Acta Metallurgica Sinica (English Letters) ›› 2024, Vol. 37 ›› Issue (6): 953-968.DOI: 10.1007/s40195-024-01690-4

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Effect of Three-High Rotary Piercing Process on Microstructure, Texture and Mechanical Properties of Magnesium Alloy Seamless Tube

Xiaofeng Ding1(), Zehao Wu1, Tong Li1, Jianxun Chen2, Yuanhua Shuang2, Baosheng Liu2   

  1. 1Heavy Machinery Engineering Research Center of Education Ministry, Taiyuan University of Science and Technology,Taiyuan 030024, China
    2College of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024,China
  • Received:2023-11-14 Revised:2024-01-08 Accepted:2024-01-12 Online:2024-06-10 Published:2024-04-15
  • Contact: Xiaofeng Ding, dingxiaofeng@tyust.edu.cn

Abstract:

Mg alloy seamless tubes (MASTs) were prepared through three-high rotary piercing process, effect of billet temperature, feed angle and plug advance on microstructure, texture and mechanical properties of tubes were investigated. The effect on the deformation mechanism and improving mechanical properties mechanism of this process for MASTs were studied. The results show that the grain size could be refined to 11.3-31.1% of the initial grain size and the microstructure was more uniform due to the accumulation of strain. The formation of high strain gradient at the grain boundary activated the non-basal slip. This piercing process could change the grain orientation of as-extruded billet and eliminate the initial basal texture to produce new favorable texture. And the process could accelerate the continuous dynamic recrystallization process. After piercing, yield strength of pierced tubes decreased by 6.7%, ultimate tensile strength (UTS) and elongation increased by 32.4 and 45%, respectively, at optimal parameters. The plate-shaped β1-Mg17Al12 orientation transformed from basal plates to prismatic plates, facilitating the increase in UTS and ductility. The decrease size of nanoscale precipitates could reduce the cracking possibility. The critical resolved shear stress ratios of pyramidal (10−11) slip and (11−22) slip to basal slip for the sample including prismatic plates both decreased compared to that including basal plates. This could enhance the ductility of tube sample. Moreover, grain boundary sliding could contribute to a better ductility via coordinating deformation and reducing stress concentration during piercing process.

Key words: Mg alloy tube, Rotary piercing, Microstructure, Texture, Mechanical properties