The extended band structures of as-cold-rolled high Cr steel sheets are recrystallisation-resistant, and tend to become aggregates of the so-called grain colonies as a partially recovered state after final annealing. Such band structures diminish formability and become origin of the so-called ridging. A novel processing will be shown here, which involves strain-path change by introducing one-pass ECAP prior to cold-rolling, and facilitates recrystallisation. Indeed, the recrystallisation temperature was reduced by 100℃, compared with cold-rolling alone imposing an equivalent strain. Grain- scale microshear bands introduced during one-pass ECAP perturbed the banded structures in post-ECAP cold-rolling and enhanced the recrystallisation at the final annealing.
T. Ohashi, “The Origin of Ridging in 17% Cr Stainless Steel Hot-Strips,” Journal of Japan Institute of Metal, Vol. 31, No. 4, 1967, pp. 519-525.
H. Takechi, H. Kato, T. Kakunami and T. Nakayama, “On the Mechanism of Ridging Phenomenon in 17% Chromium Stainless Steel Sheets,” Journal of Japan Institute Metal, Vol. 31, No. 6, 1967, pp. 717-723.
R. N. Wright, “Anisotropic Plastic Flow in Ferritic Stainless Steels and the ‘Roping’ Phenomena,” Metallurgical Transactions, Vol. 3, No. 1, 1972, pp. 83-91.doi:10.1007/BF02680588
H. C. Chao, “Recent Studies into the Mechanism of Ridging in Ferritic Stainless Steels,” Metallurgical Transactions, Vol. 4, No. 4, 1973, pp. 1183-1186.doi:10.1007/BF02645630
O. M. Engler, Y. Huh and C. N. Tome, “Crystal-Plasticity Analysis of Ridging in Ferritic Stainless Steel Sheets,” Metallurgical Materials Transactions, Vol. 36A, No.11, 2005, pp. 3127-3139. doi:10.1007/s11661-005-0084-5
T. Tsuchiyama, R. Hirota, K. Fukunaga and S. Takaki, “Ridging-Free Ferritic Stainless Steel Produced through Recrystallization of Lath Martensite,” ISIJ International, Vol. 45, No. 6, 2005, pp. 923-929. doi:10.2355/isijinternational.45.923
N. Tsuji, K. Tsuzaki and T. Maki, “Effect of Initial Orientation on the Recrystallization Behavior of Solidifi- ed Columnar Crystals in 19% Cr Ferritic Stainless Steel,” ISIJ International, Vol. 33, No. 7, 1993, pp. 783-792.doi:10.2355/isijinternational.33.783
M. Y. Huh and O. Engler, “Effect of Intermediate An- nealing on Texture, Formability and Ridging of 17% Cr Ferritic Stainless Steel Sheet,” Materials Science and En- gineering A, Vol. 308, No. 1-2, 2001, pp. 74-87. doi:10.1016/S0921-5093(00)01995-X
M. K. Haouaoui, T. Hartwig and A. E. Payzant, “Effect of Strain Path on Texture and Annealing Microstructure Development in Bulk Pure Copper Processed by Simple Shear,” Acta Materialia, Vol. 53, No. 3, 2005, pp. 801- 810. doi:10.1016/j.actamat.2004.10.032
J. D. Embury, W. J. Poole and E. Koken, “Some Views on the Influence of Strain Path on Recrystallization,” Scripta Materialia, Vol. 27, No. 11, 1992, pp. 1465-1470.doi:10.1016/0956-716X(92)90129-3
J. H. Lee, S. H. Park and M. Y. Huh, “Modification of the Recrystallization Texture by Means of Cross Rolling in Ferritic Stainless Steel Sheets,” Materials Science Forum, Vol. 449-452, 2004, pp. 1-6. doi:10.4028/www.scientific.net/MSF.449-452.1
T. Kaneko, H. Utsunomiya, Y. Saito, T. Sakai and N. Furushiro, “Improvement of Ridging Behavior of Ferritic Stainless Steel by Spread Rolling Method,” Tetsuto-Hagane, Vol. 89, No. 6, 2003, pp. 653-658.
R. Z. Valiev and T. G. Langdon, “Principles of Equal- Channel Angular Pressing as a Processing Tool for Grain Refinement,” Progress in Materials Science, Vol. 51, No. 7, 2006, pp. 881-981. doi:10.1016/j.pmatsci.2006.02.003
H. Miyamoto, T. Xiao, T. Uenoya and M. Hatano, “Effect of Simple Shear Deformation Prior to Cold-rolling on Texture and Ridging of 16% Cr Ferritic Stainless Steel Sheets,” ISIJ International, Vol. 50, No. 11, 2010, pp. 1653-1659. doi:10.2355/isijinternational.50.1653
K. Furuno, K. Akamatsu, K. Oh-Ishi, M. Furukawa, Z. Horita and T. G. Langdon, “Microstructural Development in Equal-Channel Angular Pressing Using 60 Die,” Acta Materialia, Vol. 52, No. 9, 2004, pp. 2497-2507.doi:10.1016/j.actamat.2004.01.040
Q. Zhu and C. M. Sellars, “Effect of Deformation Paths on Static Recrystallization Behavior of an Al-2Mg Alloy,” Proceedings of the 3rd International Conference on Recrystallisation and Related Phenomena, Monterey, 21-24 October 1996, pp. 195-202.
R. L. Higginson and C. M. Sellars, “The Effect of Strain Path Reversal during Hot Rolling on Austenitic Stainless Steel,” Materials Science and Engineering A, Vol. 338, No. 1-3, 2002, pp. 323-330. doi:10.1016/S0921-5093(02)00088-6
R. Lindh, B. Hutchinson and S. Ueyama, “Effect of Redundant Deformation on Recrystallization Behavior of Copper,” Scripta Metallurgica et Materialia, Vol. 29, No. 3, 1993, pp. 347-352. doi:10.1016/0956-716X(93)90511-P
M. P. Black, R. L. Higginson and C. M. Sellars, “Effect of Strain Path on Recrystallization Kinetics during Hot Rolling of Al-Mn,” Materials Science and Technology, Vol. 17, No. 9, 2001, pp. 1055-1060.
D. T. McDonald, P. S. Bate and W. B. Hutchinson, “Effect of Strain Path Change on Recrystallization in Copper,” Materials Science and Technology, Vol. 21, No. 6, 2005, pp. 693-700. doi:10.1179/174328405X43171
Z. Lu, “The Effect of Strain Path Change on Recrystallization Temperature,” Proceedings of the International Symposium of Young Scholars on Mechanics and Material Engineering for Science and Experiments, Changsha, 11- 16 August 2001, pp. 561-564.
C. M. Sellars and Q. Zhu, “The Effect of Strain Path on Mechanical Behavior and Microstructure,” Proceedings of 20th Riso International Symposium on Materials Science, Deformation-Induced Microstructures, Analysis and Relation to Properties, Roskilde, 6-10 September 1999, pp. 167-182.
T. Hasegawa and T. Yakou, “Forward and Reverse Rearrangements of Dislocations in Tangled Walls,” Materials Science and Engineering, Vol. 81, No. 1-2, 1986, pp. 189-199. doi:10.1016/0025-5416(86)90262-4
J. R. Cowan, R. L. Higginson, W. B. Hutchinson and P. S. Bate, “Recrystallisation Following Non-Proportional Straining in Aluminum,” Materials Science and Techno- logy, Vol. 11, No. 11, 1995, pp. 1104-1109.doi:10.1179/026708395790164517
J. Hjelen, R. Orsund and E. Nes, “On the Origin of Recrystallization Textures in Aluminium,” Acta Metallurgica et Materia, Vol. 39, No. 7, 1991, pp. 1377-1404.doi:10.1016/0956-7151(91)90225-P
F. J. Humphreys and M. Hatherly, “Recrystallisation and Related Annealing Phenomena,” 2nd Edition, Elsevier, Oxford, 2004, p. 41, 259.
P. J. Hurley and F. J. Humphreys, “The Application of EBSD to the Study of Substructural Development in a Cold-Rolled Single-Phase Aluminum Alloy,” Acta Materialia, Vol. 51, No. 4, 2003, pp. 1087-1102. doi:10.1016/S1359-6454(02)00513-X
D. A. Hughes and N. Hansen, “Microstructure and Strength of Nickel at Large Strains,” Acta Materialia, Vol. 48, No. 11, 2000, pp. 2985-3004.doi:10.1016/S1359-6454(00)00082-3
H. Miyamoto, A. Vinogradov, S. Hashimoto and R. Yoda, “Formation of Deformation Twins and Related Shear Bands in Copper Single Crystal Deformed by Equal- Channel Angular Pressing for One Pass at Room Temperature,” Materials Transactions, Vol. 50, No. 8, 2009, pp. 1924-1929. doi:10.2320/matertrans.M2009054