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斜轧穿孔法制备Ti80合金无缝管工艺分析
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西北工业大学 凝固技术国家重点实验室

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国家重点研发计划资助(项目编号2016YFB0301203)


Study on rotary piercing technique of Ti80 titanium alloy seamless tube
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1.State Key Laboratory of Solidification Processing,Northwest Polytechnical University,Xi’an 710072;2.China

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    摘要:

    运用有限元技术模拟了两辊斜轧穿孔法制备Ti80合金无缝管坯的三维热力耦合过程。仿真结果能动态显示坯料从咬入到稳定穿孔再到穿出三个阶段复杂的塑性成形过程,并能辅助分析中心孔腔的形成机理以及坯料在穿孔阶段各物理场量的分布。结果表明:坯料刚接触顶头时,中心金属存在明显塑性变形,结合中心线上的应力状态为(+, -, +),判断中心孔腔的形成为拉应力下的塑性开裂。在穿孔过程中,应变分布沿轴向呈U1+W+2U2,沿径向为片层状,最终毛管等效应变可达5-11;坯料外表面与导盘接触区的应变速率为0.71~3.6s-1,而与轧辊接触区高达4.6~26s-1,大的应变速率有助于塑性成形过程;顶头前坯料温度最高,与穿孔工具接触的区域温度略有降低,但都处于单相区。基于有限元优化的工艺条件,在实验轧机上顺利穿制出Ti80合金无缝管坯,其显微组织展现为单一的魏氏组织形态,且由于变形剧烈,从外表面到中间层再到内表面均为等轴细小的β动态再结晶晶粒;力学性能测试表明穿孔管坯强度和塑性均满足指标要求。

    Abstract:

    This paper deals with the simulation of rotary piercing process of Ti80 alloy seamless tube via a 3D thermal-mechanical coupling model. The model can visualize the complex continuous piercing process from biting to steady piercing and to final drilling. Concurrently, the simulated result helps to understand the central fracturing and physical fields distribution. Combining the stress state of (+, -, +) along the rolling centerline with non-negligible plastic deformation at the centre of the billet, the cavity formation was determined to be caused by plastic cracking under tensile stress. During the piercing process, the strain distribution was U1+W+2U2 along the axial direction and lamellar along the radial direction. The final equivalent strain of the capillary can reach 5-11. The strain rate in the contact area between the blank surface and the discs was 0.71~3.6s-1, while that between the surface and the rolls was up to 4.6~26s-1, thus contributing to the plastic forming process. The billet temperature in front of the plug was the highest, and the area in contact with the piercing tools decreased slightly. But they were still in the single β phase field. Based on the parameters optimized by the finite element method, the Ti80 alloy seamless tube was successfully pierced through the experimental Diescher mill. The microstructure of the tube was presented as a single Widmanstatten microstructure. Due to the severe deformation, the fine and equiaxed dynamic recrystallization β grains were found from outer surface to the middle layer and to inner surface. The mechanical property test showed that the strength and plasticity of the tube can meet the requirements of the project.

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周大地,曾卫东,徐建伟,陈威.斜轧穿孔法制备Ti80合金无缝管工艺分析[J].稀有金属材料与工程,2020,49(3):1045~1050.[Zhou Dadi, Zeng Weidong, Xu Jianwei, Chen Wei. Study on rotary piercing technique of Ti80 titanium alloy seamless tube[J]. Rare Metal Materials and Engineering,2020,49(3):1045~1050.]
DOI:10.12442/j. issn.1002-185X.17Ti2019038

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  • 收稿日期:2019-01-09
  • 最后修改日期:2019-07-15
  • 录用日期:2019-07-30
  • 在线发布日期: 2020-04-08
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