Main characteristics and applications of titanium materials
This is high-purity titanium obtained by iodide method,so it is called iodine titanium,or chemically pure titanium.However,there is still oxygen in it Nitrogen Carbon These interstitial impurity elements have a great influence on the mechanical properties of pure titanium.With the improvement of titanium purity,the strength and hardness of titanium decreased significantly.It is characterized by good chemical stability,but low strength.
Industrial pure titanium:
The difference between industrial pure titanium and chemical pure titanium is that it contains more oxygen Nitrogen Carbon and many other elements(such as iron,silicon,etc.)are essentially a titanium alloy with low alloy content.Compared with chemically pure titanium,its strength is greatly improved due to more magazine elements,and its mechanical properties and chemical properties are similar to those of stainless steel(but its strength is still low compared with titanium alloy).
The characteristics of industrial pure titanium are:low strength,good plasticity,easy to process into lines,good stamping,welding and cutting performance;It has good corrosion resistance in atmosphere,seawater,wet chlorine and oxidizing,neutral and weak reducing media.Its oxidation resistance is better than most austenitic stainless steels,but its heat resistance is poor and the service temperature is not too high.
Industrial pure titanium is divided into TA1 and TA1 according to its impurity content TA2 and TA3.The interstitial impurity elements of these three kinds of industrial pure titanium increase gradually,so their mechanical strength and hardness also increase step by step,but their plasticity Toughness decreases accordingly.
TA2 is commonly used in industry because of its moderate corrosion resistance and comprehensive mechanical properties.TA3 can be used when the requirements for corrosion resistance and strength are high.TA1 can be used when better molding performance is required.
αType titanium alloy:
This kind of alloy can be used at room temperature and service temperatureαIt is in single-phase state and cannot be strengthened by heat treatment(chase out is the only treatment method),which mainly depends on solid solution strengthening.The strength at room temperature is generally lower thanβType andα+βType titanium alloy(but higher than industrial pure titanium),but the strength and transformation at high temperature(500℃-600℃)are the highest among the three types of titanium alloys,with stable structure,good oxidation resistance and welding performance,good corrosion resistance and machinability,but low plasticity(thermoplastic is still good)and poor stamping performance at room temperature.Among them,TA7 is the most widely used.It has medium strength and sufficient plasticity in the annealed state,and has good welding performance.It can be used below 500℃.When the content of interstitial impurity elements(oxygen,hydrogen,nitrogen,etc.)is very low,it also has good toughness and comprehensive mechanical properties at ultra-low temperature.It is one of the excellent ultra-low temperature alloys.
βType titanium alloy:
The main alloying elements of this kind of alloy are molybdenum,chromium,vanadium and so onβStabilizing elements It is easy to reduce the high temperature during normalizing or secondary fireβThe phase was retained to room temperature to obtain metastableβMonophasic organization,so it is calledβType titanium alloy.
βType titanium alloy can be strengthened by heat treatment,has high strength,good weldability and pressure workability;However,the performance is not stable enough and the smelting process is complex,so the application is not as good as thatαTypeα+βType titanium alloys are widely used.
α+βType titanium alloy:
This kind of alloy is at high temperatureα+βType two-phase structure,so it is calledα+βType titanium alloy.It has good comprehensive mechanical properties,most of which can be strengthened by heat treatment(but Tc1,TC2 and TC7 cannot be strengthened by heat treatment),good forging,stamping and welding properties,machinable and high strength at room temperature.It has good heat resistance below 150-500℃,and some(such as Tc1,TC2,TC3 and TC4)have good low-temperature toughness and good resistance to seawater stress corrosion and hot salt stress corrosion.The disadvantage is that it is not stable enough.
TC4 is the most widely used alloy,accounting for about half of the existing titanium alloy production.The alloy not only has good mechanical properties at room temperature,high temperature and low temperature,but also has excellent corrosion resistance in a variety of media.At the same time,it can be welded,cold and hot formed and strengthened by heat treatment;Therefore,it is widely used in aerospace,shipbuilding,weapons,chemical industry and other industrial sectors.