Abstract In order to overcome the problems of existing methods for preparing thick-walled tubes of nickel-base superalloy (TWNS), the rotary tube piercing (RTP) process was proposed. For this purpose, an improved piercing mill was designed, and the influences of process parameters on strain, temperature, biting condition, lose stability of mandrel, defects control and microstructure distribution were studied by the combination of finite element model (FEM) and experiments. Based on the control variable method, the ranges of process parameters corresponding to the second biting condition and the critical condition of mandrel instability were determined by the simulation results. The experiment results indicate that the external separation layer defect (ESLD) is significantly affected by roll speed and reduction rate. The internal separation layer defect (ISLD) is mainly controlled by reduction rate. The preferred process parameters are determined as temperature 1040℃, reduction rate 13 %, roll speed 35 rpm, feed angle 8°, cross angle 15°, and plug advance against gorge 12 mm. The equiaxed grains with average grain size of 25 μm are obtained due to the complete dynamic recrystallization (DRX) process.

中文翻译：

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镍基高温合金厚壁管旋转穿孔工艺试验与数值分析

摘要 为了克服现有镍基高温合金厚壁管（TWNS）制备方法存在的问题，提出了旋转管穿孔（RTP）工艺。为此，设计了一种改进的穿孔机，结合有限元模型(FEM)和实验研究了工艺参数对应变、温度、咬合条件、芯棒失稳、缺陷控制和组织分布的影响。基于控制变量法，通过仿真结果确定了第二次咬合条件和芯棒失稳临界条件对应的工艺参数范围。实验结果表明，外部分离层缺陷（ESLD）受辊速和压下率的影响显着。内部分离层缺陷（ISLD）主要受还原率控制。优选的工艺参数确定为温度1040℃，压下率13%，辊速35rpm，进料角8°，交叉角15°，塞子顶进12mm。由于完全动态再结晶（DRX）过程，获得平均晶粒尺寸为25μm的等轴晶粒。