Development of TA18 titanium alloy thick-walled tubes for the petroleum industry

Published Time:

2014-07-17

　　Currently, China mainly uses a combination of two-roll and three-roll cold rolling to produce TA18 titanium alloy tubes. The main problems encountered in the production of thick-walled TA18 titanium alloy tubes for the petroleum industry are: ① When using multi-roll mills to roll thick-walled tubes with a diameter-to-thickness ratio <10, there are many rolling passes, and defects such as cracking and inner surface adhesion are easy to occur; ② The cold straightening method cannot guarantee that the flatness of the finished tubes meets the requirement of 0.3～1 mm/m. In view of the above problems, the feasibility of two different cold rolling processes for producing TA18 titanium alloy thick-walled tubes is compared, the influence of annealing temperature on the microstructure and properties of the tubes is studied, as well as the subsequent processing technology of the tubes, aiming to provide guidance for the industrial production of high-quality TA18 titanium alloy thick-walled tubes for the petroleum industry.

　　The experimental TA18 titanium alloy is a Φ600mm×2400mm ingot obtained by twice melting in a 3t vacuum consumable arc furnace. The ingot is then forged into a billet by a 16MN fast forging machine, and after drilling a hole by a deep-hole drilling and boring machine, it is coated with a copper sheet and extruded into a Φ70mm×8㎜ tube blank on a 3500t extrusion machine. The tube blank is rolled into a Φ48mm×5mm finished tube using the following two cold rolling processes.

　　Process 1: Φ70mm×8㎜ tube blank, two-roll cold rolling of the blank → Φ54mm×6㎜, annealing, finishing → Φ54mm×6㎜, three-roll cold rolling → Φ51mm×5.5㎜, three-roll cold rolling → Φ48mm×5㎜ finished tube.

　　Process 2: Φ70mm×8㎜ tube blank, two-roll cold rolling of the blank → Φ54mm×6㎜, annealing, finishing → Φ54mm×6㎜, two-roll cold rolling → Φ48mm×5㎜ finished tube.

　　The Φ48mm×5㎜ tubes produced by processes 1 and 2 were vacuum annealed at 600℃×1h, 650℃×1h, 700℃×1h, and 750℃×1h, respectively. After heat treatment, they were heated to 500～600℃ in an RX-600 box-type resistance furnace for 30min for straightening, and their flatness was measured using a 150A14 caliper. Then, the oxidation contamination layers on the inner and outer surfaces of the tubes were removed by boring and mechanical polishing to obtain the final finished tubes. The experimental results show:

　　(1) Compared with process 1, process 2 can more easily obtain TA18 thick-walled tubes that meet the standard requirements, and the rolling process is relatively stable. It not only shortens the production cycle and improves production efficiency, but its comprehensive performance is also superior to the tubes produced by process 1.

　　(2) With 700℃×1h vacuum annealing, the room temperature mechanical properties of the tubes can achieve the best match, and the equiaxed grains are finer and more uniform.

　　(3) After heat straightening, the flatness of the TA18 thick-walled tubes can reach about 0.75mm/m, and the average roughness of the inner surface after boring is 0.864μm.

Previous Page

Solving China's major aircraft development bottleneck, this award is well-deserved!

None

Next Page

Sorry，当前栏目暂无内容!

您可以查看其他栏目或返回 首页

Sorry，The current column has no content!

You can view other columns or return Home