Processing method for realizing super high plasticity performance of titanium alloy welded joint

A technology for welding joints and processing methods, applied in the field of titanium alloy welding, can solve the problems of increasing the difficulty of superplastic forming of joints, increasing the difficulty of welding, affecting the quality of joints, etc., and achieves increased mechanical properties, reduced oxidation degree, and low superplastic temperature. Effect

Active Publication Date: 2019-05-03
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition, even if the above two problems are solved, the viscosity of titanium alloy at high temperature makes it usually bond with the backing plate, which will also affect the quality of the joint
Many researchers use static shoulders, or water-cooled backing plates, auxiliary heat sources, etc., but greatly increase the difficulty of welding
In conclusion, it is very challenging to obtain defect-free welded joints in titanium alloys
[0005] On the other hand, the more important challenge comes from the regulation of titanium alloy joint structure: the key to realize the overall superplastic forming of titanium alloy friction stir welded joint is to make the weld nugget area obtain a superplastic deformation capacity similar to that of the base metal
Although the lamellar structure of the friction stir welding nugget can also obtain 500% superplasticity at 800 °C (Wu et al, Achieving superior low-temperature superplasticity for lamellar microstructure in nugget of afriction stir welded Ti-6Al-4V joint Scripta Mater.122 (2016)26-30), but the flow stress is too high, exceeding 70MPa, which greatly increases the difficulty of actual superplastic forming of the joint and poor operability

Method used

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  • Processing method for realizing super high plasticity performance of titanium alloy welded joint
  • Processing method for realizing super high plasticity performance of titanium alloy welded joint
  • Processing method for realizing super high plasticity performance of titanium alloy welded joint

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] A 2 mm thick TC4 titanium alloy plate was used, 0.2 wt% hydrogen was placed in a hydrogen atmosphere, and a stirring head with a shoulder diameter of 11 mm was used for welding. During the welding process, the joint was protected by argon and the weld was rapidly cooled, and the friction stir welding was performed under the welding parameters of the tool rotation speed of 300 rpm and the travel speed of 100 mm / min. The typical lamellar structure of friction stir welding nugget of TC4 titanium alloy is as follows: figure 1 As shown, it can be seen that the grains in the nugget area are uniform and fine lamellar structures. A high-quality welded joint with a lamellar length-to-diameter ratio of 7:1 and a lamellar thickness of 120 nm was obtained.

[0038] The high temperature superplasticity tensile test shows that the optimum superplasticity temperature of the weld nugget is 800℃. When the superplastic temperature is 800°C, the strain rate is 1×10 -3 the s -1 , the m...

Embodiment 2

[0042] Use TC4 titanium alloy plate, and use 0.2wt% hydrogen before welding. Use a W-Re stirring head with a shoulder diameter of 11 mm for welding. During the welding process, use argon to protect the joint and rapidly cool the weld. Under the welding parameters, a high-quality welded joint with fine nugget lamellar structure (sheet thickness 80-200 nanometers, aspect ratio 6:1-12:1) is obtained. The high-temperature superplasticity tensile test shows that the optimal superplasticity temperature of the weld nugget at a tool speed of 400 rpm and a travel speed of 100 mm / min is 825 °C. When the superplastic temperature is 825°C and the strain rate is 1×10 -3 the s -1 When the maximum elongation of the weld nugget is 600%, the flow stress is only 28MPa, such as figure 2 shown.

[0043] The sample of the TC4 titanium alloy friction stir welding nugget prepared in this example after being stretched at 825°C is as follows image 3 .

Embodiment 3

[0047] Use a 2mm thick as-rolled annealed TC4 titanium alloy plate with 0.2wt% hydrogen before welding. Welding is carried out with a stirring head with a shoulder diameter of 11 mm, the joint is protected by argon gas during the welding process and the weld is cooled rapidly, and high quality is obtained under the welding parameters of tool rotation speed of 500 rpm and travel speed of 150 mm / min of welded joints. The high-temperature superplastic tensile test shows that when the superplastic temperature is 800°C, the strain rate is 3×10 -3 the s -1 , the maximum elongation of the weld nugget is more than 600%, and the flow stress is only 36MPa.

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Abstract

The invention discloses a processing method for realizing super high plasticity performance of a titanium alloy welded joint, and belongs to the technical field of titanium alloy welding. The processing method includes the steps that firstly, hydrogenation treatment is conducted on a titanium board to be welded in a pure hydrogen atmosphere; then stirring friction welding is conducted on the titanium board subjected to the hydrogenation treatment to make a welding nugget to be of a tiny laminated structure; and super plasticity tensile deformation is conducted on a joint welding nugget after stirring friction welding, a part of a base metal and the entire welded joint, so that entire super plasticity processing of a titanium alloy workpiece is realized. Through the processing method for realizing the super high plasticity performance of the titanium alloy welded joint, the super plasticity of the titanium alloy welded joint can be obviously improved, the super plasticity temperature and flow stress are lowered, the difficulty of super plasticity forming and the welding cost are lowered greatly, the mechanical performance of a super plasticity forming component is improved, and thesuper plasticity forming of the whole joint is realized; and the processing method for realizing the super high plasticity performance of the titanium alloy welded joint particularly adapts to the super plasticity forming and high temperature forming of the titanium alloy welded joint, and can be applied to manufacture large-scale titanium alloy entire components, partial forming components and the like in space flight and aviation field.

Description

Technical field: [0001] The invention relates to the technical field of titanium alloy welding, in particular to a processing method for realizing high superplasticity of titanium alloy welded joints. Background technique: [0002] Titanium alloy superplastic forming / diffusion bonding technology is widely used in large-scale hollow structural parts in the aerospace field. However, with the development of structural parts towards integration and large-scale It is becoming more and more difficult to adapt to the requirements of the production of large overall structural parts. Currently, researchers are actively seeking the combination of superplastic forming and other welding techniques. No matter what kind of welding technology is used, the core goal of how to achieve the overall uniform superplastic forming of the welded joint is faced, which requires that all regions of the joint have similar superplastic deformation capabilities (including elongation and flow stress). ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K20/12B23K20/24B21C1/00B23P23/04
Inventor 吴利辉马宗义肖伯律薛鹏倪丁瑞
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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