A Combined Experiment and Crystal Plasticity FEM Study of Microstructure and Texture in Aluminium Processed by Reverse and Unidirectional Accumulative Roll-Bonding

Hui Wang,Kiet Tieu,Cheng Lu

doi:10.3390/cryst9020119

Abstract

In this report, reverse accumulative roll-bonding (ARB) was conducted for the first time. It was found that the microstructure after reverse ARB was relatively coarser than that after unidirectional ARB, and texture intensity was slightly weaker. In addition to the experimental study, the crystal plasticity finite element method was applied to the ARB-processed polycrystalline aluminium. The simulation followed the real deformation of reverse ARB and unidirectional ARB, and the predictions were validated by the experimental observations. Compared to the second cycle of unidirectional ARB, the crystal orientations (after the first cycle) were relatively unstable during the second cycle of reverse ARB, which is believed to be the reason for the relatively coarser microstructure after reverse ARB.

Highlights

The texture and microstructure evolution in materials processed by accumulative roll-bonding (ARB) are complex due to the repeated cycles of cutting, stacking, and roll-bonding [1,2]
The microstructure was almost uniform through the thickness, and it seems that the observed high angle grain boundaries (HAGBs) in Figure 2a were the initial HAGBs before processing but were not developed during 1-ARB
The predicted textures after 1-ARB and 2-ARB were rolling-type textures, each element was further partitioned into crystal rotation about the rolling direction (RD), transverse direction (TD), and the texture intensity after 2-unidirectional ARB (UniARB) was slightly higher than after 2-reverse ARB (RevARB), in agreement and normal direction (ND) in the manner proposed by Wert et al [21]

Summary

Introduction

The texture and microstructure evolution in materials processed by accumulative roll-bonding (ARB) are complex due to the repeated cycles of cutting, stacking, and roll-bonding [1,2]. Texture evolution in polycrystalline aluminium has been statistically studied by the Taylor model [5], ALAMEL model [4,6], and viscoplastic self-consistent model [7,8,9] Unlike these ”mean-field” crystal plasticity (CP) models, no homogenization is assumed in the ”full-field” theory—crystal plasticity finite element method (CPFEM). The CPFEM model has been applied to ARB-processed polycrystals [11,12,13], but in these studies the ARB process was simplified to plain strain compression (PSC), and the transition of microstructure and texture associated with strain path change is not reachable. Compared to unidirectional ARB (UniARB) or conventional ARB, multi-cycle RevARB can generate a different combination of shear strain through the thickness. The effect of rolling direction on microstructure and texture was investigated, which is the purpose of this study

Experiment

Texture Modelling

Results and Discussion

Conclusions