In industry, welding is well known. There is a great demand for effective and quality welding. Manufacturers seek to remain competitive in the market. They rely on their manufacturing engineers and production personnel to quickly and effectively set up manufacturing processes for new products. Gas metal arc welding is one of the most widely used processes in the industry. Input factors such as welding current, welding voltage, Gas flow rate, wire feed speed, wire size and welding speed play a significant role in determining the welding quality. Taguchi's design has been a powerful and efficient optimization tool for better quality and performance output of manufacturing processes. In this study, Gas metal arc welding has welded commercial steel under preset factors of welding voltage, wire feed speed and groove shape. Base metal groove shape X welding obtained lower tensile strength and hardness than base metal groove shape V. Taguchi's design is to determine the optimal process factors for higher tensile strength and hardness. The analysis found that welding groove shape V had higher effect on the tensile strength and hardness of the welding, while the welding voltage has obtained higher tensile strength and hardness values. The optimum combination of welding factors was base metal groove shape V, 20 V and wire feed speed of 5.9 m/min.
This paper will discuss the effect of welding variables on the transverse tensile strength and hardness of mild steel welding made by GMAW. The welding variables included are base metal thickness, welding voltage, wire feed speed (WFS), and base metal groove shape. The results show that higher welding transverse tensile strength has obtained higher FZ hardness, while they both increased with decreased welding heat input. E.g., the highest tensile strength (238 MPa) has shown 2162 HV at 768 J/mm heat input, while the lowest tensile strength (120 MPa) of welding made at 2376 J/mm has shown 2108 HV. The FZ of welding made at V groove-shaped base metal has higher hardness and transverse tensile strength, as shown 2159.5 HV and 215 MPa in order when compared to 177 MPa and 2147 HV for X groove-shaped. The hardness at V groove-shaped FZ had an average of 2159.5 HV, while the hardness at X groove-shaped had an average of 2147 HV at 10 mm base metal thickness. The increased hardness of V groove-shaped FZ could be related to the increased stresses at V groove-shaped due to interpass heat input. The intricate physical shape of FZ and HAZ for X groove configuration possibly contributes to the lower transverse tensile strength of welding. A favorably increased hardness and transverse tensile strength are associated with softer and finer ferritic and perlitic grains in FZ and less dendritic perlite structure in HAZ. The Widmanstatten ferrite has contributed to decreased tensile strength.
Gas metal arc welding is a leading process in fusion welding with increased productivity and good quality. The welding parameters are crucial in determining welding quality, cost, and productivity. In this study, mild steel with a 10-mm-thick sheet was welded by gas metal arc welding under predetermined parameters of welding voltage, wire feed speed, and groove shape. The analysis made by Taguchi’s design to investigate the effect of these parameters on tensile strength and Vickers micro-hardness of welding. The microstructure of the fusion zone and heat-affected zone is analyzed to monitor their change concerning the mechanical properties. The results showed that tensile strength decreased with decreased hardness. Also, the tensile strength and hardness were higher (a maximum of 305 MPa and 2170 HVN) at welding made at a lower voltage (20 volts), lower wire feed speed (5.9 m/min), and V-shaped base metal groove. The increased precipitation of perlite structure was shown during welding, which has lower tensile strength and hardness. Widmanstatten ferrite and coarser α-ferrite were presented for welding with a lower cooling time. Taguchi’s design showed that voltage at 20 volts has the highest effect on tensile strength, followed by wire feed speed at 5.9 m/min and V-shaped welding.
Gas tungsten metal arc welding (GTAW) is used to study the effect of the base metal thickness, welding current and welding speed on the tensile strength and hardness of mild steel welding. The analysis found that base metal thickness had the highest effect and highest means of tensile strength and hardness of the welding. Taguchi’s design (TD) suggested using higher base metal thickness, lower welding current and higher welding speed when welding mild steel in order to obtain maximum tensile strength and hardness. The welding that has higher tensile strength showed higher hardness. However, the hardness increased proportionally with the increased internal stresses of the welding. The welding showed wider heat affected zone (HAZ) with the increase in internal stresses of the welding.
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.
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