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Rolling process of high strength TA18 titanium alloy pipe for aviation
Apr 22, 2016


        Rolling process of high strength TA18 titanium alloy pipe for aviation


Is a kind of low alloy near alpha titanium alloy ta18 alloy Ti-3A1-2.5V alloy, not only has excellent room


temperature, high temperature mechanical properties and corrosion resistance, but also has good cold and hot


 workability and welding performance. Therefore, the alloy has become the preferred material for the 


aerospace piping system. With the continuous development of the aerospace industry, the demand for TA18 alloy tube with excellent performance has continued to grow.



At present, the domestic production intensity of 860MPa grade TA18 pipe is not mature by cold rolling 


technology. During the rolling process, the tube is easy to crack, and the high strength and high plasticity


 of the finished product can not be guaranteed at the same time. Therefore, the domestic demand for high 


strength and high toughness TA18 alloy tube has been dependent on imports.



Scientific research personnel through trial production of different specifications of ta18 tube, diameter of 


reducing diameter and wall thickness reduction ratio of wall Q ratios and cumulative deformation rate E and 


the annealing temperature affect the microstructure and properties of the finished tube, so as to optimize 


the processing technology of alloy and provide technical guidance and reference for the localization of high strength and high toughness of ta18 alloy tube.


Experimental material selection of a sponge titanium, A1-V intermediate alloy and Al Bean, Al foil.


 After several vacuum consumable arc melting furnace made phi 430mm ta18 alloy ingots. Ingot with beta 


bloom, in the alpha + beta intercritical forging 130mm diameter rods and then squeeze to 2500t horizontal 


machine packed with diameter of 45mm x 8mm alloy tube. By multi pass cold rolling and surface treatment in 


two and LG and three and LD mill, then in vacuum annealing furnace annealing. The preparation of a pipe


 diameter of 25 mm x 1.8mm, 22mm diameter x 1.6mm, Phi 20mm * 1.5mm, f 18mm * 1.3mm, 16mm x 1.2mm, diameter


 of 14mm x 1mm, Phi 12mm * 0.9mm, 10mm * 0.7mm, 8mm x 0.6 mm and phi 6mm x 0.5 mm 10 kinds of 


specifications of the finished product.



Room temperature tensile test tube in 10t sans testing machine, test standard for ASTM E8 M. After grinding, polishing tube, axial section of specimen for anti-corrosion corrosion, erosion time was 15 ~ 20s. 


Microstructure of samples was observed by optical microscope. Test results show that:



(1) when the cumulative deformation rate is less than 55%, and the ratio of the diameter reduction ratio and wall thickness reduction ratio of Q value is controlled at 1.14 ~ 0.53, the TA18 test tube can be smoothly rolled on the two roll mill.



(2) the strength of the processing state of the TA18 test tube increases gradually with the increase of the deformation rate, but the effect of the deformation rate on the plastic properties of the pipe has a critical value. When the deformation rate is less than 44%, the deformation rate has little effect on the plastic deformation of the tube. When the deformation rate is over 44%, the plastic deformation rate increases with the increase of the deformation rate.



(3) with the increase of the annealing temperature, the strength of the TA18 tube is gradually reduced, the elongation increases gradually, and the hardening effect caused by different deformation rate decreases. When the deformation rate is 80% ~ 30%, the recrystallization annealing can almost completely eliminate the effect of the deformation rate on the mechanical properties of the pipe. But when the deformation rate is too small (23%), the plastic is still low, which is caused by the uneven distribution of the grain size distribution of the tube with a small deformation rate.



(4) when the deformation rate is 51%, annealing system to 550 DEG C, 90min, the mechanical properties of phi 12mm * 0.9mm ta18 experimental tubes for: UTS=920MPa, YS=755MPa, El=14%.



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