Industrial pure titanium is divided into four grades according to the number of impurity elements it contains, namely TA1, TA2, TA3, and TA4. They basically correspond to grades 1 to 4 of titanium in the United States, namely Gr.1, Gr.2, Gr.3, and Gr.4 titanium plate.
As the purity decreases, the strength and hardness of industrial pure titanium increase, while the plasticity, impact toughness, and fatigue resistance decrease. When high requirements on strength, hardness and wear resistance are required, TA3 and TA4 can be selected. When better formability is required, TA1 and TA2 can be used.
TA4 titanium alloy is an α-type titanium alloy. 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). It mainly relies on solid solution strengthening.
The room temperature strength of TA4 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 temperature (500-600℃) are the highest among the three types of titanium alloys. And the structure is stable, the oxidation resistance and welding performance are good, the corrosion resistance and machinability are also good, but the plasticity is low (the thermoplastic is still good), and the room temperature stamping performance is poor. Among them, the most widely used is TA7, which has moderate strength and sufficient plasticity in the annealed state, good weldability, and can be used below 500 ° C; when its interstitial impurity elements (oxygen, hydrogen, nitrogen, etc.) content are 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 in the medium strength range. It is mainly used as welding wire in China, and it is widely used in the high-end electroplating hanger industry abroad.