An experimental study into the effects of bending on the mechanical properties of mild (AISI 1018) steel pipes

Abstract

AISI 1018 mild steel is a versatile industrial material due to its excellent mechanical properties and numerous industrial applications. It possesses a good balance of high strength, ductility, weldability, and excellent thermal and electrical conductivity. Just like other industrial materials, mechanical components made from mild steel are susceptible to fracture or cracks when subjected to varying loading or stress conditions. This study therefore used experimental method to investigate the effect of bending on the mechanical properties of mild steel (AISI 1018). The test samples were prepared based on the standards of American Iron and Steel Institute (AISI). The findings of the study showed that, with the exception of the percentage strain (which increased averagely for L, C and S samples by 0.122%, 0.2895% and 0.06% respectively), the bending and welding samples adversely affected the other mechanical properties studied; (i.e. Ultimate Tensile Strength, Yield Strength, Elastic Moduli, impact and deformation characteristics) of the samples witnessed reductions in values after bending, welding and testing. This increase in strain of the welded sample L- shape is attributable to the heat induced during the electric arc welding processes and the bending of the C – shape samples. The study also showed that, the grain size of the samples improved in the welded sample L; as there was a near even distribution of dark and gray spots in the micrographs. The findings of this study could therefore help metal fabrication professionals and regulators to appreciate the impact of bending and electric arc welding on the microstructure and mechanical properties of mild steel pipe components and structures. Also, it may assist industry regulators to promulgate standards to regulate the bending and welding of mild steel and possibly other industrial materials in order to preserve the natural properties of the material