PSI - Issue 57

Ahmad Qaralleh et al. / Procedia Structural Integrity 57 (2024) 649–657 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

651

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2. Component, Material, and Specimen 2.1. Material

The steering knuckle being examined in this study is constructed from bainitic forged steel (18MnCrMoV6-4-8), a material renowned for its exceptional mechanical properties, including high fatigue strength and toughness. The selection of bainitic steel is often motivated by its advantageous characteristics such as ductility and resistance to impact. The chemical composition of the bainitic steel used in this context is provided in Table 1. It is worth emphasizing that careful control of heat management during the cooling phase from the forging temperature is paramount in achieving the desired microstructure, especially in critical areas of the component subjected to high stress.

Table 1 Typical chemical composition of bainitic steel. Chemical Element C

Si

Mn

Mo

Cr

V

wt%

0.17

0.51

1.35

0.70

1.00

0.12

2.2. Component The steering knuckle is a crucial component of a vehicle's suspension system. Typically, the components attached to the steering knuckle wear out before the steering knuckle itself, and the primary cause of damage to the steering knuckle is collision-related incidents. The component investigated in this research is a steering knuckle used in commercial vehicles with a maximum permissible weight of 12 tons. Fig. 1 shows an unmachined steering knuckle including forging allowance. a.) b.)

Fig. 1 Unmachined steering knuckle including forging allowance. a.) front view; b.) bottom view.

2.3. Specimen To investigate the cyclic material behavior of the material, a series of experimental tests are conducted on specimens removed from the steering knuckle. A flat and smooth specimen were used with a gauge length of 10mm and a thickness of 2mm. The specimen geometry is shown in Erreur ! Source du renvoi introuvable. .