Introduction to several common applications of titanium alloy materials such as titanium rods and titanium anodes

- Feb 23, 2019-

Introduction to several common applications of titanium alloy materials such as titanium rods and titanium anodes

Common applications of titanium and titanium alloys:

(1) Titanium iodide, grade TAD

It is a high-purity titanium obtained by the iodination method, so it is called iodine titanium, or chemically pure titanium. However, it still contains interstitial impurity elements such as oxygen, nitrogen and carbon, which have a great influence 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.

Since high-purity titanium has low strength, it has little significance as a structural material and is rarely used in the industry. Industrially pure titanium and titanium alloys are currently widely used in the industry.

(2) Industrial pure titanium

The difference from chemically pure titanium is that industrial pure titanium contains a large amount of oxygen, nitrogen, carbon and various other impurity elements (such as iron, silicon, etc.), which is essentially a low alloy content titanium alloy. Compared with chemically pure titanium, its strength is greatly improved due to the presence of more impurity elements. Its mechanical properties and chemical properties are similar to those of stainless steel (but the strength is still lower than that of titanium alloy).

Industrial pure titanium is characterized by low strength, good plasticity, easy processing, stamping, welding, and good machinability; good in atmospheric, seawater, wet chlorine, and oxidizing, neutral, and weak reducing media. Corrosion resistance and oxidation resistance are better than most austenitic stainless steels; however, the heat resistance is poor and the use temperature should not be too high.

Industrial pure titanium is divided into three grades of TA1, TA2 and TA3 according to its impurity content. The interstitial impurity elements of these three industrial pure titanium are gradually increased, so the mechanical strength and hardness are also gradually increased, but the plasticity and toughness are correspondingly decreased.

The industrial pure titanium commonly used in the industry is TA2 because of its moderate corrosion resistance and comprehensive mechanical properties. TA3 is available for higher wear and strength requirements. TA1 can be used for better forming properties.

Industrial pure titanium is mainly used for working temperature below 350 °C, but the force is not large, but it requires plastic parts and corrosion-resistant structural parts, such as: aircraft skeleton, skin, engine accessories; marine seawater corrosion resistant pipeline, Valves, pumps and hydrofoil, desalination system components; chemical heat exchangers, pump bodies, distillation columns, coolers, mixers, tees, impellers, fasteners, ion pumps, compressor valves and diesel Engine pistons, connecting rods, leaf springs, etc.

(3) α-type titanium alloy, grades TA4, TA5, TA6, TA7.

These alloys have an alpha-type single-phase state at room temperature and service temperature, and cannot be heat-treated (annealing is the only heat treatment form), mainly relying on solid solution strengthening. The room temperature strength is generally lower than that of β-type and α+β-type titanium alloys (but higher than industrial pure titanium), while the strength and creep strength at high temperatures (500-600 ° C) are the highest among the three types of titanium alloys; The structure is stable, the oxidation resistance and the welding performance are good, the corrosion resistance and the machinability are also good, but the plasticity is low (the thermoplastic is still good), and the room temperature punching performance is poor. Among them, TA7 is the most widely used, which has medium-high strength and sufficient plasticity in the annealed state, and has good weldability and can be used below 500 ° C; when the content of interstitial impurities (oxygen, hydrogen, nitrogen, etc.) is extremely low, It also has good toughness and comprehensive mechanical properties at ultra-low temperature and is one of the excellent ultra-low temperature alloys.

The tensile strength of TA4 is slightly higher than that of industrial pure titanium, and it can be used as a structural material of medium strength range. It is mainly used as a welding wire in China.

TA5 and TA6 are used for parts and weldments working in corrosive media below 400 °C, such as aircraft skins, skeleton parts, compressor casings, blades, ship parts, etc.

TA7 is used for structural parts and various die-casting parts for long-term operation below 500 °C, and can be used up to 900 °C for short-term use. It can also be used for ultra-low temperature (-253 ° C) parts (such as containers for ultra-low temperature).

(4) β-type titanium alloy, grade TB2.

The main alloying elements of these alloys are β phase stabilizing elements such as molybdenum, chromium and vanadium. It is easy to keep the high temperature β phase to room temperature during normalizing and quenching, and obtain a relatively stable β phase structure, so it is called β type titanium alloy. .

The β-type titanium alloy can be heat-treated and strengthened, has high strength, good welding performance and pressure processing performance; but the performance is not stable enough, and the melting process is complicated, so the application is not as extensive as the α-type and α+β-type titanium alloys.

It can be used for parts below 350 °C, mainly used for manufacturing all kinds of integral heat treatment (solution and age) sheet metal stampings and welded parts; such as compressor blades, discs, shafts and other heavy-duty rotating parts and aircraft components Wait. TB2 alloys are generally delivered under solution treatment and used after solution and aging.

(5) α+β type titanium rod and titanium alloy Commonly used grades TC6, TC9, TC10

Such alloys exhibit an α+β type two-phase structure at room temperature, hence the name α+β type titanium alloy. It has good comprehensive mechanical properties, most of which can be heat-treated and strengthened (but TC1, TC2, TC7 can not be heat-treated and strengthened), forging, stamping and welding performance are good, machinable processing, high room temperature strength, high below 150-500 °C The heat resistance, some (such as TC1, TC2, TC3, TC4) also has good low temperature toughness and good resistance to seawater stress corrosion and resistance to hot salt stress corrosion; the disadvantage is that the organization is not stable enough.

These alloys are the most widely used TC4, accounting for about half of the 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, and can be welded, cold and hot formed, and can be strengthened by heat treatment; thus in aerospace, ship and chemical industries, etc. The industrial sector is widely used.

TC1 and TC2 can be used for stampings, weldments and die forgings and bending parts under 400 °C. These two alloys can also be used as low temperature structural materials.

TC3 and TC4 can be used as parts for long-term operation below 400 °C, modules for structural use, various containers, pumps, cryogenic components, ship pressure-resistant housings, tank tracks, etc. The intensity is higher than TC1 and TC2.

TC6 can be used below 400 ° C, mainly used as aircraft engine structural materials. The TC9 can be used to make parts that operate for long periods of time below 560 ° C, mainly used on compressor discs and blades of aircraft jet engines.

The TC10 can be used to manufacture parts that operate for long periods of time below 450 °C, such as aircraft structural parts, landing gear, cellular connecting components, missile engine casings, weapon structural components, and the like.