Introduction to pure titanium rods and titanium alloy rod materials
Titanium and titanium alloys have good welding, hot and cold pressure processing and mechanical processing properties, and can be processed into various titanium profiles, titanium rods, titanium plates and titanium pipes for supply.
Titanium is an ideal structural material. The density of titanium is not high, only 4.5g/m3, which is 43% lighter than steel. However, titanium is twice as strong as iron and nearly 5 times stronger than pure aluminum. It has low density and high strength properties. This combination of high strength and low density makes titanium rods occupy a very important position in technology. At the same time, the corrosion resistance of titanium alloy rods is close to or exceeds that of stainless steel, so it is widely used in petroleum, chemicals, pesticides, dyes, papermaking, light industry, aviation, aerospace development, ocean engineering, and ETC.
Titanium alloys have high specific strength (ratio of strength to density). Titanium alloy rods and pure titanium rods play an irreplaceable role in aviation, military industry, shipbuilding, chemical industry, metallurgy, machinery, medical and other fields. For example, after heat treatment, the alloy composed of titanium and aluminum, chromium, vanadium, molybdenum, manganese and other elements has a maximum strength of 1176.8-1471MPa and a specific strength of 27-33. The specific strength of alloy steel with the same strength is only 15.5 -19. Titanium alloys not only have high strength but are also corrosion-resistant, so they are widely used in shipbuilding, chemical machinery, medical equipment and other fields. Among them, corrosion-resistant titanium alloys are mainly used in reactors, towers, autoclaves, heat exchangers, pumps, valves, centrifuges, pipes, fittings, electrolyzers, etc. in various highly corrosive environments. However, the high price of titanium alloys limits its applications.
Applications of different types of titanium alloys
1. Titanium iodide , trade name TAD: It is high-purity titanium obtained by the iodination method, so it is called titanium iodide, or chemically pure titanium. However, it still contains interstitial impurity elements such as oxygen, nitrogen, and carbon, which have a great impact on the mechanical properties of pure titanium. As the purity of titanium increases, the strength and hardness of titanium decrease significantly; therefore, it is characterized by: good chemical stability, but low strength. Due to the low strength of high-purity titanium, its application as a structural material is of little significance, so it is rarely used in industry. Currently, industrial pure titanium rods and titanium alloy rods are widely used in industry.
2. Industrial pure titanium : Unlike chemically pure titanium, industrial pure titanium contains larger amounts of oxygen, nitrogen, carbon and a variety of other impurity elements (such as iron, silicon, etc.). It is low alloy content in nature. Titanium alloy. Compared with chemically pure titanium, its strength is greatly improved because it contains more impurity elements. Its mechanical and chemical properties are similar to stainless steel (but still less strong than titanium alloys). The characteristics of industrial pure titanium are: low strength, but good plasticity, easy to process, stamp, and weld, and has good machinability; it has good performance in atmosphere, seawater, wet chlorine, oxidizing, neutral, and weakly reducing media. performance. The corrosion resistance and oxidation resistance are better than most austenitic stainless steels; but the heat resistance is poor, and the use temperature should not be too high. Industrial pure titanium is divided into three grades: GR1, GR2, and GR3 based on impurity content. The interstitial impurity elements of these three types of industrial pure titanium gradually increase, so their mechanical strength and hardness also gradually increase, but the plasticity and toughness decrease accordingly. The commercially pure titanium commonly used in industry is GR2 because of its moderate corrosion resistance and comprehensive mechanical properties. GR3 can be used when wear resistance and strength requirements are high. GR1 can be selected when better forming performance is required.
Industrial pure titanium is mainly used for stamping parts and corrosion-resistant structural parts with working temperatures below 350°C and low stress but requiring good plasticity, such as aircraft frames, skins, engine accessories, etc.; seawater corrosion-resistant pipes, valves, and pumps for ships. and hydrofoils, desalination system components; chemical heat exchangers, pump bodies, distillation towers, coolers, agitators, tees, impellers, fasteners, ion pumps, compressor valves and diesel engine pistons, connecting rods, plates Huang etc.
3. α-type titanium alloy , brands GR4 titanium rod, BT5 titanium rod, GR6 titanium rod: This type of alloy is in an α-type single-phase state at room temperature and service temperature, and cannot be strengthened by heat treatment (annealing is the only form of heat treatment). Mainly relies on solid solution strengthening. Room temperature strength is generally lower than β-type and α-β-type titanium alloys (but higher than industrial pure titanium), but the strength and creep strength at high temperatures (500-600°C) are the highest among the three types of titanium alloys; Structure It has good stability, oxidation resistance and welding performance, as well as good corrosion resistance and cutting processability, but its plasticity is low (the thermoplasticity is still good) and its room temperature stamping performance is poor. Among them, GR6 is the most widely used. It has medium to high strength and sufficient plasticity in the annealed state. It has good weldability and can be used below 500℃. When the content of interstitial impurity elements (oxygen, hydrogen, nitrogen, etc.) is extremely low, it also has good toughness and comprehensive mechanical properties at ultra-low temperatures, making it one of the excellent ultra-low temperature alloys.
The tensile strength of GR4 is slightly higher than that of industrial pure titanium and can be used as a structural material in the medium strength range. Mainly used as welding wire in our country. TA5 and BT5 are used for parts and weldments working in corrosive media below 400°C, such as aircraft skins, frame parts, compressor casings, blades, ship parts, etc. GR6 is used for structural parts and various die forgings that work at 500°C for a long time, and can reach 900°C for short-term use. It can also be used for ultra-low temperature (-253℃) parts (such as ultra-low temperature containers).
4. β-type titanium alloy , brand TB2: The main alloying elements of this type of alloy are β-phase stabilizing elements such as molybdenum, chromium, and vanadium. During normalizing and quenching, it is easy to retain the high-temperature β phase to room temperature and obtain a more stable β phase structure, so it is called β-type titanium alloy. β-type titanium alloy can be strengthened through heat treatment, has high strength, and has good welding performance and pressure processing performance; however, its performance is not stable enough, the smelting process is complex, and its application is not as widespread as α-type and α-β-type titanium alloys. Parts that can be used below 350°C are mainly used to manufacture various plate stampings and welded parts with overall heat treatment (solid solution, aging); such as compressor blades, discs, shafts and other heavy-duty rotating parts, as well as aircraft parts, etc. . TB2 alloy is generally delivered in a solution-treated state and used after solution aging.
5. Commonly used grades of αβ titanium rods and titanium alloy titanium rods are BT3-1 titanium rods and Ti-662 titanium rods: This type of alloy exhibits an αβ two-phase structure at room temperature, hence the name αβ titanium alloy. It has good comprehensive mechanical properties, and most of them can be strengthened by heat treatment (but Ti-2AL-1.5Mn, Ti-4AL-1.5Mn, and TC7 cannot be strengthened by heat treatment). It has good forging, stamping and welding properties, can be machined, has high strength at room temperature, and has high strength below 150-500℃. Heat resistance, some (such as Ti-2AL-1.5Mn, Ti-4AL-1.5Mn, Ti-5AL-4V, GR5) also have good low-temperature toughness and good resistance to seawater stress corrosion and hot salt stress corrosion; the disadvantage is that the structure is not stable enough.
GR5 is the most widely used alloy of this type , and consumption of GR5 titanium rods accounts for approximately half of existing titanium alloy production. The alloy not only has good room temperature, high temperature and low temperature mechanical properties, but also has excellent corrosion resistance in a variety of media. It can also be welded, hot formed, cold formed, and heat treated to strengthen; therefore, it is widely used in aerospace, shipbuilding, chemical industry and other industrial sectors. Ti-2AL-1.5Mn and Ti-4AL-1.5Mn can be used for stamping parts, welded parts, die forgings and bent parts working under 400℃. Both alloys are also used as low-temperature structural materials. Ti-5AL-4V and GR5 can be used as long-term working parts below 400℃, structural modules, various containers, pumps, cryogenic components, ship pressure-resistant shells, tank tracks, etc., with higher strength than Ti-2AL-1.5Mn and Ti-4AL-1.5Mn. BT3-1 can be used below 400℃ and is mainly used as aero-engine structural material. TC9 can be used to manufacture parts that operate below 560°C for a long time, and is mainly used for compressor disks and blades of aircraft jet engines.
Ti-662 can be used to manufacture parts that operate below 450°C for a long time, such as aircraft structural parts, landing gear, honeycomb connection parts, missile engine casings, weapon structural parts, etc.
