Abstract

Rotating backward extrusion (RBE) as a new severe plastic deformation technique is a continuous process to produce cylindrical tubes with fine grains and superior properties. In this study, the RBE process with an open punch was applied to the AZ80 alloy at 653 K, and the deformation mechanisms and the microstructure evolution were examined by the finite element method (FEM) and thermal simulation experiment. The results showed that the effective strain of the RBE process was higher than that of the conventional backward extrusion (CBE) process, and the strain increased with revolutions increasing. The strain improvement of the RBE process was related to the large cumulative plastic deformation imposed by the continuous rotation of the open punch. Furthermore, the extrusion load was reduced significantly in the RBE process comparing with the CBE process, due to the change of friction stress and stress state of the materials. And the maximum load reduction of the FEM and experiment was 47.33% and 31.6%, respectively. The average grain size of the RBE sample could be reduced by up to 90% in the region A at 30 N compared with the CBE sample. The maximum increase in microhardness of the RBE sample relative to the CBE sample was 23% at 30 N in the region A. Therefore, the grain refinement and mechanical properties of the materials can be substantially improved by the RBE process.

Graphic Abstract

中文翻译：

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新型SPD旋转后向挤压的数值和实验分析

摘要

旋转向后挤压（RBE）作为一种新的严重塑性变形技术，是生产具有细晶粒和优异性能的圆柱形管的连续过程。在这项研究中，在653 K的温度下对AZ80合金应用了开放式冲头的RBE工艺，并通过有限元方法（FEM）和热模拟实验检查了变形机理和微观组织演变。结果表明，RBE工艺的有效应变高于常规的反向挤压（CBE）工艺，并且应变随着转数的增加而增加。RBE工艺的应变改善与开放式冲头的连续旋转造成的大累积塑性变形有关。此外，由于材料的摩擦应力和应力状态的变化，与CBE工艺相比，RBE工艺的挤压负荷明显降低。FEM和实验的最大负载减少分别为47.33％和31.6％。与CBE样品相比，在30 N的区域A中，RBE样品的平均晶粒尺寸可以减少多达90％。RBE样品相对于CBE样品在A区30 N时的最大显微硬度增加为23％。因此，通过RBE工艺可以显着改善材料的晶粒细化和机械性能。与CBE样品相比，在30 N的区域A中，RBE样品的平均晶粒尺寸可以减少多达90％。RBE样品相对于CBE样品在A区30 N时的最大显微硬度增加为23％。因此，通过RBE工艺可以显着改善材料的晶粒细化和机械性能。与CBE样品相比，在30 N的区域A中，RBE样品的平均晶粒尺寸可以减少多达90％。RBE样品相对于CBE样品在A区30 N时的最大显微硬度增加为23％。因此，通过RBE工艺可以显着改善材料的晶粒细化和机械性能。

图形摘要