温度对钢材在高硫高酸值原油中腐蚀行为的影响

采用高温高压釜研究了20钢、1Cr5Mo钢、304不锈钢和316L不锈钢在不同温度下在高硫高酸原油中的腐蚀行为。利用扫描电镜和能谱技术测试了腐蚀产物膜的微观形貌与产物膜的化学组成。结果表明:4种钢材在高温原油中的耐蚀性优劣为:316L不锈钢304不锈钢1Cr5Mo钢20钢;4种钢材的腐蚀速率总体上随温度的升高而增大,当温度大于200℃时,20钢和1Cr5Mo钢的腐蚀速率增加较快,而不锈钢在200℃以上时腐蚀速率随温度变化并不明显;钢材在200℃及以下的原油中主要为轻微的环烷酸腐蚀,当温度达到280℃附近时,硫开始参与反应,形成了环烷酸与活性硫协同腐蚀的环境,腐蚀速率较大。     

柠檬酸钝化9Cr1Mo钢在海洋大气环境中的耐蚀性

为了提高9Cr1Mo钢在海洋大气环境中的耐蚀性,采用柠檬酸和柠檬酸-氢氧化物复合钝化工艺对9Cr1Mo钢进行表面钝化处理,研究了两种钝化处理对其耐蚀性的影响,分析了柠檬酸钝化处理提升9Cr1Mo钢耐海洋大气腐蚀性能的原因。结果表明：未钝化处理的9Cr1Mo钢在模拟和实际海洋大气环境中均发生严重腐蚀;两种钝化处理后9Cr1Mo钢表面均形成了保护性钝化膜,确保9Cr1Mo钢在海洋大气环境中腐蚀78 d内不发生明显腐蚀,显著提高了9Cr1Mo钢耐海洋大气腐蚀性能;采用柠檬酸和柠檬酸-氢氧化物复合钝化工艺可以提高钝化膜中Cr₂O₃、Cr(OH)₃含量,且氧化物含量显著高于氢氧化物,钝化膜的稳定性和耐蚀性增强。     

模拟炼油环境中Q235钢和Cr5Mo钢表面硫化物膜稳定性及动态冲刷腐蚀行为研究

通过静态浸泡腐蚀实验装置和高温动态冲刷实验装置分别研究了硫化物膜在多种模拟炼油介质中的稳定性以及动态冲刷条件下Q235钢和Cr5Mo钢的耐冲刷腐蚀性能。结果表明,硫化物膜的形成过程是一个动态平衡过程。在无硫补充的条件下,硫化物膜快速溶解。动态冲刷作用下,Cr5Mo钢耐动态环烷酸冲刷腐蚀性能明显好于Q235钢,溶液酸值越大两者的差别越明显。     

含铬耐候钢在模拟海洋大气环境中的腐蚀行为

设计了1Cr-0.5Al-0.3Mo,5Cr-0.4Ni-0.3Cu和10Cr-0.3Ni3种不同成分的实验钢,以20MnSi钢为对比钢种,采用周期浸润加速腐蚀实验、电化学测试方法,结合SEM和XRD等手段研究了实验钢种在模拟海洋大气环境中的腐蚀行为。结果表明:实验钢的腐蚀速率随Cr含量增加而降低,1Cr钢和5Cr钢锈层为双层结构,内锈层为富铬层与贫铬层交替带状结构,10Cr钢表面出现钝化现象;随着腐蚀时间延长,5Cr钢腐蚀率先增加后趋平稳,10Cr钢腐蚀率一直稳定在较低水平,20MnSi钢腐蚀率降低;Cr可提高基体自腐蚀电位和电荷传递电阻,同时增大锈层电阻。     

二氧化碳驱注采井常用油套管钢的腐蚀行为

采用高温高压反应釜研究了N80、P110、3Cr、5Cr等4种油套管钢材在现场采出液中的抗CO_2腐蚀性能,结合扫描电镜(SEM)、能谱仪(EDS)和X射线衍射(XRD)等手段,观察分析了腐蚀产物膜形貌和成分。结果表明:随着温度的上升,4种钢材腐蚀速率均呈现出先增大后减小的趋势,最大值出现在中温区,N80、P110、5Cr钢在90℃时腐蚀速率达到最大,3Cr钢在80℃时腐蚀速率最大;4种钢材腐蚀类型主要为均匀腐蚀,未发现局部腐蚀,腐蚀产物主要为FeCO_3,含Cr钢腐蚀产物出现多层结构,主要成分除了FeCO_3,还有非晶态的腐蚀产物Cr(OH)_3;N80、P110钢的腐蚀产物细小、致密、均匀覆盖在基体表面,腐蚀速率较低;3Cr、5Cr钢的腐蚀产物覆盖不均匀、与基体结合力弱、附着性不强,易脱落,造成整体腐蚀速率较高。     

Mo对货油舱下底板用E36级船板钢耐腐蚀性能的影响

为探讨货油舱下底板腐蚀环境中Mo对于耐蚀钢腐蚀行为的影响,采用自制的货油舱下底板环境模拟装置对不同Mo含量的两种耐蚀钢进行腐蚀试验,用失重法计算腐蚀速率,应用金相显微镜观察试验钢的组织类型和晶粒尺寸,应用扫描电镜(SEM)观察试验钢表面的微观腐蚀形貌。对模拟腐蚀环境中的试验钢进行电化学和阻抗谱(EIS)分析,应用EBSD分析晶界腐蚀与晶界类型的关系。结果表明:含有Mo元素的钢板表现出更好的耐腐蚀,点蚀现象不明显,均匀腐蚀速率可降低到0.3 mm/a;小角度晶界相比于大角度晶界表现出更好的耐晶界腐蚀性。     

海洋柔性立管用高强钢的高温海水腐蚀行为

通过开展浸泡腐蚀实验和电化学腐蚀实验研究了海洋柔性立管用高强钢在高温海水环境中的腐蚀行为。通过分析实验钢的腐蚀速率、腐蚀产物物相组成、腐蚀产物形态特征以及不同腐蚀时间后实验钢动电位极化曲线,揭示了实验钢的高温海水腐蚀行为与机制。结果表明:随着腐蚀时间的延长,腐蚀速率先是快速下降随后缓慢下降并趋于稳定,稳定状态的腐蚀速率为0.071 mm/a。而基体表面附着的腐蚀产物的致密度则是随时间的延长不断增加,抑制了腐蚀过程中的电化学反应。钢中耐蚀元素Cr、Mo、Ni的添加不仅可以促进形成致密稳定的腐蚀产物层,还可提高基体的自腐蚀电位,降低自腐蚀电流,增强实验钢的耐蚀性。     

盐雾腐蚀环境对38CrMoAl钢动态力学性能的影响

对不同周期盐雾腐蚀后38Cr Mo Al钢开展了应变速率为0.001～3000 s-1的准静态和冲击拉伸试验,研究了盐雾腐蚀环境对38Cr Mo Al钢材料在高应变率条件下动态力学性能的影响,借助数字显微镜、FT-IR、SEM、EDS等手段对盐雾腐蚀后的38Cr Mo Al钢表面形貌、腐蚀坑深度、腐蚀产物成分和断口形貌等进行了分析。结果表明,腐蚀速率与盐雾腐蚀时间正相关,腐蚀加速过程遵循幂函数特征,腐蚀产物层对38CrMoAl钢的腐蚀起到促进作用;38Cr Mo Al钢的屈服强度随着应变率的提高而提高,随着腐蚀周期的增加而降低,盐雾腐蚀后的38CrMoAl钢断口呈现多处撕裂状特征,腐蚀时间越长,撕裂状痕迹越多,撕裂状断裂使得试件断口颈缩不再是均匀发展,导致屈服后抗拉强度下降,屈强比升高。对J-C本构模型中的应变率强化项和绝热软化项进行了修正,并加入了腐蚀修正参数,使得新模型可以准确地表征38CrMoAl钢在盐雾腐蚀环境中动态力学行为。     

炼油加工过程中氯离子与硫离子对 316L 不锈钢和Monel 合金腐蚀的影响

目的研究常减压装置高温原油馏分及塔顶水相中氯离子、硫离子含量对316L不锈钢和Monel合金(镍基合金)腐蚀的影响。方法通过腐蚀挂片实验,获得316L不锈钢和Monel合金在含不同浓度氯离子和硫离子的水相、油相中的腐蚀速率变化规律。利用扫描电子显微镜,研究316L和Monel合金表面腐蚀后的微观形貌,探讨两种离子对316L不锈钢和Monel合金腐蚀的影响规律。结果在酸值较高的脱后原油中,316L不锈钢和Monel合金的腐蚀速率分别为0.0091,0.0248 mm/a;在酸值较低的常二段馏分中,316L不锈钢和Monel合金的腐蚀速率分别为0.0078,0.0031 mm/a。在常二段馏分中,加入600mg/L氯离子和30 mg/L硫化钠时,316L不锈钢和Monel合金的腐蚀速率分别为0.1755,0.1707 mm/a。在相同条件的脱后原油中,316L不锈钢的腐蚀速率为0.0545 mm/a,Monel合金的腐蚀速率为0.1281mm/a。结论油相中氯离子含量较低时,环烷酸腐蚀占主导因素;而氯离子含量达到较高水平后,氯离子对腐蚀的影响占主导作用。316L不锈钢和Monel合金的腐蚀速率都随氯离子含量的增加而增加,并且硫离子的存在对腐蚀也有一定的促进作用。在塔顶水相中,氯离子和硫离子均对Monel合金腐蚀的影响不大。     

1.25Cr0.5Mo钢低残余应力的焊接工艺研究

将热焊工艺应用于1.25Cr0.5Mo钢的焊接过程中。采用小孔法对焊接试板的焊接残余应力进行测量。通过改变温度研究在不同工艺条件下1.25Cr0.5Mo钢焊接残余应力的变化规律。对各试件在酸性介质中腐蚀速率进行测量。分析了热焊工艺对焊接残余应力及应力腐蚀性能影响的机理。结果表明,热焊工艺大大降低了1.25Cr0.5Mo钢的焊接残余应力,700℃工艺温度下,横向和纵向焊接残余应力均降低80%以上,抗应力腐蚀性能提升18%。随着工艺温度的提高,残余应力降低程度增大,而降低速率呈先增加后减小的趋势。     

0Cr25Ni7Mo4、316与304不锈钢临界点蚀温度研究

采用外加恒定电位下腐蚀电流-温度扫描方法研究了0Cr25Ni7Mo4、304和316不锈钢在1 mol/L NaCl水溶液中的点蚀行为。利用不锈钢临界点蚀温度评价了材料的耐点蚀性能.测得0Cr25Ni7Mo4和316不锈钢的临界点蚀温度分别为79.5 ℃和15 ℃,304不锈钢在0 ℃以下.对0Cr25Ni7Mo4不锈钢材料优良耐点蚀性能的原因进行了分析讨论.     

不锈钢的大气腐蚀研究—12年暴露试验总结

总结了５种不锈钢在我国７个试验点的１２年大气腐蚀试验结果,材料中包括了最常用的不锈钢,环境中包括了亚热带,温带,工业性,海洋性,干燥环境及湿热环境等各种典型环境。不锈钢在大气中是耐蚀的。当含Ｃｒ量达到１８％以上时耐蚀性很好,钼能明显提高不锈钢的耐蚀性,超低碳也能提高其耐蚀性。     

Mo含量对不锈钢在环烷酸介质中腐蚀与中蚀的影响

制备了以316L为基的不同Mo含量的不锈钢，在精制环烷酸和含环烷酸的油中分别进行了静态和冲蚀实验，结果表明，316L基不锈钢在高温环烷酸介质中具有很好的抗腐蚀和冲蚀性能，随Mo含量增加，不锈钢的环烷酸腐蚀速率和冲刷腐蚀速率均逐渐减小，流体冲刷明显加剧不锈钢的环烷酸腐蚀，综合考虑不锈钢的抗蚀性能及机械性能，在设计抗环烷酸腐蚀和冲蚀的新型不锈钢时，Mo含量应保持在5%（质量分数）左右。     

Influence of tempering treatment on microstructure and pitting corrosion resistance of a new super ferritic–martensitic–austenitic stainless steels with 17%Cr

Supermartensitic stainless steels (SMSSs) allow high mechanical strength with better corrosion resistance and toughness than conventional martensitic stainless steels. The SMSS steels with 12–13%Cr have been studied and applied in the oil and gas offshore production. The increase of Cr content, and the addition of Mo and W is now being investigated to increase mechanical and pitting corrosion resistance. In this work, a new 17%Cr steel, with Mo and W additions was studied. Depending on the final tempering treatment, the steel has a complex microstructure of austenite, ferrite, martensite and precipitates. The pitting corrosion resistance also depends on the microstructure produced by tempering. It was found that the pitting potential slightly decreases with the increase of tempering temperature and is further decreased by the double-tempering treatment. The pits initiate and grow preferentially in the martensite or tempered martensite islands, due to the lower Cr, Mo and W contents of these areas.     

不锈钢海水潮汐区16年腐蚀行为

在青岛、厦门和榆林3个试验站的潮汐区对5种不锈钢暴露16年，总结其腐蚀行为和规律。在潮汐区暴露的不锈钢受点蚀和缝隙腐蚀破坏。不锈钢在潮汐区暴露1至4年的点蚀速度较大，以后点蚀速度减慢。耐点蚀性能较好的不锈钢，耐缝隙腐蚀性能也较好。不锈钢在潮汐区的腐蚀随暴露地点的海水温度升高而加重。增加Cr含量、添加Mo能明显提高不锈钢在潮汐区的耐蚀性。Ni对提高的耐蚀性有效，但影响效果较小。海生物污损能引起不锈钢的局部腐蚀，它对不锈钢在潮汐区的腐蚀有显著影响。     

pH在线监测网络远程管理系统在常减压装置上的开发与应用

针对原油在常减压装置系统管线及设备的腐蚀问题,建立并应用于克拉玛依石化公司常减压装置一脱三注控制,设计了pH在线监测及控制管理系统.讨论了该设计系统功能结构,并对减少和预防设备腐蚀,探索和发现腐蚀规律,降低安全生产风险管理具有非常重要的意义.     

Electrochemical behaviour of duplex stainless steels in caustic environment

Recent studies have shown that duplex stainless steels can be susceptible to general corrosion and stress corrosion cracking in high pH caustic environments. This difference in the corrosion resistance can be attributed to changes in the electrochemical behaviour of steels. The present study has shown that the corrosion rates of duplex stainless steels increase with an increase in temperature and sulphide addition to caustic environments. Moreover, alloying Fe with Cr and Ni helps to raise the corrosion potential and lower critical current density of DSS in an alkaline environment whereas Mo can be detrimental to the corrosion resistance of the steel.     

Naphthenic acid corrosion characteristic and corrosion product film resistance of carbon steel and Cr5Mo low alloy steel in secondary vacuum gas oil

Although naphthenic acid corrosion (NAC) has been studied for many years, the mechanism of NAC is not fully understood. The objective of this paper is to study high-temperature NAC in secondary vacuum gas oil of an industrial crude oil vacuum distillation tower. A high-temperature autoclave was applied to conduct high-temperature corrosion test to investigate NAC behaviour of carbon steel and Cr5Mo low alloy steel at different sulphur contents and total acid numbers (TAN). The result shows that the corrosion rate of carbon steel and low alloy steel is high at low TAN and high TAN while it keeps at a low value at medium TAN. Corrosion product film on Cr5Mo low alloy steel surface is denser and more compact than that of carbon steel at high TAN. The chromium present in Cr5Mo low alloy steel plays an important role in NAC resistance by the formation of Cr₇S₈ film in the inner layer of the scale. Corrosion rates of the two steels in secondary vacuum gas oil are high at low TAN and high TAN, but low at medium TAN which are strange and different from previous experimental results conducted in non-industrial oil solution. A tentative explanation for this new phenomenon is also put forward.     

Corrosion behavior of nickel alloys in wet hydrofluoric acid

Wet hydrofluoric acid at concentrations below approximately 60% is highly corrosive to glass, reactive metals, carbon steel and stainless steels. Nickel alloys offer moderate corrosion resistance over a wide range of acid concentration and temperature. The corrosion behavior of eleven commercial alloys was quantified through laboratory testing. Variables that were studied included testing time, acid concentration, temperature, vapor and liquid phases and the presence of residual stresses. Results show that the corrosion rate of a Ni‐Cu and a Ni‐Cr‐Mo‐Cu alloy increased with the acid concentration and the temperature. However, both for increasing acid concentration and temperature, the corrosion rate of the Ni‐Cu alloy increased faster than the corrosion rate of the Ni‐Cr‐Mo‐Cu alloy, especially in the vapor phase. Even in unstressed coupons, nickel alloys showed internal penetration in presence of wet HF; the mode of this internal penetration varied from alloy to alloy. Considering all the studied variables that influence corrosion, the highest ranked material for wet HF service was a Ni‐Cr‐Mo‐Cu alloy.     

New stainiess steels for sea water applications. Part. 1: Corrosion and mechanical properties of ferritic stainless steels

Two experimental ELI ferritic stainless steels (22 Cr – 2.5 Ni – 3 Mo and 22 Cr – 2.5 Ni – 3 Mo – Ti) prepared in laboratory and a commercial one (21 Cr – 3 Mo – Ti) were investigated. Electrochemical and laboratory exposure tests were carried out to define the localized corrosion resistance (pitting and crevice) of such steels in chloride solution. Intergranular and stress corrosion resistance was also evaluated. Room temperature tension tests and impact tests were performed. 22 Cr – 2.5 Ni – 3 Mo – Ti and 21 Cr – 3 Mo – Ti steels are immune to intergranular corrosion whatever temperature they are heat treated at and have the same pitting corrosion resistance as a function of temperature; crevice corrosion of 22 Cr – 2.5 Ni – 3 Mo is decidely better than in the commercial 21 Cr – 3 Mo – Ti. The experimental steels were immune to stress corrosion in hot chloride environment.