1, small density, high strength, large specific strength
The density of titanium is 4.51g/cm3, which is 57% of steel, just over half of steel, less than twice of aluminum, and three times stronger than aluminum. The specific strength of titanium alloy is the largest commonly used industrial alloy, the specific strength of titanium alloy is 3.5 times that of stainless steel, 1.3 times that of aluminum alloy, and 1.7 times that of magnesium alloy, so it is an essential structural material for the aerospace industry.
Titanium alloy rod
The comparison of density and specific strength between titanium and other metals is shown in Table 1-1.
Table 1-1 Comparison of density and specific strength of titanium with other metals
Metal Titanium (alloy) Iron aluminum (alloy) magnesium (alloy) high strength steel
Density /(g·cm-3) ratio intensity 4.5 (29) 7.87 -- 2.7 (21) 1.74 (16) -- 23
2, excellent corrosion resistance
The passivity of titanium depends on the existence of oxide film, its corrosion resistance in the oxidizing medium is much better than in the reducing medium, and high rate corrosion can occur in the reducing medium. Titanium is not corroded in some corrosive media, such as seawater, wet chlorine, chlorite and hypochlorite solutions, nitric acid, chromic acid, metal chlorides, sulfides and organic acids. However, in the medium that reacts with titanium to produce hydrogen (such as hydrochloric acid and sulfuric acid), titanium usually has a high corrosion rate. However, if a small amount of oxidizing agent is added to the acid, the titanium will form a passivation film. Therefore, in the mixture of sulfuric acid - nitric acid or hydrochloric acid - nitric acid, and even in hydrochloric acid containing free chlorine, titanium is corrosion resistant. Titanium's protective oxide film is often formed when the metal hits water, even in small amounts or in the presence of water vapor. If titanium is exposed to a strong oxidizing environment in the complete absence of water, rapid oxidation can occur and produce a violent, often spontaneous combustion reaction. Such behavior occurs when titanium reacts with fuming nitric acid containing excess nitrogen oxide and when titanium reacts with dry chlorine. However, to prevent the occurrence of such reactions, a certain amount of water must be available.