Mechanism of Grain Growth During Annealing of Si-Al Electrical Steel Strips Deformed in Tension

2010 ◽  
Vol 1276 ◽  
Author(s):  
J. Salinas B ◽  
A. Salinas R
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Electrical Steel ◽  
Electron Backscatter Diffraction ◽  
Steel Strip ◽  
Boundary Migration ◽  
Primary Recrystallization ◽  
Steel Strips ◽  
Grain Orientation Spread ◽  
Quality Maps

AbstractThe mechanism of recrystallization as a result of annealing during 600–7200 seconds at 700 °C of a Si-Al, low C electrical steel strip is investigated in samples deformed in tension. The evolution of grain size during annealing is evaluated by optical microscopy and electron backscatter diffraction in the scanning electron microscope. It is found that grain growth starts after an incubation time of 600 s with no apparent evidence of primary recrystallization. After that, the grain size-time relationship exhibits two different stages. Initially, the grain size increases linearly with time up to about 3600 s. During this time, some selected grains grow until they consume the deformed microstructure. In the second stage, the rate of growth decreases significantly and a final grain size of about 150 m is reached after 7200 seconds of annealing. Grain orientation spread maps obtained from EBSD data of deformed and partially recrystallized samples during the stage of linear growth reveals that the growing grains exhibit lower misorientation and therefore smaller stored energy than the non-recrystallized matrix grains. Analysis of image quality maps reveal that the IQ values for {100}<uvw>orientations are higher than those observed for {111}<uvw>orientations thus suggesting that the {100}<uvw>orientations grow at the expense of {111}<uvw>orientations by a mechanism of strain-induced boundary migration.

scholarly journals Evolution of Power Losses in Bending Rolled Fully Finished NO Electrical Steel Treated under Unconventional Annealing Conditions

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2200 ◽  
Author(s):  
Ivan Petryshynets ◽  
František Kováč ◽  
Ján Füzer ◽  
Ladislav Falat ◽  
Viktor Puchý ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Grain Growth ◽  
Electrical Steel ◽  
Magnetic Measurements ◽  
Boundary Migration ◽  
Stress Relief ◽  
Rolling Process ◽  
Deformation Energy ◽  
Conventional Heat Treatment ◽  
Dynamic Heating

Currently, the non-oriented (NO) iron-silicon steels are extensively used as the core materials in various electrical devises due to excellent combination of their mechanical and soft magnetic properties. The present study introduces a fairly innovative technological approach applicable for fully finished NO electrical steel before punching the laminations. It is based on specific mechanical processing by bending and rolling in combination with subsequent annealing under dynamic heating conditions. It has been revealed that the proposed unconventional treatment clearly led to effective improvement of the steel magnetic properties thanks to its beneficial effects involving additional grain growth with appropriate crystallographic orientation and residual stress relief. The philosophy of the proposed processing was based on employing the phenomena of selective grain growth by strain-induced grain boundary migration and a steep temperature gradient through the cross-section of heat treated specimens at dynamic heating conditions. The stored deformation energy necessary for the grain growth was provided by plastic deformation induced within the studied specimens during the bending and rolling process. The magnetic measurements clearly show that the specimens treated according to our approach exhibited more than 17% decrease in watt losses in comparison with the specimens treated by conventional heat treatment leading only to stress relief without additional grain growth.

Texture and Microstructure Evolution during Box Annealing of a Non-Oriented-Grain Electrical Steel

2011 ◽  
Vol 702-703 ◽  
pp. 595-598
Author(s):  
Francisco N.C. Freitas ◽  
Manoel Ribeiro da Silva ◽  
Sergio S.M. Tavares ◽  
Hamilton F.G. Abreu
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Cold Rolling ◽  
Crystallographic Texture ◽  
Electrical Steel ◽  
Electron Backscatter Diffraction ◽  
Magnetization Direction ◽  
Electrical Steels ◽  
Cold Rolling And Annealing ◽  
Work Samples

Non-oriented grain type electrical steels are used mainly in electrical rotating machines such as motors and compressors, in which the magnetization direction rotates 360 ° every cycle while remaining in the plane of the plate. The performance of these devices is affected by crystallographic texture of electrical steels due to strong anisotropy of magnetic properties. The electrical steel is supplied in the form of plates which are processed by cold rolling and subsequent annealing. Both, cold rolling and annealing directly influence the formation of crystallographic texture components. During annealing, recrystallization occurs, and this phenomenon gives rise to changes in texture that influences the quality of the final product and its application. Several works have been published in the study of the evolution of crystallographic texture and grain size in this type of electrical steel. In this work, samples have been taken in industrial conditions at various temperatures during the annealing in a coil box. Electrical steel samples cold rolled with reductions of 50% and 70% in thickness were removed during the process of annealing, and the evolution of texture with increasing temperature was studied. Aspects related to recrystallization, grain size and the evolution of texture and magnetic properties were discussed. Texture and recrystallization were studied by X-ray diffraction and electron backscatter diffraction (EBSD). The magnetic properties were measured in a vibrating sample magnetometer.

ULTRA FINE-GRAINED AZ31 MAGNESIUM ALLOY OBTAINED BY A COMBINATION OF GRAIN REFINEMENT AND EQUAL CHANNEL ANGULAR PRESSING

2012 ◽  
Vol 05 ◽  
pp. 307-315 ◽  
Author(s):  
S.A. TORBATI-SARRAF ◽  
R. MAHMUDI
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Grain Growth ◽  
Equal Channel Angular Pressing ◽  
Boundary Migration ◽  
Grain Refiner ◽  
Fine Grained ◽  
Angular Pressing ◽  
Grain Size Distributions

Different amounts of Al -5 Ti -1 B master alloy ( TiBAl ) were added to the AZ 31 magnesium alloy ( Mg -3 Al -1 Zn -0.2 Mn ) as grain refiner and the resulting microstructure and grain size distributions were studied after extrusion and equal channel angular pressing (ECAP). Results showed that the addition of 0.6% TiBAl had the strongest grain refinement effect, reducing the grain sizes by 54.5 and 48.5% in the extruded and ECAPed conditions, respectively. The observed grain refinement was partly due to the presence of the thermally-stable micron- and submicron-sized particles in the melt which act as nucleation sites during solidification. During the high-temperature extrusion and ECAP processes, dynamic recrystallization (DRX) and grain growth are likely to occur. However, the mentioned particles will help in reducing the grain size by the particle stimulated nucleation (PSN) mechanism. Furthermore, the pinning effect of these particles can oppose grain growth by reducing the grain boundary migration. These two phenomena together with the partitioning of the grains imposed by the severe plastic deformation in the ECAP process have all contributed to the achieved ultrafine-grained structure in the AZ 31 alloy.

scholarly journals A brief overview on grain growth of bulk electrodeposited nanocrystalline nickel and nickel-iron alloys

2019 ◽  
Vol 58 (1) ◽  
pp. 98-106
Author(s):  
Haitao Ni ◽  
Jiang Zhu ◽  
Zhaodong Wang ◽  
Haiyang Lv ◽  
Yongyao Su ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Growth Process ◽  
Boundary Migration ◽  
Thermal Conditions ◽  
Iron Alloys ◽  
Nanocrystalline Nickel ◽  
Nickel Iron ◽  
Average Grain Size

Abstract This review focuses on grain growth behaviors and the underlying mechanisms of bulk electrodeposited nanocrystalline nickel and nickel-iron alloys. Effects of some important factors on grain growth are described. During thermal-induced grain growth process, grain boundary migration plays a key role. For similar thermal conditions, due to grain boundary mobility with solute drag, limited grain growth occurs in nanocrystalline alloys, as compared to pure metals. Nonetheless, in the case of stress-induced grain growth process, there are a variety of mechanisms in samples having various deformation histories. As an example the grain growth of nanocrystalline nickel and Ni-20%Fe alloy with nearly the same grain-size distribution and average grain size is compared in this paper. Thermal analysis indicates nanocrystalline nickel is much more prone to rapid grain growth than nanocrystalline Ni-20%Fe alloy. Nevertheless, grain growth of nanocrystalline Ni-20%Fe is found to be more pronounced than nanocrystalline nickel during rolling deformation.

Effect of Ti3Si on Texture in Ti-Nb Based Shape Memory Alloys

2006 ◽  
Vol 980 ◽  
Author(s):  
Ryutaro Shimizu ◽  
Kei Masumoto ◽  
Yusuke Fukui ◽  
Tomonari Inamura ◽  
Kenji Wakashima ◽  
...  
Keyword(s):  
Grain Size ◽  
Recrystallization Texture ◽  
Electron Backscatter Diffraction ◽  
Boundary Migration ◽  
Solution Treatment ◽  
Rolling Texture ◽  
Β Phase ◽  
Solution Treated ◽  
Average Grain Size ◽  
Si Content

AbstractEffect of Ti3Si particles on recrystallization texture of Ti-Nb based superelastic alloys has been investigated using X-ray pole figure measurement and electron backscatter diffraction (EBSD) technique. The alloys used were Ti-24mol%Nb-3mol%Al-Xmol%Si (X=0~0.9, termed XSi) and Ti-24mol%Nb-3mol%Si alloy (termed 3Si). The apparent phase at room temperature was β-phase (bcc). Besides, (Ti, Nb)3Si particles with PTi3 type crystal structure were formed in the alloys with Si content higher than 0.7mol%. After the cold rolling of 99% reduction in thickness, a rolling texture of the β-phase was formed to be mainly {001}β<110>β regardless of the presence of the (Ti, Nb)3Si particles. After the solution treatment at 1273K, a recrystallization texture formed to be {112}β<110>β in all the alloys except for 3Si. The average grain size of the recrystallized alloys was 20~40μm. On the other hand, the solution treated 3Si exhibited the {001}β<110>βn texture and the average grain size of 3μm. It is concluded that the {001}β<110>β texture with fine grains of the solution treated 3Si is obtained by the suppression of grain boundary migration due to the existence of the (Ti, Nb)3Si particles.

The Effect of Solute Drag on Grain Growth in Thin Films

1993 ◽  
Vol 317 ◽  
Author(s):  
H.J. Frost ◽  
Y. Hayashi ◽  
C.V. Thompson ◽  
D.T. Walton
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Grain Growth ◽  
Driving Forces ◽  
Boundary Migration ◽  
Solute Drag ◽  
Polycrystalline Thin Films ◽  
Average Curvature ◽  
Grain Size Distributions ◽  
Dimensional Simulation

ABSTRACTWe have modelled the microstructural evolution of polycrystalline thin films during grain growth under the situation in which grain boundary migration becomes impeded by solute drag. For this we use a two-dimensional simulation of capillarity-driven grain growth in which grain boundaries migrate at velocities proportional to local curvature. At high driving forces, corresponding to high curvatures, the boundaries are given a mobility corresponding to drag-free motion. At low driving forces, corresponding to curvatures less than some critical value, the boundaries are given a lower mobility which models the effect of solute drag. During grain growth the average curvature of boundary segments decreases. When the boundary curvatures begin to fall below the critical curvature, the grain size distribution evolves to a lognormal distribution, which is maintained as significant further grain growth occurs. This is in accordance with many experimental grain size distributions which are commonly observed to be lognormal.

scholarly journals An Investigation on Grain Growth in a Commercial Al–Mg Alloy

1998 ◽  
Vol 30 (3-4) ◽  
pp. 191-206 ◽  
Author(s):  
I. Samajdar ◽  
L. Rabet ◽  
B. Verlinden ◽  
P. Van Houtte
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Primary Recrystallization ◽  
Abnormal Grain Growth ◽  
Grain Boundary Character Distribution ◽  
Grain Boundary Character ◽  
Character Distribution ◽  
Boundary Character Distribution ◽  
Selection Of

Alloy AA5182 contains coarse constituent particles and submicron dispersoids. While the former may cause particle stimulated nucleation (PSN) during primary recrystallization, the fine dispersoids may ‘arrest’ grain growth during subsequent annealing. Abnormal grain growth was observed after dissolution/coarsening of the dispersoids. Mainly S [{123}〈634〉] grains, but also some Brass [{011}〈112〉] and Cu [{112}〈111〉] grains, were observed to grow abnormally. Both the grain size and the grain boundary character distribution (GBCD) possibly played a role in the selection of the grains for abnormal grain growth. A dramatic increase in the number fraction of extremely low angle (1−5°) boundaries was observed with annealing, the increase being more at 470°C (when dispersoids were stable and grain growth was arrested more effectively) than at 500°C/530°C (when inhibition to grain growth was less). The nature of the CSL boundaries did not change significantly with annealing time/temperature.

scholarly journals Thermal Stability of AA1050 Aluminum Alloy after Equal Channel Angular Pressing

2017 ◽  
Vol 62 (2) ◽  
pp. 777-786 ◽  
Author(s):  
P. Koprowski ◽  
R. Bogucki ◽  
M. Bieda ◽  
J. Kawałko ◽  
K. Sztwiertnia
Keyword(s):  
Grain Size ◽  
Aluminum Alloy ◽  
Equal Channel Angular Pressing ◽  
Electron Backscatter Diffraction ◽  
Longitudinal Section ◽  
Annealing Behavior ◽  
Angular Pressing ◽  
Diffraction Patterns ◽  
Backscatter Diffraction ◽  
Quality Maps

AbstractThe annealing behavior of AA1050 aluminum alloy deformed by equal-channel angular pressing (ECAP) was studied experimentally. The material was subjected to extrusion through die with channels intersecting at an 90° angle. Samples were pressed for up to 8 passes using route BC, then cut into slices and subsequently annealed for 1 hour at temperatures from 100°C to 350°C. Hardness measurements were performed on each slice. Microstructure of material was analyzed in the longitudinal section by means of Electron Backscatter Diffraction system in a scanning electron microscope (EBSD/SEM). From the obtained sets of Kikuchi diffraction patterns orientation maps and Image Quality maps were determined. Grain size, disorientation distributions and crystallographic texture were also estimated. ECAP caused significant improvement of hardness, with stabilization after 4 passes. Refinement of microstructure was obtained with the increasing amount of passes. Material properties were stable during annealing at temperatures lower than 150°C. Annealing at higher temperatures caused a decrease in hardness corresponding to an increase of the grain size.

Recrystallization and Grain Growth Phenomena in Stainless Steels for Different Thermo-Mechanical Processes

2018 ◽  
Vol 941 ◽  
pp. 135-140 ◽  
Author(s):  
Giuseppe Napoli ◽  
Stefano Grimozzi ◽  
Claudia Rocchi ◽  
Andrea di Schino
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Grain Growth ◽  
Stainless Steels ◽  
Mechanical Characteristics ◽  
Volume Fraction ◽  
Primary Recrystallization ◽  
Drag Effect ◽  
Zener Drag ◽  
Steel Grades

The mechanical properties of steels are strictly connected to chemical composition as well as to microstructural features obtained after thermo-mechanical processing. As a consequence, recrystallization and grain growth are relevant to the mechanical properties of steels, thus suggesting the necessity of mathematical models able to predict the microstructural evolution after thermo-mechanical cycles. In particular, in stainless steel grades, mechanical characteristics, and a proper microstructure with an adequate grain size distribution, are very important in order to achieve the required formability and deep drawing properties for many applications. This paper deals with the study of microstructural changes, such as grain size variations and recrystallized volume fraction in stainless steels during isothermal treatments through the application of a mathematical model, able in general to describe the primary recrystallization and grain growth in metals. The developed model takes into account the recrystallization phenomenon and Zener drag effect. A general continuity equation is proposed describing in continuous way recrystallization and grain growth phenomena without taking into account textures effect. The influence of input parameters is analyzed.

Tales of the Abnormal: Nanocrystalline Grain Growth at Low Temperatures

2012 ◽  
Vol 715-716 ◽  
pp. 315-316
Author(s):  
Heiko Paul ◽  
Jules M. Dake ◽  
Carl E. Krill III
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Early Stage ◽  
Boundary Migration ◽  
Weighted Average ◽  
Transient Stage ◽  
Thermally Induced ◽  
Size Dependent ◽  
Dependent Change ◽  
Rate Limiting

Employing x-ray diffractometry and electron microscopy, we have investigated thermally induced microstructural evolution in ball-milled nanocrystalline Fe. At low annealing temperatures, the early-stage growth of the area-weighted and volume-weighted average grain sizes deviates strongly from the parabolic behavior expected for normal grain growth. Analysis of the ratio of these two averages indicates that the width of the grain-size distribution changes with time. This result is more consistent with the occurrence of a transient stage of abnormal grain growth than with a grain-size-dependent change in the rate-limiting mechanism for grain-boundary migration.

Sign in / Sign up

Export Citation Format

Share Document