Titanium alloys offer several advantages, including lightweight, high strength, corrosion resistance, excellent low-temperature performance, and high chemical reactivity. Additionally, they possess good fatigue resistance, crack resistance, high heat strength, biocompatibility, good thermal conductivity, and non-magnetic properties. Different combinations of titanium alloys can meet various application requirements, leading to their widespread use in aerospace, automotive, medical, chemical, and other industries.
Performance advantages of titanium alloys:
Exceptional Strength
Titanium alloys have a density of approximately 4.5g/cm3, which is only 60% of steel. Pure titanium possesses strength comparable to ordinary steel, while certain high-strength titanium alloys surpass the strength of many alloy structural steel sheets. Consequently, titanium alloys exhibit high specific strength (strength/density ratio), making them ideal for lightweight parts with high unit strength, rigidity, and durability. These alloys find applications in engine components, skeletons, skins, fasteners, and landing gear.
Superior Thermal Resistance
Titanium alloys can withstand higher temperatures than aluminum alloys, maintaining their strength even at elevated temperatures. Some titanium alloys can operate for prolonged periods at temperatures ranging from 450-500℃, exhibiting high specific strength within the temperature range of 150℃-500℃. In contrast, aluminum alloys experience a significant reduction in specific strength at 150℃. With a maximum operating temperature of 500℃, titanium alloys outperform aluminum alloys, which have a limit of below 200℃.
Excellent Corrosion Resistance
When operating in moist atmospheres or seawater environments, titanium alloys exhibit superior corrosion resistance compared to stainless steel. They demonstrate remarkable resistance to pitting corrosion, acid corrosion, and stress corrosion. Titanium alloys also display excellent resistance to alkalis, chlorides, chlorinated organic substances, nitric acid, and sulfuric acid. However, they have limited resistance to reducing agents, oxygen, and chromium salt media.
Impressive Low-Temperature Performance
Titanium alloys retain mechanical characteristics at extremely low and ultra-low temperatures. Certain titanium alloys, such as TA7, exhibit good low-temperature performance and maintain a certain level of plasticity at -253℃. Thus, titanium alloys are crucial structural materials for applications in low-temperature environments.
High Chemical Reactivity
Titanium possesses significant chemical activity, readily undergoing chemical reactions with elements such as oxygen, nitrogen, hydrogen, carbon monoxide, carbon dioxide, water vapor, and ammonia gas. For example, titanium alloys with a carbon content exceeding 0.2% form hard titanium carbide (TiC). At higher temperatures, titanium reacts with nitrogen to form a hard surface layer of titanium nitride (TiN). Titanium absorbs oxygen at temperatures above 600℃, forming a hardening layer with high hardness. Increasing hydrogen content leads to the formation of an embrittlement layer. The absorbed gases can create a hard and brittle surface layer with a depth of 0.1-0.15mm, resulting in increased friction, adhesion, and wear on the contacting surfaces.
Low Thermal Conductivity and Elastic Modulus
Titanium alloys exhibit lower thermal conductivity compared to nickel, iron, and aluminum. The thermal conductivity of titanium alloy products is approximately 1/4 of nickel, 1/5 of iron, and 1/14 of aluminum. Additionally, the thermal conductivity of various titanium alloys is about 50% lower than that of pure titanium. The elastic modulus of titanium alloys is roughly half that of steel, resulting in lower rigidity. Consequently, titanium alloys are susceptible to deformation and are not suitable for producing slender rods or thin-walled parts. During cutting processes, titanium alloys exhibit higher surface rebound volume compared to stainless steel, leading to increased friction, adhesion, and wear on the tool surface.
