Cold working characteristics of titanium alloy rods and wires and their effects

I. Cold working characteristics of titanium alloy bars and wires
In the production process of titanium and titanium alloy semi-finished products (plate, bar, tube), titanium alloy bars and wires are often processed by rolling and then drawing. Titanium alloys exhibit high strength and low plasticity at room temperature, so most of the processing is carried out by heating. However, cold deformation at 40-50°C below the phase transition point is sometimes necessary to obtain a uniform fine grain organization.
Cold deformation, hot deformation and warm deformation are the three main ways of processing titanium alloy bars and wires. Cold deformation is carried out below the recovery temperature, when the metal is mainly work hardening, plasticity decreases, deformation resistance increases. Hot deformation is carried out at high temperatures, although the deformation resistance can be reduced, but the metal oxidation is serious, affecting the surface quality and mechanical strength of products. Warm deformation is between the two, usually at 0.4-0.6 melting point temperature, can reduce the deformation resistance of the metal, while maintaining a certain degree of plasticity.
Second, the impact of cold working on titanium alloy rods and wires
Improvement of mechanical properties: cold drawing process, titanium alloy grain deformation, lattice distortion and grain fragmentation, resulting in the material processing hardening, strength increased significantly. This provides a way to improve strength for materials that cannot be strengthened by heat treatment.
High dimensional accuracy: cold-drawn material is drawn under cold deformation conditions, compared with hot processing materials, has a higher dimensional accuracy and smaller absolute value of dimensional tolerances, reducing the allowance for subsequent machining.
Good surface finish: the surface finish of the material processed under cold working condition is better, which is difficult to achieve the effect of hot working.

Microstructure changes: in the process of cold drawing, the internal grains of titanium alloy elongation, lattice distortion and grain fragmentation, the formation of obvious fiber organization, so that the material shows anisotropy.
Deformation structure: When the cold drawing deformation is large, the orientation of the internal grains of the material will tend to be more or less the same, forming a "deformation structure", this organization has the characteristics of preferential orientation.
Work hardening and performance changes: Cold work hardening increases the strength of titanium alloy, but reduces the plasticity. At the same time, the physical and physicochemical properties of the material after cold drawing, such as electrical conductivity, thermal conductivity, magnetism, etc. will also change.
Third, the application of cold working in the production of titanium alloy rods and wires
Although cold working increases the energy consumption during deformation and the number of intermediate annealing, it is still an important means of titanium alloy rods and wires production because it can obtain a smooth surface, fine size and regular shape products to meet the different needs of the industry on the material. Especially in the production of fine wire, cold working is an indispensable technology.
In summary, the cold working characteristics of titanium alloy rods and wires and its impact is multifaceted, and need to be considered in the actual production of a variety of factors in order to develop a reasonable processing technology and parameters.