Cause of Fracture on GhSiMoRct Nodular Cast Iron Exhaust Manifold in Diesel Engine

The exhaust manifold of diesel engine is usually made of GhSiMoRct nodular cast iron material with excellent high temperature mechanical properties. However, due to the many processing procedures of casting parts and the unstable casting quality, the exhaust manifold fractured during service. The causes of fracture on GhSiMoRct nodular cast iron exhaust manifold in diesel engine were analyzed by means of magnetic particle inspection, scanning electron microscope analysis, chemical composition analysis and metallographic examination. The results show that there were casting defects in the structure of the exhaust manifold. Under the action of external force, cracks produced and propagated continuously, which led to the decrease of the strength of the parts and the fracture of the exhaust manifold.