and sixty pieces of weld samples were prepared. The samples were welded together using AWS E6013 electrodes with DC arc welding process. Varying welding currents of 100 A, 120 A, 140 A were used with a terminal voltage of 80 V. The weld samples were prepared for hardness, tensile and impact test. The prepared samples were then subjected to normalising heat treatment operation at temperatures of 590°C, 600°C, 620°C, 640°C, 660°C, 680°C, and 700°C. It was observed that increase in welding current led to an increase in hardness and ultimate tensile strength values of as-weld samples while impact strength de-creases. After post heat treatment operation the hardness and ultimate tensile strengths decreases while impact strength increases. From this outcome we conclude that there is correlation between the welding current and mechanical proper-ties of weld metal on one hand and normalising temperatures and mechanical properties on the other hand. As the cur-rent increases the hardness and strength increases but impact strength reduces, while hardness and strength continuously reduces but impact strength increases as normalising temperatures increases.

Keywords

Post-Welding; Normalising; Current; Steel; Hardness; Strength

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Welding Technology Institute of Australia, “Panel 1— Guidance Note 6 PWHT,” 2003.
[2]	A. Khaleel and J. Krishnan, “Post-Weld Heat Treatment,” Proceeding of International Symposium on Thermal Spray, Mumbai, 2-4 May 2002, pp. 111-115.
[3]	I. S. Kim, et al., “An Investigation into an Intelligent System for Predicting Bead Geometry in GMA Welding Process,” Journal of Materials Processing Technology, Vol. 159, No. 1, 2005, pp. 113-118. doi:10.1016/j.jmatprotec.2004.04.415
[4]	A. V. Adedayo, S. A. Ibitoye and O. A. Oyetoyan, “Annealing Heat Treatment Effects on Steel Welds,” Journal of Minerals and Materials Characterization and Engineering, Vol. 9, No. 9, 2010, pp. 547-557.
[5]	A. V. Adedayo, S. A. Ibitoye and O. O. Oluwole, “Tempering Heat Treatment Effects on Steel Welds,” Journal of Minerals and Materials Characterization and Engineering, Vol. 10, No. 8, 2011, pp. 755-764.
[6]	R. S. Funderburk, “Key Concepts in Welding Engineering,” Welding Innovation, Vol. 15, No. 2, 1998, 2 p.
[7]	J. Raveendra and R. S. Parmar, “Mathematical Models to Predict Weld Bead Geometry for Flux Cored Arc Welding,” Metal Construct, Vol. 19, No. 1, 1987, pp. 31R- 35R.
[8]	J. I. Lee and K. W. Um, “A Prediction of Welding Process Parameters by Prediction of Back-Bead Geometry,” Journal of Materials Processing Technology, Vol. 108, No. 1, 2000, pp. 106-113. doi:10.1016/S0924-0136(00)00736-6
[9]	K. S. Prasad, C. S. Rao and D. N. Rao, “The Prediction of Weld Bead Geometry in Plasma Arc Welding Using Factorial Design Approach,” Journal of Minerals and Materials Characterization and Engineering, Vol. 10, No. 10, 2011, pp. 875-886.
[10]	P. J. Modenesi and R. C. Avelar, “The Influence of Small Variations of Wire Characteristics on Gas Metal Arc Welding Process Stability,” Journal of Materials Processing Technology, Vol. 86, No. 1-3, 1999, pp. 226-232.
[11]	J. C. McGlone and D. B. Chadwick, “The Submerged Arc Butt Welding of Mild Steel (Part 2): The Prediction of Weld Bead Geometry from the Procedure Parameters,” Welding Institute Report 80/1978/PE, 1978.
[12]	J. Doherty, et al., “The Relationships between Arc Welding Parameters and Fillet Weld Geometry for MIG Welding with Flux Cored Wires,” Welding Institute Report 82/1978/PE, 1978.
[13]	R. S. Chandel, “Mathematical Modeling of Gas Metal Arc Weld Features,” Proceedings of the 4th International Conference on Modeling of Casting and Welding Processes,” Palm Coast, 17-22 April 1988, pp. 109-120.
[14]	V. V. Kumar and N. Murugan, “Effect of FCAW Process Parameters on Weld Bead Geometry in Stainless Steel Cladding,” Journal of Minerals and Materials Characterization and Engineering, Vol. 10, No. 9, 2011, pp. 827-824.
[15]	S. P. Tewari, A. Gupta and J. Prakash, “Effect of Welding Parameters on the Weldability of Material,” International Journal of Engineering Science and Technology, Vol. 2, No. 4, 2010, pp. 512-516.
[16]	T. V. Raja, C. P. Sharma and A. Sharman, “Heat Treatment Principles and Techniques,” Prentice-Hall of India Private Limited, New Delhi, 1999, p. 243.
[17]	V. Gunaraj and N. Murugan, “Prediction and Comparison of the Area of the Heat Affected Zone for the Bead-on- Plate and Bead-on-Joint in Submerged Arc Welding of Pipes,” Journal of Materials Processing Technology, Vol. 95, No. 1-3, 1999, pp. 246-261. doi:10.1016/S0924-0136(99)00296-4
[18]	K. Sindo, “Welding Metallurgy,” 2nd Edition, John Wiley & Sons, New York, 2003, pp. 199-206.