The density of titanium is 4.5g/cm3, which is 57% of steel; titanium is less than twice heavier than aluminum and three times stronger than aluminum. Specific strength is the ratio of strength to density. When compared with different materials, the specific strength of titanium alloys is almost the largest among commonly used industrial alloys. 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 indispensable structural material for the aerospace industry. Comparison of the density and specific strength of titanium with other metals. Titanium has a high melting point, poor thermal conductivity and electrical conductivity, and is similar to or slightly lower than stainless steel. Titanium has superconductivity. The critical temperature of pure titanium is 0.38.4K. Metal titanium is a non-magnetic substance.
Titanium alloy is a single-phase alloy composed of phase solid solution and has a low density. Whether it is at a general temperature or at a higher practical application temperature, it is a phase, the structure is stable, the wear resistance is higher than that of pure titanium, and the oxidation resistance is strong. . At a temperature of 500-600 degrees, it still maintains its strength and creep resistance, can be strengthened by heat treatment, has good thermal strength and thermal stability, good welding performance, good room temperature, ultra-low temperature and high temperature performance.
Commercial pure titanium is a dense metal titanium with a titanium content of not less than 99% and containing a small amount of impurities such as iron, carbon, oxygen, nitrogen and hydrogen. The impurities with the strongest influence on the mechanical properties of pure titanium are oxygen, nitrogen and iron, especially oxygen. The reaction of hydrogen with titanium is reversible. The effect of hydrogen on the performance of titanium is mainly manifested as "hydrogen embrittlement". Usually, the hydrogen content should not exceed 0.015%, and generally contain 0.15%-0.3% oxygen and 0.03%-0.05% nitrogen. Although industrial pure titanium is a close-packed hexagonal lattice at room temperature, its axis is relatively small (c/a=1.587), and it has better workability. Pure titanium has good formability and welding performance, and is not sensitive to heat treatment.
Among titanium metals, including titanium plates, titanium rods, titanium tubes, etc., include pure titanium and titanium alloys. The obvious difference between pure titanium and titanium alloy is that titanium alloy is based on pure titanium with chemicals such as Al, Mo, Cr, Sn, etc. It is precisely because of these chemicals that these two titanium metals are The difference in performance. The following focuses on the analysis and introduction of the classification, performance and use of pure titanium.
1. Classification of pure titanium:
According to the content of impurities, titanium is divided into high-purity titanium (purity of 99.9%) and industrial pure titanium (purity of 99.5%). There are three grades of industrial pure titanium, which are denoted by TA + sequence number 1, 2, 3, the larger the number, the lower the purity.
2. Performance of pure titanium:
Ti: 4.507 g/cm3, Tm: 1688°C. With allotropic transformation, ≤882.5℃ is the α phase of the close-packed hexagonal structure, ≥882.5℃ β phase of the body-centered cubic structure.
Pure titanium has low strength, but high specific strength, good plasticity, low temperature toughness, and high corrosion resistance. Titanium has good pressure processing performance and poor cutting performance. Titanium can be burned when heated in nitrogen, so titanium should be protected by argon during heating and welding.
3. The use of pure titanium:
Impurity content has a great influence on the performance of titanium. A small amount of impurities can significantly increase the strength of titanium. Therefore, industrial pure titanium has high strength and is close to the level of high-strength aluminum alloy. It is mainly used to manufacture heat exchange for petrochemicals working below 350℃ Reactor, reactor, ship parts, etc.
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