The materials used for alloy capillary tubes include 0.001% Mg, 0.001% B, 0.001% La, 40% Ti, residual Nb and unavoidable impurities.
The preparation method includes the following steps:
(1) Vacuum smelting: the niobium sheet and titanium sheet are dried after surface treatment, put into the melting crucible, electrify melting, melting temperature is 1750~1850℃, melting time is 70~90min, filled with argon, and then add titanium foil wrapped magnesium strip and boron particles at 1750~1850℃ refining for 15~20min to produce ingot; Among them, the vacuum degree is less than 1Pa in the smelting process, and argon gas is first passed through the vacuum state of 4Mpa before casting ingot.
(2) Secondary vacuum smelting: put the ingot in step (1) into the smelting crucible, continue to melt for 60~80min at 1750~1850℃, fill with argon, then add rare earth lanthanum covered with titanium foil, and refine for 15~20min at 1750~1850℃ to obtain electrode rods; Among them, the vacuum degree is less than 1Pa in the smelting process, and argon gas is passed through 4Mpa in vacuum state before casting electrode rod.
(3) Vacuum consumable electrode furnace melting: Put the vacuum melted electrode rod in step (2) into the consumable electrode chamber of the vacuum consumable electrode furnace for melting to obtain φ200~220mm ingot, and the vacuum degree in the melting process is less than 1Pa;
(4) Hot forging: the ingot is heated to 1150~1400℃, held for 25~35min, then forging is carried out. The opening forging temperature is 1150~1400℃, and the final forging temperature is 1020~1250℃, and the final forging bar is forged to φ40-50mm;
(5) Peeling: After cutting the end and end of the forged alloy bar, the surface oxide skin is cleaned by machining to obtain φ30~40mm bright rod, and non-destructive testing is carried out;
(6) Cross-rolling perforation or machining drilling: φ30~40mm bright rod through the cross-rolling perforation or bright rod directly in the punching machine through the center hole, among which, the temperature range of cross-rolling perforation is 1100℃~1300℃, the outer diameter of φ30-50mm, the wall thickness of 10~15mm of the pipe;
(7) Rolling: pickling and grinding the waste pipe, removing the internal and external surface defects, vacuum annealing, annealing temperature of 1000~1150℃, after holding for 1~1.5h, through cold rolling to produce φ20-25mm tube blank; After vacuum annealing and cold rolling for many times, φ3-8mm tube blank is finally prepared.
(8) Diameter reduction cold drawing: After cleaning the surface of the tube blank, the tube blank is formed by 4~5 diameter reduction through the tube rolling machine or drawing machine, forging die and die. After each diameter reduction, the tube blank is processed by vacuum annealing at 800~1080℃ for 10 ~ 60min, and the tube blank is drawn to the capillary tube with diameter ≤3mm, wall thickness 0.1-0.3mm and length of 1~10m.
