Secondary Recrystallization In Fe-3 Research Articles

Secondary recrystallization in Fe-3% Si alloy with (110)[001] single-component texture

After the primary recrystallization of a preliminarily deformed (110)[001] single crystal, the texture also has the preferred (110)[001] orientation. Furthermore, the texture contains weak orientations, a major part of which is formed at the sample surface and can be described by a spectrum of scattered orientations {120}〈210〉…{351}〈103〉. A further heating leads to two concurrent processes taking place in the samples, i.e., the normal growth of Goss grains and secondary recrystallization. Abnormally grown crystals are represented by a quartet of orientations related with the initial Goss orientation by a rotation around [011], [01\(\bar 1\)], [101], and [10\(\bar 1\)] axes at an angle of ∼30°. The crystallographic relationship between the initial and final grain orientations can be explained by their closeness to special misorientations as follows: Σ9, Σ19a, Σ27a, and Σ33a (rotation around 〈110〉 axes to close angles).

Abnormal Grain Growth Approached by Sub-Boundary Enhanced Solid-State Wetting

Abnormal grain growth (AGG), which is also called the secondary recrystallization, often takes place after primary recrystallization of deformed polycrystalline materials. A famous example is the evolution of the Goss texture after secondary recrystallization of Fe-3%Si steel. A selective AGG of Goss grains has remained a puzzle over 70 years in the metallurgy community since its first discovery by Goss in 1935. We suggested the sub-boundary enhanced solid-state wetting as a mechanism of selective AGG of Goss grains. According to this mechanism, if Goss grains have sub-boundaries of low energy, they have an exclusively high probability to grow by solid-state wetting along a triple junction compared with other grains without sub-boundaries. This aspect has been confirmed by Monte-Carlo and Phase Field Model simulations. The simulations showed that if the abnormally-growing grain has a high fraction of low energy boundaries with the matrix grains, it favors the sub-boundary enhanced solid-state wetting and produces many island and peninsular grains frequently observed near the growth front of abnormally-growing Goss grains. For example, the {111}<112> orientation has a S9 relationship with a Goss grain. Therefore, grains with the {111}<112> orientation provide a favorable condition for sub-boundary enhanced solid-state wetting. Three or four-sided grains with convex-inward boundaries, which are observed on a two-dimensional section of polycrystalline structures, are not shrinking but are growing, indicating that they are growing by wetting along a triple junction. These and other microstructural evidences of solid-state wetting could be observed relatively easily near the growth front of abnormally-growing Goss grains. The existence of sub-boundaries exclusively in abnormally-growing Goss grains has been experimentally confirmed. In order to understand why only Goss grains have sub-boundaries, the cold rolling process of the hot-rolled Fe-3%Si steel was analyzed by finite element method (FEM). The analysis showed that a small portion of Goss grains formed during hot rolling survives after cold rolling; the survived Goss grains have the lowest stored energy and are expected to undergo only recovery without recrystallization, producing sub-boundaries.

The Effect of Cold Rolling Direction on the Secondary Recrystallization in Fe-3%Si Steel

In order to verify the origin of Goss nuclei for secondary recrystallization in Fe-3%Si steel, the effect of cold-rolling direction on the secondary recrystallization was examined in this study. The cold-rolling direction was rotated through 0 ~ 90 degrees about the hot-rolling direction on normal direction axis of hot-rolled sheet. In spite of the different initial texture before cold rolling, the 88% cold rolled texture was formed by similar α and γ fiber regardless of the rotation of cold rolling direction. Likewise, regardless of the cold rolling direction, the primary recrystallized sheets had a similar texture. In particular, the area fraction of Goss component (tolerance angle within 15º) in the primary recrystallized sheets was increased in the cold rolling condition of rotating through 60, 90 degrees from the hot rolling direction. After high temperature annealing at 1200°C, the secondary recrystallized grain was fully evolved in the all conditions. The sharpness of Goss texture in secondary recrystallized sheet was decreased as increasing the rotation angle of cold rolling direction.

Characteristic Microstructure and Grain Boundary Motion in Secondary Recrystallization of Fe-3%Si Alloys

The microstructure of Fe-3 mass% Si alloys before secondary recrystallization has been characterized by analyzing precipitates and grain boundary segregated elements. The samples used were mainly sheets of Fe-3%Si alloys containing manganese, sulfur, aluminum, nitrogen and tin, which were decarburized and annealed up to secondary recrystallization. Grain boundary segregation in primarily recrystallized samples was studied using Auger electron spectroscopy (AES), and precipitates were analyzed using transmission electron microscopy (TEM) with an energy dispersive X-ray spectrometer (EDX). AES spectra showed that tin and nitrogen were enriched on grain boundaries in the Fe-3 mass% Si alloys. TEM/EDX analysis showed that the morphology and distribution of the fine precipitates such as manganese sulfide and aluminum nitride were influenced by addition of tin. The characteristic structure formed by secondary recrystallization of grain oriented silicon steel is considered to be influenced by the fine precipitates and segregation of a small amount of elements, as the abnormal motion of grain boundaries of the silicon steel was correlated with the precipitation and segregation of the alloying elements.

Influence of the Goss Grain Neighbourhood during Secondary Recrystallization of Fe-3%Si Sheets

Influence of the Goss Grain Neighbourhood during Secondary Recrystallization of Fe-3%Si Sheets

Fe-3%Si合金の二次再結晶挙動におよぼす冷延率の影響

Fe-3%Si合金の二次再結晶挙動におよぼす冷延率の影響

Mechanism of Orientation Selectivity During Grain Growth of Secondary Recrystallization in Fe-3%Si Alloy

Selective growth of {110}〈001〉 grains in the temperature gradient annealing has been studied in Fe–3%Si alloy. As grains grow, the average deviation angle from the ideal {110}〈001〉 orientation becomes smaller and orientation distribution changes corresponding to that of coincidence grains in the matrix. Secondary recrystallization temperature depends on the orientation of secondary recrystallized grain and sharper {110} 〈001〉 grains grow preferentially at lower temperatures.These phenomena are explained by modified Hillert's model of grain growth. Interfacial energy of coincidence boundary is lower than that of general boundary. Therefore, sharper {110}〈001〉 grains, which have higher frequency of coincidence grains in the primary recrystallized matrix, suffer lower pinning effect from the second phase particles and thus grow preferentially at lower temperatures.

Recrystallization and Related Phenomena. Mechanism of Orientation Selectivity of Secondary Recrystallization in Fe-3%Si Alloy.

Selective growth behavior of {110} <001> grains has been studied utilizing the temperature gradient annealing method. As grains grow, the average deviation angle from the ideal {110} <001> orientation becomes smaller and orientation distribution changes corresponding to that of coincidence grains in the matrix. Secondary recrystallization temperature depends on the orientation of secondary recrystallized grain and sharper {110} <001> grains grow preferentially at lower temperatures. These phenomena are explained by modified Hillert's model of grain growth, which takes the grain boundary characteristics into account. Sharper {110} <001> grains, which have higher frequency of coincidence grains in the primary recrystallized matrix, suffer lower pinning force from the precipitates and thus grow preferentially at lower temperatures.

Influence of primary Recrystallized Structure on Secondary Recrystallization in Fe-3%Si Alloy

Influence of primary Recrystallized Structure on Secondary Recrystallization in Fe-3%Si Alloy

Computer Simulation of the Influence of Inhibitor Intensity on Secondary Recrystallization in Fe-3%Si Alloy

Computer Simulation of the Influence of Inhibitor Intensity on Secondary Recrystallization in Fe-3%Si Alloy

Influence of Inhibitor Intensity on Secondary Recrystallization in Fe-3%Si Alloy

Influence of Inhibitor Intensity on Secondary Recrystallization in Fe-3%Si Alloy

Effect of thickness on secondary recrystallization of Fe-3%Si

A study was made on the effect of the final thickness (0.60-0.18 mm) on the secondary recrystallization of Fe-3%Si using MnS and AlN as inhibitors. When heated in hydrogen during final annealing, the 0.60 mm thick specimen underwent a complete secondary recrystallization, but the 0.36 mm and thinner specimens did an incomplete secondary recrystallization. When heated in a mixture gas of hydrogen and nitrogen during final annealing, all specimens underwent a complete secondary recrystallization, but the thinner the specimen, the lower the magnetic flux densities were. The reduction of final thickness makes the specimen too sensitive to the atmosphere during final annealing to get a precisely Goss-oriented secondary-recrystallized texture.

3mass%Si鋼の二次再結晶過程に及ぼすSn添加の影響

3mass%Si鋼の二次再結晶過程に及ぼすSn添加の影響

Coincidence grain boundary and role of inhibitor for secondary recrystallization in Fe-3% Si alloy

Secondary recrystallization behavior in the presence of AlN and MnS precipitates in Fe-3% Si alloy, processed by one stage cold rolling method, was investigated with special reference to a role of inhibitor for secondary recrystallization. The sharpness of Goss secondary texture is higher in the early stage of secondary recrystallization. In the case of stronger grain growth inhibition by precipitates during secondary recrystallization, the evolution of secondary recrystallized grains in orientations dispersed from Goss orientation is smaller than that in the case of weaker grain growth inhibition. The mechanism of these experimental results is explained by the specific grain boundary migration characteristics in the presence of inhibitor, namely, the critical frequency of Σ9 coincidence oriented grains in relation to nucleus for the evolution of secondary recrystallization is considered to be higher in the case of stronger grain growth inhibition during secondary recrystallization.

Fe-3%Si合金の2次再結晶に対する1次冷間圧延前焼鈍の影響

Secondary recrystallization of Fe-3%Si alloy containing AlN and MnS precipitates, which is usually given a heavy reduction at the final cold-rolling stage, was investigated with special reference to an influence of annealing of hot-rolled band before first cold rolling. In the annealing process of hot-rolled band, fine carbides or nitrides with 10∼20 nm in diameter precipitated, resulting in increasing the dislocation density with tangling dislocations around those precipitates. Accordingly, on the annealing stage after the first cold-rolling, the recrystallized microstructure was finer and more homogeneous. In addition, a decrease in {211}〈011〉∼{100}〈011〉 (RD\varparallel〈011〉) oriented grains and an increase in {111}〈112〉 ones occurred. Annealing of hot-rolled band is probable to have an important effect on enhancement of {110}〈001〉 secondary recrystallized grain growth, because of more {111}〈112〉 primary recrystallized grains, which has Σ9 coincidence orientation relationship to the {110}〈001〉 orientation.

Coincidence grain boundary and (100)[011] secondary recrystallization in Fe-3% Si

Secondary recrystallization texture consisting of (100)[011], as a major component, and (100)[001], as a minor component, are evolved from cross rolled and annealed Fe-3% Si. On the assumption that a Σ7 boundary is more mobile than a Σ9 boundary, the mechanism of the evolution of (100)[001] and (100)[011] secondary recrystallization can be explained as follows. (100)[011] grains are evolved as this orientation has the second highest value of I C Σ7 and the highest value of P CN Σ7 among orientations with P CN Σ1 values less than 100. Here the I C Σ7 value is the intensity of Σ7 oriented grains calculated for the nucleus orientation N, namely (100)[011], and the P CN Σ7 value is a product of the intensity of a nucleus orientation ( I N) and the I C Σ7 in matrix texture before grain growth. P CN Σ1 value is a product of the intensity of a nucleus orientation ( I N) and the intensity of Σ1 oriented grains ( I C Σ1) for the nucleus orientation (100)[011] in the matrix texture before grain growth (100)[001] grains are evolved as this orientation has effectively the highest value of I C Σ7 in the matrix texture before grain growth. The number of (100)[001] grains evolved is smaller than that of (100)[011] grains due to the low intensity of the nucleus orientation ( I N = (100)[001]).

Coincidence grain boundary and (100) [001] secondary recrystallization in Fe-3% Si

The mechanism of the (100) [001] texture evolution by grain growth was investigated by X-ray diffraction and back-reflection Laue diffraction method. The main results obtained are as follows. (1) (100) [001] secondary recrystallization texture evolved from a primary texture having a major orientation of {236} 〈5 15 9⦔ and including precipitates of AIN and MnS. The deviation angle of secondary grains from an ideal (100) [001] orientation increased with elevating annealing temperature. The evolution of a small amount of secondary grains other than (100) [001] orientation are also observed. They are (100) [001] (at 1150°C) and (100) [001] (at 1100°C and 1200°C). (2) The mechanism of the evolution of the (100) [001] texture by secondary recrystallization was found to be due to the highest frequency of Σ7 coincidence boundaries in relation to (100) [001] orientation in the matrix texture before the onset of secondary recrystallization. The evolution of the (100) [001] oriented secondary grains at the latter stage of the secondary recrystallization annealing was considered to be due to the second highest frequency of Σ7 coincidence boundaries in relation to (100) [011] orientation. The increase in the scatter of the orientation of (100) [001] secondaries from an ideal (100)[001] orientation was considered to be due to the decrease in the frequency of Σ7 coincidence boundaries with increasing deviation angle from an ideal (100) [001] orientation. (3) Present results supports the hypothesis proposed by the present authors that grains having the highest frequency of coincidence boundaries in the matrix can grow largest in the grain growth process.

Fe-3%Si合金の2次再結晶に及ぼすAlN析出の影響

Fe-3%Si合金の2次再結晶に及ぼすAlN析出の影響