What material was used in the Model T's frame for lightweight strength?

Vanadium steel was used in the Ford Model T’s frame for lightweight strength.

Ford used vanadium steel alloy in important Model T components because it offered a valuable combination of strength, toughness, and relatively low weight. That helped the car withstand the rough roads and demanding service common in the early twentieth century without requiring an excessively heavy frame.

The material choice was part of the Model T’s broader engineering strategy. The car was designed to be affordable and easy to maintain, but Ford did not achieve low cost simply by using inferior materials. Vanadium steel gave the chassis and other stressed parts improved durability, helping support the Model T’s reputation for surviving hard use.

The answer refers to vanadium steel, not pure vanadium. Vanadium was an alloying element added to steel, and the resulting alloy was used in selected automotive components. Carbon fiber and titanium are associated with much later lightweight engineering, while aluminum was used in some automotive applications but is not the signature frame material linked with the Model T. The alloy’s reputation became one of the car’s notable examples of advanced materials engineering.