Cr对低合金钢在流动NaCl溶液中耐蚀性的影响

对碳钢和Cr含量不同的实验钢在流速为0.8m/s的流动的3.5％(质量分数)NaCl溶液中的腐蚀行为进行研究,最长腐蚀周期为192h.对4种实验钢的腐蚀失重进行了比较,并利用动电位极化曲线、SEM、EPMA和TEM等分析手段,对实验钢表面形成锈层的特征进行了系统研究.结果表明,含Cr实验钢的腐蚀失重低于碳钢,并且随Cr的质量分数由0.5％提高至2％,腐蚀失重亦降低.Cr元素在内锈层中的富集是含Cr钢耐蚀性改善的重要原因.这种富集可使腐蚀产物颗粒获得细小的尺寸,致密内锈层形成的原因就是由于这种尺寸细小的腐蚀产物的形成,使内锈层的保护性获得明显的改善.     

Cr对流动NaCl溶液中普碳钢锈层特征的影响

对碳钢和耐蚀管用含Cr低合金钢进行流动加速腐蚀实验,研究了实验钢在流动腐蚀性条件下的锈层结构以及Cr元素对锈层的影响机理.利用极化曲线、SEM、TEM及XPS等分析手段研究了Cr元素对实验钢耐流动加速腐蚀性的影响,以及含Cr钢内锈层的腐蚀形貌,深入分析了Cr在内锈层中的分布及存在状态.结果表明,含Cr钢内锈层致密均匀,Cr元素在内锈层中富集并以Fe2CrO4的形式存在.Fe2CrO4细小的颗粒尺寸是形成致密内锈层的原因,致密的内锈层对基体具有很好的保护作用.     

Effect of Cr on Characteristic of Rust Layer Formed on Low Alloy Steel in Flow-accelerated Corrosion Environment

The flow-accelerated corrosion experiments were carried out to research the effect of Cr on the rust layers formed on the carbon steel and Cr-containing steel,as well as the structure of rust layer of the two experimental steels.The influence of Cr on the flow-accelerated corrosion resistance and the corrosion morphology of inner rust layer formed on the Cr-containing steel were studied by the methods of polarization curves,scanning electron microscope,transmission electron microscope,and X-ray photoelectron spectroscope.The distribution of Cr and its form of existence in the inner rust layer were analyzed.The results show that corroded mass loss of Cr-containing steel is lower than that of carbon steel and its inner rust layer is compact.Cr exists in the form of Fe2CrO4 and is enriched in the inner rust layer.This concentration could make the inner rust layer exhibit the tendency of amorphous.This phenomenon is related to fine Fe2CrO4.The inner rust layer becomes more compact because of the formation of fine Fe2CrO4,and the protectiveness of inner rust layer could be improved remarkably.     

Effect of microstructure on corrosion behavior of low carbon high chrome steel

The two types of microstructure of low carbon and high chromium steel (5Cr) were obtained through the test smelting, rolling and quenching after rolling.Corrosion performance of 5 mass%Cr steel and Q235 steel were researched by means of cyclic wetting and drying corrosion test in 2 mass% NaCl solution.Corrosion behavior and corrosion rust layers were analyzed by OM, SEM, EDS, XRD, cyclic wetting and drying corrosion tester and electrochemical testing. The results show that after the specimens were immersed and etched in 2 mass% NaCl solution for 72h, the different microstructures of 5Cr steel have great influence on the resistance to chloride ion corrosion. B+F+M microstructure of 5Cr steel shows lower corrosion rate than Q235 steel, 5Cr steel with martensite microstructure also shows lower corrosion rate than Q235 steel. Corrosion susceptibility of 5Cr steel with martensite structure is weaker than complex organization.The stratification of chromium oxide, oxyhydroxide, and iron oxide exists in the chromium- containing steel rust layer, in which the Cr enrichment maximum value is 17 mass%, and the lowest is 1 mass%.Lath martensite formed by quenching process makes the corrosion potential rise, ??- FeOOH and ??- FeOOH form. Bainite+ferrite phase and adverse phenomenon of Cr steel may cause the poor corrosion resistance.     

稀土对低碳钢耐工业大气腐蚀性的影响

研究了在江津地区暴晒2年低碳钢和稀土钢的大气腐蚀行为。结果表明:稀土可以有效提高低碳钢耐工业大气腐蚀性,试验钢的腐蚀数据符合动力学模型D=Atn。采用扫描电镜、极化曲线、XRD及Fourier变换红外光谱等手段对腐蚀产物进行研究。发现稀土能促进稳定的保护性腐蚀产物α-FeOOH生成,降低锈层中具有反应活性的Fe3O4含量;并可以增加锈层致密性。从锈层反应的角度阐述了稀土提高低碳钢耐蚀性的机理。     

Corrosion Behavior of Rusted 550 MPa Grade Offshore Platform Steel

 The corrosion behavior of a rusted 550 MPa grade offshore platform steel in Cl- containing environment was investigated. The results revealed that the corrosion process can be divided into initial stage in which corrosion rate increased with accumulation of corrosion products and later stage in which homogeneous and compact rust layer started to protect steel substrate out of corrosion mediums. On the contrary, structural analysis of rust layers by X-ray diffraction showed that α-FeOOH increased from 1. 3% to 3. 6% and the Fe3O4 increased from 1. 0% to 1. 5% while γ-FeOOH reduced slightly according to corrosion time increased from 30 cycles to 73 cycles. The results of electron probe microanalysis indicated that Cr concentrated mainly in the inner region of the rust, inner/outer interface especially, whereas Ni and Cu were uniformly distributed all over the rust after 73 corrosion cycles. According to electrochemical measurements, it was found that the corrosion rate of rusted steel reduced from 0. 61 mm/a after 45 cycles to 0. 34 mm/a after 85 cycles, 44. 3% reduction approximately, and Rrust values increased with increment of corrosion time. Therefore, formation of compact inner rust layer and enrichment of Cr are important to improve corrosion resistance of offshore platform steel.     

低碳钢在湿热工业海洋大气中的腐蚀特征

以0.1 mol·L-1NaCl+0.01 mol·L-1 NaHSO₃溶液为腐蚀介质,采用干/湿周浸加速腐蚀实验、腐蚀失重、X射线衍射、扫描电镜和能谱分析等方法,研究了湿热工业海洋大气中低碳钢的腐蚀行为.结果表明:实验钢的腐蚀过程均遵循幂函数d=Atn分布规律,钢种不同,常系数A、n的值不同;腐蚀产物主要由非晶物质和少量Fe₃O₄、α-FeOOH、β-FeOOH、γ-FeOOH晶体组成.所得锈层可分为主体锈层和界面疏松带两部分,由内至外锈层中Fe、O含量梯度变化很小.Cl-、SO₂与水分的长期协同作用会导致内锈层结构变差,而添加稳定性或耐蚀性较高的元素可以改善锈层质量,进而增强钢材的耐腐蚀性能.      

Effect of MicroArea pH Value on Formation of Different Rust Phases of Weathering Steel in Initial Corrosion Period

 The formation of protective rust layer of atmospheric corrosion resistance was discussed for weathering steel. The Rust layers of experimental steels were made by using an accelerating industrial atmospheric corrosion test of dry-wet cyclic immersion. Furthermore XRD were used to measure and analyze the rust layers. The initial corrosion processes below thin water film were observed and the changes of micro-area PH value were measured. The results are as follows: The corrosion processes are obviously different between P-RE weathering steel and carbon steel. The surface of P-RE weathering steel rapidly forms α-FeOOH and the micro-area PH value is above 5.4 during the initial corrosion period. While the component of the rust layer for the carbon steel is mainly Fe3O4 and the micro-area PH value is below 3.8.     

Corrosion Resistance on High Strength Bainitic Steel and 09CuPCrNi After Wet-Dry Cyclic Conditions

The accelerated wet-dry cyclic corrosion tests have been carried out of a high strength bainitic steel and 09CuPCrNi. The results indicated that the corrosion resistance of 09CuPCrNi was better than that of the bainitic steel based on the mass loss measurements. The morphology and composition of the rusting products have been investigated in order to realize the mechanism of rust formation on the two steels. The rust scale on both steels was composed of a dense inner layer and a loose outer layer. The inner layer grew thicker and denser as the test proceeding. Both of inner and outer layers were mainly composed of magnetite (Fe3O4) and maghemite (γ-Fe2O3) with a small amount of lepidocrocite (γ-FeOOH) and akaganeite (β-FeOOH). The rust phase of γ-Fe2O3 was detected in a higher amount of the inner layer, resulting in a much denser inner layer. The inner rust layer of 09CuPCrNi being denser and thicker than that of the high strength bainitic steel was attributed to the alloying elements such as copper, chromium and phosphorus enriched in it. The protective inner rust layer plays an important role in the corrosion resistance of the steel.     

低合金耐候钢在含氯离子环境中的腐蚀行为

利用干湿周浸加速腐蚀实验对比研究了低合金钢A588和SPA-H在含氯离子环境下腐蚀行为,并利用金相显微镜、扫描电镜、X射线衍射和电子探针等方法分析了Ni、Mn对于低合金钢腐蚀行为的影响.结果表明:实验钢锈层中的物质主要由α-FeOOH、γ-FeOOH和Fe₃O₄组成,但其含量存在差异;Ni元素在内锈层含量高于外锈层,Mn元素在锈层的孔洞处富集;内锈层的致密程度高于外锈层;提高合金元素Mn和Ni的含量,可以提高内锈层的致密性,从而提高低合金钢的耐蚀性能.      

Atmospheric Corrosion of Q235 Carbon Steel and Q450 Weathering Steel in Turpan,China

Q235 carbon steel and Q450 weathering steel were exposed to the hot and dry environment of Turpan, China for three years.The corrosion rates of both steels were calculated and compared.The morphologies of the rust layer products were observed by optical microscopy and scanning electron microscopy.Analyses of the rust layers were performed by X-ray photoelectron spectroscopy,X-ray powder diffraction,and Raman spectroscopy,and anal-ysis results indicate that the compositions of rust are main iron rich oxide such as FeOOH,Fe3 O4 ,and Fe2 O3 .The iron oxide layer content proportion was calculated through a semi-quantitative algorithm.The resistance elements (Cr,Ni,and Cu)enhanced the resistance properties of the Q450 weathering steel matrix.Moreover,the resistance elements increased the proportion of goethite crystals in the corroded rust layer.     

碳含量和组织类型对低合金钢耐蚀性的影响

 研究了碳含量不同和显微组织不同的低合金钢的耐腐蚀性能和腐蚀行为,并和商业耐候钢09CuPCrNi做了相应的比较。在碳含量比较低的情况下,组织类型对试验钢的耐蚀性影响不大;碳含量比较高时,单相贝氏体钢的耐蚀性优于由铁素体、渗碳体(珠光体)等构成的复相组织钢。轧后水冷时,不同碳含量的钢耐蚀性差别不大;轧后空冷时,碳含量低的钢的耐蚀性优于碳含量较高的钢。用扫描电镜对锈层进行观察,可以看出耐蚀性较好的试样在腐蚀后期形成了较致密的内锈层。碳的质量分数分别为0.03%和0.1%的钢水冷后的平均腐蚀速率相差很小,但从微观角度看其点蚀发展趋势不同。加速腐蚀5个周期后,w(C)为003%的水冷钢中蚀坑尺寸不再增加,而w(C)为01%的钢中蚀坑尺寸仍有增加趋势。     

Corrosion Resistance of High Performance Weathering Steel for Bridge Building Applications

 The mechanical properties, corrosion resistance and microstructures of high performance steel (HPS) was investigated by tensile testing machine, Charpy V-Notch (CVN) testing machine, cyclic immersion corrosion tester, XRD, optical microscopy (OM), scanning electron microscopy (SEM), and electron probe micro-analyzer (EPMA). The results showed that significant differences existed in the tensile strength, yield strength and impact toughness between HPS and PCS. After 72 h cyclic immersion accelerated corrosion test, the inner rust layer on HPS was composed of α-FeOOH phase and denser than that on PCS that was a mixture of α-FeOOH and Fe3O4. The rust formed on HPS provides better protection and HPS has lower corrosion rates than PCS. Copper and chromium in HPS enrich in the rust layer and enhance the compactness of the rust layer. Based on the results of the accelerated corrosion tests and rust layer analysis, the roles of Cu and Cr against corrosion are discussed, providing HPS with chemical specification which has been industrially successful to produce weathering steel for bridge structure.     

Cr-Ni-Cu系低合金铸钢在海洋大气环境中的腐蚀行为

为满足桥梁支座用铸钢在海洋大气环境下的耐蚀性要求,设计了2种成分的Cr-Ni-Cu系耐腐蚀低合金铸钢。采用周浸加速腐蚀试验、实地大气暴露试验考察试验钢在海洋大气环境中的腐蚀行为,并结合扫描电镜、XRD、电化学手段分析了合金元素对锈层和电化学行为的影响。结果表明,2种成分的Cr-Ni-Cu系低合金铸钢的耐蚀性均较好,随着时间延长,耐蚀铸钢腐蚀率下降并达到稳定,而对比钢种20MnSi腐蚀率保持下降趋势,未达到稳定状态。周浸腐蚀316h后耐蚀铸钢与20MnSi腐蚀率差距变小;Cr元素在内锈层中呈条带状富集,有效阻碍了Cl-的扩散,Ni的加入提高钢的自腐蚀电位,促进γ-FeOOH向α-FeOOH的转化,增加锈层稳定性;Cr、Ni、Cu的复合加入增大了铸钢的电荷传递电阻,提高了耐蚀性。     

09CuPTiRE钢耐候性能及腐蚀过程研究

通过浸渍干湿循环加速腐蚀试验 ,采用失重法测量年蚀率 ,SEM观察腐蚀产物的表面形貌和断面形貌 ,XRD测定腐蚀产物的物相组成 ,电化学阻抗谱仪测定锈层的交流阻抗谱 ,研究了0 9CuPTiRE耐候钢与Q2 3 5、鞍钢耐候钢和日本耐候钢三种参比钢的耐候性能及腐蚀过程 .结果表明 :0 9CuPTiRE钢的耐候性能显著优于Q2 3 5钢 ;Q2 3 5钢锈层为一层网状、疏松且有大量纵向交错裂纹和孔洞的锈层 ,而 0 9CuPTiRE及另两种耐候钢的锈层分内外两层 ,外层与Q2 3 5钢锈层相似 ,内层均匀、连续、致密 ;Q2 3 5钢的腐蚀过程受活化控制 ,即受控于金属离子进入溶液的速度 ,而0 9CuPTiRE钢的腐蚀过程既受活化控制 ,由于保护锈层的存在还受氧的扩散控制 .     

Influence of Chromium on Mechanical Properties and CO2/H2S Corrosion Behavior of P110 Grade Tube Steel

Four kinds of P110 grade tube steels containing different chromium contents were designed to probe the in- fluence of Cr on the properties of tube steel. The microstrueture, mechanical properties and corrosion behavior of the four kinds of P110 grade tube steels were studied deeply and thoroughly. The analysis of the mechanical properties indicated that tensile strength and yield strength of the steel plates were improved, while transverse and longitudinal impact energy and elongation first increased and then decreased when Cr content rose. The impact energy and elonga tion reached the peak when Cr content was 1 ~. Cr precipitates were found only in 3 ~ Cr steel, with （Nb, Ti）（C, N） or Nb（C,N） as the core of precipitation and then grew up. The corrosion experiments demonstrated that the scales on the four steels had a two layer structure under the corrosion of CO2 and H2 S. The outer layer was mainly com- posed of FeS or FeS1 x and the inner layer consisted of FeCOa and Cr compounds. Cr was rich in the inner layer and the Cr content of the inner layer increased with the Cr content in matrix. The enriched Cr enhanced the compactness of the scales, further hindering the diffusion of ions from liquid to the surface of steel, thus reducing corrosion rate.     

高耐候结构用Q355GNH钢的开发与性能研究

通过对高耐候钢产品的性能要求分析,本试验钢在成分设计上以Cu、P为基,添加少量Cr、Ni,并制定相应的轧制及卷取工艺而成功开发了355强度级别的高耐候结构用钢.对该试验钢的各项性能进行检测,同时根据其成分设计进行了耐腐蚀性能预测,并利用实验室加速腐蚀试验方法对Q355GNH试验钢及Q345B对比钢的腐蚀速率以及其锈层构...     

Cr含量对2.25Cr-1Mo钢蒸汽氧化性能的影响

对第四代核电主体结构材料2.25Cr-1Mo钢中铬含量对蒸汽氧化性能的影响进行了研究.完成了500 ℃/0.1 MPa下600h的高温蒸气氧化实验,并利用分析天平测量氧化增重,采用扫描电镜、X射线能谱和X射线衍射仪表征氧化膜的结构特征和物相.实验结果表明,Cr质量分数为1.99％和2.37％的实验钢氧化增重曲线都符合立...     

核能用2.25Cr-1Mo钢水蒸气氧化行为

 为了研究核电用2.25Cr-1Mo钢的抗蒸汽氧化性能,在500 ℃、0.1 MPa水蒸气条件下,对2.25Cr-1Mo耐热钢进行了600 h的氧化试验,利用分析天平测定样品氧化增重,获得氧化动力学曲线,通过扫描电镜观察分析了氧化膜的形貌和结构,结合X射线衍射和能谱分析对氧化产物进行物相分析。试验结果表明,2.25Cr-1Mo耐热钢的氧化增重曲线符合立方规律;氧化膜为双层结构,氧化膜内层较为致密的主要物相为(Fe,Cr)₃O₄尖晶石,氧化膜外层疏松多孔主要物相为Fe₃O₄和少量Fe₂O₃;腐蚀速率测定结果表明,该材料具有较好的抗蒸汽氧化性能。     

高氮耐候钢锈层的电化学与物相表征

为了考察氮元素对耐候钢耐腐蚀性能的影响,研究制备了氮质量分数分别为0.0358%和0.0026%的高氮耐候钢和低氮耐候钢。应用电化学阻抗谱和X射线衍射(XRD)分析、电子探针(EPMA)面扫描技术研究了两种实验钢在模拟工业大气溶液中腐蚀电化学过程和锈层结构的异同。电化学阻抗谱显示,高氮耐候钢在高频段(点蚀诱发期)比传统耐候钢有着更加优良的耐点蚀能力,低频段(扩散型阻抗生成期)则显示腐蚀产物层具有更高的阻抗,抵御腐蚀介质侵蚀的能力较强。X射线衍射和电子探针分析结果表明耐候钢高氮含量促进了稳定结构锈层生成,锈层中非晶态α-(Fe_1-xCr_x)OOH的分布更广泛、连续,提升了耐候钢抵御Cl^-侵入的能力。高氮钢腐蚀坑具有大宽深比的特征,内锈层较薄,证明其具有良好的抑制点蚀能力。