Titanium powder and titanium alloy are mostly used in making high precision components

image_pdfimage_print

Titanium has many advantages when it is used in the automobile industry, for example, it can greatly reduce weight, reduce fuel consumption, improve work efficiency and environment as well as reduce noise. However, it is the key to find the solution of reducing titanium and titanium alloy cost to the acceptable level. According to the research, the cost of titanium product rolling is 4.4USD/kg by using traditional production technology. According to general experience, every job step will double the cost, therefore, the material cost will reach 17.6USD/kg at least. When the rolled products are made into the final machining parts, its cost will reach up to 44USD/kg. It is obviously that it is impossible to replace commonly used corresponding steel parts with these kinds of titanium. However, by using titanium powder metallurgy, the situation will be greatly changed. If currently the price of available sponge titanium powder or the scrap is 4.4-8.8USD/kg, the cost of net shape or near net shape pressing billet will be lower than 4.4USD/kg; after minimum quantity of machining, the cost of connecting rod and other parts will be 8.8-11USD/kg. Powder metallurgy can not only use low cost of raw materials, but also can reduce the machining cost. Especially that net shape or near net shape can be regarded as an effective way in producing automobile parts that have large size and low cost. It can be seen that powder metallurgy titanium will have strong competitive power in the future.

titanium powder metallurgy componentsTitanium, which has high strength mass ratio as well as high strength, corrosion resistance and heat stability under high temperature, has caused many attentions. However, the traditional usage of titanium and titanium alloy are mainly concentrated on aerospace and navigation industry. The main restriction factor of civil titanium is its high production cost. Titanium powder metallurgy is a kind of titanium part production method that is entirely different from other technologies, which uses titanium powder instead of titanium sponge; powder metallurgy can limit the waste that is related to traditional titanium production, which needs no vacuum arc remelting, electron beam melting or plasma arc melting; powder can be directly made into any shape or mill products, thus it can reduce the raw material that used in making one part and will have very high output. This technology can also be used in making near net shape parts, which can reduce the accompanying waste in the traditional parts production, lessen the processing step and improve the output.

However, there is also some problem that needs to be improved in powder metallurgy. Among them, pollution control problem is the leading problem as metal cannot be applied to the high precision components under the effect of any pollution. Powder metallurgy titanium alloy will face numerous difficulties if they are used in the aviation market due to high construction standard of aviation field, but it can be completely applied in the civilian field that requires low construction standard. Among them, it is most likely to be widely applied in automobile industry. As automobile market is very large, once titanium is expanded in automobile industry, the demand for titanium will far exceed the aviation and aerospace market.

The application prospect of civil titanium

Currently, powder metallurgy titanium alloy has been used in new type high-performing automobiles, which is mainly used in the engine system and underpan. For example, in the engine system, titanium alloy can replace alloy steel and stainless steel and be made into valve, valve spring and other parts; in the underpan, it is mainly used as spring, exhaust system, half axle and various fasteners. Toyota Motor Corporation has developed a kind of powder forged method that can reduce the cost. By producing titanium engine valve with this method, the weight can be reduced 40 percents. The inlet valve is produced by using Ti-6Al-4V alloy as raw materials via powder forged method. Exhaust valve is made by composites that use a kind of new alloy powder processed by using boride as the enhancer, among which the volume fraction of TiB reinforced powder is about 5 percents and the matrix composition is Ti-6Al-4Sn-4Zn-1Mo-0.2Si-0.3O. This kind of composites will have excellent creep resistance.