In the Vickers hardness test, the hardness value of TA9 titanium alloy is usually between 200 and 260HV. TA9 titanium alloy, without heat treatment, has a Vickers hardness of about 230HV. However, after annealing at about 500 ° C, its hardness will decrease slightly, to about 220HV. This is mainly because the annealing process helps to remove the internal stress of the material, which increases the toughness of the material but correspondingly reduces the hardness. The heat treatment process has significant influence on the hardness of TA9 titanium alloy. After quenching, the hardness of TA9 titanium alloy can reach a higher level of 260HV, but this is also accompanied by a decline in the toughness of the material. Therefore, in practical applications, in order to balance hardness and toughness, a comprehensive heat treatment process is usually chosen. For example, the TA9 titanium alloy is held at 850 ° C for 2 hours after air cooling, which can stabilize its hardness at about 240HV, while maintaining good plasticity and strength.
In addition to the heat treatment process, cold processing is also an effective way to improve the hardness of TA9 titanium alloy. The hardness of TA9 titanium alloy can be significantly improved by cold processing such as cold rolling and cold drawing. Generally speaking, the hardness of TA9 titanium alloy after cold processing can be increased by about 15%-20%, so that the Vickers hardness can reach more than 280HV. For example, after 50% cold rolling deformation treatment of TA9 titanium alloy, its hardness can rise to 285HV, but the plasticity will be reduced accordingly. Therefore, the cold-worked TA9 titanium alloy is more suitable for scenarios requiring high hardness and low plasticity, such as fasteners and orthopedic implants. In summary, the hardness characteristics of TA9 titanium alloy are affected by many factors, including microstructure, alloying element content, heat treatment process and cold working method. In practical applications, appropriate process parameters need to be selected according to specific needs to balance performance indicators such as hardness, toughness and plasticity.
