Crash Behavior of ADI Steering Knuckles

Abstract

Within a German Egyptian Research Fund (GERF) project, prototypes of steering knuckles with varying heat treatments were produced and their crash behavior was compared to a standard type steering knuckle. Therefore, high strain rate tensile tests were performed with round bar specimens, which were extracted from steering knuckles. The ADI materials achieved tensile strength values of up to 1400 MPa and an elongation at fracture of about 1 %. Lower strength ADI qualities attained tensile strengths of about 900 MPa and 1110 MPa with elongations at fracture of about 9 % and 14 %, respectively. For comparison a standard ductile cast iron for steering knuckles achieved a tensile strength of approximately 500 MPa and an elongation at fracture of about 23 %. These results demonstrate that ADI materials may exhibit a good potential for crash loaded automotive components. The TRIP effect which leads to high strength in combination with relatively high elongation at fracture was investigated by metallographic examination and X-ray-diffraction analysis.