Effect of Mn Addition on High Temperature Tensile Behavior of 23%Cr Low Nickel Type Duplex Stainless Steel
DENG Yahui, YANG Yinhui(), PU Chaobo, NI Ke, PAN Xiaoyu
School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China
Cite this article:
DENG Yahui, YANG Yinhui, PU Chaobo, NI Ke, PAN Xiaoyu. Effect of Mn Addition on High Temperature Tensile Behavior of 23%Cr Low Nickel Type Duplex Stainless Steel. Acta Metall Sin, 2020, 56(7): 949-959.
There are different crystal structures and stacking fault energies (SFEs) for two phases of duplex stainless steel (DSS), and the Mn substitution for Ni also can change SFE of two phases and cause austenite stability variation during high temperature deformation. Thus, the thermal deformation behavior of DSS with Mn addition become more complex compared with that of single phase steel during high temperature tensile process. In this work, the high temperature tensile behavior of 23%Cr low nickel type DSS with different Mn contents (6.26%~14.13%, mass fraction) has been studied in the temperature of 300~1050 ℃ at strain rate of 0.01 s-1 by using a thermal simulation machine. The results showed that the austenite phases mainly accommodate tensile deformation stress, and the volume fraction of them increased with increasing Mn contents, which is beneficial to enhance the thermoplasticity, and has little effect on the tensile strength. With more Mn addition, the reduction of area increases when deformed in the temperature of 550~1050 ℃, but decreases at lower temperature of 300 ℃. The value of crack sensitive point increased slightly when stretched at lower temperature (450 ℃, 750 ℃) with more Mn addition, and optimum plastic temperature zones are in the range of 500~650 ℃ and 850~1050 ℃. The effect of Mn addition on work hardening rate is slight when deformed at 300 ℃, while high Mn addition is favorable for dynamic recrystallization occurence at lower strain when deformed at higher temperature of 1050 ℃. The tensile deformation microstructure of different Mn addition samples are mainly dependent on the austenite dislocations evolution. As the Mn content attained 14.13%, a large number of dislocation cells with high density and small size formed in austenite phase, which is contributed to grains refinement and improves thermoplasticity.
Table 1 Chemical compositions of duplex stainless steels
Fig.1 True stress-true strain curves of different Mn addition duplex stainless steel samples tensiled at strain rate 0.01 s-1 under di?erent temperatures(a) 6.26%Mn(b) 10.27%Mn(c) 14.13%Mn
Fig.2 OM images showing the deformation microstructures of near fracture morphologies normal to the tensile direction for the duplex stainless steel samples solution treated (a, c, e) and tensioned at 550 ℃ (b, d, f) (a, b) 6.26%Mn (c, d) 10.27%Mn (e, f) 14.13%Mn
Fig.3 Volume fraction variations of austenite phase for the duplex stainless steel samples solution treated and tensioned at 550 ℃ with different Mn additions
Fig.4 Strain hardening rate-strain curves of different Mn addition duplex stainless steel samples under tensile temperatures of 300 ℃ (a), 550 ℃ (b), 800 ℃ (c) and 1050 ℃ (d) (εp—peak strain)
Fig.5 Tensile strength (a) and reduction of area (b) at different tensile temperatures for the duplex stainless steel samples with different Mn additions
Fig.6 Characteristic curves of high temperature tensile strength versus reduction of area for the duplex stainless steel samples (a) 6.26%Mn (b) 10.27%Mn (c) 14.13%Mn
Fig.7 Tensile fracture SEM images of duplex stainless steel samples tensioned under 300 ℃ (a, c, e) and 550 ℃ (b, d, f) (a, b) 6.26%Mn (c, d) 10.27%Mn (e, f) 14.27%Mn
Fig.8 SEM fractographs (a, c, e) and corresponding EDS of inclusions (b, d, f) taken at the edge parts of tensile duplex stainless steel samples at 550 ℃ (a, b) 6.26%Mn (c, d) 10.27%Mn (e, f) 14.27%Mn
Fig.9 Bright field TEM images at the near parts of tensile fractured duplex stainless steel samples with different Mn addition at 550 ℃ (a) 6.26%Mn, sub-grain structure(b) 6.26%Mn, cellular structure in austenite phase(c) 6.26%Mn, two phases(d) 10.27%Mn, two phases(e) 10.27%Mn, tangled dislocations in austenite phase(f) 10.27%Mn, cellular structure in austenite phase(g) 14.13%Mn, two phases(h, i) 14.13%Mn, cellular structure in austenite phase
[1]
Liljas M, Johansson P, Liu H P, et al. Development of a lean duplex stainless steel [J]. Steel Res. Int., 2008, 79: 466
[2]
Miranda M A R, Sasaki J M, Tavares S S M, et al. The use of X-ray diffraction, microscopy, and magnetic measurements for analysing microstructural features of a duplex stainless steel [J]. Mater. Charact., 2005, 54: 387
[3]
Charles J, Chemelle P, translated by Hu J C, Zhang W. The history of duplex developments, nowadays DSS properties and duplex market future trends [J]. World Iron Steel, 2012, 12(1): 46
Sato Y S, Nelson T W, Sterling C J, et al. Microstructure and mechanical properties of friction stir welded SAF 2507 super duplex stainless steel [J]. Mater. Sci. Eng., 2005, A397: 376
[5]
Su Y S, Yang Y H, Cao J C, et al. Research on hot working behavior of low-nickel duplex stainless steel 2101 [J]. Acta Metall. Sin., 2018, 54: 485
Mcirdi L, Baptiste D, Inal K, et al. Multi-scale behaviour modelling of an austeno-ferritic steel [J]. J. Neut. Res., 2001, 9: 217
[7]
Moverare J J, Odén M. Deformation behaviour of a prestrained duplex stainless steel [J]. Mater. Sci. Eng., 2002, A337: 25
[8]
Siegmund T, Werner E, Fischer F D. On the thermomechanical deformation behavior of duplex-type materials [J]. J. Mech. Phys. Solids, 1995, 43: 495
[9]
Iza-Mendia A, Piñol-Juez A, Urcola J J, et al. Microstructural and mechanical behavior of a duplex stainless steel under hot working conditions [J]. Metall. Mater. Trans., 1998, 29A: 2975
[10]
Cabrera J M, Mateo A, Llanes L, et al. Hot deformation of duplex stainless steels [J]. J. Mater. Process. Technol., 2003, 143-144: 321
[11]
Zhang P X, Ren X P, Xie J X, et al. Superplasticity mechanism of duplex stainless steels [J]. J. Univ. Sci. Technol. Beijing, 2005, 27: 68
Farahat A I Z, Hamed O, El-Sisi A, et al. Effect of hot forging and Mn content on austenitic stainless steel containing high carbon [J]. Mater. Sci. Eng., 2011, A530: 98
[15]
Liu H B, Liu J H, Wu B W, et al. Effect of Mn and Al contents on hot ductility of high alloy Fe-xMn-C-yAl austenite TWIP steels [J]. Mater. Sci. Eng., 2017, A708: 360
[16]
Balancin O, Hoffmann W A M, Jonas J J. Influence of microstructure on the flow behavior of duplex stainless steels at high temperatures [J]. Metall. Mater. Trans., 2000, 31A: 1353
[17]
Chen L, Wang L M, Du X J. et al. Hot deformation behavior of 2205 duplex stainless steel [J]. Acta Metall. Sin., 2010, 46: 52
Park Y H, Lee Z H. The effect of nitrogen and heat treatment on the microstructure and tensile properties of 25Cr-7Ni-1.5Mo-3W-xN duplex stainless steel castings [J]. Mater. Sci. Eng., 2001, A297: 78
[21]
Song Y Q, Guan Z P, Ma P K, et al. Theoretical and experimental standardization of strain hardening index in tensile deformation [J]. Acta Metall. Sin., 2006, 42: 673
Mittra J, Dubey J S, Kulkarni U D, et al. Role of dislocation density in raising the stage II work-hardening rate of alloy 625 [J]. Mater. Sci. Eng., 2009, A512: 87
[23]
Morris D G, Muñoz-Morris M A, Requejo L M. Work hardening in Fe-Al alloys [J]. Mater. Sci. Eng., 2007, A460-461: 163
[24]
Barnett M R. Twinning and the ductility of magnesium alloys: Part I: “Tension” twins [J]. Mater. Sci. Eng., 2007, A464: 1
[25]
Zhang Y J. Research on deformation induced plastic behavior of the lean duplex stainless steel [D]. Qinhuangdao: Yanshan University, 2017
(张英杰. 节约型双相不锈钢形变诱导塑性行为机理的研究 [D]. 秦皇岛: 燕山大学, 2017)
[26]
Lu S, Hu Q M, Johansson B, et al. Stacking fault energies of Mn, Co and Nb alloyed austenitic stainless steels [J]. Acta Mater., 2011, 59: 5728
[27]
Estrin Y, Mecking M. A unified phenomenological description of work hardening and creep based on one-parameter models [J]. Acta Metall., 1984, 32: 57
[28]
Chen Z W, Dai Q X, Li D S, et al. Properties of Cr18Ni9Cu3NbN austenitic stainless steel [J]. Heat Treat. Met., 2010, 35(10): 52
Herrera C, Ponge D, Raabe D. Design of a novel Mn-based 1 GPa duplex stainless TRIP steel with 60% ductility by a reduction of austenite stability [J]. Acta Mater., 2011, 59: 4653
[30]
Ren M, Li B H. The mechanism and preventing method of cracking on the steel ingot [J]. Heavy Cast. Forg., 1992, (3): 36
Zhao X, Jing T F, Gao Y W, et al. Morphology of graphite in hot-compressed nodular iron [J]. J. Mater. Sci., 2004, 39: 6093
[34]
Dai Q X, Wang A D, Cheng X N, et al. Effect of alloying elements and temperature on strength of cryogenic austenitic steels [J]. Mater. Sci. Eng., 2001, A311: 205
[35]
Remy L, Pineau A. Twinning and strain-induced F.C.C. →H.C.P. transformation in the Fe-Mn-Cr-C system [J]. Mater. Sci. Eng., 1997, A28: 99
[36]
Byun T S. On the stress dependence of partial dislocation separation and deformation microstructure in austenitic stainless steels [J]. Acta Mater., 2003, 51: 3063
[37]
Michel D J, Moteff J, Lovell A J. Substructure of type 316 stainless steel deformed in slow tension at temperatures between 21 ℃ and 816 ℃ [J]. Acta Metall., 1973, 21: 1269
[38]
Chen C, Wang M P, Wang S. et al. Evolution of dislocation microstructures in Ta-7.5%W alloy foils during cold-rolling [J]. Acta Metall. Sin., 2011, 47: 984
Yu Y N. Principles of Metallography [M]. Beijing: Metallurgical Industry Press, 2000: 48
(余永宁. 金属学原理 [M]. 北京: 冶金工业出版社, 2000: 408)
[40]
Jiang T H, Liu M P, Xie X F, et al. Grain boundary structure of Al-Mg alloys processed by high pressure torsion [J]. Chin. J. Mater. Res., 2014, 28: 371
Hu G D, Wang P, Li D Z, et al. The tensile behaviors of vanadium-containing 25Cr-20Ni austenitic stainless steel at temperature between 200 ℃ and 900 ℃ [J]. Mater. Sci. Eng., 2018: A711: 543
[42]
Hu G X, Cai X, Rong Y H. Fundamentals of Materials Science [M]. 3rd Ed., Shanghai: Shanghai Jiaotong University Press, 2003: 201
Duprez L, De Cooman B C, Akdut N. Flow stress and ductility of duplex stainless steel during high-temperature torsion deformation [J]. Metall. Mater. Trans., 2002, 33A: 1931
