- Email: [email protected]
Improvement of the anti-corrosion property of twinning-induced plasticity steel by twin-induced grain boundary engineering
Accepted Manuscript Improvement of the anti-corrosion property of twinning-induced plasticity steel by twin-induced grain boundary engineering Kun Wang, Aiping Wei, Xian Tong, Jixing Lin, Lufan Jin, Xintao Zhong, Dan Wang PII: DOI: Reference:
S0167-577X(17)31447-7 https://doi.org/10.1016/j.matlet.2017.09.102 MLBLUE 23216
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
10 August 2017 24 September 2017 26 September 2017
Please cite this article as: K. Wang, A. Wei, X. Tong, J. Lin, L. Jin, X. Zhong, D. Wang, Improvement of the anticorrosion property of twinning-induced plasticity steel by twin-induced grain boundary engineering, Materials Letters (2017), doi: https://doi.org/10.1016/j.matlet.2017.09.102
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Improvement of the anti-corrosion property of twinning-induced plasticity steel by twin-induced grain boundary engineering Kun Wang a,*, Aiping Wei a, Xian Tong b , Jixing Lin a, Lufan Jin a, Xintao Zhong a, Dan Wang c a
Department of Material Engineering, Zhejiang Industry & Trade Vocational College, Wenzhou 325003, China;
b
School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105，China; c
Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Abstract: The effects of thermal-mechanical processing (TMP) on the microstructure and anti-corrosion property of twinning-induced plasticity (TWIP) steel are investigated. It is found that, the corrosion resistance of TWIP steel has been significantly improved with the corrosion potential increased from -0.92 V to -0.69 V and the corrosion current density reduced from 8.76×10-5 A/cm2 to 1.92×10-5 A/cm2. Electron back-scatter diffraction (EBSD) technique is employed to analyze the grain boundaries distributions of TWIP samples. The results indicate that the interrupted high angle boundaries network is the key to the improvement of the corrosion resistance of TWIP steel while the fraction of low-Σ coincidence site lattice boundaries is just slightly increased from 81% to 86%.
Keywords TWIP steel; Annealing twins; Grain boundaries; Corrosion; Microstructure
1. Introduction Twinning-induced plasticity (TWIP) steel has renewed the interest of automotive industry for its fascinating microstructural behavior and unique mechanical properties. All these characteristics benefit
*
Corresponding author. E-mail: [email protected]; Tel: +86 0577-88313017
from the dynamical Hall-Petch effect as the nanoscale strain-induced twins reduce the dislocation mean free path [1-3]. As a prerequisite for twinning , the stacking fault energy (SFE) of TWIP steel should fall in the 18~45mJ/m2 [4] range. Therefore, the TWIP steel is commonly alloyed with a massive manganese （＞~15wt.%, such as Fe–15Mn–1.5Al–0.6C [5], Fe–22Mn–0.6C [3, 6], Fe–30Mn-3Al-3Si [7], etc.）to increase the SFE. However, when the TWIP steel is immersed in chloride and acidic solutions, the high concentration of Mn with high dissolution rate makes it difficult for TWIP steel to form a stable passive film [8-10]. As the twin boundary is not susceptible to corrosion, twin-induced grain boundary engineering has successful application in improvement of the corrosion resistance of some face-centered cubic (fcc) metal materials with low to medium SFE, such as 304 stainless steel [11], copper and Ni-based alloys [12] by thermal-mechanical processing (TMP). Yuan [13] found that the occurrence frequency and distribution characteristic of twin-related (especially Σ3n (n=1, 2, 3…) coincidence site lattice (CSL)) grain boundaries play a particularly important role in optimizing the anti-corrosion ability. In this work, the TMP was employed to optimize the microstructure and anti-corrosion property of TWIP steel.
2. Material and methods The cold rolled Fe-30Mn-3Al-3Si TWIP steel was annealed at 1000℃ for 4h followed by water quenching for the starting material A. The sample A was cold rolled by 5% (reduction of thickness) and annealed at 1000℃ for 15min. Then, this rolling and annealing process (namely TMP) was repeated four times to obtain the sample B. The grain boundaries distributions were analyzed by a field-emission scanning electron microscope (SEM, FEI Nova Nano SEM 450) fitted with an electron backscatter diffraction device (EBSD,
HKL/Channel 5 system). The samples for EBSD analysis were electrolyticaly polished in a solution of 20% perchloric acid, 10% acetic acid and balanced ethanol using 0.5mA current and 20V voltage after the grinding and polishing processes. The corrosion behavior of samples in 3.5wt.% NaCl solution was measured using the potentiodynamic polarization tests. A platinum electrode, saturated calomel electrode (SCE), and the sample A and sample B with an exposed area of 0.5cm2 were employed with the counter electrode, reference electrode, and working electrode, respectively. Before the potentiodynamic polarization tests, the working electrode was immersed in 3.5wt.% NaCl solution for stability. The tests was recorded at a scanning rate of 2mV·s-1 and room temperature.
3. Results and discuss
The potentiodynamic polarization curves in Fig.1 show that the corrosion resistance of TWIP steel has been significantly improved by TMP with the corrosion potential increased from -0.92V to -0.69V and the corrosion current density reduced from 8.76×10-5 A/cm2 to 1.92×10-5 A/cm2.
In twin-induced grain boundary engineering, the small prestrain level is a key point to enhance the low-Σ CSL grain boundaries while a large prestrain is more likely to promote recrystallization and generate corrosive random boundaries [11, 14]. Apparently, the bigger grain size in sample B indicates no recrystallization occurred by TMP as shown in Fig.2.
Based on the Palumbo–Aust criterion[15], Fig.3 gives the grain boundaries distributions of samples A and B. The high-Σ CSL grain boundaries are defined as random grain boundaries indicated by black lines, while the low-Σ CSL (Σ≤29) grain boundaries are indicated by different color lines. After TMP, the fraction of low-Σ CSL grain boundaries is slightly increased from 81% to 86%. Meanwhile, the twin boundaries still contain various facets on their end and lateral sides. The boundary energy is less when the curved boundary breaks into an array of the facets which are frequently parallel to the most densely
packed planes of coincidence sites lattice formed by two lattices of abutting grains [16]. For this reason, in our opinion, these facets could help to improve the anti-corrosion property of TWIP steel. As the metastable facet becomes stable when the temperature decreases[17], these facets in our studied samples should be stable as the annealing temperature is so low, just 0.65 Tm (Tm is the melting temperature). However, it still needs a systematic study on the influence of faceting/roughening phenomenon on the anti-corrosion property of TWIP steel. There are two types in the twin boundaries, coherent (Σ3) twin boundaries and incoherent (Σ3ic) ones. The EBSD-based single-section trace analysis suggests that not all straight Σ3 boundaries in the grain boundary reconstruction are coherent while that curved ones are definitely incoherent [14]. Interestingly, some of the new formed Σ3 ic boundaries constitute isolated islands far away from the grain boundaries as shown in Fig.3b. How do these islands form? It is suspected that, the nucleation of these isolated Σ3 ic islands can be attributed to the recovery of deformation structure within grains. These islands grow up with the migration of their Σ3 ic boundaries induced by the stored energy by deformation. If the stored energy is consumed when their Σ3 ic boundaries have not met any other boundaries, the isolated Σ3 ic islands are left within grains. And what if the existed and new formed annealing twins meet each other or the high angle boundaries (HABs)? According to the reaction constrain as follow[18]:
Σ 3 n + Σ 3m = Σ 3n ± m
(1)
where n and m are positive integers. If the annealing twins meet each other，the Σ3-Σ3-Σ9 junctions would be formed as[14, 18]:
Σ3 + Σ3 = Σ9
(2)
However, this reaction would not have any effect on the HABs network which is more susceptible to corrosion. Now, the question is what significantly improves the anti-corrosion property of TWIP steel while the fraction of low-Σ CSL grain boundaries is just slightly increased?
Fig.4 sketches the forming process of Σ3-Σ9-Σ27 junctions in Fig.3b. Based on the experimental observations, Kumar [12] and Shimada[11] argued that, the HABs could partially transformed into low-Σ CSL grain boundaries by twin emission which can be attributed to the HABs aided mechanism. At the beginning of thermal treatment, a random boundary emitted the annealing twin 2 to form the Σ3-Σ27-Σ81 junction as shown in Fig.4b:
Σ81 = Σ 27 + Σ3
(3)
The energy of HABs, incoherent Σ3 ic and coherent Σ3 boundaries is 1.2, 0.1~0.6 and 0.01 J/mm2 respectively [14]. Thus, the coherent segments of twin 1 and 2 could be regarded as immobile while the random boundary and the incoherent Σ3 ic segment of twin 2 would move driven by the stored strain energy. As a result of the lateral growth of incoherent Σ3ic segment of twin 2, this random boundary was transformed into a Σ27 boundary continuously. Subsequently, also due to the strain-induced boundary migration, this Σ27 boundary encountered twin 1 to form the Σ3-Σ9-Σ27 junctions as:
Σ27 + Σ3=Σ9
(4)
As the HABs network is more susceptible to corrosion, the above chain reactions (3) and (4) would interrupt the HABs network by forming many triple junctions of Σ3n-type boundaries which would form
the grain clusters or twin chains [19-21]. Therefore, the corrosion resistance of TWIP steel would be improved.
4. Conclusions The thermal-mechanical processing has significantly improved the anti-corrosion property of TWIP steel with the corrosion potential increased from -0.92V to -0.69V and the corrosion current density reduced from 8.76×10-5A/cm2 to 1.92×10-5A/cm2. EBSD observations indicate that there are more Σ3 ic twin boundaries induced by TMP, and the fraction of low-Σ CSL grain boundaries is slightly increased from 81% to 86%. The improvement of the corrosion resistance of TWIP steel can be attributed to the interrupted HABs network which is more susceptible to corrosion.
Acknowledgement This work was supported by the National Natural Science Foundation of China under Grant No. 51701206, General Scientific Project of Zhejiang Provincial Education Department (Y201636887), Scientific and Technological Projects of Wenzhou City (G20160022).
References [1] S. Allain, J.P. Chateau, O. Bouaziz, Mater Sci Eng A, 387-389 (2004) 143-147. [2] K. Wang, D. Wang, F. Han, Mater Sci Eng A, 642 (2015) 249-252. [3] I. Gutierrez-Urrutia, S. Zaefferer, D. Raabe, Mater Sci Eng A, 527 (2010) 3552-3560. [4] S. Curtze, V.T. Kuokkala, Acta Mater, 58 (2010) 5129-5141. [5] Y.Y. Zhao, J.F Wang, S. Zhou, X.D. Wang, Mater Sci Eng A, 608 (2014) 106-113. [6] S.J. Lee, J. Kim, S.N. Kane, B.C.D. Cooman, Acta Mater, 59 (2011) 6809-6819. [7] K. Wang, D. Wang, F.S. Han, Acta Mech Sin, 32 (2015) 181-187.
[8] A.S. Hamada, L.P. Karjalainen, Open Corrosion J, 3 (2010) 1-6. [9] Y.S. Zhang, X.M. Zhu, Corros Sci, 41 (1999) 1817-1833. [10] G.R. Razavi, H. Monajati, Adv Mater Res, 457-458 (2012) 334-337. [11] M. Shimada, H. Kokawa, Z.J. Wang, Y.S. Sato, I. Karibe, Acta Mater, 50 (2002) 2331-2341. [12] M. Kumar, A.J. Schwartz, W.E. King, Acta Mater, 50 (2002) 2599-2612. [13] X. Yuan, L. Chen, Acta Metallurgica Sinica, 52 (2016) 1345-1352. [14] W.G. Wang, H. Guo, Mater Sci Eng A, 445-446 (2007) 155-162. [15] G. Palumbo, K.T. Aust, Acta Metall Mater, 38 (1990) 2343-2352. [16] B.B. Straumal, O.A. Kogtenkova, A.S. Gornakova, V.G. Sursaeva, B. Baretzky, J Mater Sci, 51 (2015) 382-404. [17] B.B. Straumal, S.A. Polyakov, E.J. Mittemeijer, Acta Mater, 54 (2006) 167-172. [18] V. Randle, Acta Mater, 47 (1999) 4187-4196. [19] S. Xia, B.X. Zhou, W.J. Chen, Metall Mater Trans A, 40 (2009) 3016-3030. [20] T. Liu, S. Xia, H. Li, B. Zhou, Q. Bai, Mater Character, 91 (2014) 89-100. [21] T. Liu, S. Xia, H. Li, B. Zhou, Q. Bai, Mater Lett, 133 (2014) 97-100.
Figure Captions Fig.1 Potentiodynamic polarization curves of TWIP samples A and B. Fig.2 EBSD observations of samples A (a) and B (b). Fig.3 Grain boundaries distributions of samples A (a) and B (b). Fig.4 Sketch map of the forming process of Σ3-Σ9-Σ27 junctions.
Highlights:
(1) Twin induced grain boundary engineering is employed. (2) Some isolated islands consist of incoherent twin boundaries. (3) The high angle boundaries network is interrupted. (4) The possible influence of the facets on the anti-corrosion property is discussed.
S0167-577X(17)31447-7 https://doi.org/10.1016/j.matlet.2017.09.102 MLBLUE 23216
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
10 August 2017 24 September 2017 26 September 2017
Please cite this article as: K. Wang, A. Wei, X. Tong, J. Lin, L. Jin, X. Zhong, D. Wang, Improvement of the anticorrosion property of twinning-induced plasticity steel by twin-induced grain boundary engineering, Materials Letters (2017), doi: https://doi.org/10.1016/j.matlet.2017.09.102
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Improvement of the anti-corrosion property of twinning-induced plasticity steel by twin-induced grain boundary engineering Kun Wang a,*, Aiping Wei a, Xian Tong b , Jixing Lin a, Lufan Jin a, Xintao Zhong a, Dan Wang c a
Department of Material Engineering, Zhejiang Industry & Trade Vocational College, Wenzhou 325003, China;
b
School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105，China; c
Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Abstract: The effects of thermal-mechanical processing (TMP) on the microstructure and anti-corrosion property of twinning-induced plasticity (TWIP) steel are investigated. It is found that, the corrosion resistance of TWIP steel has been significantly improved with the corrosion potential increased from -0.92 V to -0.69 V and the corrosion current density reduced from 8.76×10-5 A/cm2 to 1.92×10-5 A/cm2. Electron back-scatter diffraction (EBSD) technique is employed to analyze the grain boundaries distributions of TWIP samples. The results indicate that the interrupted high angle boundaries network is the key to the improvement of the corrosion resistance of TWIP steel while the fraction of low-Σ coincidence site lattice boundaries is just slightly increased from 81% to 86%.
Keywords TWIP steel; Annealing twins; Grain boundaries; Corrosion; Microstructure
1. Introduction Twinning-induced plasticity (TWIP) steel has renewed the interest of automotive industry for its fascinating microstructural behavior and unique mechanical properties. All these characteristics benefit
*
Corresponding author. E-mail: [email protected]; Tel: +86 0577-88313017
from the dynamical Hall-Petch effect as the nanoscale strain-induced twins reduce the dislocation mean free path [1-3]. As a prerequisite for twinning , the stacking fault energy (SFE) of TWIP steel should fall in the 18~45mJ/m2 [4] range. Therefore, the TWIP steel is commonly alloyed with a massive manganese （＞~15wt.%, such as Fe–15Mn–1.5Al–0.6C [5], Fe–22Mn–0.6C [3, 6], Fe–30Mn-3Al-3Si [7], etc.）to increase the SFE. However, when the TWIP steel is immersed in chloride and acidic solutions, the high concentration of Mn with high dissolution rate makes it difficult for TWIP steel to form a stable passive film [8-10]. As the twin boundary is not susceptible to corrosion, twin-induced grain boundary engineering has successful application in improvement of the corrosion resistance of some face-centered cubic (fcc) metal materials with low to medium SFE, such as 304 stainless steel [11], copper and Ni-based alloys [12] by thermal-mechanical processing (TMP). Yuan [13] found that the occurrence frequency and distribution characteristic of twin-related (especially Σ3n (n=1, 2, 3…) coincidence site lattice (CSL)) grain boundaries play a particularly important role in optimizing the anti-corrosion ability. In this work, the TMP was employed to optimize the microstructure and anti-corrosion property of TWIP steel.
2. Material and methods The cold rolled Fe-30Mn-3Al-3Si TWIP steel was annealed at 1000℃ for 4h followed by water quenching for the starting material A. The sample A was cold rolled by 5% (reduction of thickness) and annealed at 1000℃ for 15min. Then, this rolling and annealing process (namely TMP) was repeated four times to obtain the sample B. The grain boundaries distributions were analyzed by a field-emission scanning electron microscope (SEM, FEI Nova Nano SEM 450) fitted with an electron backscatter diffraction device (EBSD,
HKL/Channel 5 system). The samples for EBSD analysis were electrolyticaly polished in a solution of 20% perchloric acid, 10% acetic acid and balanced ethanol using 0.5mA current and 20V voltage after the grinding and polishing processes. The corrosion behavior of samples in 3.5wt.% NaCl solution was measured using the potentiodynamic polarization tests. A platinum electrode, saturated calomel electrode (SCE), and the sample A and sample B with an exposed area of 0.5cm2 were employed with the counter electrode, reference electrode, and working electrode, respectively. Before the potentiodynamic polarization tests, the working electrode was immersed in 3.5wt.% NaCl solution for stability. The tests was recorded at a scanning rate of 2mV·s-1 and room temperature.
3. Results and discuss
The potentiodynamic polarization curves in Fig.1 show that the corrosion resistance of TWIP steel has been significantly improved by TMP with the corrosion potential increased from -0.92V to -0.69V and the corrosion current density reduced from 8.76×10-5 A/cm2 to 1.92×10-5 A/cm2.
In twin-induced grain boundary engineering, the small prestrain level is a key point to enhance the low-Σ CSL grain boundaries while a large prestrain is more likely to promote recrystallization and generate corrosive random boundaries [11, 14]. Apparently, the bigger grain size in sample B indicates no recrystallization occurred by TMP as shown in Fig.2.
Based on the Palumbo–Aust criterion[15], Fig.3 gives the grain boundaries distributions of samples A and B. The high-Σ CSL grain boundaries are defined as random grain boundaries indicated by black lines, while the low-Σ CSL (Σ≤29) grain boundaries are indicated by different color lines. After TMP, the fraction of low-Σ CSL grain boundaries is slightly increased from 81% to 86%. Meanwhile, the twin boundaries still contain various facets on their end and lateral sides. The boundary energy is less when the curved boundary breaks into an array of the facets which are frequently parallel to the most densely
packed planes of coincidence sites lattice formed by two lattices of abutting grains [16]. For this reason, in our opinion, these facets could help to improve the anti-corrosion property of TWIP steel. As the metastable facet becomes stable when the temperature decreases[17], these facets in our studied samples should be stable as the annealing temperature is so low, just 0.65 Tm (Tm is the melting temperature). However, it still needs a systematic study on the influence of faceting/roughening phenomenon on the anti-corrosion property of TWIP steel. There are two types in the twin boundaries, coherent (Σ3) twin boundaries and incoherent (Σ3ic) ones. The EBSD-based single-section trace analysis suggests that not all straight Σ3 boundaries in the grain boundary reconstruction are coherent while that curved ones are definitely incoherent [14]. Interestingly, some of the new formed Σ3 ic boundaries constitute isolated islands far away from the grain boundaries as shown in Fig.3b. How do these islands form? It is suspected that, the nucleation of these isolated Σ3 ic islands can be attributed to the recovery of deformation structure within grains. These islands grow up with the migration of their Σ3 ic boundaries induced by the stored energy by deformation. If the stored energy is consumed when their Σ3 ic boundaries have not met any other boundaries, the isolated Σ3 ic islands are left within grains. And what if the existed and new formed annealing twins meet each other or the high angle boundaries (HABs)? According to the reaction constrain as follow[18]:
Σ 3 n + Σ 3m = Σ 3n ± m
(1)
where n and m are positive integers. If the annealing twins meet each other，the Σ3-Σ3-Σ9 junctions would be formed as[14, 18]:
Σ3 + Σ3 = Σ9
(2)
However, this reaction would not have any effect on the HABs network which is more susceptible to corrosion. Now, the question is what significantly improves the anti-corrosion property of TWIP steel while the fraction of low-Σ CSL grain boundaries is just slightly increased?
Fig.4 sketches the forming process of Σ3-Σ9-Σ27 junctions in Fig.3b. Based on the experimental observations, Kumar [12] and Shimada[11] argued that, the HABs could partially transformed into low-Σ CSL grain boundaries by twin emission which can be attributed to the HABs aided mechanism. At the beginning of thermal treatment, a random boundary emitted the annealing twin 2 to form the Σ3-Σ27-Σ81 junction as shown in Fig.4b:
Σ81 = Σ 27 + Σ3
(3)
The energy of HABs, incoherent Σ3 ic and coherent Σ3 boundaries is 1.2, 0.1~0.6 and 0.01 J/mm2 respectively [14]. Thus, the coherent segments of twin 1 and 2 could be regarded as immobile while the random boundary and the incoherent Σ3 ic segment of twin 2 would move driven by the stored strain energy. As a result of the lateral growth of incoherent Σ3ic segment of twin 2, this random boundary was transformed into a Σ27 boundary continuously. Subsequently, also due to the strain-induced boundary migration, this Σ27 boundary encountered twin 1 to form the Σ3-Σ9-Σ27 junctions as:
Σ27 + Σ3=Σ9
(4)
As the HABs network is more susceptible to corrosion, the above chain reactions (3) and (4) would interrupt the HABs network by forming many triple junctions of Σ3n-type boundaries which would form
the grain clusters or twin chains [19-21]. Therefore, the corrosion resistance of TWIP steel would be improved.
4. Conclusions The thermal-mechanical processing has significantly improved the anti-corrosion property of TWIP steel with the corrosion potential increased from -0.92V to -0.69V and the corrosion current density reduced from 8.76×10-5A/cm2 to 1.92×10-5A/cm2. EBSD observations indicate that there are more Σ3 ic twin boundaries induced by TMP, and the fraction of low-Σ CSL grain boundaries is slightly increased from 81% to 86%. The improvement of the corrosion resistance of TWIP steel can be attributed to the interrupted HABs network which is more susceptible to corrosion.
Acknowledgement This work was supported by the National Natural Science Foundation of China under Grant No. 51701206, General Scientific Project of Zhejiang Provincial Education Department (Y201636887), Scientific and Technological Projects of Wenzhou City (G20160022).
References [1] S. Allain, J.P. Chateau, O. Bouaziz, Mater Sci Eng A, 387-389 (2004) 143-147. [2] K. Wang, D. Wang, F. Han, Mater Sci Eng A, 642 (2015) 249-252. [3] I. Gutierrez-Urrutia, S. Zaefferer, D. Raabe, Mater Sci Eng A, 527 (2010) 3552-3560. [4] S. Curtze, V.T. Kuokkala, Acta Mater, 58 (2010) 5129-5141. [5] Y.Y. Zhao, J.F Wang, S. Zhou, X.D. Wang, Mater Sci Eng A, 608 (2014) 106-113. [6] S.J. Lee, J. Kim, S.N. Kane, B.C.D. Cooman, Acta Mater, 59 (2011) 6809-6819. [7] K. Wang, D. Wang, F.S. Han, Acta Mech Sin, 32 (2015) 181-187.
[8] A.S. Hamada, L.P. Karjalainen, Open Corrosion J, 3 (2010) 1-6. [9] Y.S. Zhang, X.M. Zhu, Corros Sci, 41 (1999) 1817-1833. [10] G.R. Razavi, H. Monajati, Adv Mater Res, 457-458 (2012) 334-337. [11] M. Shimada, H. Kokawa, Z.J. Wang, Y.S. Sato, I. Karibe, Acta Mater, 50 (2002) 2331-2341. [12] M. Kumar, A.J. Schwartz, W.E. King, Acta Mater, 50 (2002) 2599-2612. [13] X. Yuan, L. Chen, Acta Metallurgica Sinica, 52 (2016) 1345-1352. [14] W.G. Wang, H. Guo, Mater Sci Eng A, 445-446 (2007) 155-162. [15] G. Palumbo, K.T. Aust, Acta Metall Mater, 38 (1990) 2343-2352. [16] B.B. Straumal, O.A. Kogtenkova, A.S. Gornakova, V.G. Sursaeva, B. Baretzky, J Mater Sci, 51 (2015) 382-404. [17] B.B. Straumal, S.A. Polyakov, E.J. Mittemeijer, Acta Mater, 54 (2006) 167-172. [18] V. Randle, Acta Mater, 47 (1999) 4187-4196. [19] S. Xia, B.X. Zhou, W.J. Chen, Metall Mater Trans A, 40 (2009) 3016-3030. [20] T. Liu, S. Xia, H. Li, B. Zhou, Q. Bai, Mater Character, 91 (2014) 89-100. [21] T. Liu, S. Xia, H. Li, B. Zhou, Q. Bai, Mater Lett, 133 (2014) 97-100.
Figure Captions Fig.1 Potentiodynamic polarization curves of TWIP samples A and B. Fig.2 EBSD observations of samples A (a) and B (b). Fig.3 Grain boundaries distributions of samples A (a) and B (b). Fig.4 Sketch map of the forming process of Σ3-Σ9-Σ27 junctions.
Highlights:
(1) Twin induced grain boundary engineering is employed. (2) Some isolated islands consist of incoherent twin boundaries. (3) The high angle boundaries network is interrupted. (4) The possible influence of the facets on the anti-corrosion property is discussed.