抗高温氧化腐蚀专用焊条

通过A402，A302，A202及Cr24Ni7不锈钢焊条熔敷金属的抗高温氧化腐蚀性能对比试验分析，设计了新的专用焊条合金系统Cr26Nil6，并在焊条药皮中分别添加微量稀土氧化物La2O3及CeO2，研究不同稀土氧化物添加量对焊条熔敷金属在空气中和含硫气氛中抗高温氧化及腐蚀性能的影响，从而确定了合理的稀土氧化物加入量。最后，对合金系统为Cr26Nil6的专用焊条进行工艺评价。结果表明，专用焊条工艺性好，用该焊条所焊焊缝的性能可满足抗高温氧化腐蚀使用要求。微量稀土氧化物在焊条药皮中的加入，对其熔敷金属的抗高温氧化性能有所提高，对在含硫气氛中的抗高温腐蚀性能有显著提高；加入La2O3的焊条熔敷金属比加入CeO2的焊条熔敷金属抗高温氧化及硫化腐蚀性能更好。     

Development of RM-1 type coated electrode for reducing retorts in magnesium refining

According to the working condition of high temperature oxidation and sulphidation corrosion of the ZG35Cr24Ni7SiN heat-resisting stainless steel used for reducing retort in magnesium refining, and the practical situation which the weld metal between the body and cover of reducing retort must possess resisting high temperature oxidation and corrosion, a kind of RM-1 type coated electrode for reducing retorts in magnesium refining with special alloying system and excellent usability has been developed. The RM-1 coated electrode is made of H0Cr21Ni10 wire core and is alloyed chromium and nickel simultaneously through coating material and wire core and some rare-earth oxides are added in coating material. The electrode has been verified to be satisfied the operation requirements of practical production.     

High temperature corrosion behaviour of a new Ni-30Fe-10Al-Cr-Alloy

The high temperature corrosion behaviour of a new duplex nickel-base alloy containing about 30 mass% iron, 10 miss% aluminium and 8 mass% chromium was determined in both air and hot process gases containing methane/hydrogen, sulphur dioxide and hydrogen sulphide, respectively. It was found that the corrosion resistance against carburisation, sulphidation and oxidation was excellent due to the formation of a dense, protective alumina scale. The adherence of the alumina scale was increased by an addition of 0.1 mass% hafnium. The concentration of chromium was found to have a remarkable impact on the oxidation and high temperature corrosion resistance. Alloys without chromium showed increased corrosion rates in both air and sulphur-containing gas atmospheres due to the initial formation of nickel oxides. In sulphidising SO₂- and H₂S- containing gases at least 4 mass% chromium are required to stabilise the formation of alumina and to prevent the formation of nickel/sulphur compounds.     

稀土含量对熔敷金属扩散氢逸出特性及性能的影响

通过碱性焊条药皮向焊缝金属过渡稀土元素的方法，并结合酒精法测氢技术、低温冲击试验以及小铁研抗裂性试验，研究了稀土含量对熔敷金属扩散氢逸出特性及性能的影响。研究结果表明，适量的稀土能显著降低熔敷金属的扩散氢含量，提高焊缝的低温韧性，并改善扩散氢的逸出特性，即使熔敷金属开始阶段扩散氢的逸出速率增加，对后期阶段的逸出速率影响较小；稀土的最佳加入量为0．5％，继续增加时，焊缝的韧性及抗裂性开始恶化。     

TUNGSTEN ELECTRODES CONTAINING THREE TYPES OF RARE EARTH OXIDES

ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｔｈｉｎｃｒｅａｓｉｎｇｄｅｍａｎｄｓｔｏｔｈｅｐｒｏｐｅｒｔｙｏｆｗｅｌｄｉｎｇｅｌｅｃｔｒｏｄｅａｎｄｂｅｔｅｒｋｎｏｗｌｅｄｇｅｏｆＴｈＷｅｌｅｃｔｒｏｄｅｍａｔｅｒｉａｌ’ｓｒａｄｉｏａｃｔｉｖｉｔｙ,ｓｏｍｅｓ...     

TUNGSTEN ELECTRODES CONTAINING THREE TYPES OF RARE EARTH OXIDES

Three types of tungsten electrodes containing three rare earth oxides, namely Y₂O₃, La₂O₃, and CeO₂ and one with Y₂O₃ and CeO₂ were prepared, in which the total contents of rare earth oxides are 2.2% in mass, and the characteristics of these electrode materials were studied. By TIG welding, the welding characteristics including arc starting, arc static properties and electrode consumption of these electrodes were also analyzed. The results suggest that the electrodes added three rare earth oxides are more favorable for processing than that added two rare earth oxides. All the electrodes activated with two or more rare earth oxides are more superior to W-ThO₂ in operating, and the electrode combined with Y₂O₃ and CeO₂ shows the best properties when it is used at a heavy current for a long time. The analyses of the results of electrode consumption indicates that the rim forming during arcing is one of the important reasons for electrode's heavy erosion, and the increased Y₂O₃ content in electrodes is beneficial to retard the formation of rim, and leads to the improvement of consumption resistance of the electrodes.     

Failure of welded dilution steam coil made of alloy 800HT

Abstract

The paper presents the results of a failure investigation carried out on a welded dilution steam coil made of alloy 800HT. The dilution steam coil leaked at the inlet of the convection section of an ethane cracking furnace after 11 years of service. The tube experienced cracking in the weld metal and the weld fusion zone. The failure investigation revealed that the dilution steam coil suffered from embrittlement due to sulphidation at the grain boundaries of the weld metal at the inner surface and intergranular oxidation and cracking of the heat affected and weld fusion zones at the outer surface. The internal sulphidation was ascribed to the influence of sulphur bearing species on the weld metal that was much higher in nickel content than the parent metal, while the external oxidation was attributed to the oxidising environment of the furnace atmosphere. The source of sulphur in the furnace effluent was possibly dimethyl disulphide injected into the furnace feed to prevent coke formation and carburisation of the furnace tubes.     

稀土对钢轨耐磨堆焊层金属组织及韧性的影响

对不同稀土含量的自保护药芯焊丝堆焊层金属进行了室温冲击试验和金相组织观察;并对冲击断口形貌进行了扫描电镜(SEM)分析和夹杂物的能谱(EDS)分析,同时对夹杂物生成自由能进行了计算。结果表明,随稀土的增加,焊缝冲击韧性先增加后降低,加入4%的稀土,具有良好的晶粒尺寸和分布,冲击韧性最高;加入量超过8%时,形成的稀土硫化物、稀土氧化物残存于焊缝中形成夹杂,焊缝冲击韧性降低。热力学计算得到了几种夹杂物的生成先后顺序,从另一个角度解释了稀土的净化除杂作用。     

低碳钢及焊缝硝酸盐露点腐蚀开裂研究

用U形恒应变实验方法，研究了20 g、16MnR、Q235-A 材及焊接材料浸泡在不同浓度硝酸铵溶液中的开裂敏感性，同时也讨论了硫的氧化物对硝酸盐露点腐蚀开裂敏感性的影响.结果表明：焊接材料比基材更易于发生硝酸盐露点腐蚀开裂，20 g比16MnR、Q235-A在硝酸盐中有更低的开裂敏感性，硫的氧化物增加了开裂敏感性.在此基础上，还探讨了硝酸盐露点腐蚀开裂的类型和机理.     

环境友好型达克罗处理技术的现状及研究进展

达克罗涂层的无氢脆、耐高温、强耐腐蚀性、附着力良好、高渗透性和强涂覆能力等特点使其近年来广泛用于汽车、家用电器、建筑、石油化工等领域。然而该涂层中的Cr⁶⁺由于具有较强的致癌、致畸、致突变作用而受到限制,且其硬度仅有1～2H,抗划伤能力差,耐磨性低,因此使用该图层的工件不适用于硬度和耐磨性要求高的场合。本文先介绍了达克罗涂液的主要组成成分(金属粉末、溶剂、铬酸盐钝化剂和特殊有机物)及铬酸盐在达克罗涂层中的作用(钝化作用、黏结作用和自愈作用);接着从环境友好型达克罗防腐涂层的成膜物质-铬酸盐替代物(无铬钝化剂-含氧酸盐及氧化物、稀土盐和有机黏结剂-硅烷偶联剂、硅烷偶联剂+缓蚀剂、树脂+缓蚀剂)的选取、无铬钝化液的配方优化、纳米微粒增强达克罗涂层三方面分别综述了国内外关于提高环境友好型达克罗涂层的硬度和耐蚀性,指出了各种成膜物质的不足并指出进一步的研究方向;最后简要介绍了稀土改性达克罗处理技术的防腐蚀机理,对环境友好型达克罗涂层研究中存在的问题进行了归纳,并对其发展方向进行了展望。在总结与分析的基础上可知,随着环境保护要求的提高,开发由有机聚合物(硅烷或树脂)和稀土盐...     

国产核级E308L焊条在高温水环境下均匀腐蚀行为

结合腐蚀增重和腐蚀失重变化并利用SEM、XRD和XPS等手段,研究了国产核级E308L不锈钢焊条熔敷金属在模拟核电一回路水环境中的均匀腐蚀性能。结果显示,随着腐蚀周期的增加,腐蚀增重和腐蚀失重均为先迅速增加,随后增加趋缓,而试样表面氧化物颗粒数量和尺寸逐渐增大,氧化膜的主要成分为Fe和Cr的氧化物。3000 h内国产核级E308L不锈钢焊条具有良好的抗均匀腐蚀性能。     

2Cr13钢表面激光熔覆Co基合金组织及其性能

采用横流连续波2kW CO2激光在2Cr13不锈钢表面进行激光熔覆处理,对熔履层的组织结构、磨损及高温和PbSO4盐热腐蚀性能进行了系统研究。试验结果表明,表面激光熔覆Co基合金后,其耐磨粒磨损性能、高温PbSO4盐热腐蚀性能均提高了2.5倍以上,熔覆层的热腐蚀机制是沿晶腐蚀及硫化-氧化循环进行造成的剥落型腐蚀破坏。     

Effects of rare earth metals addition on the resistance to pitting corrosion of super duplex stainless steel - Part 1

To elucidate the effects of rare earth metals addition on the resistance to pitting corrosion of super duplex stainless steel, a metallographic examination, potentiodynamic and potentiostatic polarization tests, a SEM-EDS and a SAM analysis of inclusion, austenite phase and ferrite phase were conducted. The addition of rare earth metals to the base alloy led to the formation of (Mn, Cr, Si, Al, Ce) oxides and (Mn, Cr, Si, Ce) oxides, which improved the resistance to pitting corrosion and caused a decrease in the preferential interface areas for the initiation of the pitting corrosion.     

热浸渗稀土（La）铝钢在含H2S介质下的耐蚀性研究

研究了加稀土La对热浸渗铝钢渗层组织和含H2S水介质下耐蚀性的影响，结果表明，随着La含量的增加，渗层中富铝层增厚，其耐蚀性逐渐提高.添加0.8 mass %La的渗层的耐蚀性最好约为不加La的3倍.     

混合稀土对工业纯铝冲压性能的影响

对稀土质量分数不同的稀土铝合金与不加稀土元素的工业纯铝进行对比实验,研究稀土质量分数及不同的热处理状态对合金冲性能的影响,探讨了不同使冲压性能,同时对稀质量分数不同的铝合金的硬度和耐蚀性进行了研究。     

Effect of slag variations on ANSI/AWS A5.1–91 E6013 electrode properties: replacement of TiO2 in electrode coating with MnO,FeO, CaO,MgO, K2O,or Na2O

Abstract

The present work is part of a research programme to study the effect of variation of the coating composition of covered rutile manual electrodes on both operational and deposited weld metal properties. According to previous results obtained for rutile electrodes, an increase of slag basicity, achieved through modifications in the coating, produces an improvement of the impact properties of the deposited weld metal, as well as a decrease in the diffusible hydrogen, along with beneficial changes in the operational properties of the electrode. The aim of the present work is to study the influence of the replacement of titanium oxide with oxides of alkali metals (sodium and potassium), alkaline earth metals (calcium and magnesium), and iron and manganese oxides in the coating of an ANSI/AWS A5.1–91 E6013 type electrode on the operational characteristics of the electrode and the microstructure, mechanical properties, and diffusible hydrogen content of the electrode weld metal. Tensile strength and Charpy V notch impact properties were measured in the all weld metal samples produced using each of the seven electrodes designed for the present study. A cross-section from each coupon was used to determine the chemical composition of the deposit and to carry out a metallographic study using a light microscope. As a result of the addition of different oxides, changes in the operational properties were observed using both direct and alternating current, as well as a decrease in the diffusible hydrogen content in the weld metal. Also, electrodes in which rutile was substituted by sodium oxide in the coating showed an improvement in the impact properties of the deposit.     

High temperature corrosion of β-NiAl intermetallic compound and pseudobinary NiAl-Cr alloys in sulphur-containing atmospheres

Sulphidation behaviour of β-NiAl intermetallic compound and NiAl-Cr alloys has been studied as a function of temperature (1073? 1273 K) and sulphur vapour pressure (10^?5?10⁴ Pa) usi ig various experimental techniques. It has been found that over the whole temperature and sulphur pressure range studied the sulphidation process follows parabolic kinetics, being thus diffusion Controlled. The sulphidation rate of β-NiAl intermetallic compound decreased with decreasing sulphur pressure, down to about 1 Pa, and at lower pressures (1-10^?5, Pa) the rate of this process became virtually pressure independent. The sulphidation rate of NiAl-Cr alloys was higher than that of β-NiAl intermetallic compound and increased with increasing chromium content in the alloy. In contrast to β-NiAl, the sulphidation rate of alloys decreased with decreasing sulphur activity over the whole pressure range studied. The scales formed on β-NiAl and NiAl-Cr alloys were heterogeneous and mostly multilayer. In addition, an internal sulphidation zone was observed in the underlying metallic phase. Nickel sulphide nodules were always present on the scale surface when the sulphur pressure in the environment exceeded the dissociation pressure of this sulphide. The main part of the scale formed on β-NiAl consisted of NiAl₂S₄ sulphospinel. Al₂S₃ inclusions were present in the internal sulphidation zone. On alloys containing up to 10 at% Cr the main part of the scale was composed of two sulphospinel phases, NiAl₂S₄ and (Cr,Al)₃S₄, while on alloys with higher chromium content a stratified scale, consisting of Ni₃S₂ and (Cr,Al)₃S₄ was formed. (Cr, Al)₃S₄ and Al₂S₃ inclusions were present in the internal sulphidation zone of all chromium-containing alloys. According to marker experiments the scales on the investigated materials grow predominantly by an outward diffusion of cations. At sulphur pressures lower than the dissociation pressure of Ni₃S₂, β-NiAl intermetallic shows excellent corrosion resistance in sulphur-containing atmospheres, its sulphidation rates being comparable with the oxidation rates of chromia forming alloys.     

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 在真空感应炉内向25CrMoVB钢中加入不同含量的混合稀土,分析了稀土加入量、钢中稀土总量(Re)与稀土固溶量(Res)之间的关系。通过硫化物应力腐蚀(SSC)和抗氢致开裂(HIC)试验,研究了稀土对试验钢抗硫化氢腐蚀性能的影响。结果表明各试验钢具有良好的抗氢致开裂能力,适量的稀土加入量可显著提高25CrMoVB钢的抗硫化物应力腐蚀能力。     

Sodium vanadate induced corrosion of MCrAlY coatings – Burner rig studies

The corrosion of several MCrAlY-coatings (M = Ni, Fe and Ni + Co) has been studied in a high velocity burner rig at 650, 800 and 950°C. The fuel used was diesel oil with additions of 3% sulphur, 200 ppm vanadium and 100 ppm sodium. The deposits formed on the specimens mainly consisted of sodium vanadates which were molten at the test temperature. Sodium sulphate was only found at and below 650°C. The corrosion mechanism involved was vanadate-induced hot corrosion. This corrosion mechanism is characterized by the formation of an oxide layer adjacent to the metal, the dissolution of oxide in the molten deposit, and precipitation of vanadates or oxides near the outer surface of the deposit. The continuous deposition of fresh vanadate on the surface served to maintain high corrosion rates for extended exposures.     

二元复合稀土钨电极材料的性能

通过粉末冶金和压力加工制备了系列二元复合稀土钨电极材料（Ｗ－Ｌａ２Ｏ３－Ｙ２Ｏ３,Ｗ－Ｌａ２Ｏ３－ＣｅＯ２,Ｗ－Ｙ２Ｏ３－ＣｅＯ２）,采用直流正接（ＤＣＳＰ）的钨极氩弧焊（ＴＩＧ）方法,系统研究了它们的焊接电弧特性,包括引弧性能、电弧静特性和电极抗烧损性能。并对它们的这些性能与单元稀土钨电极材料（Ｗ－Ｌａ２Ｏ３,Ｗ－ＣｅＯ２,Ｗ－Ｙ２Ｏ３）和钍钨电极材料进行了比较。结果表明二元复合稀土钨电极性能优