焊接工艺对316 J1L 不锈钢焊缝耐海水腐蚀性能的影响

通过提高焊接速度,减小焊接电流等手段改进316J1L的焊接工艺,提高了焊缝的耐海水腐蚀性能。利用金相显微镜、扫描电镜及X射线衍射技术对原失效焊件及改进工艺焊件三区的微观组织形貌、元素分布、物相组成等进行测定,测量2种工艺下焊件三区的动电位极化曲线,并对电化学特性进行了比较分析。结果表明:改进工艺后焊件三区平均晶粒度较大,元素分布更加均匀,腐蚀电流密度更小,腐蚀电位更高,腐蚀速率显著降低。     

热油管道阴极保护效果评价

辽河油田特石热油管线担负着重要的输送任务,防腐是管道保护的主要手段。迄今为止,对埋地管道加阴极保护是最有效的防腐蚀措施。评定和控制阴极保护的水平,仍以电位测量为主。使用试片可以更方便地测量电位,在试片上进行电化学极化测量或电位衰减测量,求得阴极保护下管道金属的腐蚀速率和保护度,对管道阴极保护有效地进行实时监测和控制。     

跨海大桥钢管桩腐蚀模拟试验及耐久性跟踪研究

通过模拟试验,研究了3种不同类型的钢管桩样片在杭州湾海域5种环境分区中的腐蚀形态和电信号反馈。实验结果表明,涂敷环氧粉末涂层的钢管桩样片表面基本没有腐蚀,涂层完好无损,而其他钢管桩样片则出现不同程度腐蚀,其中浪溅区腐蚀最严重,泥下区腐蚀较轻微;腐蚀电位逐渐变负,随后出现稳态,最后趋向于零;浪溅区腐蚀电位最负,泥下区腐蚀电位最正;相同环境中,涂敷环氧涂层的样片腐蚀电位比其他样片更正,有焊缝样片腐蚀电位比无焊缝样片稍负。     

具有剥离涂层缺陷低碳钢的阴极极化特性

为探索具有剥离涂层缺陷低碳钢的腐蚀规律与机理,以环氧树脂作为涂层材料,于实验室对Q235钢人为模拟制作了面积比例为4.91%的大块剥离涂层缺陷,采用交流阻抗技术研究了剥离涂层缺陷对Q235钢于w(NaCl)=3.5%的NaCl水溶液中的腐蚀特性和阴极保护效果的影响.试验结果表明,在较短的浸泡时间里,在阴极极化电位下涂层缺陷下方金属基体的腐蚀程度低于在自然腐蚀电位下的腐蚀程度;但在较长的浸泡时间里,阴极极化状态与自然腐蚀状态下金属基体具有相似的腐蚀程度及腐蚀特性,说明在电解质溶液大量浸入涂层后将使阴极保护的作用严重降低,而涂层下金属与电解质溶液间的缝隙腐蚀是导致阴极保护效果降低的主要原因.     

使用试样监测受阴极保护埋地管道的电位

对于联合使用涂层和阴极保护的埋地金属管道和其他设施,监测其电位是否达到电位准则的要求,是控制阴极保护正常运行和良好效果的关键,使用试样测量电位比直接对管道测量具有明显的优点,可以大大减小IR降误差,文章简要介绍了在使用试样测量电位时影响测量值正确性的一些因素。     

不锈钢管凝汽器管板电偶腐蚀的研究

研究了不锈钢管凝汽器碳钢管板电偶腐蚀的严重程度、影响因素和防护措施,并与黄铜管-碳钢腐蚀电偶对进行了比较.结果表明：凝汽器黄铜管改成不锈钢管后,碳钢管板电偶腐蚀依然存在,但腐蚀程度明显低于黄铜管.此外,面积比对电偶腐蚀影响较大,可采用阴极保护、阴极保护加管板涂层联合保护及缓蚀剂等减小电偶腐蚀.     

P92钢焊接接头耐腐蚀性能研究

P92钢是高合金耐热钢,具有良好的高温热强性和抗氧化性能,是制造电站锅炉的关键材料.本文应用动电位扫描和电化学阻抗谱技术,研究了P92钢焊接接头各区域在3.5％ NaCl模拟海水环境溶液中的腐蚀性能.结果表明:在测试周期内,P92钢焊接接头各区域的腐蚀速率随着腐蚀时间的延长先增快后减慢;在相同的腐蚀时间内,P92钢焊接接头中焊缝区的腐蚀电流密度最大,母材最小;P92钢焊接接头焊缝区的阻抗最小,母材的阻抗最大;母材区的耐蚀性相对最好,焊缝区最差,热影响区介于二者之间     

600MW机组凝汽器阴极保护系统的研究及应用

介绍了阴极保护系统的原理及在６００ ＭＷ 机组淡水凝汽器上的应用．该系统采用了多点分散控制的外加电流阴极保护和涂层联合保护的方法,设计新颖,有效地抑制了凝汽器管板和铜管的腐蚀．     

X70管线钢焊接接头组织及其海水腐蚀规律

对X70管线钢现场实际焊接工艺下的焊接接头,采用显微镜、电化学方法及失重法等方法和手段对母材、焊缝、热影响区进行了显微组织分析和在海水中的极化曲线、腐蚀速率的测试,研究焊接接头在模拟海水环境中的腐蚀性能.研究表明,X70管线钢焊接接头各区域组织不均匀,实验室模拟海水环境下的电化学行为、腐蚀速率存在明显差异;在海水腐蚀过程中腐蚀电位和腐蚀速率会发生变化,热影响区(HAZ)与母材及焊缝形成电偶腐蚀,接头腐蚀以点蚀为主.     

外部电位对碳钢局部腐蚀不同阶段闭塞区行为的影响

采用恒电位模拟闭塞电池装置研究了A3钢／0.01mol.L^-1NaCl水溶液（pH=12)体系外部电位对局部腐蚀不同阶段闭区腐蚀行为的影响,发现在局部腐蚀的引发和扩展阶段,外表面阴极极化时,闭塞区内外间电位差和电偶电流均与外部电位呈线性关系,闭塞区内电位正于外表面电位,闭塞区得到阴极保护,闭区电位与外表面电位的差值由内外溶液的扩散电位差和电迁移欧姆降组成,阴极保护抑制局部腐蚀在扩展和引发阶段有不同的机理,在本文的研究系统条件下,外部电位恒定在负于－110mV(SCE)时,扩展阶段的闭塞区腐蚀可以得到有效的抑制。     

新型不锈钢焊接材料的优化设计

所研制的新型不锈钢焊条采用了低碳钢芯，通过药皮过渡合金，通过对焊条药成分的优化设计，分析了不锈钢焊条药皮中影响焊缝气孔生成率的因素及各因素对气孔率的影响规律，解决了出现焊缝气孔的问题，并彻底克服了不锈钢焊条药皮发红开裂的缺点，同时由于低碳钢焊芯的采用增加了焊条长度，减少了更换焊条次数，并可采用较大的焊接线能量，在很大程度上提高了焊接效率，经过测验表明，本焊条过渡合金量达到设计要求，焊缝熔敷金属具有优良的抗晶间腐蚀能力和综合力学性能。     

X70钢在鹰潭酸性土壤中的应力腐蚀行为

在不同的阴极保护电位下,采用慢应变速率拉伸试验(SSRT)和电化学方法研究X70钢在水饱和鹰潭土壤中的应力腐蚀开裂行为,为酸性土壤地区的X70钢管线的腐蚀防护提供基础参考数据.结果表明,X70钢在实验所用的酸性土壤环境中能够发生穿晶应力腐蚀裂纹(TGSCC);SCC萌生与外加保护电位有关,外加电位较高、X70钢完全受阳极过程控制时的SCC敏感性较低;外加电位较低、X70钢受阴阳极混合电极过程控制或完全受阴极过程控制时均能发生SCC,且其敏感性随外加电位的降低而增加,且完全受阴极过程控制时的SCC敏感性大大高于其它情况.     

Electrochemical corrosion behavior of carbon steel with bulk coating holidays

With epoxy coal tar as the coating material, the electrochemical corrosion behavior of Q235 with different kinds of bulk coating holidays has been investigated with EIS （Electrochemical Impedance Spectroscopy） in a 3.5vo1% NaCI aqueous solution. The area ratio of bulk coating holiday to total coating area of steel is 4.91%. The experimental results showed that at free corrosion potential, the corrosion of carbon steel with disbonded coating holiday is heavier than that with broken holiday and disbonded ＆ broken holiday with time; Moreover, the effectiveness of Cathodic Protection （CP） of carbon steel with broken holiday is better than that with disbonded holiday and disbonded ＆ broken holiday on CP potential -850 mV （vs CSE）. Further analysis indicated that the two main reasons for corrosion are electrolyte solution slowly penetrating the coating, and crevice corrosion at steel/coating interface near holidays. The ratio of impedance amplitude （Z） of different frequency to minimum frequency is defined as K value. The change rate of K with frequency is related to the type of coating holiday.     

Preparation of Poly(o-toluidine)/Nano ZrO_2/Epoxy Composite Coating and Its Application for Corrosion Protection of Steel

The main objective was to study the anticorrosion performance of poly(o-toluidine)/nano ZrO_2/epoxy composite coating.Poly(o-toluidine)/nano ZrO_2 composite was prepared by in situ polymerization of o-toluidine monomer in the presence of nano ZrO_2 particles.Fourier transformation infrared spectroscopy(FT-IR),UV-visible spectroscopy(UV-vis),X-ray diffraction(XRD),Scanning electron microscopy(SEM),and Thermogravimetric analysis(TGA) were used to characterize the composition and structure of the composite.Poly(o-toluidine)/nano ZrO_2 composite was mixed with epoxy resin through a solution blending method and the three components poly(o-toluidine)/nano ZrO_2/epoxy composite coating was coated onto the surface of steel sample by the brush coating method.The anticorrosion performance of poly(o-toluidine)/nano ZrO_2/epoxy composite coating on steel sample was studied by polarization curve and electrochemical impendence spectroscopy in 3.5% Na Cl solution as corrosion environment and also compared with that of poly(o-toluidine)/epoxy composite coating and pure epoxy coating.It was observed that the composite coating containing poly(otoluidine)/nano ZrO_2 composite has got higher corrosion protection ability than that of poly(o-toluidine).The electrochemical measurement results demonstrated that poly(o-toluidine) fillers improve the electrochemical anticorrosion performance of epoxy coating and the addition of nano ZrO_2 particles increases the tortuosity of the diffusion pathway of corrosive substances.     

Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel

To obtain high-quality dissimilar weld joints, the processes of metal inert gas (MIG) welding and tungsten inert gas (TIG) welding for duplex stainless steel (DSS) and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy (SEM); the chemical compositions in different zones were detected by en-ergy-dispersive spectroscopy (EDS); the mechanical properties were measured by microhardness test, tensile test, and impact test; the corro-sion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG weld-ing. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaCl solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints pro-duced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS S31803 duplex stainless steel and low alloy steel in practical application.     

热喷涂铝涂层在矿井水中的耐蚀性能研究

应用腐蚀失重方法和电化学极化技术研究了热喷涂铝涂层在矿井水环境下的耐腐蚀性能,并与普通碳钢Ｑ２３５进行对比．实验结果表明,在一般中性矿井水中,涂层的自腐蚀电位附近的腐蚀受阴极氧扩散控制,当电位较高时,阳极上有氢析出,阳极反应由此变得复杂;用阴极极化能更好地显示涂层的电化学极化过程．热喷涂铝层具有较高的耐蚀性,实验涂层的预计使用寿命为２０ａ．比较了用失重法和电化学法计算涂层腐蚀速度的结果;分析了在２０～６０℃范围内温度对涂层腐蚀过程的影响     

液相沉积法制备TiO_2薄膜及其对304不锈钢的光生阴极防护

采用液相沉积的方法在304不锈钢基体上制备了纳米TiO2薄膜材料,采用XRD、SEM等手段研究了不同沉积时间、不同热处理工艺对薄膜微观结构的影响,采用IM6e工作站研究了薄膜材料的光电化学行为.研究表明,沉积时间为72 h、热处理温度为500℃时,TiO2薄膜具有均匀平整的微观形貌,薄膜主要由锐钛矿TiO2组成.经过热处理的薄膜材料在光照下于模拟海水电介质中均表现出了对304不锈钢的光生阴极防护作用.     

热浸镀铝钢氩弧焊焊接性的研究

研究了自熔焊和填充不锈钢焊丝这两种情况的热浸镀铝钢氩弧焊性能,并对其焊接接头的各种性能进行了测定.试验结果表明,自熔焊后喷铝可使其耐蚀性与母材相当,且力学性能满足要求.