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Rolling process of TA18(Gr 9) aviation titanium alloy pipe
2024-10-09

by cold rolling technology is not mature in China. It is difficult to guarantee the high strength and plasticity of the finished pipe. Therefore, the domestic demand for high strength and high toughness TA18(Gr 9) alloy tube has been dependent on imports. By trial-producing TA18 tubes of different specifications, the effects of ratio Q of inner diameter reduction rate and wall thickness reduction rate, cumulative deformation rate and annealing temperature on microstructure and properties of finished tubes were studied, so as to optimize the alloy processing technology and provide technical guidance and reference for the domestication of high strength and high toughness TA18(Gr 9) alloy tubes. Experiment material selection level of titanium sponge, Al - V intermediate alloy and Al bean, Al foil, after a lot of the vacuum arc furnace smelting, power consumption made Φ TA18 alloy ingot casting of 430 mm. Ingot casting breakdown by beta, alpha + beta two-phase area forging into Φ 130 mm bar, and then in 2500 t horizontal extrusion machine to squeeze into Φ 45 mm x 8 mm alloy tube billet. Through two LG LD and three roller mill roll in multichannel time on cold rolling and surface treatment, then after annealed in vacuum annealing furnace, preparation into Φ 25 mm x 1.8 mm, Φ 22 mm x 1.6 mm, Φ 20 mm x 1.5 mm, 18 mm x 1.3 mm Φ, Φ 16 mm x 1.2 mm, 14 mm x 1 mm Φ, Φ 12 mm x 0.9 mm, Φ 10 mm x 0.7 mm, 8 mm x 0.6 mm and 6 mm x 0.5 ㎜ Φ 10 kinds of specifications of the finished pipe.

The tensile properties of tubes at room temperature were tested on the New Rethinking 10T test machine, ASTM E8 M. After the tube specimen is ground and polished, the axial section of the specimen is corroded with etchant for 15 ~ 20s. The microstructure of the sample was observed by optical microscope. The experimental results show that :(1) when the cumulative deformation rate is no more than 55% and the ratio Q value between the inner diameter reduction rate and the wall thickness reduction rate is controlled within 0.53 ~ 1.14, the TA18 test tube can be rolled smoothly on a two-high mill without cracks on the inner and outer surfaces. (2) The strength of the processed state of TA18(Gr 9) experimental pipe increases gradually with the increase of deformation rate, but there is a critical value of the influence of deformation rate on the plasticity of the pipe. When the deformation rate is lower than 44%, the deformation rate has little influence on the plasticity of the processed state of the pipe. When the deformation rate exceeds 44%, the plasticity of pipe decreases gradually with the increase of deformation rate. (3) With the increase of annealing temperature, the strength and elongation of TA18(Gr 9) experimental tubes gradually decrease, and the work hardening effect caused by different deformation rates also decreases. When the deformation rate is 30% ~ 80%, recrystallization annealing can almost completely eliminate the influence of deformation rate on the mechanical properties of pipes. However, when the deformation rate was too small (23%), the plasticity of the recrystallization state of the pipe was still low, which was caused by the uneven distribution of recrystallization grain size of the pipe with too small deformation rate. (4) when the deformation rate was 51%, the system of annealing at 550 ℃, 90 min, 12 mm x 0.9 mm TA18 Φ experimental mechanics performance of steel tubes are as follows: UTS = 920 mpa, YS = 755 mpa, El = 14%.

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