Integrated Process Simulation of Non-Oriented Electrical Steel

Abstract

A tailor-made microstructure, especially regarding grain size and texture, improves the magnetic properties of non-oriented electrical steels. One way to adjust the microstructure is to control the production and processing in great detail. Simulation and modeling approaches can help to evaluate the impact of different process parameters and finally select them appropriately. We present individual model approaches for hot rolling, cold rolling, annealing and shear cutting and aim to connect the models to account for the complex interrelationships between the process steps. A layer model combined with a microstructure model describes the grain size evolution during hot rolling. The crystal plasticity finite-element method (CPFEM) predicts the cold-rolling texture. Grain size and texture evolution during annealing is captured by the level-set method and the heat treatment model GraGLeS2D+. The impact of different grain sizes across the sheet thickness on residual stress state is evaluated by the surface model. All models take heterogeneous microstructures across the sheet thickness into account. Furthermore, a relationship is established between process and material parameters and magnetic properties. The basic mathematical principles of the models are explained and demonstrated using laboratory experiments on a non-oriented electrical steel with 3.16 wt.% Si as an example.

Ultra-Fast Heating Treatment Effect on Microstructure, Mechanical Properties and Magnetic Characteristics of Non-Oriented Grain Electrical Steels

“…Therefore, these literature works support the ability to successfully process NGO electrical steels through UFH treatment, providing materials with microstructure and mechanical characteristics comparable to industrial products manufactured with conventional technologies. From the results shown, it follows that the best mechanical resistance corresponds to a T peak of 1000 • C. For this sample, the values of Rm, Ys, and A% are highly comparable with those found in the literature for sheets with the same thickness and chemical composition as that investigated in this work [55,72,73]. Therefore, these literature works support the ability to successfully process NGO electrical steels through UFH treatment, providing materials with microstructure and mechanical characteristics comparable to industrial products manufactured with conventional technologies.…”

Characterization Methods along the Process Chain of Electrical Steel Sheet—From Best Practices to Advanced Characterization

“…There are still some open topics in the literature, which are very important in view of electrical steel. In particular, a better understanding of the fundamental phenomena underlying the properties and processing steps discussed above will help to formulate physically based models for process modelling and optimization, eventually enabling the development of new material and process design strategies [ 6 ].…”

“…In a next step, the found slip systems can be correlated to the stress–strain curves and, with the help of Schmid factors, critical resolved shear stresses can be calculated, or the extent of non-Schmid flow can be quantified. This information can be used to inform crystal plasticity based deformation models [ 6 ], although size effects have to be accounted for [ 52 ]. Furthermore, the dislocation structure within a small deformed single crystal or around the boundary of a bi-crystalline micropillar can be analysed by transmission electron microscopy after preparing a thin lamella out of the micropillar.…”

“…Thereby, every publication focuses on a different aspect of this material. Two papers revolve around processing and its influence on microstructure, texture and magnetic properties [ 4 , 5 ]; one deals with integrated process simulation [ 6 ] and the last with material design [ 3 ], all drawing heavily on experimental results from the established and advanced methods described and discussed here. In the current paper, we present the key methods for fully characterizing the most important properties of electrical steel.…”

“…In addition, we present new selected experimental results to show the strengths of the respective methods using Fe2.4wt.%Si and Fe3.2wt.%Si as example materials ( Table 2 ). Some of the results from characterization can directly be used to either run or improve physically based simulation models of the different process steps (see [ 6 ] for more details). Lastly, we summarise and reflect on the use of all methods in terms of an overview that provides a rating of all methods with respect to their significances for electrical steel and their connected processing steps, the effort needed to conduct the analyses and the insights gained from each method.…”