University of Groningen
Precipitate evolution in grain oriented electrical steel and high strength low alloy steel
Zhang, Xukai
DOI:
10.33612/diss.133163231
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Publication date: 2020
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Citation for published version (APA):
Zhang, X. (2020). Precipitate evolution in grain oriented electrical steel and high strength low alloy steel. University of Groningen. https://doi.org/10.33612/diss.133163231
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Precipitate evolution in grain oriented
electrical steel and high strength low alloy steel
Xukai Zhang
2
The work presented in this thesis was performed in the Nanostructured Materials and Interfaces group of the Zernike Institute for Advanced Materials at University of Groningen, The Netherlands. This research was carried out under project number F41.5.15566 in the framework of the Partnership Program of the Materials innovation institute M2i (www.m2i.nl) and the Foundation for Fundamental Research on Matter (FOM) (www.fom.nl), which is part of the Netherlands Organization for Scientific Research (www.nwo.nl).
Zernike Institute PhD thesis series 2020-16 ISSN: 1570-1530
Cover design: Xukai Zhang Printed by: Gildeprint
Precipitate evolution in grain oriented
electrical steel and high strength low alloy steel
PhD thesis
to obtain the degree of PhD at the University of Groningen
on the authority of the Rector Magnificus Prof. C. Wijmenga
and in accordance with the decision by the College of Deans. This thesis will be defended in public on Friday 25 September 2020 at 11:00 hours
by
Xukai Zhang
born on 22 June 1991 in Hebei, China
4
Supervisors
Prof. B.J. Kooi Prof. G. PalasantzasAssessment Committee
Prof. Y. Pei Prof. J. Sietsma Prof. G. Dehm1
Table of Contents
Chapter 1 General introduction ... 5
1.1 Precipitates ... 6
1.2 Grain oriented (GO) electrical steel ... 9
1.3 High strength low alloy (HSLA) steels ... 12
1.4 Thesis outline ... 15 1.5 References ... 16
Chapter 2 Experimental ... 21
2.1 Materials ... 21 2.1.1 GO electrical steel ... 21 2.1.2 HSLA steel ... 21 2.2 VLM ... 22 2.3 SEM ... 22 2.4 EBSD ... 24 2.5 TEM ... 25 2.5.1 Electrochemical polishing ... 26 2.5.2 FIB ... 262.5.3 Carbon replica extraction ... 27
2.5.4 S/TEM observation ... 29
2.6 Matrix dissolution ... 31
2.7 SANS ... 32
2.8 Vickers hardness measurement ... 33
2.9 Tensile test ... 33
2
Chapter 3 Precipitate evolution in grain oriented electrical steel during
high temperature coil annealing ... 37
3.1 Introduction ... 37
3.2 Experimental ... 38
3.3 Results ... 39
3.3.1 Overview and type I precipitates ... 39
3.3.2 Type II precipitates ... 41
3.3.3 Type III precipitates ... 46
3.3.4 MatCalc phase simulation ... 49
3.3.5 Grain size evolution ... 50
3.4. Discussion ... 50
3.4.1 Origin of high and low number density areas of type II (AlN-based) precipitates ... 50
3.4.2 Evolution of AlN-based precipitates ... 52
3.4.3 Dissolution of Cu2-xS ... 53
3.4.4 Role of Cu in precipitation ... 54
3.4.5 Effects of precipitates on secondary recrystallization ... 55
3.4.6 Secondary recrystallization mechanism ... 57
3.5 Conclusions ... 58
3.6 References ... 59
3.7 Supplementary material ... 62
Chapter 4 Microstructure, precipitate and property evolution in
cold-rolled Ti-V high strength low alloy steel ... 65
4.1 Introduction ... 65
4.2 Experimental ... 67
4.3 Results ... 67
3 4.3.2 Electron microscopy ... 68 4.3.3 Matrix dissolution ... 73 4.3.4 SANS ... 75 4.3.5 Hardness evolution ... 78 4.4 Discussion ... 79
4.4.1 Precipitate quantification methods comparison ... 79
4.4.2 Precipitate evolution ... 82
4.4.3 Hardness evolution ... 83
4.5 Conclusions ... 84
4.6 References ... 85
4.7 Supplementary material ... 89
Chapter 5 Recrystallization kinetics and texture evolution of cold
rolled Ti-V high strength low alloy steel ... 95
5.1 Introduction ... 95
5.2 Experimental ... 96
5.3 Results ... 96
5.3.1 EBSD measurement and GND density ... 96
5.3.2 Recrystallization kinetics ... 100
5.3.3 Texture evolution ... 103
5.4 Discussion ... 105
5.4.1 Avrami exponent n ... 105
5.4.2 Effect of precipitates on recovery and recrystallization ... 107
5.5 Conclusions ... 108
5.6 References ... 108
Chapter 6 Continuous annealing of cold-rolled Ti-V high strength low
alloy steel: Early stage precipitation and recrystallization behavior .. 111
4
6.2 Experimental ... 112
6.3 Results ... 113
6.3.1 Transmission Electron Microscopy ... 113
6.3.2 Matrix dissolution ... 117 6.3.3 Recrystallization ... 119 6.3.4 Mechanical properties ... 122 6.4. Discussion ... 123 6.4.1 Precipitation behavior ... 123 6.4.2 Strengthening mechanisms ... 125
6.4.3 Comparison of recrystallization driving force and Zener pinning force .. 127
6.4.4 Effect of soaking temperature and time on mechanical properties ... 128
6.5 Conclusions ... 128
6.6 References ... 129
6.7 Supplementary material ... 132
Chapter 7 Summary and Outlook ... 133
7.1 Summary ... 133 7.1.1 GO electrical steel ... 133 7.1.2 HSLA steel ... 133 7.2 Outlook ... 135 7.2.1 GO electrical steel ... 135 7.2.2 HSLA steel ... 136
