Failure Resolution of Exhaust Manifold used in Commercial Vehicle Engines

A comprehensive metallurgical investigation was undertaken to elucidate the causes of exhaust manifold failures in both compressed natural gas and diesel engines. This investigation encompassed a thorough material analysis, encompassing chemical composition, microstructural characterization, identification of casting defects, and evaluation of mechanical properties. Additionally, fractography studies were conducted on the fractured surfaces to gain insights into crack initiation and propagation mechanisms. The findings of these analyses revealed that the observed wall thinning was potentially due to core shifting during the casting process, coupled with the presence of casting defects. These factors collectively contributed to the failure of the exhaust manifold. Keywords: Exhaust manifold, Cast iron, Wall thinning, Core shifting, Casting.