TP347H钢高温水蒸气氧化研究

研究了在600MW超临界机组屏式过热器TP347H管运行5000h后的高温蒸气氧化层。通过分析蒸气氧化层成分、相结构以及Cr的分布,并结合高温水蒸气存在的情况下氧化膜生长速度,提出了高温蒸气氧化层的形成机理。由Cr的扩散探讨了晶粒尺寸对TP347H管抗高温蒸气氧化性能的影响。结果表明:CrO2(OH)2的挥发导致了外层Fe的氧化物的形成,FeCr2O4内层的形成能够有效减缓蒸气氧化进程,进入稳态氧化阶段后氧化层厚度将保持不变;同时,随晶粒尺寸的减小TP347H的抗蒸气氧化性能提高。     

Super304H钢和TP304H钢晶间腐蚀敏感性研究

利用电化学动电位再活化法(EPR)测试了Super304H钢和TP304H钢的晶间腐蚀敏感性.结果表明,Super304H钢和TP304H钢的再活化率在同一个数量级上.Super304H钢和TP304H钢组织中都没有明显的Cr23C6析出相,所以未出现明显的基体贫铬现象,因此二者具有优良的耐晶间腐蚀性能.     

时效对TP304H钢组织及析出相的影响

对TP304H奥氏体不锈钢分别进行了时效温度为650、700、750 ℃,时效时间为30、60、150 d的时效处理,利用金相显微镜、SEM及能谱成分分析研究了TP304H钢高温时效组织形貌和析出相特征。结果表明,随着时效时间增加,晶粒逐渐长大,孪晶减少,有大量碳化物伴和少量σ相析出,析出相总量呈幂函数增长;相同时效时间下,随时效温度升高,析出量颗粒尺寸增大且数量增加。     

喷丸处理提高TP304H耐热钢锅炉管抗水蒸气氢化性能应用效果的观察

对TP304H(0Cr19Ni9)耐热不锈钢采用喷丸处理工艺进行表面处理，连同未处理管同时安装在1000t／h电站锅炉的屏式再热器上，实际运行7552h后取样分析管子内壁高温水蒸气氧化情况．观察结果表明，喷丸处理减小了内氧化倾向，合金元素Cr在表层区域富集，氧化膜层的物相构成由Fe的氧化物转变为以Cr氧化物为主的形态，氧化膜更为致密，有效提高了耐热钢的抗水蒸汽氧化性能．文中分析了喷丸对氧化机理的影响，并讨论了喷丸处理工艺对氧化过程中扩散机理的影响以及氧化膜物相组成的变化．     

Synergic Effect of Shot Blasting and Deposit RE on Corrosion Behavior of TP304H steel in SO2-O2 at 923K

The corrosion behavior of TP304H steel with combined treatment of shot blasting and electrophoresis deposited RE coating in 1%SO2 14%O2 85%Ar mixture gaseous has been studied at 923K for 150 hours. The results show that both RE coating and shot blasting can improve the corrosion resistance of TP304H steel, and combined treatment has the best effect. Combined treatment reduces 50% mass gain, enhances the continuous and compactness of scale and changes the scale phase forms from Fe2O3/Fe1-xS/Ni1-x/S to Cr2O3/FeCr2Sn/Ni3-xS2. The synergistic effects of combined treatment on corrosion resistance and the effect of shot blasting on corrosion kinetics are discussed. Shot blasting increases the outward diffusion and surface concentration of Cr, Ce coating promotes the selective oxidation of Cr.     

喷丸处理提高TP304H耐热钢锅炉管抗水蒸气氧化性能应用效果的观察

对TP30 4H(0Cr19Ni9)耐热不锈钢采用喷丸处理工艺进行表面处理 ,连同未处理管同时安装在 10 0 0t/h电站锅炉的屏式再热器上 ,实际运行 75 5 2h后取样分析管子内壁高温水蒸气氧化情况 .观察结果表明 ,喷丸处理减小了内氧化倾向 ,合金元素Cr在表层区域富集 ,氧化膜层的物相构成由Fe的氧化物转变为以Cr氧化物为主的形态 ,氧化膜更为致密 ,有效提高了耐热钢的抗水蒸汽氧化性能 .文中分析了喷丸对氧化机理的影响 ,并讨论了喷丸处理工艺对氧化过程中扩散机理的影响以及氧化膜物相组成的变化 .     

内壁喷丸处理对TP304H耐热钢锅炉管抗水蒸汽氧化性能的影响

将经表面喷丸处理和未处理的TP304H钢管安装于锅炉再热器的高温段运行7474h后,对内壁氧化膜进行形貌观察、能谱分析和X射线衍射分析。结果表明,喷丸处理可大幅度提高TP304H钢的抗水蒸汽氧化性能,氧化膜的生长速率显著降低且氧化膜的粘附性提高。显微分析表明,氧化膜由双层结构转变为单一高Cr氧化膜层,外层Fe的氧化层消失。分析认为喷丸在管子内壁产生的剧烈形变引起晶粒细化和马氏体相变,在高温下促进了Cr向表面扩散及生成富Cr的氧化层。     

CeO2薄膜对Fe-Cr合金的高温水蒸气氧化行为影响

研究了Cr含量为9 mass％和19 mass％的Fe-Cr合金表面沉积CeO2薄膜在600℃~770℃水蒸气中的氧化行为.结果表明,对9 mass％Cr含量的Fe-Cr合金,沉积稀土薄膜并没有改变氧化膜结构和明显降低氧化速率.对于19 mass％Cr含量的Fe-Cr合金,沉积稀土薄膜可促进Cr向外扩散和阻碍O向内扩散,合金表面形成连续的Cr氧化物,合金的氧化速率降低.关键词：      

TP439不锈钢在800℃高温水蒸气中的初期氧化行为

研究了TP439不锈钢在800℃高温水蒸气中的初期氧化行为。采用恒温氧化法测试了TP439不锈钢在800℃高温水蒸气中的氧化动力学曲线。通过场发射电子扫描显微镜(FE-SEM)观察试样氧化后的形貌,采用能谱分析(EDS)及X射线衍射(XRD)分析膜层的表面成分及相结构。结果表明：TP439不锈钢在初期阶段的氧化速率较快,氧化动力学符合线性氧化规律,线性速率常数kl为5.21×10(-2) mg/(cm²·h),氧化过程受界面反应控制;随着氧化时间的增加氧化膜逐渐变厚,第二阶段的氧化动力学遵循抛物线规律,抛物线速率常数kp为1.54×10^-3 mg²/(cm⁴·h),氧化速率的控制步骤由界面反应控制转为扩散控制。TP439不锈钢氧化产物的主要成分为(Cr,Fe)₂O₃和少量的Cr₂O₃、Fe₂O₃、FeCr₂O₄尖晶石氧化物。在...     

Super304H奥氏体不锈钢的高温抗氧化性能

对Super304H奥氏体不锈钢在550～800℃进行高温氧化试验,结合氧化动力学规律去研究Super304H奥氏体不锈钢的氧化机理。结果表明,Super304H奥氏体不锈钢在550～800℃氧化质量增加曲线遵循抛物线规律,在750～800℃时60 h以内氧化质量增加趋势最明显,100 h后质量增加高达0.005 mg·mm^-2。在550～750℃逐渐生成致密的氧化膜,主要由Cr₂O₃和Fe_3-xCr_xNiO₄混合氧化物和少量CuCrMnO₄构成。升高温度会促进Cr的选择性氧化,使得Cr₂O₃保护膜开裂,800℃时暴露出的Fe基体与氧原子反应生成瘤状Fe₃O₄,氧化膜厚重并伴有剥落现象。应变速率为3.2×10^-4 s^-1时,不锈钢的抗拉强度随氧化温度升高而降低,600℃的抗拉强度最大,达350 MPa; ...     

Influence of superficial coating of CeO2 on the oxidation behavior of AISI 304 stainless steel

The effect of a superficially-applied, cerium-oxide coating on the non-isothermal oxidation behavior of AISI 304 stainless steel in dry air has been investigated. The heating rate employed was 3 K/min up to a final temperature of 1423 K. The reactive oxide coating not only reduced the reaction rate but also facilitated scale adhesion to the alloy substrate. Post-oxidation analyses of the alloy/scale combination using optical microscopy, SEM, EDAX, and XRD provide evidence for a changeover in the mechanism of oxide growth from the scale/gas interface to the alloy/scale interface for the coated steel.     

TP304H/12Cr1MoV异种钢管的瞬时液相扩散连接

用FeNiCrSiB (A)合金作中间层,氩气保护,对12Cr1MoV珠光体耐热钢和TP304H奥氏体不锈钢管进行了瞬时液相扩散连接.用正交试验的方法研究了工艺参数对接头组织和性能的影响,分析了TLP连接接头的显微组织、断口形貌、力学性能和元素分布,确定出了合适的连接工艺参数.研究结果表明,连接温度1240℃,等温凝固时间3min,压力4MPa时,接头的强度最高达到590MPa,其断口呈韧性断裂特征.     

Effect of Shot Blasting on Oxidation Behavior of TP304H Steel at 610℃ -770℃ in Water Vapor

Shot blasting on a tube steel of TP304H can greatly improve the oxidation resistance at 650℃-770℃ in water vapor, by the presence of an appropriate blasting intensity. SEM and EPMA analysis indicated that the structure of the oxide scale turned from multi-layer to monolayer after blasting and Cr2O3 in predominant. The untreated sample characterized in multi-layer oxide was composed of Fe in the outer layer and Fe and Cr underneath. For blasted one, the increase of diffusion rate of Cr and the decrease of effective diffusion energy of scale led to a uniform Cr-rich oxide layer, which was dense and protective and the oxidation resistance was increased.     

耐热钢管的瞬时液相扩散焊工艺研究

用BNi2,Fe78Si9B13和FeNiCrSiB合金箔作中间层,氢气保护,分别对TP304和T91钢管进行了瞬时液相扩散(TLP)连接。分析了TLP连接接头的显微组织、力学性能和元素分布;确定出了合适的连接工艺参数。研究表明,TP304用BNi2和FeNiCrSiB作中间层,T91用FeNiCrSiB作中间层连接的接头室温下的抗拉强度和抗弯强度等于或超过基体。     

时效温度对Super304H钢析出相的影响

利用扫描电子显微镜、电子探针、X射线衍射和透射电镜研究了新型奥氏体耐热钢Super304H在高温时效条件下析出相的变化.结果表明,Super304H钢经700～1250℃时效后,组织中出现4种析出相:Nb(C,N)、富Cu相、M_(23)C_6和NbCrN.随时效温度的不同,析出相发生析出或溶解的变化,同时它们的形态、分布和数量随温度变化呈现出不同的变化规律,其中M23C6在700～900℃主要沿晶界析出,这将会降低钢的高温蠕变强度及抗晶间腐蚀性能.     

Corrosion behavior of 304 stainless steel in high temperature, hydrogenated water

The corrosion behavior of an austenitic stainless steel (UNS S30400) has been characterized in a 10,000 h test conducted in hydrogenated, ammoniated water at 260 °C. The corrosion kinetics were observed to be parabolic, the parabolic rate constant being determined by chemical descaling to be 1.16 mg dm⁻² h^−1/2. X-ray photoelectron spectroscopy, in combination with argon ion milling and target factor analysis, was applied to provide an independent estimate of the rate constant that agreed with the gravimetric result. Based on the distribution of the three oxidized alloying constituents (Fe, Cr, Ni) with respect to depth and elemental state, it was found that: (a) corrosion occurs in a non-selective manner, and (b) the corrosion film consists of two spinel oxide layers--a ferrite-based outer layer (Ni_0.2Fe_0.8)(Fe_0.95Cr_0.05)₂O₄ on top of a chromite-based inner layer (Ni_0.2Fe_0.8)(Cr_0.7Fe_0.3)₂O₄. These compositions agree closely with the solvi phases created by immiscibility in the Fe₃O₄-FeCr₂O₄ binary, implying that immiscibility plays an important role in the phase separation process.