Comparative Study on Evaluating Fatigue Performance of Forged Steel Versus Different Material Automotive Component

Abstract

The overall objective of this paper is to compare and evaluate the fatigue performance of two competing manufacturing technologies for automotive component, namely forged steel and cast iron steering knuckle. The paper details the different experimental evaluation, mechanical properties and performance of two materials and components, their results for the steering Knuckle. Fatigue is the primary cause of failure of component due to the cyclic loading and presence of stress concentrations at the fillets and critical areas. The steering knuckle consisted of mainly sections namely spindle, strut mounting holes and hub mounting attachments. The masses of both steering knuckle were similar with the forged steel at 4.8 kg and the cast iron at 4.5 kgs. Also, the failure location of the steering knuckle used in this study was in the first step and second step fillet, which agrees with the typical failure location for an automotive steering knuckle. The paper concludes that the crack growth life for both steering knuckle was a significant portion of the fatigue life during the steering knuckle testing. The crack growth rate of the forged steel steering knuckle was slower than the cast iron steering knuckle. During steering knuckle fatigue tests, circumferential cracks developed in the first step and second step fillet of both forged steel and cast iron steering knuckles which was identified as the critical location from FEA.