Purdue University Purdue e-Pubs Open Access Dissertations Theses and Dissertations January 2016 Shear-based Deformation Processing and Characterization of Electrical Steel Sheet Andrew Benjamin Kustas Purdue University Follow this and additional works at: https://docs.lib.purdue.edu/open_access_dissertations Recommended Citation Kustas, Andrew Benjamin, "Shear-based Deformation Processing and Characterization of Electrical Steel Sheet" (2016). Open Access Dissertations. 1241. https://docs.lib.purdue.edu/open_access_dissertations/1241 This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact [email protected] for additional information. Graduate School Form 30 Updated PURDUE UNIVERSITY GRADUATE SCHOOL Thesis/Dissertation Acceptance This is to certify that the thesis/dissertation prepared By Entitled For the degree of Is approved by the final examining committee: To the best of my knowledge and as understood by the student in the Thesis/Dissertation Agreement, Publication Delay, and Certification Disclaimer (Graduate School Form 32), this thesis/dissertation adheres to the provisions of Purdue University’s “Policy of Integrity in Research” and the use of copyright material. Approved by Major Professor(s): Approved by: Head of the Departmental Graduate Program Date i SHEAR-BASED DEFORMATION PROCESSING AND CHARACTERIZATION OF ELECTRICAL STEEL SHEET A Dissertation Submitted to the Faculty of Purdue University by Andrew Benjamin Kustas In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy August 2016 Purdue University West Lafayette, Indiana ii To my mother, father and brother, with love iii ACKNOWLEDGEMENTS The author would first like to thank his advisors, Prof. Kevin Trumble and Prof. Srinivasan Chandrasekar, for their excellent guidance and temperament, which allowed him to explore many interesting metallurgical processing phenomena. Furthermore, their general support and constant encouragement made the graduate experience enjoyable. The author also thanks his committee members, Prof. Rod Trice for first providing the initial phone conversation that motivated the author to attend Purdue and Prof. David Johnson, for assisting with several Fe-Si castings. The author also thanks Prof. Matthew Krane for supporting the author’s confirmation at St. Thomas Aquinas. The author acknowledges his colleagues and friends for support throughout graduate school. In particular, Logan, Michael, Dinakar, Kevin, Mert, Kristin, Kara, Travis, Derek, Alex, Kyle, Mitch, and Gamini. The author also would like to thank his loving mother, father and brother – Gretchen, Frank and Ryan – and girlfriend Jessica for continued support throughout the graduate degree. Without them, this dissertation would not have been possible. Finally, the author would like to thank God for the many blessings along the way. The Lord is my rock, and my fortress, and my deliverer; my God, my strength, in whom I will trust; my buckler, and the horn of my salvation, and my high tower (Psalm 18:2, KJV). iv TABLE OF CONTENTS Page LIST OF TABLES ............................................................................................................ vii LIST OF FIGURES ......................................................................................................... viii ABSTRACT .................................................................................................................... xvii CHAPTER 1. INTRODUCTION .................................................................................... 1 1.1 Electrical Steel Sheet for Electromagnetic Applications ................................... 1 1.2 Problem Statement ............................................................................................. 3 CHAPTER 2. BACKGROUND ...................................................................................... 5 2.1 Fundamentals of Ferromagnetic Materials......................................................... 5 2.1.1 Magnetization Curves and Magnetic Properties ......................................... 5 2.1.2 Microscale Magnetization Processes in Ferromagnets ............................. 12 2.1.3 Magnetic Anisotropy in BCC Crystals...................................................... 14 2.2 A Brief History of Iron-Silicon Development ................................................. 15 2.3 Compositional Effects ...................................................................................... 17 2.4 Flat Rolled Sheet Products ............................................................................... 22 2.4.1 Non-Grain-Oriented Sheets ....................................................................... 22 2.4.2 Grain-Oriented Sheets ............................................................................... 23 2.5 Commercial Sheets vs. Ideal Fe-Si .................................................................. 25 2.6 Workability Issues in Fe-Si .............................................................................. 27 CHAPTER 3. FUNDAMENTALS OF MACHINING.................................................. 30 3.1 Simple Shear Deformation by Machining........................................................ 30 v Page 3.1.1 Deformation Strain and Hydrostatic Pressure ........................................... 33 3.1.2 Deformation Path Control ......................................................................... 34 3.1.3 Temperature .............................................................................................. 37 CHAPTER 4. EXPERIMENTAL .................................................................................. 40 4.1 Workpiece Materials ........................................................................................ 40 4.2 Deformation Conditions ................................................................................... 42 4.3 Microstructural Characterization ..................................................................... 43 4.4 Texture Evolution Analysis ............................................................................. 44 4.5 Magnetic Property Measurements ................................................................... 44 CHAPTER 5. RESULTS – MICROSTRUCTURE AND TEXTURE EVOLUTION .. 46 5.1 Workability Issues in Rolling........................................................................... 46 5.2 Microstructure Evolution of Machined Fe-4wt%Si ......................................... 53 5.2.1 Strain Rate and Temperature Effects in Conventional Machining ........... 53 5.2.2 Strain Rate and Temperature Effects in LSEM ......................................... 58 5.2.3 Inhomogeneity at Low Vo .......................................................................... 64 5.2.4 Microstructures in Fe-6.5wt%Si ............................................................... 66 5.3 Crystallographic Texture .................................................................................. 70 5.3.1 Ideal Simple Shear Textures ..................................................................... 70 5.3.2 Low and High Temperature Deformation Textures .................................. 73 5.3.3 Recrystallization Textures ......................................................................... 76 5.3.4 Texture Inhomogeneity ............................................................................. 80 5.3.5 Range of Texture Control .......................................................................... 83 5.3.6 Textures in Fe-6.5wt%Si ........................................................................... 85 5.3.7 Grain Growth Textures.............................................................................. 87 5.3.8 Optimized Simple Shear Textures for Magnetic Applications ................. 89 5.3.9 Summary ................................................................................................... 95 vi Page CHAPTER 6. TEXTURE EVOLUTION ...................................................................... 96 6.1 Recrystallization Theories ................................................................................ 96 6.1.1 Overview of Annealing Processes............................................................. 96 6.1.2 Overview of Recrystallization Kinetics .................................................. 101 6.2 Fe-Si Microstructure Results.......................................................................... 104 6.2.1 Rolling Experiments ................................................................................ 104 6.2.2 Metal Cutting........................................................................................... 107 6.2.3 Microstructural Comparison ................................................................... 111 6.3 Avrami Kinetics Analysis .............................................................................. 115 CHAPTER 7. MAGNETIC PROPERTIES ................................................................. 120 7.1 Standard Magnetic Characterization Methods ............................................... 120 7.1.1 Open Circuit Methods ............................................................................. 121 7.1.2 Closed Circuit Methods ........................................................................... 124 7.1.2.1 Epstein Frame .................................................................................. 125 7.1.2.2 Single Sheet Tester .........................................................................