不锈钢及镍基合金在含溴醋酸中的点蚀行为

采用动电位扫描对254 SMO,Nickel 200和Hastelloy C-276三种材料在含溴醋酸中的点蚀行为进行了研究,并采用SEM观察点蚀形貌,实验结果表明,这三种材料耐点蚀的顺序从低到高为：Nickel200,254SMO和Hastelloy C-276。对于材料254 SMO,在含有少量醋酸的情况下,［Br∧-］的对数与其点蚀电位和保护电位呈线性关系,而且它们的斜率相等,采用XPS对极化后的试样进行表面分析,发现MoO2,Cr2O3对材料起到了了保护作用,阻止了点蚀的发生。     

芳烷基酚树脂玻璃钢在沸腾醋酸介质中的腐蚀性能

1 前言 沸腾醋酸是化纤行业中腐蚀性很强的一种介质,目前采用Mo2Ti不锈钢作防护材料,代价很高。我们对自己研制的芳烷基酚树脂制成的玻璃钢进行了腐蚀试验,结果表明它是一种很奸的耐沸腾醋酸腐蚀的材料。 2 试验 2.1 胶液配方 我们选用三种纤维表面处理剂,胶液配方见表1。 2.2 试样制备 按表1配好的树脂胶液,在浸胶机上浸     

00Cr17Ni13Mo2超低碳含钼不锈钢埋弧自动焊试验小结

一九七四年第三季度,上海化工机修总厂为某工程制造了一批醋酸装置,该设备系用超低碳含钼不锈钢OOCr17 Ni13Mo2材料制作。这种材料本厂没有焊接过,在完成任务过程中,通过试验和生产,对这种材料的埋弧自动焊积累了一定的经验,但由于当时任务很紧迫,对于试验和生产中曾出现过的一些问题,来不及     

耐醋酸用不锈钢

一、前言醋酸是重要的化工原料,广泛地应用于化工、化纤、医药、食品及其它工业。在醋酸生产和使用的设备中,不锈钢是最为广泛采用的金属材料。醋酸是有机酸、是腐蚀性介质。随着醋酸的浓度、温度以及存在于醋酸中的杂质含量不同,不同程度地腐蚀着不锈钢。高温醋酸、特别是在含有甲酸以及含有氯离子的醋酸中,不锈钢的腐蚀极其严重,常常造成设备腐蚀破坏,带来巨大的     

高温含杂醛酸环境中设备选材的探讨

对接触高温醋酸生产装置腐蚀行为及其选材料进行了讨论。提出了醋酸对材料的腐蚀，既要考氧的影响，也不能忽视杂质的作用；对铜，不锈钢，钛三种材料作为高温醋酸塔器用材进行了评价比较。     

高温含杂醋酸环境中设备选材的探讨

对接触高温醋酸生产装置腐蚀行为及其选材进行了讨论.提出了醋酸对材料的腐蚀,既要考氧的影响,也不能忽视杂质的作用;对铜、不锈钢、钛三种材料作为高温醋酸塔器用材进行了评价比较.     

连铸板坯三角区裂纹与偏析对中厚板组织与性能的影响

1 前言 对三角区裂纹的成因国内外资料报道较多,而有关三角区裂纹与偏析对轧制后中板的显微组织与力学性能有何影响,则研究得很少。本文对普碳钢连铸大板坯比较深入地研究了含有三角区裂纹的板坯轧制中板后,三角区裂纹和偏析区的组织结构的变化及其对力学性能的影响。2 试验方法与试验材料2.1 试验方法 从不同炉次的连铸板坯中挑20块含有三角区裂纹的试验坯,裂纹长度在15～60mm范围内,根据裂纹长度由小到大试验坯依次编号为S1～S20,板坯原始尺寸宽1540×厚220mm。试     

汽车新型半金属刹车片材料摩擦及磨损特性研究

研制获得了不同配方的半金属刹车片试样,通过试验对其微观组织、力学性能和磨损等特性进行分析。结果表明:刹车片试样已组成均匀基体;由于材料中含有金属材料,表现出较好的力学性能;服役环境改变对刹车片材料摩擦系数变化影响较大;在刹车降速过程中,随接触压力的增加,半金属刹车片磨损率呈上升趋势;半金属刹车片材料A2具有较好的力学性能、摩擦性能。     

钛在醋酸环境中的应用分析

介绍了钛在醋酸生产环境中作为结构材料的使用情况;比较了几种材料在醋酸环境中的腐蚀速率;分析了钛在醋酸环境中可使用的条件,得出钛在氧化性醋酸环境中可以作为结构材料安全使用,而在还原性缺氧、缺缓蚀剂以及副反应中有氢生成,或与活泼异种金属接触的情况下不能作为设备结构材料使用。     

金属材料在醋酸中的腐蚀行为研究

针对上海石化股份公司常用的醋酸介质，选择四种金属材料，采用电化学技术，测定其在醋酸中的极化曲线和交流阻抗特性。根据试验数据，分析四种金属在醋酸中的腐蚀行为以及醋酸浓度、温度、溶解氧等对金属腐蚀的影响。为醋酸设备的选材提供依据。     

Electrochemical behaviour of 254SMO stainless steel in comparison with 316L stainless steel and Hastelloy C276 in HCl media

Abstract

The electrochemical behaviour of 254SMO stainless steel in HCl solutions has been studied and compared with that observed for other alloys using open circuit potential measurements, potentiodynamic polarisation curves, and SEM analysis techniques. 254SMO does not display pitting corrosion at room temperature in HCl solutions having concentrations ≤5·0M. Its performance is comparable with that of Hastelloy C276 in HCl media in solutions of strength ≤1·0M. The critical pitting temperature for 254SMO exceeds 76°C in 3M HCl solutions.     

哈氏合金C276在溴胶混合液中的耐蚀性

目的研究哈氏合金C-276在溴胶溶液中的耐蚀性能,分析哈氏合金C-276在溴胶溶液中的腐蚀及失效机理。方法采用挂片试验方法,模拟溴化丁基橡胶生产过程中溴胶混合釜的腐蚀环境,研究温度、液溴含量、水含量、转速等环境因素影响哈氏合金C-276的腐蚀规律,利用SEM、XRD等现代分析技术,对腐蚀产物形貌、成分进行分析。结果哈氏合金C-276在含溴腐蚀溶液中的主要腐蚀产物为Ni Br2、Fe Br2、Mo Br2、Cr Br3等,腐蚀速率随温度、水含量、液溴含量以及转速的增加而增大。温度、水、液溴以及转速等因素均对腐蚀的发生起到了重要作用,腐蚀类型以全面腐蚀为主,伴随晶间腐蚀。结论溴胶混合液腐蚀环境下,哈氏合金C-276发生了严重的电化学腐蚀,提高温度、液溴含量、水含量、转速均会明显增加哈氏合金C-276的腐蚀速率。哈氏合金C-276不能作为溴化丁基橡胶生产设备中溴胶混合器的主材质。     

Zu einem Phänomen der Lochkorrosionsbegrenzung bei hochlegierten Sonderedelstählen und NiCrMo-Legierungen in Chloridlösungen

On a phenomenon of the limitation of pitting corrosion at high alloyed special stainless steels and NiCrMo-alloys in chloride solutions Testing the pitting corrosion resistance of high alloyed special stainless steels and NiCrMo-alloys in chloride solutions there was observed a limitation of the pitting corrosion range toward more positive potentials. Above this limitation, the so-called pitting corrosion limitation potential, the pit initiation by all means is prevented, but the growth of pits which had been initiated before in the pitting corrosion range not necessarily comes to a stop. Therefore current density-potential curves which are obtained by downward polarization after an initial potential jump into the transpassive region and chronopotentiostatic tests are more suitable to investigate this phenomenon than cyclic polarization measurements and potentiostatic alteration tests. There is indicated a dependence of this phenomenon on temperature. The phenomenon of a limitation of the pitting corrosion range toward more positive potentials has been found until now at alloy 926, alloy 31, alloy 28, alloy 59 and alloy C-276.     

Corrosion Study of Base Material and Welds of a Ni-Cr-Mo-W Alloy

Alloys containing chromium(Cr) and molybdenum(Mo),as the major alloying elements,are widely used in various industries where the material experiences corrosive environments.Chromium(Cr),when added in an optimum amount,forms a Cr_2O_3 passive film which protects the underlying metal in aggressive solutions.Molybdenum(Mo) forms its oxides in the low pH solutions,thus,enhances the uniform corrosion resistance of an alloy in reducing acids and assists in inhibition to localized corrosion.Minor alloying elements,like tungsten(W) and copper(Cu),also improve the overall corrosion resistance of an alloy in specific solutions.In the present study,corrosion resistance behavior of commercial ironbased alloys(316L SS,254 SMO and 20Cb3) and nickel-based alloys(Monel 400,Alloy 625 and C-276) was studied in the acidic solutions.While the corrosion behavior of wrought alloys has been widely studied,there is little to no information on the corrosion performance of their welds,typically being the weak regions for corrosion initiation and propagation.Therefore,an attempt was undertaken to investigate the uniform and localized corrosion performance of base metal,simulated heat-affected zone and all-weld-metal samples of a Ni-Cr-Mo-W alloy,C-276.The study was conducted in aggressive acidic solutions.Various corrosion and surface analytical techniques were utilized to analyze the results.     

金属材料在盐湖卤水中的腐蚀研究

采用极化曲线测量、腐蚀电位测量和现场暴露试验等方法研究了典型金属材料在盐湖卤水中的电化学特性和腐蚀行为.在卤水中,Q235和16Mn的腐蚀速度受阴极氧扩散控制,腐蚀较轻.304和430不锈钢在卤水中有较轻的蚀斑和缝隙腐蚀.在卤水中T2、QSi3-1的腐蚀速度受阴极活化控制,表面腐蚀均匀,且有低的腐蚀率.L6和LF6在卤水中处于活化态.暴露181d,L6和LF6发生严重的点蚀和缝隙腐蚀.     

0Cr13铁素体不锈钢在FeCl_3溶液中的点蚀行为

通过腐蚀浸泡试验、形貌观察、极化曲线等方法,研究了0Cr13铁素体不锈钢在FeCl3溶液中的点蚀行为。结果表明:在6%FeCl_3(质量分数)溶液中,0Cr13不锈钢点蚀过程伴随着明显的全面(均匀)腐蚀,温度升高,点蚀坑数量和深度随之增加,均匀腐蚀加剧;均匀腐蚀引起的试样减薄,造成点蚀形貌失真,无法真实反映点蚀程度;0Cr13不锈钢表面点蚀坑属于开放式点蚀坑,数量虽多,但蚀孔深度相对较小,304L不锈钢表面点蚀坑属于皮下型或底彻型点蚀坑,呈溃疡状特征,具有很强的"深挖动力",破坏能力更强。     

Korrosionsverhalten des Werkstoffs 1.4539 und von Nickelbasis-Legierungen in Gaswässern

Corrosion behaviour of material no. 1.4539 and nickel based alloys in gas waters Laboratory tests with synthetic gas waters containing the gases ammonia, carbon dioxide, hydrogen sulphide and hydrogen cyanide were carried out in order to examine the influence of medium components on the corrosion of material No. 1.4539 and nickel based alloys Hastelloy C-4, C-22 and C-276. Hydrogen sulfide was identified as the decisive component for corrosion. For stainless steel corrosion rates of about 2 mm ° a⁻¹ were already found at 50°C in a critical pH-range with sulfide concentrations > 2%. As cyanide stimulates corrosion by dissolving sulfide surface layers by complexation of the iron ions, an increased material loss rate per unit area was found in the critical range with increasing cyanide concentration. The much more stable nickel based alloys only revealed considerable weight losses after being exposed in the autoclave at 100°C. The graduation of the loss rates C-22 > C-4 > C-276 can be explained by the different contents of high grade alloy elements. The testing of nickel based alloys of the Hastelloy type and of material No. 1.4539 and 1.4571 by means of the dynamic tensile test (CERT-method) revealed no risks of stress corrosion cracking in the tested media. The mechanical data, such as energy at break, elongation at rupture and reduction of area when breaking, did not indicate any change in comparison to the data found in a neutral medium (glycerine). As a function of the aggressiveness of the liquid phase, the metallographic analysis showed some traces of local corrosion in the highly deformed area, ranging from pitting to limited surface cracking. These phenomena were found to nearly the same extent for all materials.     

南海大气环境下304不锈钢的点蚀特性研究

目的 研究南海大气环境中服役的304不锈钢的点蚀原因与机理。方法 以不同暴露周期的304不锈钢试样为研究对象,采用动电位极化、电化学交流阻抗谱、扫描电镜和Kelvin 探针技术对其进行分析研究。结果 随着暴露时间的延长,304不锈钢表面的点蚀坑数量和深度均逐渐增加,其极化曲线中,钝化区间缩短,点蚀电位负移,阳极极化曲线斜率明显减小,并出现反复再钝化现象,钝化曲线逐渐消失,同时阻抗测试中的膜层电阻越来越小。SEM分析表明,304不锈钢暴露初期出现不连续的点蚀,点蚀坑向纵深发展,暴露后期出现点蚀群,局部有多个点蚀坑连成一片形成溃疡状的腐蚀表面,同时随暴露时间的延长,扫描试样微区的Kelvin表面电位不均匀性逐渐增强。结论 304不锈钢试样的耐蚀能力随暴露时间的增加而不断下降,点蚀现象不断增加。暴露初期,点蚀坑主要向纵深发展;暴露后期,点蚀坑的宽度达到一定程度后,本体溶液向坑内迁移,稀释了坑内溶液的酸度,点蚀坑向纵深和横向同时发展。     

Enhancement of Corrosion Resistance of Type 304 Stainless Steel Through a Novel Thermo-mechanical Surface Treatment

The paper describes a novel thermo-mechanical surface treatment approach, involving conventional shot blasting followed by laser surface heating, to engineer microstructural modification in type 304 austenitic stainless steel for enhancing its corrosion resistance. Thermo-mechanical surface treatment resulted in the formation of fine recrystallized grains with some strain-induced martensite on the modified surface. Surface treatment of type 304 stainless steel brought about significant improvement in its resistance against uniform as well as pitting corrosion. Electrochemical impedance spectroscopic studies showed improved polarization resistance (R _p) value for thermo-mechanically treated surface indicating formation of a more protective passive film than that formed on the untreated surface. In contrast to untreated type 304 stainless steel specimens where pits preferentially initiated at the site of Al₂O₃ inclusions, thermo-mechanically treated specimen exhibited only general dissolution with a few repassivated and shallow pits. Grain refinement and dispersion of alumina inclusions on the modified surface are considered to be the key factors responsible for improvement in uniform and pitting corrosion resistance of type 304SS.