Korrosionsverhalten des Stahls WL 1.3964

Corrosion behaviour of the Steel WL 1.3964 The non‐magnetizable austenitic steel X2 CrNiMnMoNNb 21 16 5 3, WL 1.3964 is used for the fabrication of special boats like submarines and minesweepers. The main reason for its application are its good corrosion resistance and its complete amagnetic properties. The steel WL 1.3964 does not corrode on plain surface when exposed to natural seawater, nevertheless there is a slight susceptibility of pitting and crevice corrosion. Based on the susceptibility of specific forms of corrosion the test program listed below was defined: Constant immersion of non‐coated and differently coated specimens in natural seawater. Crevice corrosion tests and polarization experiments with specimens of different surface treatments at different temperatures. The results may be summarized as follows: The steel WL 1.3964 may not be used in natural seawater without any protection because it has a certain susceptibility of pitting and crevice corrosion. A zinc‐rich coating system may protect the steel from corrosion. The steel WL 1.3964 has a certain susceptibility of corrosion in molten and re‐solidified areas and also in areas with heat discoloration which have not been properly post‐treated.     

SwRK-Versuche und Rißeinleitungsuntersuchungen am neuentwickelten Duplexstahl X 3 CrMnNiMoN 25 6 4 im Vergleich zum bekannten ferritisch-austenitischen Stahl X 2 CrNiMoN 22 5

Investigation into corrosion fatigue and crack initiation with the newly developed duplex steel X 3 CrMnNiMoN 25 6 4 by comparison with the known ferritic-austenitic steel X 2 CrNiMoN 22 5 The majority of low pressure steam turbine damages are caused by corrosion fatigue. This kind of damage occurs primarily in the Wilson-zone of steam turbine machines. In spite of careful feed water washing there is still a build-up of damaging chloride-containing water impurities on the turbine blades. During the last twenty years the standard material X 20 Cr 13 often was and is still used for industrial turbine applications, although the corrosion fatigue resistance was insufficient concerning the increasing operation conditions of moder steam turbine machines. Modifications of the chemical composition of the steel and further material development did not reach a satisfying corrosion fatigue resistance till today. Recent investigations of duplex stainless-steels, especially the steel X 3 CrMnNiMoN 25 6 4 (A905; austenite/ferrite = 50/50) show both a good corrosion behaviour and a sufficient strength of this type of steels. In the present investigations the dependence on the corrosion fatigue limit on the pH-value, chloride concentration, temperature and the behaviour of corrosion cracking (crack initiation) is evaluated.     

Mechanismus des Rißwachstums bei der Spannungsrißkorrosion des austenitischen Stahls X6 CrNiTi 18 10 in wäßriger Chloridlösung bei erhöhten Temperaturen

SCC crack growth mechanism of austenitic stainless steel X6 CrNiTi 18 10 in aqueous chloride solution at elevated temperatures The SCC crack growth mechanism of steam generator heat transfer tubes from stainless steel X6 CrNiTi 18 10 under internal stress conditions at elevated temperatures is discussed. Based on crack tip characterization by means of Scanning and Transmission Electron Microscopy and the evidence of hydrogen originated throughout the corrosion process a crack propagation model is presented. The results refer to a microcrack induced gradual crack growth caused by local hydrogen embrittlement. Microcrack growth has been observed due to slip-band decohesion. The crack growth rate is mainly influenced by the stress state near the crack tip and the hydrogen evolution throughout the corrosion process.     

Vergleich des SwRK-Verhaltens eines auf hohe Duktilität vergüteten martensitaushärtenden PH 13-8 Mo Stahls mit dem Dampfturbinenlaufschaufelstahl X20 CrMoV 12 1

Corrosion fatigue behaviour of the to high ductility aged precipitation hardened steel PH 13-8 Mo and the X20 CrMoV 121 steam turbine blading steel in comparison The corrosion fatigue behaviour of the martensitic stainless steels PH 13-8 Mo and X20 CrMoV 121 is compared. The investigation includes both electrochemical and corrosion fatigue tests. Also mechanical, metallographical and SEM investigations were performed. The corrosion fatigue resistance at 150°C of the precipitation hardened steel PH 13-8 Mo in the modification with the higher strength level (cast I) varies between 100 and 135 MPa. The mean stress was 250 MPa. The influence of the pH-value is predominant to the Cl^? -concentration. The corrosion fatigue resistance of the lower strength modification of PH 13-8 Mo (cast II) is significant lower than that of cast 1. At the conventional 12% Cr-steel cracks are initiated from notches caused by corrosion under salt like deposits primarily at the grain boundaries, weakened by carbide precipitations. At the PH 13-8 Mo steel the crack initiation is located at zones of plastic deformation between the martensitic laths. Corrosion attack occurred preferably by orthogonal orientation of the laths to the surface.     

Auswirkungen des elektrochemischen Probenpotentials auf das SwRK-Verhalten des Duplexstahles X 2 CrNiMoN 22 5 3 in NaCl-Lösung

Effect of electrochemical potential on the corrosion fatigue behaviour of duplex stainless steel X 2 CrNiMoN 22 5 3 in NaCl-solution The influence of the electrochemical potential on the corrosion fatigue behaviour of the nitrogen-alloyed ferritic-austenitic steel X 2 CrNiMoN 22 5 3 (german material-number 1.4462) is investigated in 3% NaCl-solution with pH = 7 at room temperature. Smooth and notched (α_k = 2,0) specimens are tested under cyclic tension load (σ_μ/σ₀ = 0) with a frequency of 25 Hz up to 10⁷ cycles. The fatigue limits for both specimen geometries in corrosive environment at free corrosion potential reach only about 78% of the according values in air. In potentiostatic controlled corrosion fatigue tests the fatigue life respectively the fatigue limit is higher than under free corrosion. The chosen cathodic (?300 mV_SHE) and anodic (+ 700 mV_SHE) protection potentials cause important improvement to 500 N/mm² or 510 N/mm² for smooth specimens (fatigue limit in air: 490 N/mm²). For notched specimens there is an improvement to values of 98% respectively 91% of the air fatigue limit. The recordings of the polarisation current show a sudden increase of the current at the fatigue crack initiation and a further increase during crack propagation. ESCA-analytical results of the passive films for different potentials verify the better corrosion fatigue behaviour for the tested potentials.     

Untersuchung des SwRK-Verhaltens des martensitaushärtenden Stahls X 5 CrNiCuNb 17 4 PH im Vergleich zum weichmartensitischen Stahl X 4 CrNiMo 16 5 1 ESU in chloridhaltigen wäßrigen Medien. Teil 1: Korrosionsuntersuchungen und SpRK-Untersuchungen zur Optimierung der Wärmebehandlung bezüglich der SpRK-Beständigkeit

Investigations of the corrosion fatigue behaviour at a super pure martensitic stainless steel (X 5 CrNiCuNb 17 4 PH) in comparison to the soft martensitic stainless steel X 4 CrNiMo 16 5 1 ESR in chloride containing aqueous media — Part 1: Corrosion investigations and stress corrosion tests to optimize the heat treatment according to the stress corrosion resistance The aim of this investigation was to improve the reliability of operation and the economy of corrosion fatigue stresses of structural elements, especially at elevated temperatures, by optimizing the material. This investigation is of great interest both to the industry and to related fields. It concerns the influence of a higher degree of purity achieved by the secondary metallurgical aftertreatment of soft martensitic steel X4CrNiMo 16 5 1 ESR (ESR-electroslag remelting) in comparison to the corrosion fatigue behaviour of the precipitation hardening steel X5CrNiCuNb 17 4 PH, which was specially heat-treated with respect to stress corrosion cracking resistance. The stress corrosion was investigated for all heat-treatments of the 17-4 PH in 22% NaCl(pH3) solution. The precipitation hardening steel was most resistant to stress corrosion in concentrated NaCl-solution after a three-stage heat-treatment. There was no improvement of corrosion fatigue resistance after metallurgical aftertreatment of soft martensitic steel compared to the untreated material. This is due to the instable passive behaviour of the material which led to crack initiation, especially during the 150°C experiments, at chloride-induced places of pitting. The investigation of the electrochemical corrosion behaviour of both materials showed that the pH-value hardly influences corrosion restistance. An increase of the salt content leads to higher pitting induction. At temperatures of 80°C in a saturated NaCl-solution the material showed no corrosion resistance. In potentiokinetic investigations, a direct transition from the active area to the pitting potential was observed. In accordance with both the corrosion fatigue and the stress corrosion cracking investigations, it was found that pitting at the martensite precipitator starts primarily around Cu-containing or oxidic inclusions.     

Eigenschaften des schweißbaren,hoch korrosionsbeständigen Stahles X 2CrNiMoN 25 22

Properties of the weldable and corrosion resistant steel X 2 CrNiMoN 25 22 In view of the limited application of con- ventional CrNiMo steels the authors have investigated potential applications of the above mentioned steel. An optimum com- position would be (%) 0.02 C, 25Cr, 22 Ni, 2 Mo and 0.1 N. The low carbon content is a vital factor and the nickel content must not exceed 22% because higher contents would give rise to very pronounced precipitation. The new steel ist largely resistance to boil- ing nitric acid it is considerably superior to conventional steels, The high break-through potential is indicative of high pitting resist- ance. Improvements are equally remarkable with respect to mecanical properties and weldability     

Einfluß der Kerbgeometrie auf das Dauerschwing- und Schwingungsrißkorrosionsverhalten des Duplexstahles X 2 CrNiMoN 22 5 3

Influence of notch geometrie on the fatigue and corrosion fatigue behaviour of duplex stainless steel X 2 CrNiMoN 22 5 3 The fatigue behaviour of the ferritic-austenitic steel X 2 CrNi MoN 22 5 3 (German number of materials 1.4462) is investigated under cyclic tension load with a frequency of 25 Hz. Four different notch shapes with stress concentration factors varying from α_k = 1. 0 to 3.9 are researched. The experiments are carried out in laboratory air and in 3% NaCl-solution with pH = 7, both at room temperature. In air the fatigue limit of smooth specimens amounts to 490 N/mm². An increase of the stress concentration factor causes a reduction of the fatigue limit to 285 N/mm² for α_k = 3.9. The corrosion fatigue limits in 3% NaCl-solution for N = 10⁷ are 20% lower than the corresponding values in air. The calculated fatigue stress concentration factors for air and corrosive environments reveal nearly identical results. The recordings of the free corrosion potential show characteristic results. For all specimens, which do not fail under the mechanical-corrosive load, the potential remains in the passive state during the whole test duration. Higher mechanical loaded specimens announce their rupture by a sudden decrease of the potential to negative values. For equal fatigue life the remaining time until rupture of the specimen is considerable longer for higher stress concentration factors.     

焊接与切割设备的使用和维修(二十三)--OTC X系列、XC系列CO2半自动焊机的使用与维修

介绍了OTCX系列CO2半自动焊机的构成与主要功能，对焊机主电路、控制电路的工作原理进行了深入仔细的分析。     

10X11H23T3MP-BД不锈钢材料的耐蚀性能

通过高温抗氧化、盐雾腐蚀和应力腐蚀试验研究了10X11H23T3MP-BД不锈钢材料在使用状态（时效态）时的耐蚀性能.结果表明：该不锈钢材料在试验温度500℃和600℃时的空气介质中为完全抗氧化，在700℃和800℃时的空气介质中为抗氧化；500℃和600℃下的氧化动力学曲线符合对数规律，700℃和800℃下的氧化动力学曲线则符合直线规律；在35%NaCl中性盐雾介质中的抗腐蚀性能优良；在35%NaCl溶液中对应力腐蚀断裂存在一定的敏感性.     

Schwingungsrißkorrosionsverhalten des austenitischen Stahles X 6 CrNiMoTi 17 12 2 in 3%iger NaCl-Lösung unter Umlaufbiegebelastung

Corrosion fatigue behaviour of the austenitic steel X 6 CrNiMoTi 17 12 2 in 3% NaCl-solution under rotating bending load The fatigue behaviour of steel X 6 CrNiMoTi 17 12 2 (German material-number 14571, comparable to AISI 316 Ti) is investigated under rotating bending load with a frequency of 50 Hz. The fatigue strength in inert medium (thermostat oil) at room temperature is 315 N/mm². In 3% NaCl-solution of pH 7 at the same temperature the corrosion fatigue limit for N = 10⁷ reached only 94% of the mentioned value. A higher temperature (70 °C) caused a further reduction to 89% and an additional decrease of the pH-value (pH 3) lowers the dynamic strength to 86% of the reference value. The free corrosion potential, recorded during all corrosion fatigue tests, remains in the passive region for all specimens, which do not fail under the mechanical-corrosive load. The potential of specimens, which fail under a higher mechanical load, announces their rupture by a sudden decrease to negative values, which starts at least 3·10⁴ cycles (10 minutes) before.     

Die Beeinflussung des Schwingungsrißkorrosionsverhaltens des Stahles X 20 Cr 13 durch einen Molybdänzusatz in chloridhaltigen Medien

Influence on the fatigue corrosion behaviour of the steel X20Cr13 in chloride containing media by molybdenum additions The fatigue corrosion behaviour of a 13% Cr steel (used for turbine blades) has been studied in terms of its dependence on carbide shape and molybdenum additions in aqueous NaCl solutions of various concentrations at temperatures between room temperature and 200°C. Further tests in autoclaves were carried out in order to study the surface layers formed above 150°C without mechanical loads. Addition of 1% molybdenum yields a considerable increase of corrosion fatigue strength at room temperature, while there is no influence attributable to different shapes of graphite precipitations. At 150°C the corrosion fatigue strength is largely independent from sodium chloride concentration (0,1 to 27%); this means that very small quantities of sodium chloride are sufficient to produce heavy corrosion in wet steam at > 106 cycles. A range particularly suitable for such tests is the load range between ± 150 and ± 200 N/mm² at 150°C, because these conditions approach those encountered in practice. The passivating layers are very thin (interference phenomena). Considering the increase of corrosion resistance produced by 1% Mo it is expected that 2.5% Mo will produce a further improvement, in particular with regard to pitting corrosion since rupture generally starts at the pits.     

Einfluß von Beschichtungen auf das Schwingungsrißkorrosionsverhalten des Chromstahls X20Cr13

Influence of coatings on the corrosion fatigue behaviour of 13% chromium steel The influence of coatings on the corrosion fatigue behaviour of 13% chromium steel has been studied. There have been selected different coating systems: Barrier coating (enamel), diffusion coatings, (aluminizing, chromizing) and anodic coating, (aluminium, zinc, tin, cadmium). The corrosion fatigue limits of coated with uncoated specimens in neutral NaCl-solution are compared. Salt-concentrations were 0,01 and 22% (? 0,38 M) NaCl at 80°C and 150°C. The tests were carried out with alternating tensions and a constant frequency of 50 Hz. Only the use of andic coatings improved the corrosion fatigue behaviour of the chromium steel.     

Korrelation zwischen der beschleunigten Bewitterung im Laboratorium und der Freibewitterung eines kohlenstoffarmen Stahls in Meeresatmosphäre

Correlation between laboratory and weathering tests with a low carbon steel in maritime atmosphere The work presented here shows a possible correlation of the corrosion behaviour of a low carbon steel in maritime atmosphere and in a salt spray chamber. The corrosion tests in maritime atmosphere have been conducted in the open air and in a covered cabin at the coast of the Black Sea over two years. The laboratory corrosion tests have been conducted in a salt spray chamber and had a duration of 70 days. The correlation between laboratory and weathering tests is represented graphically. The chemical composition of the corrosion products is given.     

Untersuchung des SwRK-Verhaltens des hochreinen martensitaushärtenden Stahles X5CrNiCuNb 17 4 PH im Vergleich zum weichmartensitischen Stahl X4CrNiMo 16 5 1 ESU in chloridhaltigen wäßrigen Medien. Teil 2: SwRK-Untersuchungen und Rißeinleitungsmechanismen

Investigations of the corrosion fatigue behaviour at a super pure martensitic stainless steel X5CrNiCuNb 17 4 PH in comparison to the soft martensitic stainless steel X4CrNiMo 16 5 1 ESR in chloride containing aqueous media — Part 2: Corrosion fatigue tests and crack initiation mechanisms The following report concerns the study of the corrosion fatigue behaviour of the soft martensitic steel X4CrNiMo 16 5 1 ESR and the precipitation hardened X5CrNiCuNb 17 4 PH in sodium solution in the temperature range between 20° and 150 °C and the determination of their general corrosion properties and the mechanism of crack propagation. Their corrosion fatigue limits were compared with each other. A comparision was also made between an electro-slag-remelted soft martensitic steel and a charge without an ESR aftertreatment. Microfractographical fracture and crack path investigation were carried out for interpretation of the experimental results. It was observed that in both super pure steels (soft martensitic and precipitation hardened) the oxidic inclusions are not responsible for the crack intiation, as it was found in the non ESR treated steels. In the 17-4 PH steel copper containing inclusions in the crack initiation areas were observed. In concentrated sodium solution pitting corrosion was found at both steels.     

影响鞍钢X70管线钢CO2腐蚀行为的环境因素和材料因素

利用失重法、扫描电镜等,研究了X70管线钢在CO2分压为2MPa的NACE溶液中高温高压环境下的腐蚀行为,结果表明,温度和Cl-是影响X70钢腐蚀的主要环境因素,随温度的升高均匀腐蚀速率增大。钢中珠光体、粒状贝氏体组织及非金属夹杂物MnS、CaS等在腐蚀环境中促进了管线钢的腐蚀。因此在材料方面要降低珠光体及粒状贝氏体含量,细化夹杂物,并降低夹杂物级别。     

X65钢海管在CO2/H2S环境中的腐蚀研究

中海石油(中国)有限公司天津分公司为了节能减排,在渤海湾某油田开展了天然气利用项目,天然气外输海管选用X65管线钢铺设完成。随着油田不断深入开发,天然气中CO2和H2S含量都达到了较高水平,使该海底管线在运行过程中面临潜在的不确定性腐蚀风险。因此,本文研究了在不同运行工况条件下的X65钢海管焊缝区及热影响区的腐蚀形态和腐蚀规律。试验结果表明,在管线钢的焊缝区和热影响区存在不同程度的均匀腐蚀,而点蚀相对比较轻微;试样整体均匀腐蚀速率达0.1～0.3mm/a,属于中等偏高的腐蚀程度;pH降低、温度升高会使腐蚀速率增大,在管线运行和维护过程中需针对均匀腐蚀采取控制措施。本研究可以为今后海底管线选材、焊接工艺以及后期运维等工作提供借鉴。     

Einfluß des Elektronenstrahl- und Schutzgasschweißens auf das Korrosionsverhalten von X5 CrNiMo 18 10

The influence of cathode ray and inertgas arc welding on the corrosion behaviour of X 5 CrNiMo 18 10 When subjected to the Strauss test, the specimens welded by these welding processes are found to be not prone to intercrystalline corrosion. With the Huey test, on the other hand, the weld produced by inert-gas arc welding is much more prone to corrosion than the weld produced by cathode ray welding or the base metal. This is probably due to the fact that, because of the high energy density of the cathode ray, a greater homogeneity of the structure is obtained. In particular, the ferrite content, becomes Lower than with arc welding where the heat concentration is lower. In practice, however, ferrite formation is of comparatively little importance. This is because selective corrosion will only occur if the homogeneous austenite of the 18/18 steels is likewise showing marked corrosion, e. g. in certain mixtures of reducing and oxidizing acids (hydrochloric or hydrofluoric-acid with nitric acid).     

23Si2MnCrNiMoV钢固体渗碳层的影响因素

研究了渗碳温度、渗碳时间、扩散时间、深冷处理参数对23Si2Mn Cr Ni Mo V钢渗碳层的碳浓度梯度、表层低硬度区深度、有效渗硬层深度(550 HV0.3)、碳扩散距离、微观组织形貌等影响,实验研究的渗碳温度区间为890~970℃,渗碳时间为4~10 h,扩散时间为0~4 h。结果表明,较多的残留奥氏体存在是造成渗碳表层高C低硬度的主要原因,控制C浓度为0.72%~0.86%时,可获得最大硬度,若进一步增加C含量,会形成大量的残留奥氏体,反而降低渗透层的硬度;深冷处理对有效渗硬层深度几乎没有影响,但可使表层低硬度区域从距表面0.7 mm缩至0.3 mm。     

Mastercam X2在数控铣削加工中的应用

对Mastercam X2的铣削加工模块及其加工过程进行了分析与研究,以一个典型零件为例介绍了Mastercam X2铣削加工模块在数控加工中的应用,给出了加工要点,模拟了加工过程,并自动生成数控代码.