Abstract:In order to research the effect of isothermal aging on precipitation and corrosion resistance of hyper duplex stainless steel S32707,the precipitation behavior,pitting corrosion and intergranular corrosion resistance of the steel aged at 950 ℃ for different time were studied by means of microstructure characterization and electrochemical tests. The results show that,after aging for 5-30 min,σ phase preferentially precipitated at δ/δ grain boundary and δ/γ phase boundary through eutectoid reaction (δ→σ+γ2),and gradually grew into grains. After aging for 2 h,δ phase was completely transformed into σ and γ2 phases. After 12 h aging,σ phase nucleated inside the γ phase. At the beginning of aging,Cr2 N nucleated at the σ/γ2interface,and then precipitated at the σ/γ and γ/γ interfaces. With the prolongation of aging time,the pitting potential(Epit),charge transfer resistance(Rp) and double-layer capacitor(Q) of steel changed in a three-stage manner. During 0-2 h,Epit and Rp sharply decreased,and Q sharply increased; during 2-12 h,Epit and Rp slowly decreased,and Q slowly increased; during 12-48 h,Epit and Rp slightly increased,and Q slightly decreased. The intergranular corrosion sensitivity also changed in a three-stage manner,sharply increased during 0-2 h,slowly increased during 2-12 h,and slightly decreased during 12-48 h. σ phase and Cr2 N precipitation induced Cr- and Mo-depleted zones around them. The corrosion resistance of steel depended on the competition results of Cr and Mo depletion and self-healing. During 0-2 h,the rapid formation of precipitates induced extensive Cr- and Mo- depleted zones,and the corrosion resistance significantly reduced. During 2-12 h,the depletion rate of Cr and Mo was greater than their self-healing rate,so the corrosion resistance slowly decreased. During 12-48 h,the depletion rate of Cr and Mo was less than their self-healing rate,so the corrosion resistance slightly improved.
李国平, 张树才, 张彬彬, 林宝海, 李恒. 等温时效对S32707不锈钢析出行为和耐蚀性的影响[J]. 钢铁, 2023, 58(6): 102-109.
LI Guoping, ZHANG Shucai, ZHANG Binbin, LIN Baohai, LI Heng. Effect of isothermal aging on precipitation behavior and corrosion resistance of S32707 stainless steel[J]. Iron and Steel, 2023, 58(6): 102-109.
[1] 吴玖.双相不锈钢[M].北京:冶金工业出版社,1999.(WU J.Duplex Stainless Steel[M].Beijing:Metallurgical Industry Press,1999.) [2] 高娃,罗建民,杨建君.双相不锈钢的研究进展及其应用[J].兵器材料科学与工程,2005,28(3):61.(GAO W,LUO J M,YANG J J.Research progress and application of double phase stainless steel[J].Ordnance Material Science and Engineering,2005,28(3):61.) [3] 郝硕,李志国,张鑫,等.预应变对TRIP型双相不锈钢拉伸变形行为的影响[J].钢铁,2022,57(4):105.(HAO S,LI Z G,ZHANG X,et al.Influence of pre-strain on tensile deformation behavior of TRIP-assisted duplex stainless steel[J].Iron and Steel,2022,57(4):105.) [4] ZHANG S C,LI H B,JIANG Z H,et al.Catastrophic oxidation mechanism of hyper duplex stainless steel S32707 at high temperature in air[J].Materials Characterization,2018,145:233. [5] 宋志刚,丰涵,吴晓涵,等. 中国双相不锈钢的发展及研究进展[J]. 中国冶金,2022,32(6):2. (SONG Z G,FENG H,WU X H,et al. Development and research progress of duplex stainless steel in China[J]. China Metallurgy,2022,32(6):2.) [6] 吕杰晟,宋志刚,何建国,等. 固溶温度对17Cr-1Ni-3Mn-0.12N经济型不锈钢组织及力学性能影响[J]. 中国冶金,2023,33(5):71. (LÜ J S,SONG Z G,HE J G,et al. Effect of solution temperature on microstructure and mechanical properties of 17Cr-1Ni-3Mn-0.12N lean stainless steel[J]. China Metallurgy,2023,33(5):71. ) [7] 王刚,郭幼丹,郭雷,等.双相不锈钢的发展、特点及其应用[J].科技与创新,2015(7):91.(WANG G,GUO Y D,GUO L,et al.Development of duplex stainless steel,characteristics and applications[J].Science and Technology and Innovation,2015(7):91.) [8] 高祥明,裴明德,李国平.冷轧硬化对超级双相不锈钢S32750析出相的影响[J].钢铁,2019,54(9):94.(GAO X M,PEI M D,LI G P.Influence of cold rolling on precipitation of S32750 super duplex stainless steel[J].Iron and Steel,2019,54(9):94.) [9] KIM S M,KIM J S,KIM K T,et al.Effect of Ce addition on secondary phase transformation and mechanical properties of 27Cr-7Ni hyper duplex stainless steels[J].Materials Science and Engineering A,2013,573:27. [10] 刘晓,童为硕,赵良群,等. NaCl+HCl溶液中Ce对双相不锈钢腐蚀行为的影响[J]. 中国冶金,2022,32(6):87. (LIU X,TONG W S,ZHAO L Q,et al. Effect of Ce on corrosion behavior of duplex stainless steel in NaCl+HCl solution[J]. China Metallurgy,2022,32(6):87. ) [11] 谭庆丰,陈德利,闫占东,等. EAF+LF+VOD/VHD冶炼超级双相不锈钢工艺实践[J]. 中国冶金,2022,32(6):163. (TAN Q F,CHEN D L,YAN Z D,et al. Practice on EAF+LF+VOD/VHD smelting process of super duplex stainless steel[J]. China Metallurgy,2022,32(6):163. ) [12] 韩冬,蒋益明,邓博,等.时效时间对2101双相不锈钢电化学腐蚀行为的影响[J].金属学报,2009,45(8):919.(HAN D,JIANG Y M,DENG B,et al.Effect of aging time on electrochemical corrosion behavior of 2101 duplex stainless steel[J].Acta Metallurgica Sinica,2009,45(8):919.) [13] ZHANG L H,JIANG Y M,DENG B,et al.Effect of aging on the corrosion resistance of 2101 lean duplex stainless steel[J].Materials Characterization,2009,60:1522. [14] ZHANG Z Y,ZHAO H,ZHANG H Z,et al.Effect of isothermal aging on the pitting corrosion resistance of UNS S82441 duplex stainless steel based on electrochemical detection[J].Corrosion Science,2015,93:120. [15] ANGELINI E,BENEDETTI B,ROSALBINO F.Microstructural evolution and localized corrosion resistance of an aged superduplex stainless steel[J].Corrosion Science,2004,46:1351. [16] ZHANG B B,JIANG Z H,LI H B,et al.Precipitation behavior and phase transformation of hyper duplex stainless steel S32707 at nose temperature[J].Materials Characterization,2017,129:31. [17] ZHANG B B,LI H B,ZHANG S C,et al.Effect of nitrogen on precipitation behavior of hyper duplex stainless steel S32707[J].Materials Characterization,2021,175:111096. [18] 李恒.特超级双相不锈钢UNS S32707时效析出行为及耐腐蚀性能研究[D].沈阳:东北大学,2016.(LI H.Research on Aging Precipitation Behavior and Corrosion Resistance of Hyper Duplex Stainless Steel UNS S32707[D].Shenyang:Northeastern University,2016.) [19] RODRIGO M,MATER J.Kinetics of sigma phase formation in a duplex stainless steel[J].Journal of Materials Research,2009,12:321. [20] ZHENG L,HU X,KANG X,et al.Precipitation of M23C6 and its effect on tensile properties of 0.3C-20Cr-11Mn-1Mo-0.35N steel[J].Materials and Design,2015,78:42. [21] JEON S H,KIM S T,LEE I S,et al.Effects of Cu on the precipitation of intermetallic compounds and the intergranular corrosion of hyper duplex stainless steels[J].Corrosion Science,2013,66:217. [22] 曹楚南.腐蚀电化学原理[M].北京:化学工业出版社,2004.(CAO C N.Principles of Electrochemistry of Corrosion[M].Beijing:Chemical Industry Press,2004.) [23] GONG J,JIANG Y M,DENG B,et al.Evaluation of intergranular corrosion susceptibility of UNS S31803 duplex stainless steel with an optimized double loop electrochemical potentiokinetic reactivation method[J].Electrochemical Acta,2010,55:5077. [24] PARDO A,MERINO M C,COY A E,et al.Influence of Ti,C and N concentration on the intergranular corrosion behaviour of AISI 316Ti and 321 stainless steels[J].Acta Materialia,2007,55:2239. [25] HONG J F,HAN D,TAN H,et al.Evaluation of aged duplex stainless steel UNS S32750 susceptibility to intergranular corrosion by optimized double loop electrochemical potentiokinetic reactivation method[J].Corrosion Science,2013,68:249. [26] 胡赓祥,蔡珣,戎咏华.材料科学基础[M].上海:上海交通大学出版社,2006.(HU G X,CAI X,RONG Y H.Fundamentals of Materials Science[M].Shanghai:Shanghai Jiaotong University Press,2006.) [27] 谭华.双相不锈钢焊缝组织演变与腐蚀行为研究[D].上海:复旦大学,2012.(TAN H.Investigation on Corrosion Behaviors and Microstructure Evolution of Duplex Stainless Steels Welded Joint[D].Shanghai:Fudan University,2012.) [28] LEE C,ROH S,LEE C,et al.Influence of Si on sigma phase precipitation and pitting corrosion in superaustenitic stainless steel weld metal[J].Materials Chemistry and Physics,2018,207:91. [29] 张树才.超级奥氏体不锈钢S32654的制备及组织与性能研究[D].沈阳:东北大学,2019.(ZHANG S C.Manufacture,Microstructure and Properties of Super Austenitic Stainless Steel S32654[D].Shenyang:Northeastern University,2019.) [30] ZHANG S C,JIANG Z H,LI H B,et al.Detection of susceptibility to intergranular corrosion of aged super austenitic stainless steel S32654 by a modified electrochemical potentiokinetic reactivation method[J].Journal of Alloys and Compounds,2017,695:3083. [31] DENG B,JIANG Y M,XU J L,et al.Application of the modified electrochemical potentiodynamic reactivation method to detect susceptibility to intergranular corrosion of a newly developed lean duplex stainless steel LDX2101[J].Corrosion Science,2010,52:969.