Forged wheels are primarily manufactured using high-strength steel and aluminum alloys, achieving superior performance through precision forging processes. Commonly used materials include specialty steels such as 60 steel, 65Mn, and 42CrMo; these offer a solid mechanical foundation thanks to their high hardness, toughness, and excellent fatigue limits. Meanwhile, aluminum alloys have become the market mainstream due to their lightweight nature and superior heat dissipation capabilities. The forging process employs high-pressure impact to induce plastic deformation in the metal billet, eliminating internal porosity and densifying the molecular structure. This results in a strength-to-weight ratio far superior to that of cast wheels, ensuring load-bearing safety while significantly reducing unsprung mass and enhancing vehicle dynamic response.
As a representative hypoeutectoid steel, 60 steel exhibits outstanding strength and elasticity, enabling it to withstand the high-frequency loads encountered during vehicle operation. However, the material has relatively low plasticity during cold deformation and is somewhat difficult to machine; it also faces limitations regarding weldability and hardenability. Consequently, normalization is often employed during the production of large components to balance hardness with machinability, ensuring the dimensional stability and structural reliability of the finished wheel.
After undergoing heat treatment and cold-drawing hardening, 65Mn experiences a significant increase in strength while retaining a degree of toughness and plasticity. Under conditions of uniform surface quality and full hardenability, its fatigue limit rivals that of alloy spring steels. This is crucial for wheels that must endure prolonged exposure to road bumps and steering-induced impacts, effectively extending the component's service life under demanding operating conditions.
42CrMo falls into the category of ultra-high-strength steels, boasting excellent strength, toughness, and hardenability, alongside a lack of significant temper brittleness. Following quenching and tempering, its fatigue limit and resistance to repeated impacts are further enhanced, and it maintains good low-temperature impact toughness. This ensures stable mechanical performance even in cold driving environments, providing multiple safeguards for driving safety.
