Q345NS钢焊接接头耐硫酸腐蚀特性研究

采用硫酸浸泡实验,研究了Q345NS钢焊接接头耐硫酸腐蚀行为,并对焊接过程中合金元素扩散和耐硫酸腐蚀的行为与机理进行了分析.结果表明:焊接过程中,母材与焊材之间的元素浓度差促使母材中Cr、Cu、Sb等合金元素向焊缝内扩散富集,同时,焊接过程中的高温会促进该进程,导致热影响区靠近母材一侧形成了合金元素贫瘠带;焊缝处高温导...     

ND钢的焊接工艺试验研究

提高材料的耐蚀性一直是材料研究的一个重要课题。根据相关资料记载,每年全世界由于腐蚀而报废的材料约占钢总产量的1/3。耐大气腐蚀钢、耐海水腐蚀钢、耐石油腐蚀钢、耐氮、氢腐蚀钢、耐氯腐蚀钢等已广泛用于焊接结构,耐硫酸露点腐蚀钢(ND钢)也在近年发展起来了。腐蚀多发于焊接接头,如何从焊接工艺角度解决接头的抗腐蚀问题显得尤为重要。1ND钢焊接性分析耐硫酸露点腐蚀钢主要是通过向合金系统中加入适量的Cu,Cr,Sb,Ti等合金元素,以提高材料的抗腐蚀稳定性。ND钢的化学成分及力学性能见表1、表2。通常供货状态板材为热轧状态,管材为正…     

低合金耐硫酸露点腐蚀用钢板的试制及其性能研究

开发和使用低合金耐硫酸露点腐蚀钢板,对提高设备耐腐蚀性能、延长使用周期及降低材料成本非常重要。介绍了鞍钢低合金耐硫酸露点腐蚀用钢板的试制情况,本次试制通过添加Cu、Cr、Sb、Ti等合金元素并结合合理的轧制工艺,开发出4~12 mm厚耐硫酸露点腐蚀钢板。对试制钢板的显微组织以及力学性能进行了检测,同时采用硫酸浸泡腐蚀试验对试制钢板与Q235B钢板的腐蚀速率、锈层组成进行了研究。试验结果表明:试制钢板的组织以铁素体+珠光体为主、含有少量的贝氏体,其力学性能优异,远超性能设计要求;在相同腐蚀条件下,试制钢板表面生成一层均匀且致密的内锈层,其耐硫酸腐蚀性能是Q235B钢板的7倍左右。     

新型耐硫酸盐酸露点腐蚀钢的性能研究

采用全浸失重实验、电化学实验对实验室炼制的Cu-Sb-Mo低合金钢,对比钢304不锈钢和Q235B钢的耐硫酸、盐酸腐蚀性能进行评估。并且使用电化学阻抗谱(EIS)、扫描电镜(SEM)和X射线衍射(XRD)研究了试制钢在硫酸、盐酸中的耐蚀机理。结果表明:合金元素Cu,Sb和Mo的添加,可以同时抑制金属的阳极溶解反应和阴极析氢反应,降低腐蚀电流密度,增大金属的电荷转移电阻。合金元素的添加在金属表面形成了对应的氧化物、硫化物,它们在腐蚀介质中的稳定性比钢基体更高,从而抑制钢基体的进一步腐蚀。     

锑含量和硫酸溶液浓度对耐酸钢腐蚀性能的影响

以10%H_2SO_4+3.5%NaCl和20%H_2SO_4+3.5%NaCl的混合溶液为腐蚀介质,在室温条件下对不同锑含量的耐酸钢和Q345B钢进行了全浸腐蚀实验,对比研究了铁路货车用耐酸钢和对比钢Q345B的腐蚀行为。结果表明:在10%H_2SO_4+3.5%NaCl环境下,Q345B腐蚀速率为4.95 mm/a,两种不同含Sb耐酸腐蚀钢的耐蚀性能良好。随着Sb含量增加,腐蚀速率下降,0.12%Sb耐酸钢腐蚀速率为0.66 mm/a,相对于Q345B的腐蚀速率为13%。合金元素锑的添加有效地提高了钢的耐硫酸腐蚀性能。随着硫酸浓度上升,0.06%Sb钢腐蚀速率从1.235 mm/a下降到1.031 mm/a。     

含锑低合金马氏体钢的耐磨蚀性能

利用OM和SEM对0％Sb和0.2％Sb的两种马氏体钢的微观组织与腐蚀产物进行表征,测量其硬度和力学性能,并进行腐蚀磨损试验,研究了Sb元素的加入对试验钢耐磨蚀性能的影响。结果表明:试验钢具有高抗拉强度、高硬度及良好的低温(-20 ℃)冲击性能,分别能够达到1400 MPa、40 HRC以及45 J以上,0.2％Sb钢的耐磨蚀性更好。Sb元素的加入提高了钢在酸性高氯离子及高硫酸根离子环境中的耐蚀性,保证力学性能与硬度的同时提高了耐磨蚀性能。     

新型低碳高强耐磨铸钢NMZ1在模拟海水中的腐蚀形貌

借助全浸泡试验和腐蚀表面形貌观察,研究了新型低碳、高硅海洋用钢NMZ1在模拟静态海水中的腐蚀行为,并以常用离心泵叶轮材料20Cr5Cu及泥浆输送管道材料Q345为对比,评价其耐蚀性。结果表明,NMZ1钢的耐海水腐蚀性能优于Q345而不及20Cr5Cu,其在3.5%NaCl中的腐蚀速率为0.1215mm/a,约为Q345的2/3和20Cr5Cu的1.5倍;其合金化元素有助于提高表面产物膜的保护性并抑制点蚀发生,故其表现出均匀腐蚀形态且腐蚀速率较低。     

经济型高耐候钢耐大气腐蚀性能研究

在周浸腐蚀条件下，研究了不同Cr-Sb组合高耐候钢的腐蚀行为。结果表明，随着Sb的增加，耐蚀性不断提升；但Sb的添加，增加了试验钢的点蚀倾向。可以通过降Cr提Sb提升试验钢的腐蚀性能，但当Cr降到3.5%时，耐蚀性出现了拐点，腐蚀速率大幅提升。Cr-Sb协同不改变试验钢锈层的物相组成。Cu在锈层与腐蚀坑内富集形核，抑制了S向基体内扩散，提升了材料的耐蚀性。     

低铬油套管CO2/H2S腐蚀研究进展

介绍了低Cr油套管开发的工程背景。综述了低Cr油套管的耐CO_2/H2S腐蚀性能,详述了多种因素(如Cr含量、温度、p H值、流速等)对低Cr油套管在含甜性气体(仅含CO_2)环境中的腐蚀行为和腐蚀产物膜表面特征的影响,以及低Cr油套管在含酸性气体(H2S)环境中的腐蚀行为及其抗硫化物应力开裂(SSC)的性能。探寻了低Cr钢的抗CO_2腐蚀机理和H2S腐蚀机理。研究发现,低Cr钢因Cr元素能在产物膜中富集,形成非晶体化合物Cr(OH)3,腐蚀产物膜因此具有阳离子选择性,降低了腐蚀产物膜与金属基体界面处的阴离子浓度,抑制了阳极反应,进而提高了低Cr钢耐CO_2/H2S均匀腐蚀性能,同时也减少了Cl-在界面处团聚、形核的可能性,抑制了局部腐蚀,尤其是点蚀的发生。但是要想消除点蚀,钢基体中Cr元素的质量分数不应低于3%。另外,Cr元素在晶界及晶内以粒状碳化物析出并弥散分布,进一步增强了其抗SSC性能。简述了低Cr油套管的应用现状,最后对其发展前景进行了展望,利用钢的化学成分-工艺-组织-性能"四位一体"法得到的"经济型"低Cr抗CO_2/H2S腐蚀的油套管,是未来发展趋势的代表。     

低合金高强度抗应力腐蚀开裂海洋软管用钢的开发

通过合金成分设计,轧制、热处理工艺的探索,开发了低合金高强度海洋软管用钢,其屈服强度大于600 MPa且满足抗氢脆、抗氢致开裂、抗应力腐蚀开裂性能,并通过全浸腐蚀实验对该钢的海水腐蚀行为进行了研究。结果表明,采用低C、低Mn并复合添加耐蚀元素Cr、Mo和采用合理的热轧、冷轧、调质处理工艺,可获得满足抗应力腐蚀开裂性能的600 MPa级高强钢。耐蚀元素的添加使实验钢具有良好的耐海水腐蚀能力,腐蚀稳定状态下的平均年腐蚀速率为0.11 mm/a。     

Corrosion of API XL 52 steel in presence of Clostridium celerecrescens

During the characterization of sediments formed in pipelines transporting hydrocarbons, the knowledge of the microbiological diversity becomes very interesting, especially when it is related to microbiologically influenced corrosion (MIC). The presence of microorganisms is considered as one of the factors that affect the corrosion processes occurring at the pipeline; therefore, their corrosiveness must be determined. In this way, the identification of new species affecting the MIC processes is still considered relevant. In this work, the effect of Clostridium celerecrescens upon the corrosion of API KL 52 steel was evaluated. This microorganism was isolated and identified from the sediments collected during the inner cleaning procedures of a gas pipeline. The polarization resistance (PR) and electrochemical impedance spectroscopy (EIS) techniques were considered to estimate the microorganism behavior during the corrosion process. The results were complemented with a metal surface analysis, using a scanning electron microscope (SEM). The resistance values induced by the presence of the microorganisms clearly indicated that C. celerecrescens has an effect on the corrosion process occurring at the API XL 52 steel surface.     

抗硫酸露点腐蚀钢的表面研究

以高硫重油为燃料的锅炉烟气中常含有较多的ＳＯ２、ＳＯ３在锅炉的低温部位，如空气预热器、集尘器、烟道、烟囱等处引起所谓的“硫酸露点腐蚀”。日本开发的各种Ｓ－ＴＥＮ烟具有良好的抗硫酸露点腐蚀性能。在成分上，Ｓ－ＴＥＮ钢与普通碳钢不同的是：它含有少量的Ｃｕ、Ｓｂ元素，但这些合金元素提高抗硫酸露点腐蚀的机理仍不清楚。本工作对供货状态的、以及在硫酸中浸泡过的Ｓ－ＴＥＮ钢进行ＡＥＳ分析和ＳＥＭ观察及能谱分析，     

湿气温度对3Cr管线钢CO2腐蚀行为的影响

利用高温高压冷凝反应釜模拟深海湿气管道的现场环境,研究了湿气温度对3Cr管线钢湿气CO2腐蚀行为的影响;运用扫描电镜(SEM)和能谱(EDS)等分析技术对试样表面腐蚀产物的形貌和成分进行了分析。结果表明,在相同管壁温度(10℃)下,湿气温度在30～90℃内范围变化时,3Cr管线钢的平均腐蚀速率随湿气温度的升高而增大,且都没有发生局部腐蚀。在这些湿气温度条件下,3Cr管线钢的腐蚀产物膜是两层结构,外层膜的主要成分为FeCO3,内层为非晶态的富Cr膜。     

Effect of tungsten on the corrosion behavior of sulfuric acid-resistant steels for flue gas desulfurization system

Flue gas desulfurization systems (FGDs) are operated in severely corrosive environments that cause sulfuric acid dew-point corrosion. The corrosion behavior of low-alloy steels was tested using electrochemical techniques (electrochemical impedance spectroscopy, potentiodynamic tests, potentiostatic tests), and the corrosion products were analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical results showed that alloying W with small amounts of Sb, Cu, and Co improves the corrosion resistance of steels. The results of surface analyses showed that the surface of the steels alloyed with W consisted of W oxides and higher amounts of Sb and Cu oxides. This suggests that the addition of W promotes the formation of a protective WO₃ film, in addition to Sb₂O₅ and CuO films on the surface.     

X80管线钢埋弧焊焊接接头的组织和腐蚀性能

采用H08MnMoA焊丝埋弧焊焊接X80管线钢.利用扫描电镜分析焊接接头微观组织;采用动电位极化和电化学阻抗法研究了X80管线钢其焊接接头在0.5 mol/LNaHCO3+0.02 mol/L NaCl溶液中的腐蚀行为.结果表明,在0.5 mol/L NaHCO3+0.02mol/L NaCl溶液中,由于显微组织上的差...     

Corrosion resistance and corrosion behavior of high-copper-bearing steel in marine environments

Thus far, research on the corrosion resistance of copper-containing steel has been limited to Cu content of less than 1%, and the corrosion resistance of antibacterial Cu-containing steel with Cu content above 3% has not been reported. In this study, 0Cu3 carbon steel (CS), 0Cr15Cu3 stainless steel (SS), and Q345 CS were investigated. The corrosion resistance and corrosive behavior of high-copper (high-Cu)-bearing steel in a marine environment were examined by scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction, electrochemical impedance spectroscopy, and potentiodynamic polarization. Coupon test results showed that the Cu in the 0Cr15Cu3 SS and 0Cu3 CS can promote the formation of stable α-FeOOH from γ-FeOOH in the outer rust layers, and make the rust layers more thick and dense. In the electrochemical experiment, the impedance loop diameters and R_ct values of the 0Cr15Cu3 SS and 0Cu3 CS were higher than those of Q345, while the I_corr was less than that of Q345, which indicates that the anticorrosion property of these two types of high-Cu-bearing steel was higher than that of Q345. The aim of this study was to define the properties of corrosion resistance and corrosive behavior in high-Cu-bearing steels to promote their application in marine engineering.     

降碳增氮对马氏体不锈钢淬火组织和性能的影响

采用激光扫描共聚焦显微镜、扫描电镜、硬度计、X射线衍射仪和盐雾试验机,研究了不同温度(950、1000、1050、1100℃)下30Cr13和30Cr14N钢在马弗炉中空淬后,氮含量对30Cr13钢显微组织、碳化物、硬度和耐蚀性能的影响。结果表明,淬火温度相同,30Cr14N钢比30Cr13钢硬度高、碳化物少和耐蚀性能好。氮不仅影响马氏体不锈钢的显微组织及硬度,还能通过降碳增氮,避免因碳化物过多的析出而引起的晶间腐蚀,而FeNiN的析出不会像Cr₂₃C₆析出造成显著的晶间腐蚀。因此,降碳增氮是改善马氏体不锈钢组织和性能的一种有效途径。     

Erosion‐corrosion of Q235 and 5Cr1/2Mo steels in oil with naphthenic acid and/or sulfur compound at high temperature

The erosion‐corrosion behaviors of Q235 steel and 5Cr1/2Mo steel in oil with naphthenic acid and/or sulfur compound at high temperature were studied in a hot oil loop simulating oil refining environments. The effects of impinging flow rate, incidence angle, and total acid number (TAN), and sulfur content on erosion‐corrosion behavior were assessed. The eroded surfaces were characterized by scanning electron microscopy (SEM) and XPS. The results showed that both corrosion resistance and hardness of steels play an important role in combating erosion‐corrosion. Sulfide films formed on the surface were significant in understanding the erosion‐corrosion behavior when both naphthenic acid and sulfur compound were present. Erosion‐corrosion regimes were determined on the basis of mechanism analysis of the damage process.