Flow-formability of a Ca-added AZ31 magnesium alloy tube is investigated. The flow-forming process is conducted at various temperatures (100–500 °C), thickness reductions (30–85%), and feed rates (0.1–0.56 mm/rev). Inner and outer surfaces of the tubes are heated by means of a thermal element embedded inside the mandrel and a radiation element, respectively. The formed tubes are visually inspected for the occurrence of cracking and fractures. Microstructures and tensile properties of the samples are analyzed by optical microscopy and tensile test, respectively. It is shown that deformation above 200 °C is required for sound processing with the occurrence of dynamic recrystallization (DRX). Up to 200 °C, the twinning-induced shear banding is the dominant phenomenon in microstructural evolution and responsible for the early strain localization and subsequent fracture. By increasing the temperature, the maximum achievable thickness reduction increases. However, at about 300 °C, the maximum thickness reduction reaches a limit value of about 76%. A twist in the deformed part of the tube occurs at greater thickness reductions. A simple analytical model is presented to analyze the occurrence of the twist phenomenon. Accordingly, a flow-formability map is proposed for the alloy. The DRX grain size is shown to follow a power law with the temperature compensated strain rate known as the Zener–Hollomon parameter. While the grain size is not affected by the feed rate, dimensional accuracy is deteriorated at feed rates over 0.2 mm/rev due to the diametral growth of the workpiece. Based on the tensile test results, by increasing the deformation temperature, the tensile strength increases and the ductility decreases, so that the sample processed at 500 °C shows a brittle fracture. The impacts of temperature on the strength and ductility are attributed to the combined effects of microstructural and texture evolutions during the flow-forming process.

研究了添加钙的AZ31镁合金管的流动成形性。成形过程是在各种温度（100–500°C），厚度减小（30–85％）和进给速度（0.1–0.56 mm / rev）下进行的。通过分别嵌入心轴内部的热元件和辐射元件来加热管的内表面和外表面。目视检查形成的管是否破裂和断裂。分别通过光学显微镜和拉伸试验分析样品的微观结构和拉伸性能。结果表明，声音处理需要200°C以上的变形，并且会发生动态重结晶（DRX）。最高200°C，孪生诱发的剪切带是微观结构演变中的主要现象，并导致早期的应变局部化和随后的断裂。通过提高温度，最大可实现的厚度减小量增加。但是，在约300°C时，最大厚度减小量达到约76％的极限值。管的变形部分在更大的厚度减小处发生扭曲。提出了一个简单的分析模型来分析扭曲现象的发生。因此，提出了合金的流动性图。结果表明，DRX晶粒尺寸遵循幂定律，并具有温度补偿的应变率，即齐纳-所罗门参数。尽管晶粒尺寸不受进给速度的影响，但进给速度超过0时，尺寸精度会降低。由于工件的直径增长，为2 mm / rev。根据拉伸试验结果，通过提高变形温度，拉伸强度增加，延展性降低，因此在500℃下处理的样品显示出脆性断裂。温度对强度和延展性的影响归因于流动形成过程中微观结构和织构演变的综合作用。