X80管线钢焊接接头的模拟重构及电偶腐蚀行为表征
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摘要
利用离散、热模拟处理和模块化重构的微电极阵列对X80管线钢焊接接头进行模拟重构,并联用经典电化学测试技术和微电极阵列测试技术研究了X80钢模拟焊接接头及孤立分区在CO2饱和的NACE溶液中的电偶腐蚀行为。结果表明,在NACE溶液中,孤立的细晶区开路电位最正,腐蚀倾向小,而焊缝的电位最负,腐蚀倾向大;各部分的腐蚀电流密度大小关系为:部分相变区>细晶区>粗晶区>母材>焊缝;模拟X80钢焊接接头组织中,粒状贝氏体与铁素体的混合组织的开路电位最正,极化电阻最小。当各组成部分耦合后,模拟焊接接头中的焊缝和粗晶区作为主要阳极,腐蚀加速;细晶区和部分相变区作为主要阴极,腐蚀减缓;邻近热影响区的母材微电极以阳极性电流为主,远离热影响区的母材微电极以阴极性电流为主。提出电偶腐蚀强度因子用于表征电偶腐蚀强度。孤立的焊缝区的自腐蚀电流密度虽最小,但在电偶腐蚀的加速作用下,焊缝与粗晶区作为模拟焊接接头的薄弱环节,首先因腐蚀而失效。
Welding is widely used for pipeline connection. Composition, microstructures and properties of the welded joints are highly heterogeneous and the resultant corrosion such as galvanic corrosion between different parts is widely present and influence the long-time service and safety. In this sense, the fundamental research in the electrochemical behavior of such joint parts is required. Electrochemical corrosion behavior of simulated X80 steel welded joint, accurately modeled by wire beam electrode(WBE)technique, was investigated by classical electrochemical techniques and microelectrode array(MEA)technique. A new index, namely the galvanic corrosion intensity factor, was proposed and verified to succeed in characterizing the degree of galvanic corrosion. Results showed that microstructure of granular bainite mixed with ferrite showed the highest positive open circuit potential and lowest polarization resistance. Furthermore, the corrosion tendency of the isolated electrodes that constituted the X80 steel welded joint was found to increase in the following order: fine grain heat affected zone(FGHAZ) < intercritical heat affected zone(ICHAZ) < base metal(BM) < coarse grain heat affected zone(CGHAZ) < weld metal(WM). Due to the difference in potential and the polarization characteristics, the WM displayed the highest polarization resistance but the most positive current density. The CGHAZ possessed a lower polarization resistance and a higher positive current density. In comparison, the FGHAZ and ICHAZ performed a lower polarization resistance but higher negative current densities. The WM and CGHAZ acted as the main anode, while the FGHAZ and ICHAZ acted as the main cathode and the galvanic current polarity of some BM electrodes changed with time during the immersion test. The intensity of galvanic corrosion of simulated X80 steel welded joint plateaued with immersion time. The results revealed that WM and CGHAZ were the weak links in the simulated X80 pipeline steel welded joints during its long-term service.
Welding is widely used for pipeline connection. Composition, microstructures and properties of the welded joints are highly heterogeneous and the resultant corrosion such as galvanic corrosion between different parts is widely present and influence the long-time service and safety. In this sense, the fundamental research in the electrochemical behavior of such joint parts is required. Electrochemical corrosion behavior of simulated X80 steel welded joint, accurately modeled by wire beam electrode(WBE)technique, was investigated by classical electrochemical techniques and microelectrode array(MEA)technique. A new index, namely the galvanic corrosion intensity factor, was proposed and verified to succeed in characterizing the degree of galvanic corrosion. Results showed that microstructure of granular bainite mixed with ferrite showed the highest positive open circuit potential and lowest polarization resistance. Furthermore, the corrosion tendency of the isolated electrodes that constituted the X80 steel welded joint was found to increase in the following order: fine grain heat affected zone(FGHAZ) < intercritical heat affected zone(ICHAZ) < base metal(BM) < coarse grain heat affected zone(CGHAZ) < weld metal(WM). Due to the difference in potential and the polarization characteristics, the WM displayed the highest polarization resistance but the most positive current density. The CGHAZ possessed a lower polarization resistance and a higher positive current density. In comparison, the FGHAZ and ICHAZ performed a lower polarization resistance but higher negative current densities. The WM and CGHAZ acted as the main anode, while the FGHAZ and ICHAZ acted as the main cathode and the galvanic current polarity of some BM electrodes changed with time during the immersion test. The intensity of galvanic corrosion of simulated X80 steel welded joint plateaued with immersion time. The results revealed that WM and CGHAZ were the weak links in the simulated X80 pipeline steel welded joints during its long-term service.
引文
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[24]Li W,Brown B,Young D,et al.Investigation of pseudo-passivation of mild steel in CO2corrosion[J].Corrosion,2013,70:294
[25]Nazari M H,Allahkaram S R.The effect of acetic acid on the CO2corrosion of grade X70 steel[J].Mater.Des.,2010,31:4290
[26]Liu D,Chen Z Y,Guo X P.The effect of acetic acid and acetate on CO2corrosion of carbon steel[J].Anti-Corros.Methods Mater.,2008,55:130
[27]Jia Z J,Li X G,Du C W,et al.Effect of acetic acid on CO2corrosion of 3Cr low-alloy steel[J].Mater.Chem.Phys.,2012,132:258
[28]Mansfeld F.The relationship between galvanic current and dissolution rates[J].Corrosion,1973,29:403
[29]Tan Y J,Aung N N,Liu T.Evaluating localised corrosion intensity using the wire beam electrode[J].Corros.Sci.,2012,63:379
[30]Lu Y X,Jing H Y,Han Y D,et al.Recommend design of filler metal to minimize carbon steel weld metal preferential corrosion in CO2-saturated oilfield produced water[J].Appl.Surf.Sci.,2016,389:609
[31]Paolinelli L D,Pérez T,Simison S N.The influence of Cr content on the efficiency of inhibitor of C-Mn steel CO2corrosion[A].Proceedings of NACE International Corrosion Conference[C].San Diego,CA:NACE International,2006:369
[32]Jin T Y,Cheng Y F.In situ characterization by localized electrochemical impedance spectroscopy of the electrochemical activity of microscopic inclusions in an X100 steel[J].Corros.Sci.,2011,53:850
[33]Tang X,Cheng Y F.Micro-electrochemical characterization of the effect of applied stress on local anodic dissolution behavior of pipeline steel under near-neutral p H condition[J].Electrochim.Acta,2009,54:1499
[2]Zhao W,Zou Y,Matsuda K,et al.Corrosion behavior of reheated CGHAZ of X80 pipeline steel in H2S-containing environments[J].Mater.Des.,2016,99:44
[3]Ballesteros A F,Gomes J A P,Bott I S.Corrosion evaluation of SAW welded API 5L X-80 joints in H2S-containing solution[J].Mater.Res.,2015,18:417
[4]Alizadeh M,Bordbar S.The influence of microstructure on the protective properties of the corrosion product layer generated on the welded API X70 steel in chloride solution[J].Corros.Sci.,2013,70:170
[5]Ma G,Zuo X R,Hong L,et al.Investigation of corrosion behavior of welded joint of X70 pipeline steel for deep sea[J].Acta Metall.Sin.,2018,54:527(马歌,左秀荣,洪良等.深海用X70管线钢焊接接头腐蚀行为研究[J].金属学报,2018,54:527)
[6]Bordbar S,Alizadeh M,Hashemi S H.Effects of microstructure alteration on corrosion behavior of welded joint in API X70 pipeline steel[J].Mater.Des.,2013,45:597
[7]El-Sherik A M.Trends in Oil and Gas Corrosion Research and Technologies[M].Boston:Woodhead Publishing,2017:249
[8]Zhu J Y,Xu L N,Feng Z C,et al.Galvanic corrosion of a welded joint in 3Cr low alloy pipeline steel[J].Corros.Sci.,2016,111:391
[9]Wang L W,Liu Z Y,Cui Z Y,et al.In situ corrosion characterization of simulated weld heat affected zone on API X80 pipeline steel[J].Corros.Sci.,2014,85:401
[10]Sun Q L,Cao B,Wu Y S.Electrochemical behavior of various micro-areas on the welded joint of Q235 steel[J].J.Univ.Sci.Technol.Beijing,2009,31:41(孙齐磊,曹备,吴荫顺.Q235管线钢焊接接头微区电化学行为[J].北京科技大学学报,2009,31:41)
[11]Fushimi K,Naganuma A,Azumi K,et al.Current distribution during galvanic corrosion of carbon steel welded with type-309 stainless steel in Na Cl solution[J].Corros.Sci.,2008,50:903
[12]Alawadhi K,Robinson M J.Preferential weld corrosion of X65pipeline steel in flowing brines containing carbon dioxide[J].Corros.Eng.Sci.Technol.,2011,46:318
[13]Eliyan F F,Alfantazi A.Corrosion of the heat-affected zones(HAZs)of API-X100 pipeline steel in dilute bicarbonate solutions at 90℃-An electrochemical evaluation[J].Corros.Sci.,2013,74:297
[14]Moeinifar S,Kokabi A H,Hosseini H R M.Role of tandem submerged arc welding thermal cycles on properties of the heat affected zone in X80 microalloyed pipe line steel[J].J.Mater.Process.Technol.,2011,211:368
[15]Li Y,Yang R.Modularized array electrode of precision simulate welded joint and manufacturing method thereof[P].Chin Pat,CN201310339519.8,2013(李焰,杨瑞.精确模拟焊接接头的模块化阵列电极及其制备方法[P].中国专利,CN201310339519.8,2013)
[16]Li Y,Liu Y,Zhang D L.Multi-channel galvanic corrosion test system and method based on micro electrode array[P].Chin Pat,CN201210477941.5,2013(李焰,刘玉,张大磊.基于微电极阵列的多通道电偶腐蚀测试系统及测试方法[P].中国专利,CN201210477941.5,2013)
[17]Zhang D L,Wang W,Li Y.An electrode array study of electrochemical inhomogeneity of zinc in zinc/steel couple during galvanic corrosion[J].Corros.Sci.,2010,52:1277
[18]Ju H,Yang Y F,Liu Y F,et al.Mapping the galvanic corrosion of three metals coupled with a wire beam electrode:The influence of temperature and relative geometrical position[J].Materials,2018,11:357
[19]Ju H,Duan J Z,Yang Y F,et al.Mapping the galvanic corrosion of three coupled metal alloys using coupled multielectrode array:Influence of chloride ion concentration[J].Materials,2018,11:634
[20]Chen C F,Lu M X,Zhao G X,et al.Effects of temperature,Clconcentration and Cr on electrode reactions of CO2corrosion of N80 steel[J].Acta Metall.Sin.,2003,39:848(陈长风,路民旭,赵国仙等.温度、Cl-浓度、Cr元素对N80钢CO2腐蚀电极过程的影响[J].金属学报,2003,39:848)
[21]Das Chagas Almeida T,Bandeira M C E,Moreira R M,et al.New insights on the role of CO2in the mechanism of carbon steel corrosion[J].Corros.Sci.,2017,120:239
[22]Tran T,Brown B,Nesic S,et al.Investigation of the mechanism for acetic acid corrosion of mild steel[A].Proceedings of the NACE International Corrosion Conference[C].Orlando:NACEInternational,2013:12
[23]Zhang G A,Cheng Y F.Corrosion of X65 steel in CO2-saturated oilfield formation water in the absence and presence of acetic acid[J].Corros.Sci.,2009,51:1589
[24]Li W,Brown B,Young D,et al.Investigation of pseudo-passivation of mild steel in CO2corrosion[J].Corrosion,2013,70:294
[25]Nazari M H,Allahkaram S R.The effect of acetic acid on the CO2corrosion of grade X70 steel[J].Mater.Des.,2010,31:4290
[26]Liu D,Chen Z Y,Guo X P.The effect of acetic acid and acetate on CO2corrosion of carbon steel[J].Anti-Corros.Methods Mater.,2008,55:130
[27]Jia Z J,Li X G,Du C W,et al.Effect of acetic acid on CO2corrosion of 3Cr low-alloy steel[J].Mater.Chem.Phys.,2012,132:258
[28]Mansfeld F.The relationship between galvanic current and dissolution rates[J].Corrosion,1973,29:403
[29]Tan Y J,Aung N N,Liu T.Evaluating localised corrosion intensity using the wire beam electrode[J].Corros.Sci.,2012,63:379
[30]Lu Y X,Jing H Y,Han Y D,et al.Recommend design of filler metal to minimize carbon steel weld metal preferential corrosion in CO2-saturated oilfield produced water[J].Appl.Surf.Sci.,2016,389:609
[31]Paolinelli L D,Pérez T,Simison S N.The influence of Cr content on the efficiency of inhibitor of C-Mn steel CO2corrosion[A].Proceedings of NACE International Corrosion Conference[C].San Diego,CA:NACE International,2006:369
[32]Jin T Y,Cheng Y F.In situ characterization by localized electrochemical impedance spectroscopy of the electrochemical activity of microscopic inclusions in an X100 steel[J].Corros.Sci.,2011,53:850
[33]Tang X,Cheng Y F.Micro-electrochemical characterization of the effect of applied stress on local anodic dissolution behavior of pipeline steel under near-neutral p H condition[J].Electrochim.Acta,2009,54:1499