Effect of GTAW on the Mechanical Properties of Mild Steel

Abstract

Tungsten metal arc welding (GTAW) is a highly popular welding technique in manufacturing. The welding factors such as welding current, voltage, speed, and gas flow rate play a significant role in determining the welding quality. This study discusses the effect of GTAW factors on the mechanical properties of commercial steel welding. Base metal thickness, welding speed, and current are the factors to be optimised for maximum tensile strength and hardness by Taguchi design (TD). The analysis showed that higher tensile strength welding has higher hardness. The increased tensile strength is obtained at increased base metal thickness, higher welding speed and lower welding current. In addition, higher tensile strength has been shown to obtain higher hardness—the higher hardness demonstrated at welding exposed to increased heat input that caused higher internal stresses. The higher base metal thickness obtained higher tensile strength due to the increased welding sample cross-section area and due to the phenomenon of the heat sink that minimised the effect of heat input and, thus, internal stresses. The welding made at 10 mm base metal thickness affected the results the most and obtained higher means, followed by samples fabricated at 150 A, while welding speed variation did not have much difference on the results. To obtain higher tensile strength, it is recommended to go for more increased base metal thickness, lower welding current, and faster welding speed when welding mild steel by GTAW.