Quantifying the Contribution of Crystallographic Texture and Grain Morphology on the Elastic and Plastic Anisotropy of bcc Steel

Martin Diehl,Enrico Bruder,Jörn Niehuesbernd

doi:10.3390/met9121252

Martin Diehl, Enrico Bruder + Show 1 more

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https://doi.org/10.3390/met9121252

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Abstract

The influence of grain shape and crystallographic orientation on the global and local elastic and plastic behaviour of strongly textured materials is investigated with the help of full-field simulations based on texture data from electron backscatter diffraction (EBSD) measurements. To this end, eight different microstructures are generated from experimental data of a high-strength low-alloy (HSLA) steel processed by linear flow splitting. It is shown that the most significant factor on the global elastic stress–strain response (i.e., Young’s modulus) is the crystallographic texture. Therefore, simple texture-based models and an analytic expression based on the geometric mean to determine the orientation dependent Young’s modulus are able to give accurate predictions. In contrast, with regards to the plastic anisotropy (i.e., yield stress), simple analytic approaches based on the calculation of the Taylor factor, yield different results than full-field microstructure simulations. Moreover, in the case of full-field models, the selected microstructure representation influences the outcome of the simulations. In addition, the full-field simulations, allow to investigate the micro-mechanical fields, which are not readily available from the analytic expressions. As the stress–strain partitioning visible from these fields is the underlying reason for the observed macroscopic behaviour, studying them makes it possible to evaluate the microstructure representations with respect to their capabilities of reproducing experimental results.

Highlights

The plastic deformation induced during processing of metallic materials typically results in strong crystallographic textures and, thereby, macroscopically anisotropic mechanical properties
As the anisotropic elastic and plastic behaviour induced by texture and grain morphology has a significant influence on formability and dimensional accuracy, it is imperative to account for the anisotropy when conducting high-precision metal forming simulations [1]
The material investigated here is a high-strength low-alloy (HSLA) steel processed by linear flow splitting

Summary

Introduction

The plastic deformation induced during processing of metallic materials typically results in strong crystallographic textures and, thereby, macroscopically anisotropic mechanical properties. As the anisotropic elastic and plastic behaviour induced by texture and grain morphology has a significant influence on formability and dimensional accuracy, it is imperative to account for the anisotropy when conducting high-precision metal forming simulations [1]. The direct multi-scale inclusion of all microstructure details is usually computationally prohibitive. Homogenization methods like the Relaxed Grain Cluster (RGC) scheme by Tjahjanto et al [5]. Despite these efforts to include microstructure details, usually analytic yield surface descriptions are Metals 2019, 9, 1252; doi:10.3390/met9121252 www.mdpi.com/journal/metals Approaches to reduce the computational efforts include model order reduction schemes [2,3], the use of Statistically Similar Representative Volume Elements (SSRVEs) [4]

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