Analysis of welding defects and tensile strength in GTAW of ST-37 steel to prevent material quality degradation

Gas Tungsten Arc Welding (GTAW) is a widely used welding method in construction due to its high precision and efficiency. This study aims to identify welding defects and determine the tensile strength of ST 37 steel when welded using GTAW with varying tungsten electrode diameters and current levels. The diameters of the tungsten electrodes used were 1.6mm, 2.4mm, and 3.2mm, combined with current levels of 60 A, 80 A, and 100 A. After welding, two tests were conducted: A penetrant test, following ASME 2010 Section 6, and a tensile strength test according to ASTM E8 standards. The penetrant test results indicated that the combination of a 3.2mm tungsten electrode and a 60 A current resulted in the highest number of welding defects, with eight instances of porosity, cracks, and tungsten inclusion. In contrast, the same 3.2mm electrode with a 100 A current produced the fewest defects, registering only two points of defects, namely cluster porosity and tungsten inclusion. Tensile strength testing showed that the 3.2mm electrode with a 100 A current produced the highest tensile strength, measuring 43.13kg/mm2. On the other hand, the combination of a 1.6mm electrode and 60 A current resulted in the lowest tensile strength, measuring 29.75kg/mm2. The findings suggest that higher current levels in GMAW welding lead to fewer defects and higher tensile strength, while lower current levels result in more defects and lower tensile strength in ST 37 steel. These insights are crucial for optimizing welding parameters in industrial applications.