Ti6242 titanium alloy has a nominal composition of Ti-6Al-2Sn-4Zr-2Mo-0.1Si. As a near-α high-temperature titanium alloy with excellent creep resistance, it can operate continuously at temperatures ranging from 470℃ to 550℃. It is mainly used for high-pressure compressor disks and blades in aero-engines.
Ti6242 titanium alloy ingots are heated to 150℃–200℃ above their phase transformation point and held for 240–480 minutes. During forging, the forging ratio is controlled between 1.2 and 1.6 to produce a billet with an initially fragmented as-cast structure. The 3–5 ton ingots are produced via a vacuum arc furnace, with chemical composition limits as follows (mass percentage): Al 5.50%–6.50%, Sn 1.80%–2.20%, Zr 3.60%–4.40%, Mo 1.80%–2.20%, Si 0.06%–0.1%, Fe ≤ 0.10%, O ≤ 0.15%, C ≤ 0.05%, N ≤ 0.05%, balance titanium and unavoidable impurities.
The billet with a preliminarily broken as-cast structure is then processed through 7-fire forging. It is heated to a range from 40℃ below the phase transformation point to 100℃ above it, held for 120–420 minutes, with an upsetting ratio of 1.3–1.7 and a drawing deformation of 25%–45%. The final forging temperature is kept above 850℃, achieving a billet with fully broken and uniformly refined grains.
Subsequently, the refined billet undergoes 2–3 fire forging steps. It is heated to 60℃–40℃ below the phase transformation point, held for 60–180 minutes, with deformation controlled above 40% and the final forging temperature above 800℃, yielding black-skinned bars.
The black-skinned bars are then annealed and peeled. The annealing regime consists of 970℃–990℃ for 1 hour, air cooling, plus 595℃ for 8 hours, followed by air cooling, producing finished Ti6242 titanium alloy bars with diameters from Φ20 mm to Φ100 mm. This invention provides a manufacturing method for small-diameter Ti6242 bars for aero-engine blades with highly uniform microstructure. Multi-stage forging and drawing effectively eliminate microstructural inhomogeneity and anisotropy between the edge and core regions. Compared with products from other domestic manufacturers, the Ti6242 bars produced by this process show no obvious metallurgical defects in macrostructure, presenting uniform microstructures and a blurred crystalline appearance.
In China, with the rapid development of advanced aircraft, particularly large commercial jets, the demand for higher aero-engine thrust-to-weight ratios is continuously growing. This raises stricter requirements for small-diameter Ti6242 titanium alloy blades in terms of metallurgical quality, microstructural homogeneity, mechanical properties, and batch stability. Achieving high microstructural uniformity and stability is essential to meet these demanding standards.
