Cooling rates of mild steel welds during gmaw process made at different positions

Abstract

This paper is aimed at examining the cooling rates of mild steel welds made at different welding positions, being the horizontal, vertical and overhead positions. The cooling rate affects the microstructure of the weld metal and in turn the microstructure determines the quality of the weld. Therefore the welding position which produces the weld with the best microstructural view is examined. Both experimental and computational methods are used for analyzing the problem statement. From the results obtained in this study, it was found that the cooling rates at the horizontal, vertical and overhead positions are 4.77oC/s, 4.99oC/s and 8.72oC/s respectively. From the microstructural analysis of the weld, it is found that the microstructure of the weld made at the horizontal position is of the best quality with minute to no trace of gas entrapment. The grains size from the microstructural view appears to be small and paste like, which indicates that the weld texture is very smooth. From this study, it has been shown that welding in the horizontal position when using Gas Metal Arc Welding (GMAW) process produces a weld of good quality microstructure.