Archives of Civil and Mechanical Engineering ( IF 4.4 ) Pub Date : 2021-07-03 , DOI: 10.1007/s43452-021-00263-x Xiao-Lei Cui 1, 2 , Shijian Yuan 1
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Stress states on a multi-branch tubular part are the most complicated change in all types of hydroforming process, which result in severe variation of thickness. In this paper, an experimental and numerical research was conducted on a multi-step hydroforming process including intermediate annealing treatment to obtain effect of stress state on the thickness variation of a superalloy GH4169 complex T-shaped tubular part with expanded diameter, which corresponds to a real product used in aerospace industry. The material flow behavior at typical points on hydroformed tube blank was first analyzed. Then, the thickness variation on the hydroformed GH4169 tube blanks was discussed in every step. It is shown that the materials have different flow directions to form the side branch, where the thickness is always thinned during the four-step hydroforming process. Large axial feeding induces a continuous thickening between transition areas and tube ends. The thickness invariant dividing line in the side branch zone moves toward the tube ends with forming going on. However, in the hemisphere zone, it moves slightly towards the center of the side branch. Moreover, the stress states at three typical positions, as well as their effect on the thickness variation, were analyzed based on a sequential correspondence law between stress and strain components. On this basis, the mechanism of thickening in the left transition area, thinning at the top of side branch and thickness variation at the hemispheric pole was revealed. These results are very important for obtaining the thickness distribution of a complex T-shaped tubular part in multi-step hydroforming, and revealing the thickness variation mechanism by using engineering plasticity theory.
Graphic abstract
中文翻译：
镍基高温合金复杂T形管件液压成形厚度变化及应力状态分析
多分支管状零件上的应力状态是所有类型的液压成形工艺中最复杂的变化，会导致严重的厚度变化。在本文中，对包括中间退火处理的多步液压成形工艺进行了实验和数值研究，以获得应力状态对具有扩径的高温合金 GH4169 复杂 T 形管件厚度变化的影响，这对应于用于航空航天工业的真实产品。首先分析了液压成型管坯上典型点的材料流动行为。然后，在每个步骤中讨论了液压成型 GH4169 管坯的厚度变化。表明材料具有不同的流动方向形成侧支，在四步液压成型过程中，厚度总是变薄。大的轴向进料导致过渡区域和管端之间的连续增厚。随着成形的进行，侧支区厚度不变的分界线向管端移动。然而，在半球区域中，它稍微向侧枝的中心移动。此外，基于应力和应变分量之间的顺序对应律，分析了三个典型位置的应力状态及其对厚度变化的影响。在此基础上，揭示了左过渡区增厚、侧枝顶端减薄和半球极部厚度变化的机理。
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