Research And Development Of TC4 Titanium Alloy Rod Forging Equipment
Aug 13, 2025
It is generally believed that high hydrogen content or poor microstructure uniformity in TC4 titanium alloy rods will reduce their room temperature notch stress rupture performance. Domestic technical standards set the upper limit for the size of this type of TC4 titanium alloy rod to be >220mm. Currently, there are no published reports domestically or internationally on research into the preparation process for TC4 titanium alloy rods requiring notch stress rupture performance. In industrial mass production, it is common for such rods to fail to meet standards for notch stress rupture performance due to improper processing.
TC4 (Ti-6Al-4V) titanium alloy was successfully developed in 1954 and has become a universally used titanium alloy worldwide. It is a typical two-phase titanium alloy, and its small-sized rods are widely used in aviation, aerospace, power plants, oil fields, medical treatment, and automotive applications. Rolling is one of the primary methods for producing small-sized titanium alloy rods. Continuous high-speed wire rod production is widely used in steel production, suitable for large-volume, low-variety production. Titanium alloy bar products are characterized by demand for small batches and a wide variety of products. The production cost of continuous high-speed wire rod production is high. Currently, titanium alloy bar production primarily utilizes three-roll horizontal mills, making research on the rolling deformation process in horizontal mills essential. Rolling deformation, as a key factor in rolling deformation, significantly impacts the final product properties of rolled bars, making its study of rolling deformation of significant significance.
The macrostructures of as-forged TC4 titanium alloy bars (less than 50 mm) produced using two different processes are shown. The TC4 titanium bar produced using process 1 exhibits poor macrostructure uniformity, exhibiting a gradual transition from fuzzy crystals at the edges to semi-clear crystals in the center. The bar produced using process 2 exhibits excellent macrostructure uniformity, with fuzzy crystals throughout the entire sample. This shows that when process 1 is used for forging, the core structure of the ingot and intermediate billet is not sufficiently crushed and refined, which is directly related to the small total deformation. Due to the large deformation resistance of titanium alloy and the large volume of large-sized titanium bar billets, it is difficult to ensure sufficient deformation of the billet core by single straight drawing deformation. However, process 2 makes full use of the large tonnage forging pressure of the 4500t fast forging machine to make the large-sized billet undergo upsetting deformation in the two-phase zone, ensuring the forgeability of the billet, and using the anvil drawing length to reduce the billet deformation "dead zone", so that different parts of the billet are fully deformed, and a good crushing and refinement and good consistency of the structure is obtained. (1) By using the forging process of p-phase zone opening and two-phase zone upsetting + straight drawing, a large-sized TC4 titanium alloy bar with a diameter of 350mm can be produced, which meets the supply technical requirements in terms of structure, performance and flaw detection level. (2) The well-equiaxed structure of the primary a-phase is conducive to improving the room temperature notch stress fracture performance, while the short rod-shaped a-phase structure with strong directional consistency will reduce the notch stress fracture performance.
75 mm long bars were cut longitudinally from 50 mm TC4 titanium alloy bars obtained by two forging processes and subjected to ordinary annealing treatment at two temperatures. The annealing conditions were M1 (720° x2h/AC) and M2 (790° x2h/AC), respectively. The low-magnification structure of the forged bars was observed with the naked eye; metallographic specimens were cut transversely at 1/2 radius on the bar liner after forging and annealing, and their microstructures were observed using a 0LMPUS optical microscope. The specimen blanks were cut longitudinally at 1/2 radius of the annealed bars and machined into test specimens that met the room temperature tensile and notch stress fracture performance standards. The specimens were subjected to mechanical property tests using an InStron 4507 tensile testing machine and a DN2 notch tensile testing machine, and the microstructure of the notch area of the notch stress fracture specimens was observed. The TC4 titanium alloy finished bars forged by the two forging processes were subjected to ultrasonic nondestructive testing using a SONIC-138VFD ultrasonic flaw detector.
The company boasts leading domestic titanium processing production lines, including:
German-imported precision titanium tube production line (annual production capacity: 30,000 tons);
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Fully automated titanium rod continuous extrusion line;
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The MES system enables digital control and management of the entire production process, achieving product dimensional accuracy of ±0.01μm.
