氧化对Cr25Ni35Nb与Cr35Ni45Nb合金组织和磁性的影响
|
摘要
采用光学显微镜、扫描电镜、X射线衍射仪和振动样品磁强计分析了Cr25Ni35Nb和Cr35Ni45Nb两类合金长期服役后的氧化行为以及其对磁性的影响。结果表明:长期服役后形成的氧化层主要由Cr2O3、SiO_2、Fe2O3组成,并且氧化膜发生了破裂,外壁和内壁氧化膜的破裂分别是Cr2O3在高温下的不稳定性和周期性的结焦/清焦所造成的;裂解炉管内壁和外壁均出现了氧化层、贫碳化物区、碳化物区,外表层为连续的Cr2O3氧化层,SiO_2则在贫碳化物区沿晶界分布;氧化前两种奥氏体耐热合金均为顺磁性结构,经氧化后形成的贫碳化物区中,基体的Cr含量较低,因而转变为铁磁性结构,其饱和磁化强度均超过20 emu/g。因此,氧化也是乙烯炉管长期服役后转变为铁磁性结构的重要因素。
In this work,the oxidation behavior and the magnetic properties of Cr25Ni35Nb and Cr35Ni45Nb alloys after a long-term service were investigated by employing OM,SEM,XRD and VSM analysis. The results show that the oxidation layer formed consists of Cr_2O_3,SiO_2 and Fe_2O_3,and exhibits cracks and rupture. The high-temperature instability of Cr_2O_3 and the cyclic coking/decoking operation during long-term service are found to contribute to the rupture of the outer and inner surface oxidation layers,respectively. There could be observed three zones,i. e. oxidation layer,carbide-depleted zone and carbides zone,at both inner and outer walls of the pyrolysis furnace tubes. The oxidation film is a continuous Cr_2O_3 oxide layer,and SiO_2 disperses along the grain boundaries at the carbide-depleted zone. The original two kinds of austenitic heatresistant alloys are paramagnetic. And due to the lower Cr content of matrix at the carbide-depleted zones,the paramagnetic structures are transformed into ferromagnetic structures,with saturation magnetizations larger than 20 emu/g. Therefore,it could be concluded that oxidation is also one of the critical factors that impel ethylene pyrolysis furnace tube to the transformation into ferromagnetic structure.
In this work,the oxidation behavior and the magnetic properties of Cr25Ni35Nb and Cr35Ni45Nb alloys after a long-term service were investigated by employing OM,SEM,XRD and VSM analysis. The results show that the oxidation layer formed consists of Cr_2O_3,SiO_2 and Fe_2O_3,and exhibits cracks and rupture. The high-temperature instability of Cr_2O_3 and the cyclic coking/decoking operation during long-term service are found to contribute to the rupture of the outer and inner surface oxidation layers,respectively. There could be observed three zones,i. e. oxidation layer,carbide-depleted zone and carbides zone,at both inner and outer walls of the pyrolysis furnace tubes. The oxidation film is a continuous Cr_2O_3 oxide layer,and SiO_2 disperses along the grain boundaries at the carbide-depleted zone. The original two kinds of austenitic heatresistant alloys are paramagnetic. And due to the lower Cr content of matrix at the carbide-depleted zones,the paramagnetic structures are transformed into ferromagnetic structures,with saturation magnetizations larger than 20 emu/g. Therefore,it could be concluded that oxidation is also one of the critical factors that impel ethylene pyrolysis furnace tube to the transformation into ferromagnetic structure.
引文
1 Reihani A,Haghighi R D.Engineering Failure Analysis,2015,52,97.
2 Petkovicluton P,Ramanarayanan T A.Oxidation of Metals,1990,34(5-6),381.
3 Kaya A A.Materials Characterization,2002,49(1),23.
4 Chun C M,Desai S,Hershkowitz F,et al.Materials and CorrosionWerkstoffe Und Korrosion,2014,65(3),282.
5 Konosu S,Koshimizu K,Iijima T,et al.Journal of Mechanical Design,1993,115(1),41.
6 Chauhan A,Anwar M,Montero K,et al.Journal of Phase Equilibria and Diffusion,2006,27(6),684.
7 Wu Xinqiang,Yang Yuansheng,Zhan Qian,et al.Acta Metallurgica Sinica,1998,34(10),1043(in Chinese).吴欣强,杨院生,詹倩,等.金属学报,1998,34(10),1043.
8 Wang H,Du C Y,Li W,et al.Hot Working Technology,2014(18),101(in Chinese).王辉,杜晨阳,李伟,等.热加工工艺,2014(18),101.
9 Song R K,Zhang M C,Peng Y C,et al.Journal of University of Science and Technology Beijing,2014,36(8),1045(in Chinese).宋若康,张麦仓,彭以超,等.北京科技大学学报,2014,36(8),1045.
10 Wang F G.Petro-Chemical Equipment Technology,1992(2),19(in Chinese).王富岗.石油化工设备技术,1992(2),19.
11 Yu Y S,Tan J L,Wu Y L,et al.Journal of Dalian University of Technology,1990,30(1),53(in Chinese).于永泗,谭家隆,武云灵,等.大连理工大学学报,1990,30(1),53.
12 Khodamorad S H,Haghshenas D F.Engineering Failure Analysis,2012,25,81.
13 Hasegawa K,Oikawa T,Kasai N.Journal of Nondestructive Evaluation,2012,31(4),349.
14 Kasai N,Ogawa S,Oikawa T,et al.Journal of Nondestructive Evaluation,2010,29(3),175.
15 Li T F.High temperature oxidation and hot corrosion of metals,Chemical Industry Press,China,2003(in Chinese).李铁藩.金属高温氧化和热腐蚀,化学工业出版社,2003.
16 Blanckenhagen P V,Majumbar A K.Physical Review B,1984,29,4079.
17 Stevens K J,Parbhu A,Soltis J,et al.Journal of Physics D-Applied Physics,2003,36(2),164.
18 Silva I C,Silva L L,Silva R S,et al.Scripta Materialia,2007,56(4),317.
19 Silva I C,Rebello J M A,Bruno A C,et al.Scripta Materialia,2008,59(9),1010.
2 Petkovicluton P,Ramanarayanan T A.Oxidation of Metals,1990,34(5-6),381.
3 Kaya A A.Materials Characterization,2002,49(1),23.
4 Chun C M,Desai S,Hershkowitz F,et al.Materials and CorrosionWerkstoffe Und Korrosion,2014,65(3),282.
5 Konosu S,Koshimizu K,Iijima T,et al.Journal of Mechanical Design,1993,115(1),41.
6 Chauhan A,Anwar M,Montero K,et al.Journal of Phase Equilibria and Diffusion,2006,27(6),684.
7 Wu Xinqiang,Yang Yuansheng,Zhan Qian,et al.Acta Metallurgica Sinica,1998,34(10),1043(in Chinese).吴欣强,杨院生,詹倩,等.金属学报,1998,34(10),1043.
8 Wang H,Du C Y,Li W,et al.Hot Working Technology,2014(18),101(in Chinese).王辉,杜晨阳,李伟,等.热加工工艺,2014(18),101.
9 Song R K,Zhang M C,Peng Y C,et al.Journal of University of Science and Technology Beijing,2014,36(8),1045(in Chinese).宋若康,张麦仓,彭以超,等.北京科技大学学报,2014,36(8),1045.
10 Wang F G.Petro-Chemical Equipment Technology,1992(2),19(in Chinese).王富岗.石油化工设备技术,1992(2),19.
11 Yu Y S,Tan J L,Wu Y L,et al.Journal of Dalian University of Technology,1990,30(1),53(in Chinese).于永泗,谭家隆,武云灵,等.大连理工大学学报,1990,30(1),53.
12 Khodamorad S H,Haghshenas D F.Engineering Failure Analysis,2012,25,81.
13 Hasegawa K,Oikawa T,Kasai N.Journal of Nondestructive Evaluation,2012,31(4),349.
14 Kasai N,Ogawa S,Oikawa T,et al.Journal of Nondestructive Evaluation,2010,29(3),175.
15 Li T F.High temperature oxidation and hot corrosion of metals,Chemical Industry Press,China,2003(in Chinese).李铁藩.金属高温氧化和热腐蚀,化学工业出版社,2003.
16 Blanckenhagen P V,Majumbar A K.Physical Review B,1984,29,4079.
17 Stevens K J,Parbhu A,Soltis J,et al.Journal of Physics D-Applied Physics,2003,36(2),164.
18 Silva I C,Silva L L,Silva R S,et al.Scripta Materialia,2007,56(4),317.
19 Silva I C,Rebello J M A,Bruno A C,et al.Scripta Materialia,2008,59(9),1010.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |