Void closure behavior during plastic deformation using the representative volume element model
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Void closure behavior during plastic deformation using the representative volume element model Fei Chen1 · Xiaodong Zhao1 · Huiqin Chen1 · Jinyu Ren1 Received: 17 April 2020 / Accepted: 3 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The process of smelting, pouring, and solidification for steel determines the inevitable existence of all kinds of macroscopic and microscopic void defects in the ingot. These voids need to be eliminated by a proper plastic forming process. However, the mechanism of void closure is not well understood at present. In particular, the investigation on the evolution law of void closure under complex stress state is not deep enough. Based on the representative volume element model, numerical simulations and theoretical analysis, the effects of the spherical stress tensor and the deviatoric stress tensor on the evolution of void are expounded. It is found that the relative size of the three principal values of the deviatoric stress tensor determines the shape change of the void during plastic deformation. Besides, the change of the relative value of the principal values of the deviatoric stress tensor has little effect on the maximum compressive strain required for void closure. Moreover, the smaller the principal value of the spherical stress tensor is, the smaller the strain required for void closure is. Keywords Void closure · Spherical stress tensor · Deviatoric stress tensor · The representative volume element
1 Introduction The processes of smelting, pouring, and solidification of steel form all kinds of macroscopic and microscopic void defects in the ingot, such as shrinkage cavity, blowhole, shrinkage porosity and the likes [1, 2]. If these defects cannot be eliminated effectively in the subsequent hot deformation, the service life of the forging will be affected seriously [3]. Generally, there are two main forms of void defects in steel ingot. One is the single void, which is distributed in the ingot randomly. During plastic deformation, the distance between two voids is too long to affect each other, such as the shrinkage cavity and blowhole [4]. The other is the dense voids that appear in the state of aggregation. During deformation, due to the close distance between the voids, the stress states of the matrix materials around the voids affect each other seriously. The dense voids are represented by shrinkage porosity [5]. The main content of this paper * Huiqin Chen [email protected] 1
College of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, People’s Republic of China
is to analyze the evolution of the single void during plastic deformation. Many scholars have done a lot of research on single void closure behavior under plastic deformation. Tanaka et al. [6, 7] used the rigid-plastic finite element method to explore the relationship between the change of void and the stress and strain surrounding the void. And they believed that the equivalent strain around the void and the time integr
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