Prozessanalyse und Eigenschaftsoptimierung einer Near-α-Titan-Legierung für den Motorsport

This work characterizes a near-α titanium alloy (P226) for use as a connecting rod material in motorsports and links process control, microstructure, and mechanical properties with the aim of identifying a heat treatment that is adapted and optimized for the manufacturing process.
Compared to Ti-6Al-4V, P226 has a lower density and a higher Young's modulus, but lower hardness and fracture toughness. Pulse tests also deviate from simulations, indicating fatigue behavior that is not fully understood yet. Overall, aging at 500 °C/2 h is promising for static properties, while susceptibility to crack-initiating edge zones, reduced toughness, discrepancies under dynamic load, and higher material costs limit the immediate substitution of Ti-6Al-4V and require further verification.
Along the process chain, multiple forming leads to a forged connecting rod with high dislocation density, texture, and refined lamellar spacing within secondary α grains. This results in residual stresses, which lead to higher tool wear in the following subtractive finishing process. Subsequent solution annealing homogenizes the microstructure and increases ductility. A systematic series of aging tests shows a suitable parameter window at 500°C/2h, which delivers the best strength-ductility ratio. In contrast, 540°C/6h causes pronounced embrittlement (elongation at break ≈ 1.3%), driven by grain boundary enrichment of β-stabilizing elements and α₂ precipitation detected by TEM-SAED.