304控氮不锈钢应力腐蚀过程中声发射信号聚类分析

研究了304控氮不锈钢试样在酸性氯化钠溶液中慢应变速率拉伸过程的声发射特征.采用基于自组织映射神经网络和K-均值聚类算法对长时间慢拉伸实验的声发射信号进行聚类分析,通过分析各类信号的持续时间、上升时间、振铃、能量、幅值、波形、频带能量等特征,从中找出了裂纹信号.将分类后的信号作为样本训练神经网络,对短时间慢拉伸实验检测...     

Q235、Q345R与304不锈钢在NaCl溶液中腐蚀声发射监测实验研究

应用声发射技术对Q235、Q345R和304不锈钢3种材料在NaCl溶液中的腐蚀过程进行了监测,获取了3种材料腐蚀过程中腐蚀产物的生成与剥落和气泡在材料表面的波动所导致的声发射信号。并应用声发射信号特征参量分析法和小波特征能谱系数分析方法,分析了3种材料在NaCl溶液中腐蚀产生的声发射信号的特征。     

304不锈钢应力腐蚀的临界氯离子浓度

通过慢拉伸实验得出了304不锈钢应力腐蚀敏感性与溶液中Cl-浓度的关系,用扫描电镜对拉伸试样的断口形貌进行了分析,得出了304不锈钢发生应力腐蚀的临界氯离子浓度。采用自行设计的装置对304不锈钢试样施加拉应力,通过恒应变条件下的电化学原位测试研究了304不锈钢钝化膜破裂电位与氯离子浓度的关系。得出导致钝化膜破裂电位突变的Cl-浓度与发生应力腐蚀破裂的临界Cl-浓度是基本一致的结论。     

304L不锈钢在液态锂铅合金中的表面腐蚀研究

采用挂片法、失重法和扫描电镜分析,开展了结构材料304L不锈钢在液态锂铅合金中表面腐蚀行为的研究。研究结果表明：304L不锈钢中的组分元素,在液态锂铅合金中发生了溶解和质量迁移,这是导致材料腐蚀的主要原因,温度与合金中的氧含量是影响表面腐蚀行为最重要的参数。     

采用ICP对304不锈钢表面黑色腐蚀物的分析

通过采用ICP对304不锈钢表面黑色腐蚀物的分析,发现黑色腐蚀物具有富Ni、贫Fe、Cr的特征,各金属的含量分别达到：Fe13．55％、Cr23．29％、Ni57．54％。分析了黑色腐蚀物在不同环境下的溶解性,并推测了对碱液质量的影响。     

304管道应力腐蚀开裂原因分析和应对措施

某码头苯酚介质采用304不锈钢管道输送，管线直管段发现3处开裂情况。通过对管线使用工况、无损检测、保温材料成分分析、金相分析。得出结论：管线开裂是由于氯离子应力腐蚀开裂，涂刷防腐层有效解决304不锈钢应力腐蚀开裂问题。     

Q235均匀腐蚀过程声发射监测实验研究

应用声发射技术分别对Q235均匀腐蚀过程中的气泡产生与金属溶解两个过程进行了监测,获取了Q235均匀腐蚀过程中的气泡产生与金属溶解声发射信号。并应用特征参量分析法,分析了气泡产生与金属溶解过程的声发射信号特性。研究发现应用能量、质心频率和峰值频率3种特征参量能准确区分两种不同的腐蚀信号。研究结果为Q235均匀腐蚀过程的声发射研究和噪声信号的分离提供了参考。     

基于声发射检测的罐底腐蚀安全评估

常压储罐一旦发生泄漏,往往会造成人员伤亡、财产损失和环境污染等严重后果,因此对于储罐的安全评估尤为重要。现有的检测方法存在耗时长、易漏检、经济效益低等不足之处。以实例说明了声发射在线检测技术应用于罐底腐蚀检测的高可靠性与便捷性;解释了机械噪声、环境噪声以及电磁噪声形成的原因,并提出了相应的滤除方法;描述了基于声发射检测的罐底腐蚀安全评估的过程与评价依据,并进行评估。     

常压立式储罐底板腐蚀过程声发射源特性分析及试验研究

介绍了常压立式储罐底板腐蚀声发射信号产生的机理,研究了断铅声发射信号在罐内水中的衰减规律,分析了腐蚀声发射信号在不同传播介质中的特征参量取值范围及腐蚀规律。提取并对比分析了放入水中的传感器在不同腐蚀阶段接收到的信号波形特性,为常压立式储罐的腐蚀状态安全性评价提供依据。     

DEIS assessment of AISI 304 stainless steel dissolution process in conditions of intergranular corrosion

Results presented in this paper are first that demonstrate instantaneous impedance changes versus reactivation potential detected by means of dynamic electrochemical impedance spectroscopy (DEIS) technique for AISI 304 stainless steel dissolution process proceeding during intergranular corrosion (IG) in 0.5 M SO₄²⁻ + 0.01 M KSCN solution of different pHs. Application of DEIS method made it possible to evaluate dynamic changes of the examined system's impedance in conditions of IG. As a result, controlling stage of the overall rate of AISI 304 SS dissolution process was determined. Moreover, the paper proposes an alternative way of assessment of AISI 304 SS dissolution rate during intergranular corrosion based on approximation to theory of iron dissolution in sulfuric acid medium. Simultaneously, on the basis of the DEIS measurements it was possible to obtain information about the degree of sensitization (DOS) of the examined material. Accordingly, performed researches revealed the advantage of the DEIS technique over the electrochemical potentiokinetic reactivation (EPR) tests when investigating intergranular corrosion process.     

低浓度含氯介质中氯离子向局部腐蚀闭塞区内的迁移规律及其对应力腐蚀破裂的影响

The enrichment of chloride anion within the occluded cell （OC） for Type 304 austenitic stainless steel in low chloride concentration solution has been investigated by means of a simulated OC. The influence of the enrichment of chloride anion on stress corrosion crack （SCC） of Type 304 stainless steel has been studied. It was observed that the amount of chloride anion migration was proportional to the charge flowing through the anode. Owning to the effects of enrichment of chloride anion, low chloride concentration solution could induce SCC for Type 304 stainless steel.     

DEIS evaluation of the relative effective surface area of AISI 304 stainless steel dissolution process in conditions of intergranular corrosion

The results presented in this paper contribute further information concerning examinations of AISI 304 stainless steel dissolution process in conditions of proceeding intergranular corrosion (IG) which have been determined on the basis of dynamic electrochemical impedance spectroscopy (DEIS) measurements. For the first time changes of the relative effective surface area versus time of AISI 304 stainless steel dissolution process in conditions of proceeding intergranular corrosion (IG) in 0.5 M H₂SO₄ + 0.01 M KSCN solution within the range of reactivation polarization scan have been demonstrated. The assessment of the effective surface area of the investigated process was based on approximation to theory of iron dissolution in sulfuric acid medium according to the shape of instantaneous impedance spectra recorded by means of DEIS technique. As a result, it was possible to evaluate that initially changes of the employed equivalent circuit parameters are not only caused by the changes of the relative effective surface area but also by the changes of the AISI 304 SS dissolution process kinetics. Further progress of the examined process implied that changes of the equivalent circuit parameters are only affected by the changes of the relative effective surface area during proceeding IG. Moreover, it was found that the character of changes of the relative effective surface area in conditions of proceeding IG can be described by exponential function.     

循环水中304不锈钢发生点蚀的Cl~-浓度阈值研究

采用电化学法研究了循环水中304不锈钢点蚀电位(Eb)、蚀孔深度、蚀孔数量与氯离子浓度的关系。结果表明,常温下304不锈钢的Eb总是随着氯离子浓度的增大而减小,当氯离子质量浓度小于800 mg/L时,增大氯离子浓度易导致点蚀敏感,而大于该值时增大氯离子浓度不会明显增大点蚀倾向;从蚀孔深度和表面蚀孔数量得出的304不锈钢点蚀倾向由大变小的氯离子质量浓度阈值为770 mg/L。     

应变和氯离子浓度对304不锈钢点蚀敏感性的影响

The effects of strain and chloride concentration on pitting susceptibility for type 304 stainless steel were studied in situ using the electrochemical technology under constant strain. The impact factor fc was brought forward to value the effect of strain on pitting. The pitting behaviors of type 304 stainless steel in various chloride concentrations under the strain levels 0%, 10%, and 30% were investigated. Potentiostatic polarization technology was used to study how the chloride concentration affected corrosion current density. The results indicated that fc increased substantially and pitting potential varied remarkably when chloride concentration was over 90 mg.L . Under the three levels of strain mentioned above, when chloride concentration was below 463 mg.L^-1,121 mg.L^-1, and 98 mg.L^-1 respectively, the pitting potential shifted towards positivity and, the passive film became more stable. When the strain was below 10%, the pitting susceptibility of type 304 stainless steel varied greatly as strain increased, whereas the susceptibility only changed a little when the strain was over 10%.     

Effect of PgTPhPBr on the electrochemical and corrosion behaviour of 304 stainless steel in H2SO4 solution

Weight-loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements were used to study the inhibition of 304 stainless steel corrosion in 1 M H₂SO₄ at 50 °C by propargyltriphenylphosphonium bromide (PgTPhPBr). The inhibiting effects of propyltriphenylphosphonium bromide (PrTPhPBr) and propargyl alcohol (PA) were also studied for the sake of comparison. For the investigated compounds, Tafel extrapolation in the cathodic region gave a corrosion inhibition efficiency of 98% at 1 × 10^–3 M. Adsorption of both PgTPhPBr and PA was found to follow Frumkin's isotherm while adsorption of PrTPhPBr obeys that of Temkin. In the anodic domain, PgTPhPBr acted as a good passivator. The impedance spectra recorded at the corrosion potential (E _cor) revealed that the charge transfer process in the inhibited and uninhibited states controls corrosion of 304 stainless steel.     

Silybum marianum extract as a natural source inhibitor for 304 stainless steel corrosion in 1.0 M HCl

The use of Silybum marianum leaves extract as a 304 stainless steel corrosion inhibitor in 1.0 M HCl solution was investigated by weight loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. Potentiodynamic polarization curves indicated that S. marianum extract behaves as mixed-type inhibitor. The adsorption of the extract constituents was further discussed in view of Langmuir adsorption isotherm. The effect of temperature on the inhibition efficiency was studied. Quantum chemical parameters were also calculated, which provided reasonable theoretical explanation for the adsorption and inhibition behavior of S. marianum extract on the 304 stainless steel.     

304不锈钢上纳米TiO2涂层的制备与防腐蚀性能研究

采用溶胶–凝胶法和浸渍提拉法在304不锈钢上制备出均匀致密、彩色透明的纳米TiO2防腐蚀涂层。制备的最佳工艺条件是提拉4次,400°C热处理1h。在w(NaCl)=3%的NaCl溶液中的电化学测试表明,纳米TiO2/304不锈钢在有紫外光照射下其腐蚀电位低于304不锈钢基体。纳米TiO2涂层作为非牺牲性阳极对304不锈钢基体具有阴极保护作用和优异的防腐蚀性能。     

AISI 304 L stainless steel decontamination by a corrosion process using cerium IV regenerated by ozone Part I: Study of the accelerated corrosion process

This paper describes the study of a new decontamination process of AISI 304L stainless steel from dismantled nuclear power plants. A very thin active contaminated surface layer was stripped from the underlying metal by corrosion in a solution of nitric acid with the addition of cerium nitrate. The Ce⁴⁺/Ce³⁺ concentration ratio was initially equal to unity and ozone/oxygen bubbles were used to regenerate Ce³⁺ ions into Ce⁴⁺ ions. The study was performed in a laboratory cell prior to preliminary optimization in a three-litre reactor. The objective was to obtain a corrosion rate of about 10 micrometers per day. This target was reached in 10^–2 mol l^–1 of cerium nitrate with bubbling of a 1.56 g h^–1 ozone flow in a 60 l h^–1 total gas flow. The corrosion rate depended essentially on the Ce⁴⁺ concentration. The stainless steel exhibited intergranular corrosion. The corrosion rate was monitored by measuring the solution oxidizing potential using a precious metal electrode.