The role of grain boundary character distribution in secondary recrystallization of electrical steels

Hayakawa, Y.; Szpunar, Jerzy A.

doi:10.1016/s1359-6454(96)00251-0

Cited by 185 publications

(94 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been proposed, based on experiments, that this phenomenon arose from the grain boundary pinning by precipitates, [1][2][3] surface energy anisotropy and surface grooving, [4][5][6][7] recrystallization texture, 8,9) or grains with coincidence site lattice (CSL) orientations. [10][11][12] But the dominant mechanism is yet to be determined. One of the unresolved questions is if AGG can occur in this alloy without developing any texture.…”

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Grain Boundary Structure and Grain Growth in Bulk Silicon-Iron.

Choi

Yoon

2003

ISIJ International

View full text Add to dashboard Cite

Grain boundary shapes and grain growth in bulk 2.61 wt% silicon-iron have been studied by heat-treating at temperatures between 700 and 1 200°C. Initial microstructure with fairly uniform fine grains has been obtained by recrystallization at 800°C for 5 min after deformation. When subsequently heat-treated at 700 and 800°C, a fraction of the grain boundaries have hill-and-valley shapes with several facet planes or kinks. Some of these facet boundary segments are expected to be singular. Abnormal grain growth occurs at 700 and 800°C and is attributed to step growth of the boundaries. When heat-treated at 1 000°C, all grain boundaries are defaceted with smoothly curved shapes, indicating that they are atomically rough. At temperatures above 1 000°C, normal grain growth occurs, because the rough grain boundaries move continuously. This correlation between grain boundary structure and grain growth is consistent with the earlier observations in other metals and oxides. It is thus shown that the abnormal grain growth in this alloy occurs at low temperatures because of the singular grain boundary structure.KEY WORDS: silicon-iron; silicon-steel; abnormal grain growth; grain boundary faceting; singular grain boundary.ing along the grain boundaries using an image analysis program. For the specimens with fine grains, about 500-2 000 grains were measured, and for those with large grains, about 100-300 grains were measured. The grain boundary shapes were also examined in a transmission electron microscope (TEM). Results and DiscussionWet chemical analysis of the heat-treated bar showed that the Si content was 2.61 wt% and the major impurities were P (0.015 wt%), Ni (0.06 wt%), and Cr (0.01 wt%). The C, Mn, and S contents were about 0.005 wt%. The specimens heat-treated at 800°C for 5 min after compressing to 66.7 % in height had typical primary recrystallization structures with fine grains of 8.7 mm in average radius as shown in Fig. 1. The X-ray pole figure and electron back-scattered pattern (EBSP) analysis of these specimens did not show any macroscopic or microscopic texture. Figure 1 is the initial microstructure for all subsequent heat-treatments at various temperatures to observe the grain growth behavior.The grain growth during the heat-treatment at 600°C was very slow. After 250 h at 600°C, the grains were only slightly larger than those shown in Fig. 1. During the heattreatment at 700°C, typical AGG behavior was observed as shown in the microstructures of Fig. 2, and grain size distributions in Fig. 3. After 3 h, some large grains began to appear as shown in Fig. 2(a), and after 24 h, some grains had grown to about 700 mm radius as shown in Fig. 2(d). In Fig. 3, those large grains that could be clearly identified as the abnormal grains are marked by arrows. The fine matrix grains grew slowly as can be seen in Figs. 2 and 3.When the heat-treatment temperature was increased to 800°C, distinct AGG behavior was again observed during 24 h, but the number density of the abnormal grains was larger than that observed at ...

show abstract

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Grain Boundary Structure and Grain Growth in Bulk Silicon-Iron.

Choi

Yoon

2003

ISIJ International

View full text Add to dashboard Cite

show abstract

“…The magnetic induction measured at 800 A/m (B 8 ) correlates well with the orientation degree of Goss texture 2 . The typical B 8 results of CGO and HGO steels are 1840 and 1930 mT, respectively 3 . The Goss texture of grain oriented silicon steel is obtained in the final high temperature annealing by abnormal grain growth or secondary recrystallization from a recrystallized matrix , named primary matrix, where the normal grain growth is inhibited by a dispersion of second phase particles 4 .…”

Section: Introductionmentioning

confidence: 99%

“…Taking into account this model, some works suggests that CSL Σ9 and CSL Σ5 boundaries play an important role in growth selection of Goss grains in HI-B and CGO steels, respectively [6][7][8] . The second model is based on the assumption that the high mobility is a feature of the so called "high energy" (HE) boundaries defined as boundaries between grains misoriented by the angle of 20 to 45° [ 3,9] . In the same way, the advantage of the Goss grains would come from the fact that they have the highest probability of forming HE boundaries with neighboring grains in the primary matrix.…”

Section: Introductionmentioning

confidence: 99%

Effect of the low temperature annealing on primary and secondary structures and magnetic properties of Fe-3% Si

et al. 2011

View full text Add to dashboard Cite

The processing of 3% Si steel is characterized by the use of MnS particles as a normal grain growth inhibitor. Experiments were carried out to investigate the grain growth in this material during heat treatments at low temperature. Industrial decarburized samples were annealed in the range 825-845 °C and a detailed study of grain size and texture was made by EBSD measurements. The primary grain size and texture were related to the secondary structure obtained after high temperature final annealing. The heat treatments for grain growth led to an increase in the mean grain size by 1.2 to 3 times, depending on the stability of MnS particles distribution. The increase of the primary grain size increased the core loss and decreased the magnetic induction of the fully processed material.

show abstract

“…10,11) Such boundaries are expected to have larger precipitates associated with them which coarsen more quickly during the heating stage, but before dissolution. Thus, at a critical stage they will be subject to less pinning, giving a growth advantage.…”

Section: Introductionmentioning

confidence: 99%

Formation of the Goss Texture in a Thin Foil Experiment on Fe–3.2%Si

2010

View full text Add to dashboard Cite

shows the same areas, only this time the Goss orientations are shaded. The Goss grains are located in the h fibre distribution and in this the Goss grains are concentrated. It is plain from Figs. 2 and 3 that the h fibre is more intense in some regions than in others, i.e., it occurs in patches across the sheet plane and it is most concentrated in the sub-surface quarter thickness layers. Figure 4 shows the effects of heating at 970°C in a salt bath for 1, 5 and 10 min. Secondary recrystallization has begun in the top surface after 1 min, Fig. 4(a), and that it originates at both surfaces is the most probable explanation for the centre-line effect after 5 min annealing, Fig. 4(b). After 10 min secondary grains have grown to impinge both surfaces, and the process is now almost complete, Fig. 4(c). The orientation of the obvious secondary grains are widely scattered around the Goss orientation after 1 min, and the texture quite obviously becomes much more closely aligned with Goss as time at 970°C continues, ISIJ International, Vol. 50 (2010) TD cross sections covering the whole sheet thickness of a primary recrystallized sample. The orientations outlined by gray and dark lines correspond to ( Fig. 2(a and b)) the central thickness g fibre grains and subsurface h fibre (Fig. 2(c and d)) grains, respectively., Fig. 4(f). This texture sharpening is also well-known. In order to check the effects of the as-processed surface on subsequent secondary recrystallization, about 20-25 mm of material was removed from both sides before annealing. This is indicated schematically in Fig. 5(a), and the texture results after complete secondary recrystallization i.e., when secondaries were of sheet thickness, are shown in Fig. 5(b). Comparing Figs. 4(f) with 5(b) shows that any effects associated with the surfaces are not significant.A sub-surface foil of 80 mm in thickness was carefully electropolished from the as-received sheet, and another foil of this thickness was prepared from the centre of the sheet. The geometry is shown in Fig. 6(a). It was found that secondary recrystallization occurred rapidly in both foils, but growth stagnated after 570 min at 1 000°C in the vacuum furnace. In the sub-surface foil grains ranged in size from 100 to 1 300 mm, while in the central foil the range was smaller, i.e., from 100 to 900 mm. In all cases the largest grains occupied the whole thickness of the foils. Fig. 6(b) shows a {100} pole figure of all the grains of size greater than 100 mm, and Fig. 6(c) those larger than 600 mm found in the sub-surface foil. It is plain that the largest grains shown in Fig. 6(b) contain a subset clustered around the Goss orientation, Fig. 6(c). When the data from the central foil is similarly processed, the texture is mostly {111}͗hkl͘ Fig. 6(d), as is the subset from the largest grains, Fig. 6(e). This set of results indicate that Goss oriented grains, which exist throughout the thickness of the sheet, Fig. 3, grow preferentially in the subsurface h fibre layer Fig. 2. That it can and does grow prefe...

show abstract

The role of grain boundary character distribution in secondary recrystallization of electrical steels

Cited by 185 publications

References 42 publications

Temperature Dependence of Grain Boundary Structure and Grain Growth in Bulk Silicon-Iron.

Temperature Dependence of Grain Boundary Structure and Grain Growth in Bulk Silicon-Iron.

Effect of the low temperature annealing on primary and secondary structures and magnetic properties of Fe-3% Si

Formation of the Goss Texture in a Thin Foil Experiment on Fe–3.2%Si

Contact Info

Product

Resources

About