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Acta Metall Sin  2018, Vol. 54 Issue (1): 55-64    DOI: 10.11900/0412.1961.2017.00291
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Effect of Nitrogen Content on Precipitation Behavior and Mechanical Properties of Mn18Cr18NAustenitic Stainless Steel
Fengming QIN, Yajie LI, Xiaodong ZHAO, Wenwu HE, Huiqin CHEN()
School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China
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Abstract  

Mn18Cr18N austenitic stainless steel with excellent mechanical properties and corrosion resistance is widely used in nuclear industries, power plants and medicine field. However, precipitation of the second phases during hot deformation deteriorates the mechanical properties and hot formability. In order to clarify the precipitation behavior of this steel, the precipitation behavior and its influence on mechanical properties of Mn18Cr18N austenitic stainless steel with different nitrogen contents were investigated by JmatPro software, OM, SEM and TEM analytical methods. The results indicate that precipitation phases consist of Cr2N and a few M23C6, in which Cr2N preferentially precipitates along grain bound aries and then grows up to the interior of austenite grain by discontinuous cellular. With increasing of ageing temperature, the precipitation of Cr2N became more sensitive. When the nitrogen content increases to 0.7%, the most sensitive precipitation temperature of Cr2N is 750 ℃ with an incubation period of 10 min. However, M23C6 mainly precipitates by granular at austenitic grain boundaries and maintains cube-on-cube orientation relationship with adjacent austenite grain. The results of mechanical property test indicate that the precipitation of Cr2N has a negligible effect on strength and obvious deterioration on plasticity of Mn18Cr18N austenitic stainless steel. The precipitation of Cr2N after ageing treatment leads to remarkable decrease in elongation and reduction of area, and the elongation reduced from 52.9% to 27.7%. Meanwhile, fracture mode also transformed from ductile fracture to intergranular fracture and transgranular fracture with the increasing of Cr2N. TEM analysis shows that solution treatment sample reveals good plastic deformation ability and coordinates deformation by slip and twinning, simultaneously. Nevertheless, dislocations slipped, propagated and eventually piled up between lamellas of Cr2N and around granular M23C6 after ageing treatment, which induce the degeneration of the plastic deformation capacity of Mn18Cr18N austenitic stainless steel.

Key words:  Mn18Cr18N austenitic stainless steel      precipitation behavior      microstructure      mechanical property     
Received:  12 July 2017     
ZTFLH:  TG142.71  
Fund: Supported by National Natural Science Foundation of China (No.51575372), Natural Science Foundation of Shanxi Province (No.2014011015-4) and Science and Technology Research Plan (Industrial) Project of Shanxi Province (No.201603D121006-2)

Cite this article: 

Fengming QIN, Yajie LI, Xiaodong ZHAO, Wenwu HE, Huiqin CHEN. Effect of Nitrogen Content on Precipitation Behavior and Mechanical Properties of Mn18Cr18NAustenitic Stainless Steel. Acta Metall Sin, 2018, 54(1): 55-64.

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https://www.ams.org.cn/EN/10.11900/0412.1961.2017.00291     OR     https://www.ams.org.cn/EN/Y2018/V54/I1/55

Fig.1  Schematic of tensile test specimen (unit: mm)
Fig.2  Phase diagrams of Mn18Cr18N steel with different nitrogen contents (a) 0.5N (b) 0.6N (c) 0.7N
Fig.3  Time-temperature-transformation (TTT) curves for Mn18Cr18N steel with different nitrogen
contents (a) 0.5N (b) 0.6N (c) 0.7N
Fig.4  Microstructures of Mn18Cr18N steel aged at different conditions(a~d) Mn18Cr18N0.5 steel aged at 700 ℃ for 2 h, 4 h, 8 h, 24 h (e~h) Mn18Cr18N0.6 steel aged at 750 ℃ for 2 h, 4 h, 8 h, 24 h (i~l) Mn18Cr18N0.7 steel aged at 750 ℃ for 10 min, 1 h, 4 h, 24 h
Fig.5  SEM images of Cr2N precipitation in Mn18Cr18N steel aged at 750 ℃ for 8 h (a) 0.5N (b) 0.6N (c) 0.7N
Fig.6  TEM images and EDS analyses of precipitations of Mn18Cr18N0.7 steel aged at 750 ℃ for 24 h(a) lamellar Cr2N and SAED pattern (inset) (b) M23C6 and SAED pattern (inset)(c) EDS of Cr2N (d) EDS of M23C6
Fig.7  Stress-strain curves of Mn18Cr18N steel(a) solution treated (b) aged at 750 ℃ for 8 h
Fig.8  SEM images of tensile fracture surfaces of Mn18Cr18N alloy with 0.5N (a, b), 0.6N (c) and 0.7N (d) solution treated (a) and aged at 750 ℃ for 8 h (b~d)
Fig.9  Microstructures of tensile fracture surfaces of Mn18Cr18N0.7 steel with solution treated (a) and aged at 750 ℃ for 1 h (b), 4 h (c) and 8 h (d)
Fig.10  TEM images of tensile sample fracture of Mn18Cr18N0.7 alloy with solution treated (a, b) and aged at 750 ℃ for 24 h (c, d) (Inset shows SAED pattern of deformation twins)
[1] Xu M Z, Wang J J, Liu C M.Low temperature deformation behavior of high-nitrogen nickel-free austenitic stainless steels[J]. Acta Metall. Sin., 2011, 47: 1335(徐明舟, 王建军, 刘春明. 新型无Ni高N奥氏体不锈钢的低温变形行为[J]. 金属学报, 2011, 47: 1335)
[2] Knutsen R D, Lang C I, Basson J A.Discontinuous cellular precipitation in a Cr-Mn-N steel with niobium and vanadium additions[J]. Acta Mater., 2004, 52: 2407
[3] He W W, Liu J S, Guo Y F, et al.Grain growth behavior of Mn18Cr18N retaining ring steel during multi-heating hot forging process[J]. Mater. Mech. Eng., 2010, 34(7): 20(何文武, 刘建生, 郭银芳等. Mn18Cr18N护环钢多火次热锻过程中晶粒的长大规律[J]. 机械工程材料, 2010, 34(7): 20)
[4] Shi F, Qi Y, Liu C M.Effects of Mo on the precipitation behaviors in high-nitrogen austenitic stainless steels[J]. J. Mater. Sci. Technol., 2011, 27: 1125
[5] Shi F, Wang L J, Cui W F, et al.Precipitation kinetics of Cr2N in high nitrogen austenitic stainless steel[J]. J. Iron Steel Res. Int., 2008, 15(6): 72
[6] Lee T H, Kim S J, Jung Y C.Crystallographic details of precipitates in Fe-22Cr-21Ni-6Mo-(N) superaustenitic stainless steels aged at 900 ℃[J]. Metall. Mater. Trans., 2000, 31A: 1713
[7] Wasnik D N, Dey G K, Kain V, et al.Precipitation stages in a 316L austenitic stainless steel[J]. Scr. Mater., 2003, 49: 135
[8] Padilha A F, Escriba D M, Materna-Morris E, et al.Precipitation in AISI 316L (N) during creep tests at 550 and 600 ℃ up to 10 years[J]. J. Nucl. Mater., 2007, 362: 132
[9] Terada M, Saiki M, Costa I, et al.Microstructure and intergranular corrosion of the austenitic stainless steel 1.4970[J]. J. Nucl. Mater., 2006, 358: 40
[10] Voice W E, Faulkner R G.The discontinuous precipitation of M23C6 in Nimonic 80A[J]. J. Mater. Sci., 1987, 22: 4221
[11] Hong H U, Rho B S, Nam S W.Correlation of the M23C6 precipitation morphology with grain boundary characteristics in austenitic stainless steel[J]. Mater. Sci. Eng., 2001, A318: 285
[12] Lee T H, Oh C S, Lee C G, et al.Precipitation characteristics of the second phases in high-nitrogen austenitic 18Cr-18Mn-2Mo-0.9N steel during isothermal aging[J]. Met. Mater. Int., 2004, 10: 231
[13] Kikuchi M, Kajihara M, Choi S K.Cellular precipitation involving both substitutional and interstitial solutes: Cellular precipitation of Cr2N in Cr-Ni austenitic steels[J]. Mater. Sci. Eng., 1991, A146: 131
[14] Li H B, Jiang J H, Feng H, et al.Aging precipitation behavior of 18Cr-16Mn-2Mo-1.1N high nitrogen austenitic stainless steel and its influences on mechanical properties[J]. J. Iron Steel Res. Int., 2012, 19(8): 43
[15] Vanderschaeve F, Taillard R, Foct J.Discontinuous precipitation of Cr2N in a high nitrogen, chromium-manganese austenitic stainless steel[J]. J. Mater. Sci., 1995, 30: 6035
[16] Srinivas N C S, Kutumbarao V V. On the discontinuous precipitation of Cr2N in Cr-Mn-N austenitic stainless steels[J]. Scr. Mater., 1997, 37: 285
[17] Shi F, Wang L J, Cui W F, et al.Precipitation behavior of M2N in a high-nitrogen austenitic stainless steel during isothermal aging[J]. Acta Metall. Sin.(Engl. Lett.), 2007, 20: 95
[18] Lee T H, Ha H Y, Kim S J.Precipitation of second phases in high-interstitial-alloyed austenitic steel[J]. Metall. Mater. Trans., 2011, 42A: 3543
[19] Kartik B, Veerababu R, Sundararaman M, et al.Effect of high temperature ageing on microstructure and mechanical properties of a nickel-free high nitrogen austenitic stainless steel[J]. Mater. Sci. Eng., 2015, 642: 288
[20] Lee T H, Kim S J, Takaki S.Time-temperature-precipitation characteristics of high-nitrogen austenitic Fe-18Cr-18Mn-2Mo-0.9N steel[J]. Metall. Mater. Trans., 2006, 37A: 3445
[21] Qin F M, Zhu H, Wang Z X, et al.Dislocation and twinning mechanisms for dynamic recrystallization of as-cast Mn18Cr18N steel[J]. Mater. Sci. Eng., 2017, A684: 634
[22] Humphreys F J, Hatherly M.Recrystallization and Related Annealing Phenomena[M]. 2nd Ed., Oxford UK: Elsevier Ltd., 2004: 262
[23] Wang S T, Yang K, Shan Y Y, et al.Study of cold deformation behaviors of a high nitrogen austenitic stainless steel and 316L stainless steel[J]. Acta Metall. Sin., 2007, 43: 171(王松涛, 杨柯, 单以银等. 高氮奥氏体不锈钢与316L不锈钢的冷变形行为研究[J]. 金属学报, 2007, 43: 171)
[24] Landon P R, Caligiuri R D, Duletsky P S.The influence of the M23(C, N)6 compound on the mechanical properties of type 422 stainless steel[J]. Metall. Trans., 1983, 14A: 1395
[25] Tavassoli A A, Colombe G.Mechanical and microstructural properties of alloy 800[J]. Metall. Trans., 1978, 9A: 1203
[26] Zhang X S, Xu Y, Zhang S H, et al.Research on the collaborative effect of plastic deformation and solution treatment in the intergranular corrosion property of austenite stainless steel[J]. Acta Metall. Sin., 2017, 53: 335(张晓嵩, 徐勇, 张士宏等. 塑性变形及固溶处理对奥氏体不锈钢晶间腐蚀性能的协同作用研究[J]. 金属学报, 2017, 53: 335)
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