The preparation method of Ti-6Al-4V titanium alloy fine-grained rod materials involves selecting a uniformly composed Ti-6Al-4V titanium alloy ingot, heating and holding it above the β transformation temperature, and performing one-time upsetting and drawing forging; then heating and holding it below the β transformation temperature for multiple times of straight drawing forging; heating and holding it below the β transformation temperature for one or two times of rolling to form a rod blank; and finally, performing heat treatment, straightening and polishing on the obtained rod blank to obtain Ti6Al4V titanium alloy fine-grained rod materials. This invention realizes the control of the microstructure of the rod materials through the combination of forging and rolling, combined with a lower deformation temperature and single-fire large deformation. By using this invention's method to prepare Ti6Al4V titanium alloy fine-grained rod materials, the process is shorter than the traditional process (repeated upsetting), the cost is lower, and the transverse microstructure grains can be stably obtained, which are fine and uniform, meeting the ETTC2 rating chart A1-A3 levels, and all performance meets the relevant standard requirements.
Ti-6Al-4V is a typical two-phase titanium alloy, featuring low density, appropriate strength, high fatigue strength, and excellent corrosion resistance. It is widely used in the fields of aviation, aerospace, and biomedical applications. The Ti6Al4V titanium alloy was successfully developed in 1954 and has now become a universally used titanium alloy worldwide, accounting for 50% of the total titanium alloy production and 90% of all titanium alloy processed parts. Currently, it is the most widely used titanium alloy. The traditional processing methods for Ti6Al4V titanium alloy rods and wires are relatively conservative. Generally, they achieve the fragmentation and refinement of the cast structure through repeated upsetting and forging. The microstructure of the rods and wires is required to meet the A1-A9 grade of the ETTC2 standard chart, which is rather rough.
In recent years, with the deepening of product application research, the requirements for the raw materials of parts have become increasingly higher. It is generally believed that when the Ti-6Al-4V titanium alloy has fine and uniform, dispersed α+β phases, the comprehensive properties of the rod at room temperature are excellent, with high fatigue strength and good damage tolerance. The traditional process of Ti6Al4V titanium alloy has a high popularity rate, but it is difficult to produce rod products with fine and uniform transverse and longitudinal structures using conventional preparation methods, especially when it comes to batch production, the stability control becomes even more challenging.
The preparation method of Ti6Al4V titanium alloy fine-grained rod materials involves the combination of heavy hydraulic press forging and rolling, along with a lower deformation temperature and single-fire large deformation, to achieve the control of the material's microstructure. By using the method of this invention to prepare Ti6Al4V titanium alloy fine-grained rod materials, the process is shorter than the traditional process (repeated upsetting), and the cost is lower. The transverse microstructure grains are fine and uniform, meeting the ETTC2 rating chart levels A1-A3, and all performance parameters meet the requirements of relevant standards.
The preparation method of Ti-6Al-4V titanium alloy fine-grained rod materials, which is used to produce Ti6Al4V (containing ELI) titanium alloy fine-grained rod materials with a diameter of ≤ Φ37mm, specifically includes the following steps: Select a uniformly composed Ti6Al4V titanium alloy ingot, place it in a box-type resistance furnace, heat it at a temperature above the β transformation temperature by 170℃ to 200℃, with the shortest holding time being (where is the radius of the heated ingot in mm)， and perform one-time upsetting and drawing forging， with a forging ratio of 1.8 to 2.4 and a cumulative deformation amount of 63% to 70%. In the box-type resistance furnace， for the rod billet obtained in step 1， heat it below the β transformation temperature by 50℃ to 70℃， with the shortest holding time being the longest holding time， and perform multiple fire times of straight pulling forging， with a single fire deformation amount of 40% to 65%， and a cumulative deformation amount of ≥ 93%. The forged billet is heated in the box-type resistance furnace below the β transformation temperature at 80℃ to 100℃， perform one or two fire times of rolling， with a single fire deformation amount ≥ 58%， and a cumulative deformation amount ≥ 80%. After the processed rod billet is heated at 700℃ to 750℃ for 1h to 2h and then air-cooled for heat treatment， it is straightened and polished to obtain Ti6Al4V titanium alloy fine-grained rod materials.
Through the combination of forging and rolling by heavy hydraulic presses, along with a lower deformation temperature and a large deformation per firing cycle, the microstructure of the bar material can be controlled. The traditional Ti6Al4V titanium alloy ingot relies on repeated upsetting and fragmentation of the microstructure above the β transformation temperature, combined with subsequent hot processing at a temperature 30°C to 40°C below the β transformation temperature, to achieve the processing of the bar material, and the resulting product microstructure can only meet the ETTC2 rating chart levels A1 to A7. By using the method of this invention to prepare Ti-6Al-4V titanium alloy fine-grained bars, the process is shorter than the traditional process (repeated upsetting), the efficiency is higher, and the cost is lower. The transverse microstructure has fine and uniform grains, meeting the ETTC2 rating chart levels A1 to A3, and all performance meets the requirements of relevant standards.
