Titanium possesses a strong affinity for nitrogen, oxygen, and carbon, rendering it an effective deoxidizing agent and catalyst for fixed nitrogen and carbon. The compound formed by titanium and carbon, known as TiC, exhibits remarkable stability and a robust binding force. Only when exposed to temperatures above 1000°C does TiC slowly dissolve into an iron solid solution. The inclusion of TiC particles in steel impedes the growth and coarsening of steel grains.
Furthermore, titanium acts as a potent ferrite-forming element, reducing the austenite phase region. In the solution state, the presence of titanium enhances the hardenability of steel, but with TiC particles, it diminishes. Once the titanium content reaches a specific threshold, precipitation hardening occurs due to the dispersion of TiFe2.
When titanium exists as a solid solution within ferrite, its strengthening effect surpasses that of aluminum, manganese, nickel, and molybdenum, but falls short compared to beryllium, phosphorus, copper, and silicon.
The influence of titanium on the mechanical properties of steel depends on its form, the Ti to C ratio, and the applied heat treatment. In the mass fraction range of 0.03% to 0.1% Ti, the yield strength experiences improvement. However, when the Ti to C ratio exceeds 4, both strength and toughness exhibit a sharp decline. Titanium contributes to enhanced endurance strength and creep resistance while also improving the toughness of steel, particularly its impact toughness at low temperatures.
Considering a mass fraction surpassing 0.025%, titanium can be regarded as an alloying element. Its application extends to various steel types, including ordinary low alloy steel, alloy structural steel, alloy tool steel, high-speed tool steel, stainless acid-resistant steel, heat-resistant steel, permanent magnet alloys, and cast steel.
