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Materials Science and Engineering A 527 (2010) 1882–1890

Contents lists available at ScienceDirect

Materials Science and Engineering A

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exture and grain growth characteristics in a boron added interstitial free steelfter severe cold rolling and annealing

ajib Saha ∗, R.K. Ray&D Division Tata Steel, Jamshedpur 831001, India

r t i c l e i n f o

rticle history:eceived 28 August 2009eceived in revised form 5 November 2009ccepted 5 November 2009

a b s t r a c t

A boron added interstitial free steel was cold rolled (CR) 90% and 98%, followed by batch annealing fordifferent lengths of time at 650 ◦C. Crystallographic textures were determined for the cold rolled, partiallyrecrystallized and the fully recrystallized materials. The overall texture of the 98% cold rolled sample wassharper than that of the 90% cold rolled material, though both showed the presence of the gamma andthe alpha fibres. Recrystallization led to a decrease in the texture intensity of the 90% cold rolled steel,

eywords:nterstitial free steelevere cold rollingextureelective growth

while reverse was the case for the 98% cold rolled material. The r bar value of the 98% cold rolled andrecrystallized steel was only marginally less than that of its 90% counterpart. Selective growth of grainswith {5 5 4} 〈2 2 5〉 and {1 1 1} 〈1 2 3〉 orientations (for the 98% cold rolled material) and with {1 1 3} 〈4 7 1〉and {2 2 3} 〈6 9 2〉 orientations (for the 90% cold rolled material) was observed after recrystallization. The�11 and the �13b CSL boundaries appeared to be involved in this process.

oincidence site lattice (CSL)rain boundary misorientation distribution

. Introduction

In the steel industry throughout the world, cost reduction,nvironmental safety and resource saving have become impor-ant issues. Attempts are going on to meet these objectives byndertaking research directed towards developing either neweraterials (steels) or modifying existing materials (steels). A large

ercentage of low and ultra low carbon steels is mainly used forither the automotive or packaging sector. Apart from aluminium,teel is another essential material generally used in the packagingndustry.

Now a days, the world automotive as well as packaging indus-ry is keen to develop low gauge or thin steel sheets to produceight weight products which will help in saving significant amountf material and energy. One way of achieving this could be to goor cold deformation levels much higher than what is practised

85–90%) now a days [1]. It is well known that the amount ofrior cold deformation plays an important role in determining thenal properties by controlling the texture and microstructure afterecrystallization [1–3]. A large amount of research work has been

Abbreviations: HR, hot rolled; CR, cold rolled; HAGB, high angle grain boundaries;AGB, low angle grain boundaries; CSL, coincidence site lattice boundaries; CR90,0% cold rolled; CR98, 98% cold rolled; CR98210, 90% cold rolled and annealed for10 min; CR98210, 98% cold rolled and annealed for 210 min.∗ Corresponding author. Tel.: +91 657 2147445; fax: +91 657 2345407.

E-mail addresses: rajib.saha@tatasteel.com, rajib31@gmail.com (R. Saha).

921-5093/$ – see front matter © 2009 Elsevier B.V. All rights reserved.oi:10.1016/j.msea.2009.11.019

© 2009 Elsevier B.V. All rights reserved.

carried out on the development of recrystallization texture andmicrostructure after low to moderate amount of cold deformation.The development of crystallographic texture and microstructureduring recrystallization and grain growth of severely cold rolled(CR) steel sheets has hardly been reported. Hence there is a need toinvestigate these aspects thoroughly.

In recent years, there has been quite a bit of work to understandthe effects of severe plastic deformation (SPD) techniques such asthe equal channel angular pressing (ECAP) and the accumulatedroll bonding (ARB) on texture, microstructure and grain boundarycharacter distribution (GBCD), specially in FCC metals [4–9] and tosome extent in steels [10]. Information on the GBCD in severely coldrolled IF steel is hardly available except in the work by Reis et al. [11]and Li et al. [12] and in some recently published work by the presentauthors [13–17]. It has often been suggested [18–19] that duringgrain growth, selective growth of grains of some particular orienta-tions could be controlled by specific types of coincidence site lattice(CSL) boundaries. The CSL boundaries which are of most interest inthis respect are

∑9,

∑11,

∑13b,

∑19a,

∑27a and

∑33c. The

behaviour of CSL boundaries produced under normal cold rollingand annealing conditions has been studied to some extent [15].However, the effects of severe cold rolling on the development ofmicrostructure, texture and GBCD during recrystallization and on

the role of CSL boundaries on grain growth are not clear yet.

In the present investigation, a systematic study has been carriedout to understand the textural changes and changes in the graingrowth characteristics in a boron added IF steel after being sub-jected to two different amounts of cold rolling, namely 90% and 98%.

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R. Saha, R.K. Ray / Materials Science

n attempt has also been made to explain the role of CSL boundariesuring grain growth.

. Experimental

The chemical composition of the steel is: 0.004%C, 0.12%Mn,.008%S, 0.045%P, 0.01%Si, 0.04%Al, 0.0033%N, 0.043%Nb, 0.042%Ti,.0009%B (wt%). The steel was hot rolled 80% in several passes.he Finish Rolling Temperature (FRT) was kept within ±10 ◦C of00 ◦C. The hot rolled steel was then cold rolled by an amount 90%

ε = 2.3) and 98% (ε = 3.92). The cold rolled samples were subjectedo isothermal annealing at 650 ◦C in H2 atmosphere for differentengths of time to understand the texture development duringecrystallization and the grain growth behaviour. Crystallographicextures were determined from the mid thickness regions of the hot

Fig. 1. �1 sections of the ODFs (Bunge) of (a) 90% (b) 98% cold rolled; a

gineering A 527 (2010) 1882–1890 1883

rolled as well as cold rolled and annealed sheets using a FEI-Quanta200 Scanning Electron Microscope (SEM), coupled with an EBSDfacility. The details of data collection during EBSD scanning havebeen reported by the authors in several published papers [13–17].ODFs (orientation distribution functions) were calculated, using theTSL-OIM software and �1 sections (Bunge notation) were deter-mined therefrom. The distributions of misorientations and CSLboundaries were determined and the crystal orientation maps weregenerated using the same software. Specimens for transmissionelectron microscopy (TEM) were prepared from the longitudinal

sections of the severely cold rolled ultra thin sheets by dimplingand ion milling technique. The TEM work was carried out in a JEOL2000FX-II electron microscope operated at 160 kV. The details ofTEM specimen preparation can be found in the previous publishedpapers [13–14].

nnealed at 650 ◦C for 210 min of (c) 90% (d) 98% cold rolled steel.

1884 R. Saha, R.K. Ray / Materials Science and Engineering A 527 (2010) 1882–1890

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Fig. 1.

. Results

.1. Textural development

.1.1. ODF and fibre plotsThe �1 section ODFs of the 90% and 98% CR and annealed steels

re shown in Fig. 1(a–d). Overall, the texture of the 98% cold rolledaterial is much sharper than that of the 90% cold rolled sample.

he ODFs clearly indicate the presence of reasonably sharp � andfibres in both. These cold rolled materials become fully recrys-

allized after annealing at 650 ◦C for 210 min as has been showny microstructural studies. Annealing of the cold rolled materialsoes not change the basic textural characteristics. However, whilehe texture intensity of the annealed 90% cold rolled steel shows a

ecrease from that in the cold rolled condition, reverse is true forhe 98% cold rolled material. In fact, a very sharp � fibre is obtainedn the latter after annealing.

The plots for the � and � fibres for the cold rolled as well ashe annealed materials are presented in Fig. 2(a–d). In these plots,

inued)

in addition to the fibres of the cold rolled and fully recrystallizedsteels, the fibres from the intermediate annealing stages have alsobeen incorporated. By and large, these plots corroborate the resultsfrom the ODF plots. Although sharp � fibres are obtained in boththe fully recrystallized 90% and 98% cold rolled samples, havingtheir maxima at {1 1 1}〈1 1 2〉 locations, the intensity of the � fibrefor the 98% and annealed material appears to be nearly twice assharp compared to the 90% case. Similarly, the � fibre of the fullyrecrystallized 98% cold rolled material is also nearly twice as strongas that in the 90% cold rolled steel. it is further observed that inboth the materials, during annealing, the � fibre intensity shows aninitial increase, followed by a decrease after prolonged annealing.

3.1.2. Volume fractions of texture components

The analysis of the ODF data yielded a large number of texture

components. Out of these, the following components are foundto be part of the � fibre: {1 1 1}〈1 1 2〉, {1 1 1}〈1 2 3〉, {1 1 1}〈1 3 4〉,{5 5 4}〈2 2 5〉 and {1 1 1}〈1 1 0〉. On the other hand, the followingorientations are part of the � fiber: {0 0 1}〈1 1 0〉, {1 1 2}〈1 1 0〉,

R. Saha, R.K. Ray / Materials Science and Engineering A 527 (2010) 1882–1890 1885

fibre

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noticeable decrease in their volume fractions at the initial stages ofrecrystallization, beyond which they increase again. The important� fibre components in the recrystallization texture are{1 1 1}〈1 2 3〉,{1 1 1}〈1 3 4〉 and {1 1 1}〈1 1 2〉.Two major � fibre components of

Table 1Volume fractions of texture components of 90% CR and 210 min annealed IF steel.

Texture component Volume fraction

90% cold rolled Annealed for 210 min at 650 ◦C

{1 1 1}〈1 1 2〉 3.5 3.8{1 1 1}〈1 2 3〉 5.2 5.8{1 1 1}〈1 3 4〉 4.5 4.6{1 1 1}〈1 1 0〉 1.5 1.0{5 5 4}〈2 2 5〉 1.0 3.2{1 1 2}〈1 1 0〉 7.6 3.5{1 1 3}〈1 1 0〉 7.0 3.1{1 1 4}〈1 1 0〉 10.7 5.8{5 5 4}〈1 1 0〉 1.8 1.8{2 2 3}〈1 1 0〉 3.2 1.7{1 0 0}〈0 1 1〉 11.6 5.6

Fig. 2. (a) � Fibre (b) � fibre plots of 90% cold rolled steel and (c) � fibre (d) �

1 1 4}〈1 1 0〉, {1 1 3}〈1 1 0〉, {5 5 4}〈1 1 0〉 and {2 2 3}〈1 1 0〉. In addi-ion to these, the following components are normally found to beresent: {11 11 8}〈4 4 11〉, {2 2 3}〈6 7 2〉, {2 2 3}〈6 9 2〉, {9 3 4}〈1 1 3〉,1 1 3}〈4 7 1〉 and {0 0 1}〈1 0 0〉. Out of these {11 11 8}〈4 4 11〉,2 2 3}〈6 7 2〉 and {2 2 3}〈6 9 2〉 are close to the � fibre, while9 3 4}〈1 1 3〉 and {1 1 3}〈4 7 1〉 are close to the � fibre. For the sakef clarity, the volume fractions of the different texture componentsfter cold rolling and annealing have been presented in a set ofhree plots. The plots for the 90% cold rolled and annealed steel arehown in Fig. 3(a–c). The volume fractions of the different textureomponents for the 90% cold rolled as well as the annealed mate-ial are also presented in Table 1. The major components of the �bre in the recrystallization texture are {1 1 1}〈1 2 3〉, {1 1 1}〈124〉nd {1 1 1}〈1 1 2〉 while the minor components are {5 5 4}〈2 2 5〉 and1 1 1}〈1 1 0〉. The volume fractions of most of these componentso not vary significantly during the initial stages of annealing andttain minimum values after 30 min of annealing, beyond whichhey intensify and finally level off after longer periods of anneal-ng. So far as the � fibre is concerned, two of the components,he {1 1 4}〈1 1 0〉 and {1 0 0}〈1 1 0〉 become quite intense during thenitial stages of annealing. Later on, however, all the componentsf the � fibre assume low volume fractions after full recrystal-ization. Among the other texture components, the three most

mportant ones are {2 2 3}〈4 7 2〉, {2 2 3}〈6 9 2〉 and {1 1 3}〈4 7 2〉.hese three components are present in substantial volume frac-ions in the texture of the recrystallized steel. In addition, ratherow volume fractions of two other components such as {9 3 4}〈1 1 3〉nd {11 11 8}〈4 4 11〉 are also present.

plots of 98% cold rolled steel annealed at 650 ◦C for various lengths of time.

The volume fractions of texture components versus annealingtime plots for the 98% cold rolled and annealed steel are presentedin Fig. 4(a–c) and the relevant data are also shown in a tabular formin Table 2. The � fibre components of the cold rolled texture show a

{11 11 8}〈4 4 11〉 0.6 2.6{9 3 4}〈1 1 3〉 2.2 5.1{1 1 3}〈4 7 1〉 6.9 14.0{2 2 3}〈4 7 2〉 5.9 14.5{2 2 3}〈6 9 2〉 9.3 13.5

1886 R. Saha, R.K. Ray / Materials Science and Engineering A 527 (2010) 1882–1890

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Fig. 3. Plots of volume fractions of texture components for 90% cold rolled an

he cold rolling texture, namely, {1 0 0}〈0 1 1〉 and {1 1 4}〈1 1 0〉how a very rapid increase in their volume fractions during the ini-ial stages of recrystallization. Finally, the {1 1 4}〈1 1 0〉 componentecomes much weaker as recrystallization progresses. The minor �bre components of the recrystallization texture are {1 1 3}〈1 1 0〉,

1 1 2}〈1 1 0〉 and {2 2 3}〈1 1 0〉. In addition to the � and � fibre com-onents, two other texture components, namely, {2 2 3}〈6 9 2〉 and9 3 4}〈1 1 3〉 are also present in the recrystallization texture in sub-tantial amount.

able 2olume fractions of texture components of 98% CR and 210 min annealed IF steel.

Texture component Volume fraction

98% cold rolled Annealed for 210 min at 650 ◦C

{1 1 1}〈1 1 2〉 3.0 5.8{1 1 1}〈1 2 3〉 5.0 18.5{1 1 1}〈1 3 4〉 6.9 10.5{1 1 1}〈1 1 0〉 2.7 3.4{5 5 4}〈2 2 5〉 0.5 2.8{1 1 2}〈1 1 0〉 7.8 0.8{1 1 3}〈1 1 0〉 5.3 0.7{1 1 4}〈1 1 0〉 11.6 6.5{5 5 4}〈1 1 0〉 6.8 10.1{2 2 3}〈1 1 0〉 8.3 3.6{1 0 0}〈0 1 1〉 14.9 16.8{11 11 8}〈4 4 11〉 0.3 0.2{9 3 4}〈1 1 3〉 1.4 1.1{1 1 3}〈4 7 1〉 3.5 1.4{2 2 3}〈4 7 2〉 2.0 1.1{2 2 3}〈6 9 2〉 6.3 3.6

ealed at 650 ◦C for different time (a) � fibre (b) � fibre (c) other components.

3.2. Microstructural development

Fig. 5(a–b) represents typical longitudinal section TEM micro-graphs of the steel, cold rolled by an amount 90% and 98%. The TEMmicrograph of the 90% cold rolled steel shows a highly deformedand elongated cell structure. Cold rolling leads to the fragmenta-tion of grains and the onset of recovery inside a few cells. Enhanceddislocation density and more extensive recovery in specific regionsis visible in Fig. 5(b), which shows the TEM micrograph from the98% cold rolled steel. The average thicknesses of the cells in the 90%cold rolled steel is lower as compared to 98% cold rolled materials.

3.3. Grain boundary character distribution (GBCD)

The plots of misorientation angles between grains versus theirnumber fractions have been presented in Fig. 6(a–d). These plotsclearly indicate that the low misorientation angle grain boundaryfraction decreases and the high misorientation angle grain bound-ary fraction increases as the amount of cold rolling increase from90% to 98%. Among all the cold rolled as well as annealed materi-als, the largest number fraction of high misorientation boundariescan be found for the 210 min annealed 98% cold rolled steel. Themisorientation plots clearly indicate that none of them follows therandom Mackenzie type distribution. However, a couple of humps

can be observed in the misorientation plots, in the ranges of 30–35◦

and 50–60◦.The grain boundary character distribution of the cold rolled (90%

and 98%), partially and fully recrystallized materials are depictedin Fig. 7(a and b). The 90% cold rolled material possesses a higher

R. Saha, R.K. Ray / Materials Science and Engineering A 527 (2010) 1882–1890 1887

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Fig. 4. Plots of volume fractions of texture components for 98% cold rolled an

ensity of low angle grain boundaries (LAGB) as compared to highngle grain boundaries (HAGB). In this steel, there is a progres-ive increase of the HAGB fraction at the expense of the LAGBith annealing. After 30 min of annealing, equal number fractions

Fig. 5. TEM micrographs of the cold rolled IF

ealed at 650 ◦C for different time (a) � fibre (b) � fibre (c) other components.

of LAGB and HAGB are produced and after full recrystallizationand some grain growth, the HAGB fraction is significantly higherthan the LAGB fraction (Fig. 7(a)). The 98% cold rolled steel showsa higher fraction of HAGBs than LAGBs. Near equalization of the

steel (a) 90% (b) 98% (ND-RD section).

1888 R. Saha, R.K. Ray / Materials Science and Engineering A 527 (2010) 1882–1890

nd b)

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Fig. 6. Misorientation angle distribution plots of (a a

AGB and LAGB fractions occurs after annealing for a period ofmin (Fig. 7(b)). After full recrystallization and some grain growth,owever, the HAGB fraction becomes much larger than the LAGB

raction. The distributions of coincidence site lattice (CSL) bound-ries are also shown in Fig. 8. It is clear that increase in the amountf deformation from 90% to 98% leads to increase in the CSL num-er fraction from 0.1 to 0.14. Annealing of these steels brings aboutbrupt changes in the number fraction of CSL boundaries; after10 min of annealing, where recrystallization appears to be almostomplete, the number fraction of CSL boundaries remain higherhan in case of the cold rolled steels.

The CSL boundaries (Fig. 8) in the 90% and 98% cold rolled materi-ls account for about 7% and 13% of the total number of boundaries,espectively. After 210 min of annealing these values change to1% and 14%, respectively. Among the CSL boundaries, the mostrominent ones are

∑3,

∑9,

∑11,

∑13b,

∑31b and

∑33a. The

ensities of∑

3 and∑

9 CSL boundaries are significantly higher inhe 98% cold rolled case as compared to the 90% cold rolled material.nnealing of both the 90% and 98% cold rolled materials enhances

he number fraction of CSL boundaries, particularly those of the3,

∑9, and

∑13b; however, the increase in the frequency of

hese CSL boundaries is higher for the annealed 98% cold rolledaterial as compared to the 90% case.

. Discussion

The microstructures of the 90% and 98% cold rolled steels areade up of elongated ribbon like cells, the cell thicknesses are much

90% (c and d) 98% cold rolled and annealed IF steel.

narrower in the 98% as compared to the 90% cold rolled steel. Sig-nificant amounts of recovery appear to have taken place in the coldrolled condition specially at the higher level of deformation. Suchbehaviour may be attributed to adiabatic heating of the materialduring deformation. Such high rate of recovery due to heavy defor-mation leads to the generation of nano to ultrafine size grains andsub-grains in this steel [13–14].

Cold rolling by 90% leads to the formation of a sharp textureconsisting of both the � and the � fibres, as expected. Increasingthe amount of cold reduction to 98% sharpens the overall textureintensity without changing the nature of the texture. After fullrecrystallization, the overall intensity of the texture decreases incase of the 90% cold rolled steel. However, recrystallization appearsto sharpen the overall texture to a large extent in the 98% cold rolledsteel. In the latter case, there is a marked improvement in the sharp-ness of both the � and the � fibres. These differences between the90% and the 98% cold rolled and annealed materials can be seenmore distinctly in the intensity plots for the gamma and alpha fibreswith the progress of annealing (Fig. 2). The fibre plots further showthat although the intensity of the � fibre is only marginally higherin the 98% cold rolled material than the intensity of the same fibrein the 90% cold rolled steel, the � fibre intensity in the former isdoubly more sharp than in the latter after full recrystallization.

Again, while the � fibre intensities are quite high and compara-ble in the 90% and 98% cold rolled steels, the intensities of this fibredecrease very significantly in both of them after recrystallization.It therefore becomes quite clear that in spite of the heavy amountof cold deformation (98%) which is much more than what is prac-

R. Saha, R.K. Ray / Materials Science and Engineering A 527 (2010) 1882–1890 1889

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ig. 7. Grain boundary character distribution plots of (a) 90% (b) 98% cold rolled andnnealed IF-B steel.

ised conventionally, the textural evolution after recrystallizationay be quite conducive to satisfactory deep-drawability. In fact,

he r bar values have been found to be 1.6 for the 90% cold rolled

nd annealed material, whereas the 98% cold rolled and annealedteel shows an r bar value of 1.5. Thus the deep-drawability of bothhe 90% and the 98% cold rolled steels is quite comparable, thoughhe latter treatment will yield a much thinner sheet thickness as

ig. 8. CSL distribution plots of (a) 90% (b) 98% cold rolled and 650 ◦C annealed IFteel.

Fig. 9. (a) IQ orientation maps of the 90% cold rolled steel; annealed at 650 ◦C for210 min, (b) IQ orientation maps of the 98% cold rolled steel; annealed at 650 ◦C for210 min.

compared to the former. This clearly shows that for making indus-trial ultra thin steel sheets, higher degree of cold rolling may be abeneficial option.

The present work has clearly shown that after full recrystal-lization, normal grain growth appears to take place in the 90%cold rolled steel (Fig. 9(a)), though the average grain sizes arefound to be larger for grains with the {1 1 3}〈4 7 1〉 and {2 2 3}〈6 9 2〉orientations. On the other hand, the 98% cold rolled steel, whenannealed for 210 min, clearly shows abnormal growth of the grainshaving orientations {5 5 4}〈2 2 5〉 and {1 1 1}〈1 2 3〉 (Fig. 9b). The{1 1 3}〈4 7 1〉 and {2 2 3}〈6 9 2〉 oriented grains, which possess largeraverage grain sizes as compared to the other grains in the 90% coldrolled and recrystallized material, assume a much lower volumefraction (from 14% to 1.4% and from 13.5% to 3.6%) in the 98% coldrolled and recrystallized material. Thus, selective growth of grainsof certain orientations, such as the {5 5 4}〈2 2 5〉 and {1 1 1}〈1 2 3〉,seems to predominate in the 98% cold rolled and recrystallizedmaterial. Some growth selection may, however, be taking place forthe {1 1 3}〈4 7 1〉 and {2 2 3}〈6 9 2〉 oriented grains in the 90% coldrolled and recrystallized steel.

The concept of selective growth during recrystallization is basedon the observation that certain nuclei, which have particular mis-orientation with respect to the matrix have high growth rate [20].In BCC materials these misorientations can be described in termsof rotations by angles of ±27◦ [20] and ±35◦ [21] about a common

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890 R. Saha, R.K. Ray / Materials Science

1 1 0〉 axis. Fig. 6, where misorientation angles have been plottedgainst their number fractions, clearly shows presence of humpst the angular ranges of 25–30◦ and 55–60◦. The misorientationngles for selective growth may have something to do with theoincidence site lattice (CSL) relationship. Jonas and Urabe [22]uggested that CSL boundaries have higher mobilities because ofheir lower free volume and that they contain less of solute atomshat are responsible for drag. Thus the CSL boundaries may playn active part during selective growth. Recently, Urabe and Jonas23] simulated texture formation in IF steels using the concept ofelective growth. They assumed that grain boundaries character-zed by rotations of 27◦ around 〈1 1 0〉 axes have high motilities.hese boundaries are nothing but

∑19a CSL boundaries. In this

onnection it may be stated that the following CSL boundaries mayf interest for selective growth:

∑9 (38.9◦),

∑11 (50.5◦),

∑13b

27.8◦),∑

19a (26.5◦),∑

27a (31.6◦) and∑

33c (59.0◦). From Fig. 8t is quite clear that

∑11 and

∑13b are the two most important CSL

oundaries in both the recrystallized materials. The∑

11 denotes0.5◦ rotations around the 〈1 1 0〉 while the

∑13b relates to 27.8◦

otation around the 〈1 1 1〉 axis. These angles very much correspondo the locations of the two humps in the misorientation distributionlots (Fig. 6).

The two most high volume fraction components in the 90%old rolled and recrystallized material are the {1 1 3}〈4 7 1〉 and2 2 3}〈6 9 2〉, though their volume fractions in the cold rolled con-ition were not that significant. The {1 1 3}〈4 7 1〉 component iselated to the {1 1 2}〈1 1 0〉 component by 26◦ rotation. This couldossibly suggest that {1 1 3}〈4 7 1〉 might have grown by growthelection. Again, the two most prominent high volume fraction ori-ntations in the 98% cold rolled and recrystallized material, the5 5 4}〈2 2 5〉 and the {1 1 1}〈1 2 3〉, can be described by the Eulerngles (26◦, 52◦, 51◦) and (19◦, 55◦, 45◦) respectively. Thus it isuite clear that these two orientations do not differ much in their

ocation in the Euler space. Not only that but also both theserientations could be related to the orientation {1 1 2}〈1 1 0〉 by5–30◦ rotation. The fact that the latter orientation shows a clearut decrease in volume fraction with the progress of recrystalliza-ion, while the two former orientations increase in volume fractiont the same time may indicate that the grains with orientations5 5 4}〈2 2 5〉 and {1 1 1}〈1 2 3〉 could be growing at the expense ofhe {1 1 2}〈1 1 0〉. Thus it appears that selective grain growth takeslace in both the 90% and the 98% cold rolled materials after recrys-allization, though the effect is much more prominent in case of theatter.

Earlier severe cold rolling (95%) of ultra low carbon steelas been found to cause the appearance of the {5 5 4}〈2 2 5〉nd {1 1 3}〈4 7 1〉 texture components during the final stages ofecrystallization [24]. The formation of these two components hasccompanied by the disappearance of the dominant {1 1 2}〈1 1 0〉D fibre component, which is related by a 26.5◦ 〈1 1 0〉 rotationith the above two components. It may be stated here that in theresent investigation {1 1 3}〈4 7 1〉 is one of the two most domi-ant components in the final recrystallization texture of the 90%old rolled steel. On the other hand, {5 5 4}〈2 2 5〉 is one of the two

ost prominent components in the recrystallization texture of the

8% cold rolled material. The texture components {1 1 3}〈4 7 1〉 and5 5 4}〈2 2 5〉 have also been found to increase in intensity at thexpense of the {1 1 2}〈1 1 0〉 component during the recrytstalliza-ion of a warm rolled low carbon steel [25].

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gineering A 527 (2010) 1882–1890

5. Conclusions

(1) In the experimental steel, the overall texture is much sharper inthe 98% cold rolled material, as compared to the 90% cold rolledmaterial. Both, however, show strong � and � fibres.

(2) The texture intensity for the 90% cold rolled steel decreases afterrecrystallization annealing; by contrast, the 98% cold rolledmaterial shows an increase in texture intensity after recrys-tallization. A very sharp gamma fibre is obtained in the lattercase.

(3) In spite of the very heavy deformation of 98%, the recrystallizedmaterial shows only a marginal decrease in r bar value, as com-pared to the r bar of the material, cold rolled to conventional90%, followed by recrystallization (from 1.6 to 1.5).

(4) Both the 90% and the 98% cold rolled samples show selec-tive grain growth after recrystallization. This tendency is muchmore prominent for the sample with the higher amount of colddeformation.

(5) The {1 1 3}〈4 7 1〉 and the {2 2 3}〈6 9 2〉 oriented grains are mostprone to selective growth among grains of all other orientations,in the 90% cold rolled and annealed material.

(6) The {5 5 4}〈2 2 5〉 and the {1 1 1}〈1 2 3〉 oriented grains are mostprone to selective growth among grains of all other orientations,in the 98% cold rolled and annealed material.

(7) The∑

11 and the∑

13b are the two most prominent CSLboundaries in the recrystallized materials, cold rolled to both90% and 98%. The angular rotations associated with these twotypes of CSL boundaries correspond to the angular ranges wherewell-defined humps are obtained in the misorientation distri-bution plots.

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