POWER VOLTAGE AND WELDING DEFECTS IN STEELFABRICATION PROJECTS OF CONSTRUCTION FIRMS IN SOUTHSOUTH NIGERIA

Abstract

Welding quality plays a critical role in the structural performance of steel fabrication projects in the construction industry. In many developing regions, including South-South Nigeria, unstable power supply and improper control of welding voltage often contribute to welding defects and reduced joint performance. This study investigates the effect of welding voltage on the mechanical properties of welded steel joints with the aim of identifying optimal voltage conditions that minimize defects and enhance joint strength. Submerged arc welding was employed to produce full-penetration butt joints using pressure-vessel-grade carbon steel. Welding was carried out at three different voltage levels— 26 V, 30 V, and 34 V—while welding current, speed, and electrode orientation were kept constant. Tensile tests were performed on the welded specimens, and stress–strain curves were generated to evaluate key mechanical properties, including maximum tensile force, maximum tensile stress, yield tensile stress, breaking stress, and strain energy absorbed up to fracture. The results show a clear correlation between welding voltage and mechanical performance. Increasing welding voltage led to improved tensile strength, higher ductility, and greater strain energy absorption. Welded joints produced at higher voltage exhibited superior mechanical properties, with strain energy showing the greatest sensitivity to voltage variation. The findings indicate that appropriate control of welding voltage significantly enhances weld quality and reduces the likelihood of welding defects associated with inadequate fusion and poor mechanical bonding. The study concludes that welding voltage is a critical parameter in steel fabrication, and its optimization can substantially improve the structural integrity and reliability of welded joints in construction projects. The results provide useful guidance for construction firms and fabricators seeking to improve welding quality under variable power supply conditions