稀土元素（La，Ce）对镁合金电偶腐蚀的影响

针对镁合金化学和电化学活性较高，与其他金属材料接触时易产生电偶腐蚀的特点，主要研究了其电偶腐蚀特性及环境因素的影响规律。采用电化学方法通过测定电偶电流密度，研究了添加约1％混合稀土RE（45％La，50％Ce）的AZ91合金在NaCl溶液中与A3钢、紫铜偶接时的电偶腐蚀行为，探讨了溶液中氯离子浓度、偶接金属种类以及阴阳极面积比对电偶电流密度Jg^Mg的影响。结果表明：Cl^-浓度增大，Jg^Mg变大；阴阳极面积比越大，Jg^Mg也越大；偶接金属A3钢比紫铜更易促进镁合金的腐蚀；稀土La，Ce的添加使电偶腐蚀有效距离变窄。     

稀土元素(La,Ce)对镁合电偶腐蚀的影响

针对镁合金化学和电化学活性较高,与其他金属材料接触时易产生电偶腐蚀的特点,主要研究了其电偶腐蚀特性及环境因素的影响规律.采用电化学方法通过测定电偶电流密度,研究了添加约1%混合稀土RE(45%La,50?)的AZ91合金在NaCl溶液中与A3钢、紫铜偶接时的电偶腐蚀行为,探讨了溶液中氯离子浓度、偶接金属种类以及阴阳极面积比对电偶电流密度JgMg的影响.结果表明:Cl-浓度增大,JgMg变大;阴阳极面积比越大,JgMg也越大;偶接金属A3钢比紫铜更易促进镁合金的腐蚀;稀土La,Ce的添加使电偶腐蚀有效距离变窄.     

用失重法研究二氧化碳环境中的电偶腐蚀

采用失重法研究了二氧化碳腐蚀环境中碳钢/不锈钢(N80/S31803)电偶对在高温高压下的电偶腐蚀行为,探讨了温度、压力及面积比对电偶腐蚀的影响.结果表明:常压下,随着温度的升高,CO2腐蚀环境中电偶对阳极(N80钢)的腐蚀速率有一个极大值;腐蚀速率的对数值与面积比的对数值呈线性关系.CO2分压为2.5 MPa、阴阳极面积比≤4时,电偶对阳极(N80钢)的腐蚀速率在不同温度下分别存在一个极大值和一个极小值;腐蚀速率都随着面积比的增大而增大.     

Mg合金AE44/低碳钢在3.5%NaCl溶液中的电偶腐蚀研究

基于大型仿真软件COMSOL Multiphysics,研究了25℃阴阳极面积变化时低碳钢/Mg合金AE44电偶对在3.5%NaCl溶液中的腐蚀行为,并在此基础上加入Al合金隔离器,研究Al合金面积的大小对低碳钢/Mg合金/引起电极极性逆转,且随着阴阳极面积比的增加Mg合金的腐蚀速率变快;当阴阳极面积比小于1∶1 200时阳极的腐蚀速率将会达到最小极限值;面积比为1∶1∶1的低碳钢/Al合金/Mg合金复杂电偶对的最大电解质电流密度仅为面积比为1∶1的低碳钢/Mg合金电偶对最大电解质电流密度的40%左右;低碳钢/Al合金/Mg合金组成的复杂电偶对中,Mg合金AE44表面最大电流密度随Al合金的长度的增加而减小,且符合对数关系。     

牺牲阳极合金在海水中的接触腐蚀行为

研究了作为牺牲阳极材料的Ｚｎ－Ａｌ－Ｃｄ,Ａｌ－Ｚｎ－Ｉｎ－Ｓｉ－Ｍｎ和Ｍｇ－Ａｌ－Ｚｎ－Ｍｇ合金在海水中与Ａ３钢等异种金属偶接时,偶对阴极金属材料和阴阳极面积比Ａｃ／Ａｎ不同,以及偶接时间和溶液湿度等对三种合金阳极电偶电流密度ｊｇ的影响。     

NaCl溶液中Zn－Al－Cd合金的接触腐蚀研究

研究了作为牺牲阳极材料的Ｚｎ－Ａｌ－Ｃｄ合金在ＮａＣｌ溶液中与Ａ３钢、３０２不锈钢和纯铜偶接时的接触腐蚀行为，探讨了溶液中Ｃｌ－浓度变化，以及电偶对中阴极金属材料和阴阳极面积比Ａｃ／Ａａ不同时对电偶电流密度ｊＺｎｇ和电偶电势Ｅｇ的影响。结果表明，电偶对中阴极金属材料不同，ｊＺｎｇ随Ｃｌ－浓度增大有不同的变化趋势；ｊＺｎｇ与Ａｃ／Ａａ成正比关系；Ｃｌ－浓度变化对Ｅｇ的影响较大，而大多数浓度下阴极金属材料和阴阳极面积比不同对Ｅｇ的影响较小     

塑性变形条件下16MnR钢的CO2腐蚀电化学行为

油气田管材常常在各种应力和变形状态下服役,为了研究应力和变形对钢CO2腐蚀电化学行为的影响,利用电化学技术分别测量了16MnR钢在不同弯曲塑性变形状态下的CO2腐蚀电化学阻抗谱、线性极化电阻和自然腐蚀电位.结果表明:随着应变的增大,自然腐蚀电位负移,线性极化电阻逐渐减小,腐蚀速率增大.在拉伸和压缩塑性变形状态下16MnR钢CO2腐蚀的电化学阻抗谱均由高频容抗弧和低频感抗弧组成.随着应变的增大,容抗弧和感抗弧逐渐收缩,反应的总阻抗减小.冷加工变形增大了16MnR钢的电化学活性,使阳极溶解加快,腐蚀速率增大.     

高温高酸性环境下镍基合金718与异种金属偶接的电偶腐蚀行为

高温/高压高酸性腐蚀环境中镍基合金718常作为可靠的材料使用,但不可避免会与其他金属偶接使用,易产生电偶腐蚀。模拟150℃,H_2S分压1.0 MPa,CO2分压1.5 MPa,Cl~-浓度200 000 mg/L的高温高酸性腐蚀环境,采用高温高压电化学测试技术和浸泡腐蚀模拟试验,研究了镍基合金718分别与低合金钢35Cr Mo、C110和不锈钢13Cr偶接后的电偶腐蚀行为。结果表明:在模拟高温高酸性环境下,3种金属分别与718合金偶接后,均发生了一定程度的电偶腐蚀,其中C110电偶腐蚀速率最大,而不锈钢13Cr的电偶腐蚀速率最小。电偶腐蚀的驱动力是2种金属的自腐蚀电位差,异种金属偶接后的电偶效应与两偶接材料的电位差成正比,而阳极材料自身的极化特性决定了其与耐蚀合金偶接后的电偶腐蚀程度。     

超级13Cr和P110油管钢在NaCl溶液中电偶腐蚀行为的研究

采用电化学方法研究了超级13Cr-P110钢偶对在NaCl溶液中的电偶腐蚀行为,测试了开路电位、电偶电流和电偶电位,采用SEM、EDS和XRD分别对腐蚀形貌和产物进行了表征。结果表明,超级13Cr和P110钢在NaCl溶液中存在明显的电位差,两者偶接时超级13Cr作为阴极被保护,而P110钢作为阳极被加速腐蚀,该电偶对产生的电偶电流密度会形成严重的电偶腐蚀,随着Sc/Sa的增大,电偶电流明显增大,阳极的腐蚀程度加重,腐蚀产物为氧化物,腐蚀破坏的形式由腐蚀产物疏松转变为腐蚀膜层开裂形成的片层状脱落。     

模拟沿海大气环境下铝合金搭接件电偶腐蚀行为研究

铝合金搭接结构材料2A12与螺栓材料ML30CrMnSiA因存在电位差,在沿海潮湿的大气环境中服役时会发生电偶腐蚀。采用自制实验装置模拟沿海大气环境,通过电化学极化曲线测试法分别测量铝合金材料和螺栓材料在0.5mm厚液膜下的边界值,运用数值仿真软件BEASY对搭接件表面偶合后的电位、电流密度分布及腐蚀速率进行模拟计算。研究结果表明,铝合金板2A12与螺栓搭接后作为偶对阳极电位正移:与螺栓直接接触的位置,阳极极化程度最高,电偶腐蚀速率最大;随与螺栓距离增大,铝合金板的电偶腐蚀速率向两侧递减。     

Untersuchung zur Gefügestabilität und Korrosionsbeständigkeit von Nickelbasislegierungen unter fertigungsüblichen Schweißbedingungen am Beispiel der Werkstofftypen NiMo28 und NiMo16Cr16Ti

Structure examinations and corrosion sensitiveness of welded nickel alloys NiMo28 and NiMo16Cr16Ti The sensitivity of NiMo 28 (Hastelloy B-2) and NiMo 16Cr 16Ti (Hastelloy C-4) to intercrystalline corrosion in the heat-affected zone of welded joints was investigated. The temperature-cycles in welded joints typically used in the construction of chemical equipment were experimentally determined. The effect of thermal stress on both the structural stability and corrosion sensitivity was then determined by metallographic examination. The results showed Hastelloy C-4 to have a distinctly improved structural stability over the previously available Hastelloy C-276. Under the test conditions we employed no negative effect on corrosion sensitivity in the area of the heat-affected zone of the welded joint is to be expected. Hastelloy B-2 shows – dependent on heat input – more or less significant structural changes of the grain boundary, the existence of droplet-like heterogenicity suggests the possibility of intergranular corrosion.     

Failure cases related to material issues in wet-process phosphoric acid plant

The present paper describes three failure cases of metallic components handling wet-process phosphoric acid at ambient temperatures in a phosphate fertilizer plant. All the three cases of failure were related not directly to the corrosive environment rather to wrong selection or inferior quality of materials. In the first case, pipeline of stainless steel 316L failed due to inferior quality of material used in the elbow region. The elbow material was not a low carbon grade stainless steel and was also in heavily sensitized condition which led to intergranular corrosion and intergranular cracking. The other two cases were related to failures of pump sleeves made up of cast alloys equivalent to stainless steel 316 and Hastelloy C-276 respectively. SS 316 showed through-wall pitting and cracking while Hastelloy C-276 had undergone extensive corrosion along the interdendritic boundaries. Both the materials contained high carbon content which led to heavy precipitation of carbides (Cr-rich carbides in SS 316 and Mo-rich carbides in C-276) along inter-dendritic boundaries during solidification of the casting reducing their corrosion resistance. Recommendations to avoid such failures are also suggested.     

316L和Hastelloy C合金在不同温度循环废酸中的耐蚀性能

为了解316L和HastelloyC合金在不同温度的循环废酸中的耐蚀性能,利用静态挂片试验、电化学试验和扫描电镜研究了2种合金在不同温度循环废酸中的腐蚀速率及形貌。结果表明：在50℃的循环废酸中,316L和HastelloyC合金均具有优异的耐蚀性,且耐蚀性相当;316L和HastelloyC合金的腐蚀速率均随循环废酸温度的升高而增加,316L合金的增加缓慢,HastelloyC合金的增加急剧;当温度由50℃升高到80℃时,循环废酸的氧化性增加,Mo含量较高的HastelloyC合金在循环废酸中不能形成完整、致密的钝化膜,从而使其耐蚀性急剧下降。     

Failure of Hastelloy C-276 pump impeller in hydrochloric acid

This paper presents the results of a failure investigation carried out on a cast Hastelloy C-276 pump impeller that suffered general corrosion in 32% hydrochloric acid at ambient temperature in a chemical plant. Microscopic examination revealed that the attack was crystallographic in nature. The attack was more enhanced at the interdendritic arm spacing as well as the boundaries of columnar grains, resulting in deep grooves. Taking into consideration that the local temperature could reach up to 50 °C in the summer months, Hastelloy C-276 was judged to be unsuitable material for applications involving 32% HCl. A search into a suitable alternative alloy did not provide a satisfactory answer. Therefore, rubber-lined pump impeller was considered the better alternative.     

热成形工艺参数对C-276合金耐蚀性的影响

通过分析锻造温度、热处理温度和时间对C-276合金耐蚀性的影响,确定析出相u为其耐蚀性的主要影响因素。基于该分析结果,在避免u相析出的前提下确定C-276合金的热成形工艺参数并进行热成形试验,结果显示该工艺参数可以获得最佳的耐蚀性能。     

一种高性能低偏析耐蚀合金的研究

研究了硫对Hastelloy C-4合金凝固偏析和耐蚀性的影响。结果表明，严格控制硫含量，能减小固液两相区的间隔和温度范围以及合金的偏析程度，明显改善合金耐蚀性能。     

Mechanische Eigenschaften der Legierung Hastelloy alloy C 22®

Mechanical Properties of Hastelloy alloy C-22 Hastelloy alloy C-22 is an advanced alloy of the Hastelloy alloy C-series with outstanding corrosion resistance. The alloy is used in the construction of pressure vessels which are used in the temperature range of ?196°C to 400°C. For this application, mechanical properties and fabrication data were documented. The testing program included as mill annealed material as well as material in conditions typically experienced during vessel fabrication. The mechanical behavior of alloy C-22 was found to be comparable to the other C-type alloys. The alloy possesses high toughness at low temperatures even in a cold worked condition and it has good weldability.     

土壤盐浓差对碳钢/铝合金电偶腐蚀行为影响

利用砂土作为模拟土壤 ,通过失重法及电化学方法相结合 ,研究了土壤盐浓差( 2 0 %Cl-及 0 2 %Cl-)对A3钢 LC4铝合金电偶腐蚀的影响规律。结果表明 ,其电偶腐蚀主要取决于电偶对阴极A3钢所处的土壤条件 ,而与电偶对阳极所处的土壤条件关系不大。电偶对阴极处在高盐土壤中 ,其阴极保护效率较高 ,电偶对阳极LC4铝合金与同样试验条件下自然腐蚀相比 ,其腐蚀速率最大增加了 145倍。