High strength ductile cast iron in suspension components - structural durability and impact energy absorption

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High strength ductile cast iron in suspension components - structural durability and impact energy absorption

Heinrietz, Andre / Zinke, Rüdiger / Streicher, Manfred / Bartels, Christine

Nodular cast materials allow the production of near-net-shape components and are characterized by good fatigue performance and ductility. The fatigue performance and the impact behavior of two variants of a MAN heavy truck suspension arm are compared by experimental and computational investigations. The first variant is made of ENGJS- 400-15 (cast iron with a tensile strength Su > 400 MPa) which has a ferritic microstructure. The other variant is made of austempered EN-GJS-800 - 8 (cast iron with a tensile strength Su > 800 MPa) which has an austenitic-ferritic microstructure. The fatigue properties of components of both materials have been investigated under constant and variable amplitude loading, with and without preliminary overload, simulating a special event. Considering the impact behavior corresponding to a misuse event, the energy absorption capacity of the component made from EN GJS-800 - 8 is significantly higher. Because of the higher yield strength its ability to deform under impact load is lower than that one made of EN-GJS-400-15. This restricted ability to deform has to be taken into account when designing components made from high strength cast materials. The design variant presented takes the component's total deformation behavior and the structural durability into account. However, the achieved local material quality of a component made of high strength cast iron is decisive for its strength properties.