Stress Analysis and Microstructure Evolution of Titanium Alloy Pipe during Flattening Processing

Abstract:

TA24 titanium alloy pipe with 638mm diameter and 19mm wall thickness is carried out continuous load flatten test, and the stress of internal and external pipe wall during flatten process is studied in this paper. The results show that the TA24 titanium alloy tube has good flattening performance, and the flattening process has experienced original stage, flattened oblate stage, flattened straight wall stage, flattened depressed stage, flattened concave contact stage. During the flattening process, the outer layer of the upper and lower wall of the tube is subjected to compressive stress, and the inner layer material is subjected to tensile stress. The tensile and compressive forces cause the vertical part of the upper and lower walls to be concave. The outer layer of the left and right circular arc parts is subjected to tensile stress and the inner layer is subjected to tensile stress. The compressive stress also causes the radius of the arc to decrease due to the combined force of the tensile and compressive forces, that is, the flattening occurs. With the decrease of and pressing distance under continuous loading condition, the metal on the left and right sides of the pipe gathers toward the middle depression, which aggravates the deformation of the upper and lower walls until the upper and lower walls contact, and the arc radius of the left and right walls decreases until the outer surface cracks. The pipe microstructure changes significantly into elongated deformation structure during the flattening process. The most severe part of the deformation is the left and right end arc of the pipe, followed by the upper and lower end depression.

• Periodical: Materials Science Forum (Volume 944)
• Pages: 1088-1093
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.944.1088
• Online since: January 2019
• Authors: Jun Chen*, She Wei Xin, Wei Zhou, Qian Li, Si Yuan Zhang, Lei Li, Hai Ying Yang, Ting Xun Wang
• Keywords: Depressed Position, Flattening Deformation Microstructure, Flattening Pipe, Flattening Spacing, TA24 Titanium Alloy

References

[1] R. Sui, Study on two kinds of flattening methods for metal pipes, Physics Test. (1992) 11-14.

[2] GB/T 246-2007 metal materials pipe flattening test, Chinese national standard (2007).

[3] Y.B. Chen, Z.F. Mei, Improvement and display of pipe flattening test, Metal. Technol. (1990) 21-24.

[4] J.M. Pan, Y.F. Yao, Regression Analysis of Process Properties and Mechanical Properties of 1Cr18Ni9Ti Stainless Seamless Steel Tube, Sichuan Metal. (1993) 88-91, 29.

[5] Z.X. He, Y.J. Hu, Application Research of Ti-31 Alloy on Nuclear Power Plant, Ship Sci. and Technol. (1996) 38-43.

[6] GB/T 3624-2007 titanium and titanium alloy pipes, Chinese national standard (2007).

[7] Y.L. Liu, M. Zhan, H. Yang, P. Xie, B. Li, Q.Q. Leng, Establishment of finite element model and cross-section distortion of pipe flattening-pressure bending continuous deformation process, J. of Plastic Engin. 15 (2008) 102-107.

[8] D.X. Deng, Research on the process of flattening deformation of heat transfer micro-groove pipe, Mechan. Design & Manuf. (2010) 118-120.