Effect of phase boundary and grain boundary characteristics on mechanical properties and corrosion resistance of S32750 duplex stainless steel
LI Hao-qing1, TIAN Yu-jing1, ZHAO Er-tuan1, GUO Hong2, FANG Xiao-ying1
1. School of Mechanical Engineering, Shandong University of Technology, Zibo 255000, Shandong, China;
2. Center of Testing and Analysis, Shandong University of Technology, Zibo 255000, Shandong, China
Abstract：S32750 duplex stainless steel samples with different initial microstructures obtained by solid solution heat treatment (SHT) were cold rolled with the thickness reduction of 80% and subsequently annealed at 1050℃. The distribution of phase boundary and grain boundary character for the as-processed samples was investigated by SEM-EBSD and XRD techniques. Furthermore, the effect of microstructure on mechanical properties and intergranular corrosion resistance was analyzed by means of tensile testing, nano-indentation and double loop electrochemical potential reactivation (DL-EPR) method. The results show that the fine-grained microstructure with the areal ratio of α to γ about 1, the highest fraction of phase boundaries out of the total interfaces (grain boundaries +phase boundaries), and the least grain clustering within the respective α and γ phases was obtained in the sample previously treated by high temperature SHT and subsequent cold rolling and annealing. As a result, the sample exhibits excellent mechanical properties. After the cold-rolled and annealed samples are sensitized at 750℃ for 4 h, the σ phase precipitates readily along the α grain boundary. The sample previously treated by high temperature SHT and subsequent cold rolling and annealing also possess better intergranular corrosion resistance due to the relatively small amount of α grain boundary and high population of phase boundaries meeting K-S orientation relationship between α and γ. Therefore, the strength and intergranular corrosion resistance might be improved simultaneously by controlling and designing interface character distribution via appropriate thermal mechanical treatment in duplex stainless steel.
[1] 康利梅. 双相不锈钢的发展及应用综述[J]. 科技广场, 2010(8):165-168. KANG L M. Review of development and application of duplex stainless steel[J]. Science Mosaic, 2010(8): 165-168.
[2] 陆世英,张延凯,康喜范.不锈钢[M]. 北京:原子能出版社,1995:16-18. LU S Y, ZHANG Y K, KANG X F. Stainless steel[M]. Beijing: Atomic Energy Press, 1995:16-18.
[3] NILSSON J O,郑德清. 超级双相不锈钢[J]. 大连特殊钢, 1993(5):1-18. NILSSON J O,ZHENG D Q. Super duplex stainless steel[J]. Dalian Special Steel, 1993(5):1-18.
[4] 杜海涛. 超级双相不锈钢在典型服役环境中的腐蚀行为研究[D]. 沈阳:东北大学, 2014. DU H T. Corrosion behavior of super duplex stainless steel in typical service environment[D]. Shenyang: Northeastern University, 2014.
[5] 李国平,王建军,吴天海,等. 2205双相不锈钢TIG焊接头组织及力学性能[J]. 材料研究学报, 2016, 30(12): 897-902. LI G P, WANG J J, WU T H, et al. Microstructure and mechanical properties of 2205 DSS metal inert-gas welding joints[J]. Chinese Journal of Materials Research, 2016, 30(12): 897-902.
[6] 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): 919-923. 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): 919-923.
[7] 李松梅,吴凌飞,刘建华,等. 应力比和腐蚀环境对超高强度钢AerMet100疲劳裂纹扩展的影响[J]. 航空材料学报, 2014, 34(3): 74-80. LI S M, WU L F, LIU J H, et al. Effect of load ratio and corrosion on fatigue behavior of AerMet100 ultrahigh strength steel[J]. Journal of Aeronautical Materials, 2014, 34(3): 74-80.
[8] 曹静,安立聪,齐兴,等. 含Ti铸造双相不锈钢点蚀行为研究[J]. 材料研究学报, 2017, 31(7): 553-560. CAO J, AN L C, QI X, et al. Pitting corrosion behavior of cast Ti-bearing duplex stainless steel[J]. Chinese Journal of Materials Research, 2017, 31(7): 553-560.
[9] FANG X Y, LIU Z Y, TIKHONOVA M, et al. Evolution of texture and development of ∑3<em>n grain clusters in 316 austenitic stainless steel during thermal mechanical processing[J]. Journal of Materials Science, 2013, 48(3): 997-1004.
[10] 方晓英,刘志勇, TIKHONOVA M, 等. 多向锻造和单向轧制304不锈钢高温退火后的晶界特征分布[J]. 金属学报, 2012, 48(8): 895-906. FANG X Y, LIU Z Y, TIKHONOVA M, et al. Grain boundary plane distribution in 304 steel annealed at high temperature after a parallel processing of multiple forging and direct rolling[J]. Acta Metallurgica Sinica, 2012, 48(8): 895-906.
[11] 刘锡荣,张凯,夏爽,等. 690合金中三晶交界及晶界类型对碳化物析出形貌的影响[J]. 金属学报, 2018, 54(3): 404-410. LIU X R, ZHANG K, XIA S, et al. Effects of triple junction and grain boundary characters on the morphology of carbide precipitation in alloy 690[J]. Acta Metallurgica Sinica, 2018, 54(3): 404-410.
[12] 许婷,方晓英,朱言利,等. 双相不锈钢中奥氏体沉淀相的晶粒取向及界面特征分布[J]. 材料工程, 2018, 46(2):34-40. XU T, FANG X Y, ZHU Y L, et al. Grain orientation and interface character distribution during austenite precipitation phase in duplex stainless steel[J]. Journal of Materials Engineering, 2018, 46(2): 34-40.
[13] MICHIUCHI M, KOKAWA H, WANG Z J, et al. Twin-induced grain boundary engineering for 316 austenitic stainless steel [J]. Acta Materialia, 2006, 54(19): 5179-5184.
[14] 郭丽芳,李旭晏,孙涛,等. 敏化温度对SAF2304双相不锈钢耐局部腐蚀性能的影响[J]. 金属学报, 2012, 48(12): 1503-1509. GUO L F, LI X Y, SUN T, et al. The influence of sensitive temperature on the localized corrosion resistance of duplex stainless steel SAF2304[J]. Acta Metallurgica Sinica, 2012, 48(12): 1503-1509.
[15] 朱言利,许婷,秦聪祥,等. 双相不锈钢内界面特征分布和耐晶间腐蚀性能[J]. 机械工程材料, 2017, 41(8): 18-22. ZHU Y L, XU T, QIN C X, et al. Interfacial boundary character distribution and intergranular corrosion resistance of duplex stainless steel[J]. Materials for Mechanical Engineering, 2017, 41(8): 18-22.
[16] WATANABE T, TSUREKAWA S. The control of brittleness and development of desirable mechanical properties in polycrystalline systems by grain boundary engineering[J]. Acta Materialia, 1999, 47(15/16): 4171-4185.
[17] IKEUCHI K. Role of sigma phase on hydrogen embrittlement of super duplex stainless steels[J]. Transactions of JWRI, 2005, 34(2): 63-68.
[18] JIA N, PENG R L, CHAI G C. Direct experimental mapping of microscale deformation heterogeneity in duplex stainless steel[J]. Materials Science and Engineering:A, 2008, 491(1/2): 425-433.
2020, Vol. 48 
